MK1a from ES to STS...

CLToy · Aug 23, 2015

I have been reading and preparing another AW11 for autocross. Our local club event lot is very small (high school lot) and well suited for an AW11. I am passionate about Supra’s and AW11’s…and I am taking a liking to this little autocross car. I have an 87 MK1b that is just too nice to beat on as a daily driver and wanted something else to be used for autocross as well. So I purchased a local 1986 MK1a from an Ebay seller and started preparing.

Images from the Ad...

This is a completely stock AW11, except for 14 inch OZ wheels and floor mats, but maybe even the tape deck.

I am not new to AutoX, just trying to work on my skills. There are several knowledgeable autox people here and hope that they will chime in and reduce my learning curve. The following is a list of my settings, parts, and a few images. There is also a video being uploaded as well.

I first replaced the air intake with an Amsoil dry filter and prefilter to keep water out. I did this only because the OEM air box was developing much rust and did not like the idea of rust particles being sucked into the intake. I then started working on the smaller issues, like door locks, small crack in the windshield, and replacing the OEM door cards with Techno Toy Tuning (T3) replacement door cards.

Then it was time to get serious and make some real changes:
Suspension:
- Custom T3 strut tubes (Powder coated red) with 2.5 inch Eibach coilover sleeves
- MK2 Koni Race dampers all four corners, set full soft I believe
- Front springs 600#/in
- Rear springs 400 #/in
- Sway bar removed
- T3 camber plates, all four corners
- Polyurethane bushings

Wheels/Tires:
- Enkei RPF1 15x7 +35
- Bridgestone Potenza RE-71R in 205-50-15
- New lug nuts, valve stems, and centering rings

Alignment:
- Front
o Caster: +4.7
o Camber: - 2.2 (could not get more, tire would interfere with coilover springs…will need to find a solution for this…wheel spacer?)
o Toe: 0.20 degrees IN
- Rear
o Camber: - 2.2 (matched the front)
o Toe: 0.20 degrees OUT

Ride Height:
- Set the rear to 24 inches from the shop floor to the center of wheel arch; after race the springs have settled approximately a ¼ of an inch
- Fronts were set higher at approximately 24.5 inches; did not measure settled height when I got home from first AutoX

Interior:
- Seats are OEM and you can see my helmet sticking out the top of the sunroof. Martin (gtfour77) has offered some assistance in the future.
- A Momo hub + NRG quick release hub was added to push the steering wheel away. A Momo 350mm steering wheel with the wheel NRG adapter was borrowed from one of my Supras, to save cost of another wheel

There are many more plans but this is what was needed in order to move from ES to STS. I am in hopes that more can be done to the engine, as it needs more to dual with the Miata and others.

More images and videos soon!

CLToy · Aug 23, 2015

Video Evidence...

Had a great time today and welcome feedback / constructive criticism. The car needs some work as well as my skillset. I hope you enjoy the video of half of my runs today. They are taken at different vantage points to better understand what the car is doing. Thanks for the input.

YouTube Video Located HERE...

CLToy · Aug 23, 2015

Images from the AutoX event...

The upgraded suspension completely changed the car for the better. I got compliments, was having a great time learning and making better passes, and even learning the limits. You can toss the car into a turn and it wants to go. I need to work on potential horsepower, fix that exhaust, work on keeping momentum by better right foot control, when to trail-brake if at all, and how to best use the brakes in a mid-engine car. The AW11 really needs more grunt as I was in position 3 of 6 in my class. Two Miata's were always ahead but the suspension changes really did help me focus on my driving. And as anticipated, when asked about the setup, most were very happy with how flat the car stayed and most said to put a sway bar back on....which I told them that I was committed to giving this setup a try. It honestly rode very comfortably. Jamie drove the car to and from the meet, as I was in charge of towing the club trailer, and she thought it was relatively comfortable as well. She took several hundred images of my AW11 and other event participants. Here are only a few...

The stance...I need to learn how to set my roll centers correctly. Here is an image showing the rear lower than front (on purpose) and then some images of the suspension movement...

I anticipate getting advice to increase the front and rear spring rates by 50-100 #/in per corner. The tires did not squeal much, but I do not know how to interpret the rear wanting to come around on me. Increase the front rate to keep the rear planted? With the compression noted at the rear as well, all four corners need more spring? When do you know that you have gone too far with spring rates? I did not dial any strut into the runs...I am pretty sure that they were all full soft setting as I did not change them from when they came to me. Perhaps dial in 2-3 clicks before making a spring change or do both? I am trying to learn the rationale here.

Thanks all and I do appreciate the advice and input.

Owen · Aug 23, 2015

You could mess with spring rates but... there are other things I would start with.

First, you are missing you apex's by too much, especially on the right turns. I use freeway bots dots to figure out markers on the hood (and I always need to experiment with this or I end up missing apexes by a mile). Second, you are smidge behind on the slaloms. Turn a bit earlier.

With regards to setup, you don't have enough camber. I would go to at least -2.5 front and rear, although 3+ is probably appropriate. I would also go with a smidge of toe in for the rear. Next would be tire pressures? The video of the front looks like you are hair low, but you would need to try it. Lastly, do some runs with full stiff on the struts.

There is definitely room for setup improvements. The transitions are as quick as they should be cable of. Here's and good example of what should be achievable. http://www.rhoadescamaro.com/build/?cat=23 Compared to a mk1, the his car has narrow wheels and is seriously under tired.

It's hard to tell when you are too stiff with the springs. Basically the car starts to skitter. Its hard because the force that can come from the spring or the struts. If the struts are too soft, then you can use stiffer springs. So, ultimately deciding if you have too stiff a spring forces you to consider if your struts are matched to your springs. that said, there is a good chance you are lighter than you need to be in the rear and possibly to heavy in the front. Your call.

Frankly there are too many changes above to be reasonably tried in 1 event. It's something that you should spread out a bit. Good luck,

O

CLToy · Aug 24, 2015

Owen,

The advice is much appreciated, from driving style to setup. Good idea to learn the edges of the car with the dots. I will look into this.

I agree, there are too many things to change. I will be in touch with T3 as the coilover and wheel offset prevent any additional camber...might need to go from an 8 inch spring to a 6 or 7 inch in front and make sure that my camber plates are set correctly. I do need more, though...agreed.

And when I inflated the tires to 38 psi, I thought for sure that was way too much. I only inflated them that high to help ensure that the tire flex would not hit the strut tubes...looks like I do need more pressure as well. ... might try 40-45 psi. The wear on the tires was at the edge showing rollover.

I should have made an adjustment with the struts while on course. I will look into the MK2 koni race struts and check the max/min settings and go from there.

Thanks again for the advice.
Chadrick

dreemer · Sep 1, 2015

CLToy said:
And when I inflated the tires to 38 psi, I thought for sure that was way too much. I only inflated them that high to help ensure that the tire flex would not hit the strut tubes...looks like I do need more pressure as well. ... might try 40-45 psi. The wear on the tires was at the edge showing rollover.

I've heard reports of the RE71-R liking pressures of mid to high 20's. You are losing a lot by running that high of pressures. As others have said, I would aim for much more camber. At least 3, if not closer to 4 degrees. As Owen said, camber doesn't really cause that much extra tire wear, it's mostly toe. It might cause uneven tire wear, but you can always flip the tire on the rim anyways. You definitely don't want to play with camber at an event, any change in camber changes your toe. Any wheel offset is allowed in the class, so I don't see why a spacer wouldn't be legal. I think you would want to space out the front anyways for more front track width.

Where are your ride heights relative to stock? It doesn't look that low, but overlowering can cause increased roll angle.

Any ideas on the weight of the car? I run 850F/500R spring in my 2500# Mk2, and some (XHead..) say it's too soft. Those rates might work for your lighter car though. I don't know that a 50# rate increase will do much for you.

How is the balance of the car? Is it steady state under or oversteer? Does it transition under or oversteer? I can't really tell from your video. If you can get away with rear toe out and still be stable, that is a good setup. It looks like you may not be pushing the car hard enough though.

Owen · Aug 29, 2015

In terms of modifying, focus on the camber before anything. Good chance the camber will fix the tire pressure issues. Did you install the struts yourself? If so, did you remember to preload the camber (finger tight on the strut bolts, then jack the suspension up a bit before tightening)?

Since this is primarily a toy, consider using spacers to get the clearance.

Lastly, most high level ST strut cars use camber plates that are adjusted all the way in for suspension geometry, then adjust the camber by fiddling with slop at the strut bolts.

O

CLToy · Aug 29, 2015

Owen,

Thanks again for the feedback. Here is how the 8 inch springs sit now...

This is also why I was unable to get more camber on the entire setup. So I pulled the rear to match the front.

I also messed up and oriented the camber plates incorrectly, causing one side to not give the max amount of camber...I set the gold beveled edge of the camber plate outward instead of inward limiting my camber and I have to move the camber set screws as a result. This was my bad but will be fixed when I drop the suspension again for a spring change.

This is not the correct way, boys and girls. I usually have much better attention to detail but dropped the ball in my haste to get to the alignment. Once at the alignment, I had to move the bolts closer together.

I was really hoping that XHead and some of the other guys from the older STS sticky thread would venture in here as well and provide some advice on spring rates, since I have to drop the suspension anyway.

I was comtemplating 50 to 100 lb/inch increase at all four corners...but would really appreciate someone looking at these images and video and advising. I have already moved the struts to 1/4 turn off the max firmness. I also am likely to move from an 8 inch spring to a 6 inch spring in front, in hopes that the coilover collar will sit high enough to clear the tire and give me plenty of camber adjustment, without the use of a wheel spacer, and clearance for any tire flex and movement during a race. That current gap seems very tight to me.

I also thought that spacers were illegal in STS? If not, would a slim 5 mm give me more space at the hub for more camber? You mentioned adjust max camber at plates and then dial in at the hub. I was actually hoping to max at the hub, and then dial -1.5 or so for the days I drive it to work and around town, then have another mark on the plate that gives me -3 degrees in front and -2.5 in rear...to kick it over at the event (I usually drive to events as well). Issue with this train of thought? Will toe likely be affected to a great degree (no pun intended) and not allow this type of dual adjustment?

I would like to point out that T3 has had stellar communication and even with a couple issues, they have been an excellent company to deal with and conducted business with the best interest of the customer. Much appreciated Gabriel.

Thanks again ... it is a work in progress.
Chadrick

mr2tim · Aug 29, 2015

You have sway bars?

Not that familiar w your STS prep level but looking at how your car lurches and rocks like a boat you need some major sway bar increase. Look at your pictures Chad your wheels on the high side are barely touching the racing surface. Your turning on 2 tires.

Granted you can diddle with spring rates but that does nothing to transfer the weight from your low side to the high side.

You want your car to be flat in a turn. This will allow the tires on all FOUR corners to work. Camber the crap out of the car but you will not improve the tire patch relative to weight transfer.

Coil overs aren't the answer folks. You have to think bigger and tune the whole suspension.

Have you discovered tire "treadware" tuning yet? With a 60/40 weight distribution this is a "MUST".

Mister 2 Tim
A Toyota Race Team since 1986

CLToy · Aug 30, 2015

mr2tim said:
Not that familiar w your STS prep level but looking at how your car lurches and rocks like a boat you need some major sway bar increase. Look at your pictures Chad your wheels on the high side are barely touching the racing surface. Your turning on 2 tires.

Granted you can diddle with spring rates but that does nothing to transfer the weight from your low side to the high side.

You want your car to be flat in a turn. This will allow the tires on all FOUR corners to work. Camber the crap out of the car but you will not improve the tire patch relative to weight transfer.

Coil overs aren't the answer folks. You have to think bigger and tune the whole suspension.

Have you discovered tire "treadware" tuning yet? With a 60/40 weight distribution this is a "MUST".

Mister 2 Tim
A Toyota Race Team since 1986

Thank you for the feedback. Not trying to make a big deal but I go by Chadrick, not Chad. And I admit that I am trying a new suspension setup here. I have done the big sway bar thing with a Supra and am still trying to get better handling through tuning. So I came across a sticky in this sub forum and am giving it an honest try before going back to sways. But I will look into the term "treadware tuning". What was your suspension setup, if you don't mind sharing?

Owen said:
Meh, you aint even in the ballpark for camber. Fix that first. Spin the tops and see where that gets you. New camber, playing with extreme ranges of damping is enough fiddling for one event. Everything else is future work.

Regarding clearance, yes it looks pretty darn close to me too. Are their any marks on the springs from the tires? If not, I guess you got enough. To get more, I just read the ST rules and spacers are not specifically allowed, however, I've know plenty of people who have run them and if you are worried about it, glue them to the wheels and roll it into the "any wheel" rule. Lugs and nuts are allowed using the street class rules. That said, if push comes to shove you can always slot the lower bolts for camber. It's not preferred, but it does work and I've never heard of anyone with an MR2 having problems with it.

From the pics, I would use the other strut holes and readjust the springs. This will help make ensure you have proper travel and springs stay where they should. It looks pretty short on travel as is.

Generally speaking camber isn't that bad on tire wear, although it does get notable when you are running well over 3 degrees. Toe is the real killer. It doesn't take much to send your wear through the roof. You do not want to adjust your camber before driving home, unless you also want to adjust your toe.

O

Well there are no marks on the springs or inner tires.

So my plan for the next event:
- 650#/in. 6-inch front springs
- 450 #/in. 7-inch rear springs
- correct orientation of camber plates
- I ordered caster camber gauge, toe plates, and ride height measurement tools from Lonacre and will build platforms to set my car on from my lift so I can get under it easier...alignments will get expensive.
- hopefully my new exhaust is here for installation
- run with koni race dampers at 3/4 firm
- increase tire psi to 40 psi, mark the sidewall with chalk
- zip tie a front and rear strut to check travel
- attempt to install seats from Martin and get my head inside the cabin
- order a set of 5 mm wheel spacers for the front wheels, just in case
- centric slotted rotors, centric sport pads, braided lines, and Amsoil DOT3 flush...noticed one side wanted to lock up at exit of course but not the other....need to renew and flush

I know that is a lot, but hopefully as it gets dialed in, there will be fewer adjustments at a time.

I welcome continued input.
Chadrick

Owen · Aug 30, 2015

Meh, you aint even in the ballpark for camber. Fix that first. Spin the tops and see where that gets you. New camber, playing with extreme ranges of damping is enough fiddling for one event. Everything else is future work.

Regarding clearance, yes it looks pretty darn close to me too. Are their any marks on the springs from the tires? If not, I guess you got enough. To get more, I just read the ST rules and spacers are not specifically allowed, however, I've know plenty of people who have run them and if you are worried about it, glue them to the wheels and roll it into the "any wheel" rule. Lugs and nuts are allowed using the street class rules. That said, if push comes to shove you can always slot the lower bolts for camber. It's not preferred, but it does work and I've never heard of anyone with an MR2 having problems with it.

From the pics, I would use the other strut holes and readjust the springs. This will help make ensure you have proper travel and springs stay where they should. It looks pretty short on travel as is.

Generally speaking camber isn't that bad on tire wear, although it does get notable when you are running well over 3 degrees. Toe is the real killer. It doesn't take much to send your wear through the roof. You do not want to adjust your camber before driving home, unless you also want to adjust your toe.

O

CLToy · Sep 21, 2015

AutoX on 9-20-15

Planning the next phase of this build was not so smooth. After weighing the car I was anticipating needing much larger spring rates. I installed the 600# spring from the front to the rear of the car. I then installed only the 650's in the front. I know the ratio is way off but I thought that rate in the rear was much more appropriate instead of 450. I wanted to install 900 #/in in the front but they did not arrive in time....so I went with the 650's.

I put my longacre products to work and after setting ride height, I dialed in these alignment settings:

Alignment:
- Front
o Caster: +4.7
o Camber: - 4.1 using 6 inch springs
o Total Toe: 1/4 inch IN

- Rear
o Camber: - 3.7
o Total Toe: 1/4 inch OUT

Our regional SCCA club is small so we use modified classes, rear wheel drive street tires, rear wheel drive race tires, front....etc. In the rear wheel drive street tire class, I got 4th out of 14. The guys that were ahead of me were 1) Corvette Z06 (C7), 2) BMW M3, and 3) 2015 stock Miata. The Miata was ahead by 0.615 seconds.

My times:
67.128+1 (I decided to not use brakes for some reason.)
51.190
50.454
49.591 (Pressures building, reduced to 35 psi front and rear)
48.868 (31 psi front and rear)
49.337 (30 psi front and rear)
49.040 (did not adjust pressure as I was hoping I would get some pressure back)

I think that I need stiffer springs in the rear again. I will likely need to install the 900s with the 600 rear springs and see if it changes the balance.

Also, on the last two runs, the last especially, I felt the clutch slipping. It is time to look for a clutch that I can launch and not worry too much about it. More to come here...

I have images and videos being posted soon.
Chadrick

CLToy · Sep 22, 2015

A video of this event...
Click Here

CLToy · Sep 22, 2015

Images from the event...

You can tell I dialed in much more camber for the event...

I still need to get my head in the car! Ha!

Here is a long sweeper setting up for the second pass:

another shot...

There is still too much lean. But this was expected due to front spring rates being a bit too soft.

I did make a larger jump in the rear spring rates and am a bit surprised to see the amount of movement in the back...

I slid the rear around the first turn a couple times, enough to know that traction was an issue, and even drove in aggressive enough to get the inside tire to pick up enough to lose some momentum through one of the corners.

- Wow, how much more of a jump in the rear rates do I do now?!?
- Would the front soft rates affect the rear this much or is it a separate issue?
- The car turns very well, compared to before, but feels loose coming out of the turn and you can see my attempt at trail-braking through the slalom to keep the rear end happy
- When I started reducing tire pressures between runs, my times improved. I got to 31 front and rear for my fastest run of the day. 30psi were my last two, but there were clutch issues. Perhaps I could reduce the rear pressures by a 1-2 psi and run 31 psi in front to attempt to get the car to understeer a bit more?

Thanks for the input and hope that this is at least entertaining for some.
Chadrick

Owen · Sep 27, 2015

Sounds like a solid improvement. What about all the other stuff? How's the clearance and the suspension travel? Did you get a chance to play with the strut settings or did you just check them and leave them set at 3/4's?

- Wow, how much more of a jump in the rear rates do I do now?!?

I wouldn't do anything for now. From what I have seen, you can't even be sure the springs are working like springs. Before you start spending more money and time changing out springs, you should make sure they are.

- Would the front soft rates affect the rear this much or is it a separate issue?

Related. And a good chance it's more complex than it sounds. Also probably not worth it. You think you have too much roll, but how much do you have? You can take those pictures and figure it out that you have a ~ little over 2 degrees. The angles are such that you can't really tell how much is due to tire deflection, but a ballpark from other tires is that it's probably about 25% of the total roll. The part you can control with springs and bars is difference. And for that part, if you DOUBLE both front and rear rates the roll for that difference will be cut in half -and you have about 30% less roll in the pictures.

30% less than a little isn't much of a change. And double a high rate is way too high. Translation, your days of being able to make large change to body roll and alignments by changing a spring are over.

- When I started reducing tire pressures between runs, my times improved. I got to 31 front and rear for my fastest run of the day. 30psi were my last two, but there were clutch issues. Perhaps I could reduce the rear pressures by a 1-2 psi and run 31 psi in front to attempt to get the car to understeer a bit more?

Maybe. Any pressure that is not the optimum will reduce traction compared to the optimum - up or down. Since you do not know your optimum pressure, you could actually end up with more oversteer at the limit. In fact, if you got more understeer at the limit, it would be a sign that your tire pressures are too high.

I concur that it appears to have oversteer on corner exit, but would also add that it appears to have mid-corner oversteer and entry understeer.

For the next step, fix your clutch!

If you wanted to do more would add a stock front bar on (I know, I don't like them on optimized setups, but they are cheap and useful for experimentation up to that point), bump the rear struts to max and take a half a degree of camber out using the clevis bolts (I'm willing to bet you have too much camber). At the event, I would continue experimenting with tire pressures and if you are happy with that move on to fiddling with the struts.

O

CLToy · Sep 30, 2015

Thank you for replying, Owen. I was beginning to think all this time spent on this forum was a complete waste of time. The MR2 forums I frequent just don't get the amount of traffic I would desire. Perhaps Facebook is killing this type of documentation.

Owen said:
Did you get a chance to play with the strut settings or did you just check them and leave them set at 3/4's?

I left them at 3/4. I will dial them up to just off max for the next event. When changing the front springs again, I will pull a strut and make sure I got what I paid for...the MK2 Koni Race dampers. These feel very soft.

Owen said:
I wouldn't do anything for now. From what I have seen, you can't even be sure the springs are working like springs. Before you start spending more money and time changing out springs, you should make sure they are.

Owen said:
And double a high rate is way too high. Translation, your days of being able to make large change to body roll and alignments by changing a spring are over.

Hmmm...the new front set is already shipped. I will likely stop going up on the front rates and was told that I may need to go up a touch more in the rear and ditch the 150% ratio idea...to not make the difference in rates quite as much. Time will tell after the fronts have been changed.

Owen said:
In fact, if you got more understeer at the limit, it would be a sign that your tire pressures are too high.

Owen said:
I concur that it appears to have oversteer on corner exit, but would also add that it appears to have mid-corner oversteer and entry understeer.

So this rationale would be that my pressures are too low given the oversteer? Perhaps I should change the rear toe from 1/8 OUT to 1/16 OUT or even 1/16 IN before making a tire pressure adjustment?

Owen said:
For the next step, fix your clutch!

Amen. Parts ordered. Now to decide whether to drop the engine/trans together or only the transmission in ease of repairs...hmmmm...thoughts?

Owen said:
If you wanted to do more would add a stock front bar on (I know, I don't like them on optimized setups, but they are cheap and useful for experimentation up to that point)

If I want to take rates higher, I will add the front bar back at this point and check response instead of going up on front rates anymore. Good advice for a cheap response check.

Owen said:
Take a half a degree of camber out

When I told Martin what I was running, he too said that it was too much. It is nice to know I can dial that much in with this setup. I will dial back to -3.5 front and -3 rear for the next event. And then I will try 31 psi front and 29-30 psi in rear in an attempt to turn better. But the above information makes me think that this will not improve oversteer in center to end of curve. More study is needed / advice accepted.

Thanks again for your time and effort in helping with my setup.
Chadrick

Owen · Oct 5, 2015

Face book is killing message boards, but don't feel too bad – this stuff was never really on the boards. Optimizing a setup takes a surprising amount of time and is to a large extent personal preference. Since no one runs your exact setup... you were pretty much always guaranteed this fun.

Can't help you with the clutch. The only time I've seen mine was when the engine was out for other reasons. You'd be better off asking on the general mk1 board. Good news though, changing clutches isn't really setup dependent so you will almost certainly get some solid answers!

As for tweaking the handling for auto-x, you should understand that you are still in the shake down phase. Shake down is characterized by just making sure things work as intended and you typically make gross and or multiple changes between events. This is important, because you are starting to ask tuning questions, and those will never be answered unless you are changing one thing at time (well, maaybe two).

To affect a change to the oversteer/understeer balance there are two things you can do:
1. gain traction on one end of the car.
2. lose traction on one end of the car.
Conclusion, anything that can change traction can change balance. Major things that can change traction are: struts, bars, springs, camber, tire pressure, toe, tire make, tire size, tire temperature, weight, wheel width and a slew of other things.

Realistically, changing the front springs, rear tire pressure, front camber, rear camber and thinking about changing toe makes it VERY hard to say what the total effect will be. Here's my guess as to what will happen. The camber changes will result in approx equal changes (increase) in grip both front and rear. You wont be able to feel the difference based on the rear tire pressure and the stiffer front springs will result in significant increase in understeer which will be nice mid turn and corner exit, but will add the hesitation you already have on turn in.

Of course, if it doesn't work out that way you wont know which part of the above is wrong. Which is why tuning (and experimenting) exists.

Go ahead and put in the front springs and change the camber. Play with tire pressures (ONE axle at a time) at the next event and see what happens.

As for your struts, try and get the full KONI part number. If you have it, you can get a rough idea what your valving looks like now. Even if you have what you think you do struts, a performance re-valve is not that unusual.

O

CLToy · Jan 17, 2016

I have been busy working on projects. The 1986 AW11 got a new clutch, water pump, timing belt, exhaust system from header-back, new idler pulleys, fuel filter, all new fluids, etc. etc.

I changed my suspension (spring rates likely for the last time), and set the camber to -3.5 Front and -2.7 rear with 1/8 toe in front and out in rear.

Well, the new season has started! The January event, wow was it cold. It was a smaller turnout but there were some very competitive guys there that help me judge my skill. Jamie is usually the videographer and photographer for the events but I told her to just stay home. At least when driving, you can have the heater running. It was spitting snow during the morning session and the asphalt stayed wet. I didn't even break out the GoPro this time....I should have!

Our club does 8 runs per event, on average. Given the weather, we decided to save time and have the run-group do all eight, then switch. By the 6th run, I had 0.8 second lead on the field!! My official best time was 52.617. Then a C5 Z06 got serious and beat my time by 0.037. I was laying down a good followup time, but there was a timer issue and I had to do a rerun. During the rerun, I had some handling issues and did not make up the time difference (more on this later).

By the afternoon session, the track actually started to dry up and traction was much easier to achieve. The RE usually drives a cart but was co-driving the C5 Z06 and put down a 47.+ second lap! Grip had returned!! Bad news for me as the AM guys started dropping down the list. I ended up officially in 7th. Many of the Miata guys were getting 49-51 second runs in the afternoon. As soon as it was time for fun-runs, I was dying to see how much grip was out there. I hopped in and put down a 48.87 second lap! This would have been good enough for second place. Despite the official results, the car is going in the correct direction! I wish I would have had someone take pictures or take a second to put on the GoPro. I spent time playing with tire pressures.

** Now, on to the handling issues: **
I am running the same tires as before, but my gauge said 32psi in my heated garage, 30psi during the event. I dropped the rear tires to 29 psi to try to get more traction. By the final run, I was down to 26psi front and 27 psi rear pressures. Let me explain my issues...

The car starts out with lots of grip. About halfway through the run, I can feel the car want to get more twitchy in the rear and want to over rotate. Actually the second fastest run was me letting the car power slide through the gate sideways from the right hand turn to the finish, as I did not want to touch the brakes and lose time. It must have looked awesome as guys came over to congratulate the run. I was just happy I didn't hit any cones! Ha! The longer the run, the more the rear wanted to come around on me. I wonder if I had too quick of inputs for rear to come around or too much toe out? Go to a 1/16th out in rear? I then started playing with tire pressures. Now those earlier runs felt like I may have had too much rotation but as I began to try to fix the rear, I started pushing more and more. I was pushing so hard during the last few runs that I had to get on the brakes and kill some momentum in areas where I should have been setting up for a fast section. My last run of the AM I was on 26psi front and 27 psi rear and was pushing like mad. By the time traction came back in the PM, I ran the same psi to lay down the 48 second run.

It is obvious that I have not found the right settings to keep the rear stable through the entire run and still keep the front from pushing on tighter turns. It was slippery enough to torque steer the car to align for gates...something that was only possible in my turbo Supra. It may not be a great day to make changes to the setup, given the conditions but just trying to understand what would help me limit pushing during hard cornering and keep the rear stable at higher speed gates.

My thoughts on next changes: Change from rear 1/8 toe out to 1/16 toe out? ... or maybe small toe in?!? and drop front pressures to 25 psi to help with front grip and limit push?

I will have video and images for next event. Thanks in advance for the advice.

gtfour77 · Jan 20, 2016

Chadrick, sounds to me like you need more rear camber perhaps? (running on the outside edge of the tire which overheats that section mid-run) Little less toe will not hurt but you'll loose the "rotation" of the rear. Steve is the expert here on these cars and I'd wait to hear from him. Our SSM car is setup totally differently.

CLToy · Jan 20, 2016

Thank you, Martin. Your input is much appreciated!

RyoHazuki · Jan 20, 2016

Toe changes might be in order as a guess, but the first question for you though is when does the car start to oversteer? Is it as soon as your turn in? Mid-corner? Or is it as you start to lay into the power on corner exit? Those might all suggest different possibilities. It *sounds* like you're saying it's oversteer on power (which is a little "unexpected" on a lower power car), but just want to make sure.

CLToy · Jan 20, 2016

clarification...

I think that it would start to get loose during mid-corner and if I stayed aggressive, it would want to get loose by exit and I would not be on the line I desired for the next gate. I found myself letting up instead of either being able to stay in some throttle or wishing I could get into throttle earlier for fear that the car would come on around on me. A few times I stayed in and had to counter steer to keep a line and momentum.

I was trying to be smooth with throttle and inputs but I felt like I was working pretty hard at it; this was despite a couple guys actually commenting on how smooth and flat the car looked out there.

I again apologize for not having video or images of this event. That won't happen again.

Chadrick

RyoHazuki · Jan 21, 2016

Ha, I don't think apologies are in order. Definitely sounds like an issue with either toe or the absolute grip that the rear is making. If you just changed spring rates, you may want to consider whether the rear rate is too high now? Steve is definitely the first-gen expert, so take a peek at the STS thread again for some clues perhaps.

Another thing that's always a sensitive message to relay over the Internet with nothing but text to represent your ideas: are you sure there's nothing you're doing as the driver that's causing the rear to start the sliding? Please understand that I don't mean any insult, just trying to help the diagnosis process. If you lift off the gas or brush the brakes (perhaps due to carrying speed too deep into a corner or trail braking too heavily?), you can probably expect things to start rotating quickly in a car with so short a wheelbase. Weight transfers forward, front grips more, rear slides more, etc. But, as you roll onto the gas, things should tame down as the weight goes to the rear again (not get worse). If it really doesn't tame down in the way you're suggesting, then I'd add more front spring or soften the rear as my first guess. A second band-aid might be to try more front compression if your shocks are adjustable, as that will stabilize turn-in and possibly help if the sliding is starting at corner entry and just becoming more apparent later in the corner.

Your camber numbers seem pretty reasonable for an ST car, so without some type of pyrometer evidence, it's tough to say whether the rear is actually using the tread surface inefficiently and possibly overheating. It's possible, but at -2.7 I'd be hard-pressed to believe you're too low on camber at the rear unless the springs are still pretty darn soft. I think your pressures are in the ballpark for RE71's, so it's likely something else, but you can still play there if you have the opportunity. Shocks is your easiest change assuming they're adjustable, followed by toe, then springs probably. I'd just work down the list and see what you can come up with. If you change the toe, I'd do at least 1/8" of difference. 1/16" is close enough that I'm not sure you'll definitely notice the difference; plus you can always go back a bit if you overshoot. At least it'll tell you if you're moving in the right direction which is more important than getting it 100% precise on the first shot.

Other thing that occurs to me is that you should make sure that your ride height isn't such that you're hitting bump stops in the rear. That can easily produce an unpredictable sensation like what you're describing.

Best of luck! Hope that you can get it dialed in!

CLToy · Jan 23, 2016

Thank you for the feedback!

RyoHazuki said:
If you just changed spring rates, you may want to consider whether the rear rate is too high now?

The rate may be, but I am in awe of how much my car weighs and dont think I am too far off. However, I have springs laying around to make a reduction if needed.

RyoHazuki said:
Are you sure there's nothing you're doing as the driver that's causing the rear to start the sliding? Please understand that I don't mean any insult, just trying to help the diagnosis process.

There is no offense taken. My skills definately need to improve. I made a conscious attempt at smoothing out my inputs but found that some of my throttle imputs were too aggressive for the lack of grip. I didn't even think to try trail-braking as I had in previous events! I tried to be smooth with my hands too but I am still working on this.

I never hit a cone until I pushed really hard on my second fun-run. A couple times I was certain that I hit a cone trying to backside into a right-hander...but didn't. That tells me that I am still missing my turn-in spots and still need to get closer to the cones to save time. It is a work in progress and I appreciate the delicate nature of the comments made.

RyoHazuki said:
Other thing that occurs to me is that you should make sure that your ride height isn't such that you're hitting bump stops in the rear. That can easily produce an unpredictable sensation like what you're describing.

This is a good thought! I have 8inch springs in back and do have the car a little lower in back. I figured on having to recheck alignment and ride height as these springs were installed and then the event was 12-hours later. I am sure that they will settle a bit. Another offer from a autox member was to corner balance the car as he has the equipment to do so. I am going to try to check ride height, make suspension changes, corner balance the car, and then double check my alignment again.

mr2tim said:
Our car need much bigger sway bars.

I can understand your point. Honestly, your philosophy with suspension is not incorrect but I am trying to give this different setup a go during this season. I am not against sway bars, but then again, I really dont have a lot of experience either way, yet.

mr2tim said:
I've never run that low of pressures on any street/race tire ever.

Me either! lol But with my research, I felt like I should try and see what happens. They handled the lower pressures and I think they were better like that, even in the cold weather when others were struggling for traction. More time will tell.

mr2tim said:
I must also empathize that you are changing too, too many varibles all at once. It is impossible to judge what works and what doesn't changing so many things at once.

I have to agree with you here. I am making big swings for sure. I am excited to leave an event for once and feel good about the day. It is usually frustration but not the last event. It energizes me to keep researching and playing with the setup.

XHead said:
1) Camber should be pretty close to the same front/rear. 2) Spring rates: You really have to have a pretty good roll ratio split to get the balance of the car right. 3) Toe: Rear toe is an excellent tuning tool on these cars. I would start with about 1/8th toe IN after making the above changes and get a baseline set.

Steve, I also sent you a private message in hopes that you can see that. From your response, I will do the following:

Camber: I will dial in -3.5 in rear as well for the next event. The 8 inch spring was close to the inner liner. I may need to 'massage' the rear liner to allow for more clearance.

Toe: I will keep 1/8" IN front and change to 1/8" IN rear (spec miata guys also recommended rear toe IN for upcoming track days I am invited to, but that is another story.) I was just talking to some guys about the benefits/oddity of thinking about both a toe IN front & rear and wondered how that would behave.

Caster: I will increase the caster to around +5.5. I will do some research but having the dynamic camber from caster allow me to not run -3.5 static and back it down but keep rear at -3.5? Or does the dynamic caster assist the static camber to go further negative during turning to also assist with prevention of understeer? I have more study to do!

Thanks again for your help!

********

Guys, I truly appreciate the input. I am nowhere near a national level yet, but being competitive at local events is fun.

mr2tim · Jan 21, 2016

Another 2 cents.

I've raced the AW11 SC for 2 decades+ and here's a experienced $0.02.

It took me 2 years to find out our car needed much bigger sway bars. The amount of sway you have I could never deal with. In perusing your pictures the rear tire on the inside of turn is barely touching. You appear to be racing on 1 tire at the turns. You will never be fast till you keep that rear end flat.

I've never run that low of pressures on any street/race tire ever. The split for me was (hot) 36-38 front and 34 rear. I did run Goodyear sportsman 14" slicks for 3 years at only slightly lower pressures.

I must also empathize that you are changing too, too many varibles all at once. It is impossible to judge what works and what doesn't changing so many things at once.

Best regards,

Mister 2 Tim
SupercharZed ToyZ RacZing
A Toyota Race Team since 1987.

XHead · Jan 22, 2016

Hi Chadrick,

I scanned your posts to see if I could get a read on what the current settings are. Here is what I think you had:

Spring Rates (650F/600R) (Not sure if you put stiffer springs on the front or not)
Toe 1/8th in Front/ 1/8th out Rear
Camber -3.5F/-2.7R

Your feedback says the car is going loose throughout the run. I am not surprised. The three major settings are all biased toward oversteer. Given that mid corner and exit is where this will show up the most.

Looking at the above my assumption is you are clearly overworking the rear tires. That's why it gets progressively worse throughout the run. Given that I advise the following:

1) Camber should be pretty close to the same front/rear. If anything, there rear should have more negative than the front. For now I would match the rear camber to the front at -3.5 and see how that works.

2) Spring rates: You really have to have a pretty good roll ratio split to get the balance of the car right. With 650F/600R the car will oversteer. Period. Reference the spring rate section of the ST setup thread to see how that worked for MicaCeli. I forget where he ended up but it was something like 750F/500R. At least that was the range.

3) Toe: Rear toe is an excellent tuning tool on these cars. I would start with about 1/8th toe IN after making the above changes and get a baseline set. If the car is understeering too much, reset the rear toe to 1/16th out. If its still understeering, out another 1/16th. Keep at it until the balance is where you want it. If you begin to see the problem of it oversteering more the further into the run you went too far.

Question: How much caster? Stock, the AW11 doesn't have enough caster. You want 5 to 6 degrees. The dynamic camber gain from additional caster will allow you to reduce the static camber to get better braking.

XHead · Jan 24, 2016

For road course use you will want to start with 1/8th in toe IN until you gain some experience and tune from there. Typically, you will not need the toe out for track use.

I should note that the '87 rear suspension has a different bump steer curve than the 85/86. The only experience I have with the '87+ rear suspension is to look at it and decide to stick with the 85/86. So that may effect the cars balance when cornering and is something that may influence the rear toe settings. Every stock '87+ car I have driven had a pronounced tendency to understeer. But those cars didn't have a rear bar either.

Dynamic camber: You really only need negative camber when the car is generating lateral g load. Its purpose is to counteract the distortion of the tire's contact patch and the car's body roll. So you only need negative camber when the car is turning. The nice thing about dynamic camber gain from caster is; the more you turn the wheel the more negative camber the outside front wheel gains. Therefore, caster (in addition to its other functions) allows you to run less negative static camber which provides for better braking and better tire wear. Because the rear tires don't steer they don't benefit from dynamic camber. The net result is you can likely run less static camber in front than the rear. Of course this is tire dependent and I don't have much knowledge to ST category tires.

Another note about setting up the AW11 (or any mid or rear engined car for that matter). The required static negative camber is a function of: tire deflection, body roll and camber curve. Tire deflection is a function of lateral load and available grip. So consider this: the typical mid-engined car has a F/R weight distribution of 43/57% so the outside rear tire has 14% more lateral load on it than the outside front tire. As a result the outside rear tire contact patch will deform more than the outside front. Also, under normal cornering the outside rear suspension will compress more than the outside front because the front spring is 900 lbs and the rear spring is 700 lbs. On a typical strut car, especially if lowered, the outside suspension will move to the negative side of the camber curve. That is; it will lose static camber as it compresses. These two data points are why I recommend using more static negative camber in the rear than the front.

Now consider this: The Miatas, Hondas and their contemporaries are all front engine rear drive or front wheel drive. Therefore they carry the majority of their weight on the front axle instead of the rear as the MR2 does. That is why you see these cars all typically using far more static negative camber in the front than rear. Of course the required camber is only determined through testing but understanding this will help you dial it in a LOT faster and you won't be mislead by your Miata/Honda friends who tell you to run more negative in front.

Doug L · Jan 25, 2016

Hey CLToy, nice car and nice pictures. I have a lot of competitive experience, but am new to MR2 and am working on the car for AutoX as well (87 AW20). If you are dealing with the rear end being loose, then I would suggest re-installing the front bar. Get your camera person to get a front on shot of the outside front wheel on the tightest corner and use that as a guide for more or less camber. Set camber so the wheel is vertical when it is most needed. Most of my competitive experience is rallying and there I like a lot of oversteer, so my instincts say add a rear bar and remove the front, but I suspect with a car as light in yaw as the MR2 that might be way overkill, I'll see in a handy parking lot. With adjustable shocks you can influence corner entry oversteer/understeer as well (stiffer rear for oversteer), and that may be your issue. Try to sense if the rear wants to come out early in the corner or late in the corner, and with about a thousand caveats, early look at shocks/ late look at springs. I'm babbling, sorry.

CLToy · Mar 6, 2016

Points Event #2...March 5, 2016

Attached you will find a video from a cell phone of one of the runs today. For some reason, my Hero2 GoPro was dead, even after charging all night. These are a lot of money for a bunch of hassle! Anywho, back to the autox...

I am sure that there are some constructive criticisms to be made about the setup and approach. The next post will give more information about today.

https://youtu.be/SErrr4HcSlQ

CLToy · Mar 6, 2016

Points event 2 was on a new lot for me. It was a tight course, which should have played into the hands of the AW11, but I am obviously still trying to dial this in a lot better. After all the constructive feedback from previous posts, I realized that if I am to learn about what changes affect what issue, I need to slow down a bit and do one change at a time. Now with hindsight, I wish I would have made another 1 or 2 additional changes! Ha!

It was a 36 degree morning, overcast, and drivers with high expectations. The only setting I changed was going from 1/8" toe out in rear to 5/32" toe in, per my toe plate measurements. I left the camber and caster alone. (The weather has also prevented me from working more on the car.) This run was also with 28 psi front and 28.5 psi rear.

Well, the oversteer issue from center to exit is gone...to the point that I was understeering and pushing through a few of the tighter turns. I have obviously overdone the toe in, and will be changing to 1/16" toe in and see if I can get better turn in through the center. I will also be adding the desired +6 of caster and taking at least a half degree of static camber from the front and adding at least another 0.5 degrees of negative camber to the rear. I have image proof of how the car behaved on the next post. From going from a single adjustment, welcome back big changes...swing for the fences!

Images in the next post...

Owen · Mar 23, 2016

CLToy said:
Well, the oversteer issue from center to exit is gone...to the point that I was understeering and pushing through a few of the tighter turns. I have obviously overdone the toe in, ...

Not so obvious since it was cold day. If you were overworking the tires on a normal day, you could find yourself in a situation were the reduced temperatures lead to more rear traction (i.e. understeer). It's also possible that the fronts on a normal day are just right, but on a cold day they are not getting up to temp reducing front traction (also more understeer).

Need to do some more studying before making changes.

O

CLToy · Mar 6, 2016

Random images from event...

The next event at the end of the month will be held at this area as well. Here's to expecting better times, moving forward.

CLToy · Mar 28, 2016

March 26 AutoX

I made a video of the run. I struggled a bit today to stay smooth. I missed a line and had to hit the brakes a bit too much. The course was tight and seemed to be in-between gears...I wanted to shift to 2nd but would lose grunt from a couple tight turns. I will keep working on my skills.

This was points event #3. I ran #8 of 27 entries in class (RWD street tires) and #18 of 52 total entries. More details and times at Southern WV Region - SCCA

I went +6 caster but may need to dial in a bit more camber in front and a bit more in the rear of the car too. I wish there was a LSD option for these cars. I will continue to learn to drive this car before I get crazy with a build and jump up in class.

I welcome any comments. Hope you enjoy!

MK1a from ES to STS...

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