[CLToy]

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]

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]

Thank you, Martin. Your input is much appreciated!

 

[RyoHazuki]

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]

clarification...

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.

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]

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!

 

[mr2tim]

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]

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.

 

[CLToy]

Thank you for the feedback!

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.

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.

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.

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.

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.

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.

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.

 

[XHead]

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]

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]

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]

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...

 

[CLToy]

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.

 

[Owen]

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]

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!

 

[mr2tim]

Experienced views.

Mr. Toy,

I scanned those latest pics you posted and noticed in all the cornering pics that your outside corner tire was nearly off the racing surface in all occasions. This points to an extreme sway bar problem, your car is rocking like a boat throwing momentum way out of control. I’m unsure of your classification but you need some suspension engineering as this crap with camber, toe and the rest of this talk I see here is just pissing up a rope.

I rode with you on the lastest video and noticed that you are apexing way, way too late. I would respectively suggest you brake hard earlier (while in a straight line) get back on the gas (while stabilizing the chassis) and accelerate before and thru the apex. Increasing speed before and during the apex will exhibit faster straight away speed and your car will be more stable at the same time.

Lastly if your not tuning your suspension for “traction” you need to understand how to. I’d suggest 60-120 treadware on the front and 180 and up on the rear. Remember the 40/60 weight split means you cannot expect the same performance from 4 tires having the same treadware since loading is not equal front to back.

These are constructive suggestions I offer from racing mid-engined cars for 30 years.

Drive hard & have fun.

 

[CLToy]

Thanks for the follow up...

Mr. Toy,

I scanned those latest pics you posted and noticed in all the cornering pics that your outside corner tire was nearly off the racing surface in all occasions. This points to an extreme sway bar problem, your car is rocking like a boat throwing momentum way out of control. I’m unsure of your classification but you need some suspension engineering as this crap with camber, toe and the rest of this talk I see here is just pissing up a rope.

If you were to add a sway bar, I would assume to the front? It is very easy to crank the wheel to the right and right rear wheel would break loose...even out of my driveway in the AM.

I rode with you on the lastest video and noticed that you are apexing way, way too late. I would respectively suggest you brake hard earlier (while in a straight line) get back on the gas (while stabilizing the chassis) and accelerate before and thru the apex. Increasing speed before and during the apex will exhibit faster straight away speed and your car will be more stable at the same time.

I appreciate the advice. During the walk through, I envisioned where I was supposed to apex, be through the turn, and back on the gas. It always wasn't with a corner cone but I did not have a good day and just didn't seem to hit my marks. Then I would try to make up for it by a too fast entry...disaster. I appreciate the tips and will continue to work harder here.

Lastly if your not tuning your suspension for “traction” you need to understand how to. I’d suggest 60-120 treadware on the front and 180 and up on the rear. Remember the 40/60 weight split means you cannot expect the same performance from 4 tires having the same treadware since loading is not equal front to back.

I am only able to run a 200 treadwear tire with sts rules...I am running the best tire I can. However, 2016 sts rules allows a 225 from a 205 width....but not offered yet in the tire chosen.

Thanks for commenting and helping!

 

[XHead]

Mr. Toy,

I scanned those latest pics you posted and noticed in all the cornering pics that your outside corner tire was nearly off the racing surface in all occasions. This points to an extreme sway bar problem, your car is rocking like a boat throwing momentum way out of control.

I have no idea what any of this means. What is the "outside corner tire"? And what is "off the racing surface"? I really don't think there can be an "extreme swaybar problem" if there isn't a swaybar.

I rode with you on the lastest video and noticed that you are apexing way, way too late. I would respectively suggest you brake hard earlier (while in a straight line) get back on the gas (while stabilizing the chassis) and accelerate before and thru the apex. Increasing speed before and during the apex will exhibit faster straight away speed and your car will be more stable at the same time.

A car only does three things: Brake, turn and accelerate. Combining braking and turning, or turning and accelerating, compromises both. You release the brakes as you turn into the corner. The car should be on the tightest radius, at max lateral load at the apex. You then accelerate as you unwind the wheel.

When I reviewed the in car video there are things to work on but it wasn't terrible. In the track side video and still photos the car looked pretty composed to me.

Lastly if your not tuning your suspension for “traction” you need to understand how to. I’d suggest 60-120 treadware on the front and 180 and up on the rear. Remember the 40/60 weight split means you cannot expect the same performance from 4 tires having the same treadware since loading is not equal front to back.

Tuning handling balance with tire compound is only done if you can't adjust the roll ratio with springs and bars. Using the same compound tire and tuning with roll ratio will extract the maximum performance from all four tires. If you have the option to run a wider rear wheel/tire that will help balance the car's weight distribution. But you never want to put a narrower tire on the front than is available. I prefer to use a "square" tire setup (same size all around) and tune the balance with roll ratio.

 

[MicaCeli]

And I am back. 3 years off of auto-x and the wife and I are back at it again. I literally removed the cobwebs off the car changed oil and put the new Stones on it. She is misfiring a bit though....hmm.

Oh and Steve is in my area and I might actually meet him in person

Tim in STS you can only run 200 and up treadwear tires.

So just to put down on paper again where I am with the setup.

Koni Da's
700lb Front Springs
450lb Rear Springs

1/16th toe in Front
3/16th toe out Rear

(guessing here cause I don't remember)
-2.5 camber front
-3 camber rear
or maybe other way round. I will have to check.

here is the rake:

She still rolls well