MR2 Owners Club Forum banner

1 - 20 of 26 Posts

·
Registered
Joined
·
161 Posts
Discussion Starter #1
this should help anyone who want to setup there suspension for whatever they use there MR2 for:
Front spring rate increase:
More under steer; increase in proportional weight transfer to the front when rear wheel rate is not increased; reduces front traction when rear rate is not changed.
Usable adjustment: 150-600 lbs/in
Symptoms of too much adjustment: terminal under steer; front of car hops in corners; excessive wheel spin on inside front tire on FF cars.

Front spring rate decrease:
Less under steer; decreases proportional weight transfer to the front when rear wheel rate is not increased; increases front traction when rear rate is not changed.
Usable adjustment: 150-600 lbs/in
Symptoms of to much adjustment: Too much over steer; over steer then under steer if spring is so soft that the car bottoms out on lean, car bottoms out excessively with a jolting ride.

Rear spring rate increase:
More over steer; increase in proportional weight transfer to the rear when front wheel rate is not increased; increases rear traction when front rate is not changed.
Usable range: 100-600 lbs/in
Symptoms of too much adjustment: too much over steer; sidestep hop in corners; twitchy; pretty scary.

Rear spring rate decrease:
Less over steer: decreases proportional weight transfer to the rear when front wheel rate is not changed; increases rear traction when front rate is not changed
Usable range: 100-600 lbs/in
Symptoms of too much adjustment: car under steers; if way to soft car under steers then over steers as car bottoms out on lean; car bottoms out excessively with a jolting ride.

Front anti-roll bar stiffer: more under steer
Usable range: none to 1.25 inches in diameter
Symptoms of to much adjustment: terminal under steer; lifts inside front tire off the ground witch can cause massive wheel spin on FF cars; also not good for most effective tire usage as inside tire is now doing nothing.

Front anti-roll bar softer: less under steer
Usable range: none to 1.25 inches in diameter
Symptoms of to much adjustment: overstate scary; more like fun

Rear anti-roll bar stiffer: more over steer
Usable range: none to 1 inch in diameter
Symptoms of too much adjustment: Big-time over steer. Can cause inside rear tire to lift off the ground.

Rear anti-roll bar softer: less over steer
Usable range: none to 1 inch in diameter
Symptoms of to much adjustment: under steer; slow and boring

Front tire pressure higher: less under steer by reducing slip angels on most tires
Usable adjustment: up to 55psi hot
Symptoms of too much adjustment: no traction- tire crowned so more under steer; adds wheel spin in FF cars; jarring ride; center of tire wears out

Front tire pressure lower: more under steer by increasing slip angles on most tires
Usable adjustment: not less then 20psi
Symptoms of too much adjustment: edges of tire wear quickly because tire is folding over; feels mushy; tires chunk because low pressure means heat build up.

Rear tire pressure higher: less over steer by reducing slip angles on most tires
Usable range: up to 45psi hot
Symptoms of too much adjustment: no traction?tire is crowned so more over steer; bad wheel spin on FR cars; jarring ride; center of tire wears out.

Rear tire pressure lower: more over steer by incresing slip angles on most tires.
Usable range: not less then 20psi
Symptoms of too much adjustment: edges of tire wear quickly because tire is folding over; feels mushy; tires chunk because low pressure means heat build up

More negative camber front: less under steer because of better lateral traction as tread is flatter on the ground under side load.
Usable range: up to 3.5 degrees negative
Symptoms of too much adjustment: poor braking; car is road crown sensitive; twitchy; front tires wear on inside edge

More negative camber rear: less over steer because of better lateral traction as tread is flatter on the ground under side load. More rear grip
Usable range: up to 2.5 degrees negative
Symptoms of too much adjustment: more over steer; car feels twitchy in back; tires wear out on inside edge; less breakaway warning when limit is exceeded.

Ride height to low (typical beginner mistake): car is twitchy with unpredictable dynamics. Bump steer make you life miserable.
Usable range: usually 1.5-2.0 inches lower then stock unless car has been modified to go lower.
Symptoms of too much adjustment: everything that could possibly go wrong: sudden over/under steer; twitchy due to bump steer; very harsh ride; premature tire wear.

Toe in ? front: car is stable going straight. Turn in is average
Usable range: 0-1/8th inch
Symptoms of too much adjustment: car has slow twitchiness under braking; feels odd; kills outside edge of tires

Toe out ? front: Car turns in well; works pretty well on FF car as they tend to toe-in under load.
Usable range: 0-1/4 inch
Symptoms of too much adjustment: Car is really twitchy under braking; car wanders on straight road; kills inside edge of tire

Toe in ? rear: car is less likely to over steer when the throttle is lifted
Usable range: 0-1/8th inch
Symptoms of too much adjustment: weird, slow, rocking movement in back; feels slow but still unstable; wears outside edge of tires.

Toe out ? rear: Helps car rotate useful in low speed and slalom courses; very common on FF pro rally cars.
Usable range: 0-1/8th inch
Symptoms of too much adjustment: not to good for street driving; causes lift throttle over steer; makes violent side to side rocking motions in the rear; tie wears on inside more.

Positive front caster: helps stability; suspension will get more negative camber when turning; reducing positive caster reduces steering effort. (Negative caster is not usable)
Usable range: 4-9 degrees positive
Symptoms of too much adjustment: can increase under steer especially in cars with wide low-profile tires. Can increase steering effort.

Single adjustable shock stiffer: Better turn in; better transient response; causes slower onset of over/under steer by slowing weight transfer depending on what end of the car is adjusted.
Symptoms of too much adjustment: suspension becomes unresponsive; ride gets harsh; car skips over bumps, loosing traction; Causes a big delay in weight transfer resulting in strange handling like under steer then late corner stage over steer.

Single adjustable shock softer: slower transient response; quicker onset of over/under steer
Symptoms of too much adjustment: car oscillates due to under dampened spring motion, like a boat. Car gets twitchy in turns. Feels unstable.

Hope this becomes a sticky
 

·
Registered
Joined
·
4,363 Posts
i have d2 coilovers on my mk2 umm i was reading that they are preload adjustable.? but wa is preload mean.. from wa i no.. to adjust my sus. properly i have to left up my car.?
 

·
Registered
Joined
·
161 Posts
Discussion Starter #6
The Preload adjustment determines the spring force. More preload, more required force to compress the spring. Less preload, less required force to compress the spring.
 

·
Registered
Joined
·
4,363 Posts
right now my ride is really harsh.. as harsh as my kyb agx and sportlines were.. i thought id b gettin sumin more comfortable.. so how do i fix this.? steps on how to properly adju?
 

·
Registered
Joined
·
6,783 Posts
^^jason you are right!! back breaking almost could you list your suspension mod?

I think it's your coilovers the rebound might be kind of slow but if you have aftermarket sways that could be your problem ...I have tockicos and trd spring and they are soft and grip like hell! I have not tried bilstien and ohlins yet so I can not give you an honest judgement ...forget kyb I HATE THEM!
 

·
Registered
Joined
·
2,112 Posts
The use of Wheel Spacers

Increase Front Track: Reduces Understeer.

Increase Rear Track: Increases Understeer.

If you are limited by wheel to coilover contact, wheel spacers can also increase the range of camber adjustment.

I'm not sure about the effect of spacers on snap-oversteer though. I also don't know what characteristics change when you add equivalent track to both front and rear.

Anyone want to add to the changes that wheel spacers can make?
 

·
Registered
Joined
·
786 Posts
I have to say that spacers do make a difference... I put a 25mm spacer on the rear using stock rims 205/60/14 tires and i have never experienced snap oversteer, and i never spun out. when i switched rims and tires to 225/50/16, i spun out twice... I dunno if it makes any sense. I dunno why I would spin out easier with wider tires, and a lower offset.. the stock rims I understand have a +45 offset, using the 25mm spacer would make the offset +20... but using the 25mm spacer with a +40 offset rim should make the car a lot more stable in the rear with a much lower offset +15mm.. not to mention the wider tires... but I dont know.. all I know is that when I used the spacer on the stock wheels, I could barely get sideways
 

·
Registered
Joined
·
64 Posts
heres the low down on spacers [ and a little on tire profile ]

adding spacers to just the front will lower understeer, hence giving more oversteer

adding spacers to just rear will reduse, and possibly iliminate oversteer [ in most situations ]

adding them to both front and rear as a whole makes the car more stable. and still keeps the stock [ or close to stock ] response.

the problum that you ran into with the tires could souly be based on the profile and width of the tire. [ along with tire pressure ]

when you have a lower profile and a wider tred the tire is stiffer all over. [ sidewall AND tread-patch ] this means that you have a greatly reduced "slip-angle"
[ this means that the tire dosnt give NEAR as much warnnig once it gets to its limits ]

i found this out first hand when i threw a set of TT 300ZX wheels on the back of my 1991 NA. it was WAY too easy to sldie the back end compared to my stock 205s [ which im actuly running 215 ] and it didnt let me know it was about to slide.

all in all you can look at it like this. . .

the lower, wider the tire the less warning it will give to letting go at the limit. BUT it will also let go more smoothly [ in most cases ] and come back softer.

when i go to the track this is what i run and i have NEVER spun out nor have a plowed a corner.

Front = 15mm spacer with the stock 195 / 60 / 14 @ 35psi
Rear = 25mm spacer with 215 / 60 / 14 @ 38psi

it all boils down to how you drive an what workks with your driving style.
 

·
Registered
Joined
·
43 Posts
front wheel spacers

as far as wheels spacers for the front. there is a trade off in steering response or feel maybe depending on the person. as the center of the tires moves out from the balljoint you increase scrub. i feel it as a slow down in the transitions (so to speak), you can increase your stability in the front but you can go to far as well, i think. i borrowed some 15x7 zero offset 205s and it stuck like glue but sucked to drive.
 
1 - 20 of 26 Posts
Top