camber curves, caster, and going fast

[WillM]

Hi guys

whilst im loving my zzw30 mr2, having now had it a few days im noticing one huge drawback when compared to my rev1 sw20.

understeer! its absolutely awful. I'm sure it will improve darastically once i've spent some time setting up my coilovers properly, as the previous owner had no clue on that front, but the main thing i notice is a distinct lack of camber being added as i increase the steering lock.

what i'm really asking, is has anyone actually put time and effort into researchin/correcting this? i know wilhelm racing has done wonders for the sw20 and continues to improve them, but sadly i cant find any cases of people improving this specific characteristic of the zzw30.

if i have to relearn vehicle dynamics and do the math i will! but if someone knows an easy fix (adding caster angle maybe? i dont know) then that'd be much appreciated <3

[Carolyn]

A well set up MK3 doesn't understeer. 

[WillM]

care to elaborate? any setup advice would be welcome! at the moment i think the car has too much camber and the toe is a little off, plus i want to give it a little front rake to make it more stable (i think its just been lowered too much in general) but from what little i could find on old posts this car has a low caster angle, which combined with macphearson struts should mean it has very little negative camber when cornering at lower speeds, and therefore understeer? please do correct me if im wrong i dont claim to really understand setup properly

[Carolyn]

We have a few members who are proper track animals and I'm sure they'll be along to give their assistance.

[Iain]

What is the set up you have now? Coilovers? What tyres? Had any sort of laser alignment done? 

It really shouldnt be understeering much if at all. Id like to add some more understeer to my track/soon to be race car and its hard to get the front to unstick.

[Call the midlife!]

The car was designed by Toyota to have a tendency to understeer when pushed hard as a safety feature/warning that you're reaching the limit before the arse kicks out. I'm not sure if that's what you've read about or heard about but you shouldn't be experiencing it under "normal" driving conditions.
It's fairly easy to provoke in a standard, well aligned car but we're talking limits stuff, not pottering to the shops.

[WillM]

it has had an alignment but whoever did it i dont think was used to setting up coilovers. i'll post full spec tomorrow as the car is far from stock (2zz, celica box, LSD, whiteline ARBs and much more) currently it feels like theyve wacked it up to -3 degrees of camber and lowered it, so obviously thats not gonna be fantastic, but changing those likely wont solve the fact that with high steering lock it gets understeery. obviously one way of solving it would be to make the rear end more lively so it rotates, but i'd rather maximise the grip on the front before taking that approach hence me asking if anyone here has tried similar

[WillM]

The car was designed by Toyota to have a tendency to understeer when pushed hard as a safety feature/warning that you're reaching the limit before the arse kicks out. I'm not sure if that's what you've read about or heard about but you shouldn't be experiencing it under "normal" driving conditions.
It's fairly easy to provoke in a standard, well aligned car but we're talking limits stuff, not pottering to the shops.

yes perhaps i should be very clear, this is about track/closed road/performance driving. i have been doing trackdays for a few years and racing gokarts in the years prior as a kid, latest toy is this thing! its super fun, i just want to make it perfect. i can see why toyota would design it that way because frankly the sw20 rev1 was lethal in the rain at low speeds, had it slide at 30mph before when driving normally (bet that caught alot of people out).

sadly that characteristic isnt so good for me when i'm going round a racetrack with semi slicks on my car

[Iain]

it has had an alignment but whoever did it i dont think was used to setting up coilovers. i'll post full spec tomorrow as the car is far from stock (2zz, celica box, LSD, whiteline ARBs and much more) currently it feels like theyve wacked it up to -3 degrees of camber and lowered it, so obviously thats not gonna be fantastic, but changing those likely wont solve the fact that with high steering lock it gets understeery. obviously one way of solving it would be to make the rear end more lively so it rotates, but i'd rather maximise the grip on the front before taking that approach hence me asking if anyone here has tried similar

3 degrees of camber up front is fine, most track/racers run it in that sort of area.

You can add some more caster if you rotate the top mount of the coilover inward towards the car. This will gain more desired camber when turning but it wont be a dramatic difference.

[WillM]

makes sense, would you want them coming in at sort of 45deg (toward the windscreen)?

and yeah i'm sure it wont make a huge difference but even a little improvement would be fantastic so i'll give it a go

[Iain]

makes sense, would you want them coming in at sort of 45deg (toward the windscreen)?

and yeah i'm sure it wont make a huge difference but even a little improvement would be fantastic so i'll give it a go

Yes. Inward towards the screen.

Are they BC coilovers? Im not sure if that mod works or not with other brands.

[WillM]

cusco top mounts, from  memory it should work. i've actually just found some fully adjustable lower arms which would solve my problem but they are $700! so i'll try turning the top mounts first and then go down that route if i'm not happy and report back

[Iain]

Whatever you do you need to get a proper alignment done after any suspension changes. These cars are very sensitive to it. For track focused you want, imo, a wiff of toe out up front and a good -2mm toe in at the rear.

Some people run more toe out at the front but i found it too twitchy when i tried it and ive found its happiest running almost zero toe up front.

Alot of this depends on how you drive and theres alot of trial and error. 

[Alex Knight]

This thread is absolutely pointless without data.

There are many well documented setups which work for this chassis. Find out what yours is currently, and measure how different it is from a setup which is generally accepted as working well.

I have found the following to be best:

Zero toe all round.
Circa 3 degrees of negative camber all round.

Without your comparison to something like that, we are all just pissing in the wind to be honest.

[Ardent]

@WillM

Not very helpful in the sense that yours is a track based car.

But as a starting point. This is the factory set up.
You cannot view this attachment.

As above. Be good to know what yours is now.

[Ardent]

As is often said here. Just because a garage has the latest Hunter alignment kit, that does not guarantee good results.
It's the tech operating it and knowing what they're doing that makes the difference.

[JB21]

Here is my alignment for my 2ZZ track car that handles pretty well.

Front each side:
Camber
–3°00° ± 0°25'
Right–left error 0°25' or less

Toe - out
-0°10' ± 0°02' (-1mm ± 0.2mm)
Right–left error 0°01' (0.1mm) or less

--------------------------------------------------------------------------------------------------------

Rear each side:
Camber
–3°00' ± 0°25'
Right–left error 0°25' or less

Toe - in
0°20' ± 0°02' (2mm ± 0.2mm)
Right–left error 0°01' (0.1mm) or less

--------------------------------------------------------------------------------------------------------

Non-adjustable:

Caster
3°08' ± 45'

Steering axis inclination
14°52' ± 45'

[WillM]

As is often said here. Just because a garage has the latest Hunter alignment kit, that does not guarantee good results.
It's the tech operating it and knowing what they're doing that makes the difference.

Yeah this is why I do it myself lol corner scales and a proper rope kit done by me is better than any laser that isn't calibrated in a typical tyre shop. I'll be doing it within the next few days and I'll report back with what it was at and what I set it to

Thanks for all the replies guys some useful stuff here

[WillM]

Here is my alignment for my 2ZZ track car that handles pretty well.

Front each side:
Camber
–3°00° ± 0°25'
Right–left error 0°25' or less

Toe - out
-0°10' ± 0°02' (-1mm ± 0.2mm)
Right–left error 0°01' (0.1mm) or less

--------------------------------------------------------------------------------------------------------

Rear each side:
Camber
–3°00' ± 0°25'
Right–left error 0°25' or less

Toe - in
0°20' ± 0°02' (2mm ± 0.2mm)
Right–left error 0°01' (0.1mm) or less

--------------------------------------------------------------------------------------------------------

Non-adjustable:

Caster
3°08' ± 45'

Steering axis inclination
14°52' ± 45'

What rollbars/spring rates?

[JB21]

What rollbars/spring rates?

Front and rear WLARBs. 5kg front/7kg rears

[Ardent]

Thanks for all the replies guys some useful stuff here

This is the place.

[WillM]

Front and rear WLARBs. 5kg front/7kg rears

Sweet I need to check springs but I think that's the same as mine so I'll try it and see