Terminal Understeer

[djr81]

Terminal understeer & damn near terminal frustration.

I have fitted the Whiteline suspension kit to my R32 GT-R & unfortunately with the rear sway bar on full hard & the front on full soft the thing still doesn't want to turn. It rides the bumps beautifully (Now that the workshop trimmed the bump stops properly) & puts its power down wonderfully (maybe too well), but as I said it won't turn (HICAS is locked). I have some questions:

1. Can I reasonably revert to the standard front bar (ie 20mm instead of 22 which is about 2/3rds the stiffness assuming both are solid)

2. What (in % terms) is the approximate change in stiffness between the pick up points on the lever arms on the sway bars?

3. Does anyone else supply a softer, adjustable front bar?

Anyone running the Whiteline kit on the track (with R compounds) able to help?

The part numbers are

Springs 73157 front 70191 rear

Bars BNF27Z front & BNR26XZ rear.

[giant]

Hi i also have the whiteline swaybars in my r32 gtr

i have the front on full hard and the rear on full soft, i have never had understeer issues with my car.

what a your alignment settings, how much camber & toe front & rear?

has somebody possibly fitted a front lsd to it?

cheers Russ

[djr81]

Hi i also have the whiteline swaybars in my r32 gtr

i have the front on full hard and the rear on full soft, i have never had understeer issues with my car.

what a your alignment settings, how much camber & toe front & rear?

has somebody possibly fitted a front lsd to it?

cheers Russ

Russ,

Do you have the spring package as well as the swaybars? I found the car to be more neutral with the front spring rates lower than the rears (I put the sway bars on before I installed the spring package) - which is what you would expect really. Also, what tyres are you running as I found my car was much more prone (willing) to power oversteer with street tyres rather than R compounds. It presently feels like it cannot overcome the available rear grip & hence power on understeer is there in abundance. The ATTESSA system doesn't actually feel to be doing much - the gauge barely moves when punching out of 3rd gear corners.

As for alignments:

rear toe in is 0.5mm per side (ie not much) front 0.25mm per side (ie even less)

Rear camber is -1 degree, front is much the same as I haven't yet fitted the camber kit.

I measured the tyre temps after a three lap run at Wanneroo. The track was cold (25 degrees - it was night) but the loaded ie left hand side front was a good ten degrees hotter than the rear.

I had thought that if I can find an adjustable 20mm diameter front bat that may do the trick.

Cheers

Richard

[Beer Baron]

sounds like you need some front neg camber, and + caster.

it's also sometimes a driving style thing. maybe need to be getting on the brakes a little earlier to try the ol' slow in, fast out approach. i know i'm guilty of often going in to hot, then trying to get the thing tipped in at the last moment, and not surprisingly often end up with some nasty understeer. anything you can do to get more front end grip should be a big help, so i would try the camber+caster adjustment.

[djr81]

sounds like you need some front neg camber, and + caster.

it's also sometimes a driving style thing. maybe need to be getting on the brakes a little earlier to try the ol' slow in, fast out approach. i know i'm guilty of often going in to hot, then trying to get the thing tipped in at the last moment, and not surprisingly often end up with some nasty understeer. anything you can do to get more front end grip should be a big help, so i would try the camber+caster adjustment.

You are right in what you are saying, but I suppose like any suspension fiddling it is a matter of degrees. obviously more front end grip is a better fix than less rear end grip. That is in part why I was looking for a softer front sway bar- I thought about 20mm diameter would do the trick.

I have wound the castor rods up as far as they will go, so there is no more castor to be had. Yep it does need more -ve camber at the front end, but the difference between the kits isn't huge & I am not sure it will make sufficient difference in any case.

Wanneroo has two large radius 180 degree corners where slow in fast out doesn't really work - it isn't really a point and squirt circuit. Apart from mid corner understeer, power on understeer is killing my lap times.

Has any one run the complete Whiteline kit on track with R compounds?

[Beer Baron]

yeah sorry, i wasnt really paying enough attention. definately if mid corner and power on understeer is your problem the only real solutions are more front end grip or less rear. this may sound a little strange, but have you tried softening the rear bar a little and stiffening the front? Or try going back to the stock front bar too.

[djr81]

yeah sorry, i wasnt really paying enough attention. definately if mid corner and power on understeer is your problem the only real solutions are more front end grip or less rear. this may sound a little strange, but have you tried softening the rear bar a little and stiffening the front? Or try going back to the stock front bar too.

Um, no hadn't tried that. Can I ask for the reasoning why?

I had thought of going back to the stock front, but it is hollow & hence I can't get a feel for the difference between it & the Whiteline 22dia solid bar. If it was solid it would be about 70% the stiffness which is about right assuming each adjustment on the sway bar is approx 5 - 10 %. Unfortunately Whiteline don't make a 20mm dia front bar for an R32...

What are you running in terms of suspension Richard?

Edited February 27, 2006 by djr81

[Sydneykid]

On full soft 24mm front bar and full hard 24mm rear bar you should not have corner exit understeer, my suggestions follow;

1. Toe the front out about 2mm each side

2. It needs at least 2.5 degrees negative camber on the front to match the 1 degree negative camber on the rear.

3. Don't have the front ride height too low, around 350 mm is as low as I would go. They can easily run out of travel.

4. All the fast circuit race GTR's have zero rake (ie; they are NOT nose down). The roll centre is much higher at the rear than the front, if you run it nose down, that just makes the difference greater. This causes the excessive roll to the outside front tyre. Match the roll centre more closely and you don't get that.

5. You could stiffen up the front bar to fix #4 but it may lead to corner entry understeer as you don't get that initial bite from the weight transfer. Try the ride height first, then maybe try increasing the front bar setting just to be sure you have some logic to the adjustment process.

Hope that helps

cheers

Edited February 27, 2006 by Sydneykid

[djr81]

Thanks Gary,

Answers as follows:

1. Toe the front out about 2mm each side

Basically running very little positive on the front end. Bit worried about what toe out may do on the road.

2. It needs at least 2.5 degrees negative camber on the front to match the 1 degree negative camber on the rear.

I am waiting for my 94 to be complied & will put the camber kit into that. At the moment it needs more -ve camber at the front, but I don't want to waste the $500 to do this & then sell the car in a few months.

3. Don't have the front ride height too low, around 350 mm is as low as I would go. They can easily run out of travel.

Ride height is set at 350mm as recommended.

4. All the fast circuit race GTR's have zero rake (ie; they are NOT nose down). The roll centre is much higher at the rear than the front, if you run it nose down, that just makes the difference greater. This causes the excessive roll to the outside front tyre. Match the roll centre more closely and you don't get that.

See answer to #3.

5. You could stiffen up the front bar to fix #4 but it may lead to corner entry understeer as you don't get that initial bite from the weight transfer. Try the ride height first, then maybe try increasing the front bar setting just to be sure you have some logic to the adjustment process.

Might try lowering the rear ride height, just hope I dont end up with too much -ve camber....

[Sydneykid]

Thanks Gary,

Answers as follows:

1. Toe the front out about 2mm each side

Basically running very little positive on the front end. Bit worried about what toe out may do on the road.

2. It needs at least 2.5 degrees negative camber on the front to match the 1 degree negative camber on the rear.

I am waiting for my 94 to be complied & will put the camber kit into that. At the moment it needs more -ve camber at the front, but I don't want to waste the $500 to do this & then sell the car in a few months.

3. Don't have the front ride height too low, around 350 mm is as low as I would go. They can easily run out of travel.

Ride height is set at 350mm as recommended.

4. All the fast circuit race GTR's have zero rake (ie; they are NOT nose down). The roll centre is much higher at the rear than the front, if you run it nose down, that just makes the difference greater. This causes the excessive roll to the outside front tyre. Match the roll centre more closely and you don't get that.

See answer to #3.

5. You could stiffen up the front bar to fix #4 but it may lead to corner entry understeer as you don't get that initial bite from the weight transfer. Try the ride height first, then maybe try increasing the front bar setting just to be sure you have some logic to the adjustment process.

Might try lowering the rear ride height, just hope I dont end up with too much -ve camber....

Quick clarification;

2. It is pretty easy to swap over the upper control arms, only 2 bolts. If they are the same series then stick a camber kit in the current car and swap the arms over when the new one arrives.

4. What's the rear hide height? If higher than 345 mm, then worth trying down to a min of 330 mm. They are extemely sensitive to ride height. You should be able to feel the differences, 2-3 mm is noticeable.

:bigrin: cheers

Edited February 27, 2006 by Sydneykid

[djr81]

2. It is pretty easy to swap over the upper control arms, only 2 bolts. If they are the same series then stick a camber kit in the current car and swap the arms over when the new one arrives.

Good call, I will have a look - if the bushes are all contained within a control arm the it should be sweet. I trust the '89 is no different to the 94 on an R32 GT-R.

4. What's the rear hide height? If higher than 345 mm, then worth trying down to a min of 330 mm. They are extemely sensitive to ride height. You should be able to feel the differences, 2-3 mm is noticeable.

I went with the settings that arrived on the dampers - haven't fiddled with them. I am a little worried about the rear guard clearance, but 5mm shouldn't hurt.

The car looks like this on corner exit.

http://www.circlework.com.au/

Then go to the Speedeeventseries on the 18th February, Page 4 - it is the white R32 in the top right hand side of the page.

The photo is on exit to the corner coming onto pit straight at Wanneroo - power is down & the front end is pushing pretty hard as you can see. Front camber is woeful...

cheers - even bigger grin...

[Beer Baron]

the logic i was given for trying stiffer front was that it will help mid corner stability, at the expensive of possibly some turn in understeer. I havent tried it myself as i was a bit skeptical, but the advice was give to me by a bilstein suspension guy whilst we were at the track.

my car is running bilstein dampers, with japanese springs. adjustable castor rods with ~9 degress castor. got some swaybars on the way, and a hicas lock kit stiing here. then just deciding between adjustable upper arm, or bush kit.

[confuzion]

Interesting,

My R also suffers from really bad corner entry understeer, will try the above things also. Dont mean to hijack the thread sorry

[Gts-t]

Quick clarification;

2. It is pretty easy to swap over the upper control arms, only 2 bolts. If they are the same series then stick a camber kit in the current car and swap the arms over when the new one arrives.

4. What's the rear hide height? If higher than 345 mm, then worth trying down to a min of 330 mm. They are extemely sensitive to ride height. You should be able to feel the differences, 2-3 mm is noticeable.

:bigrin: cheers

Not that im having any real problems but does this apply to gtst's as well SK? I have your package set the way it arrives as recommended. It is worth taking the rear down a little??

Thanks!

[Sydneykid]

Not that im having any real problems but does this apply to gtst's as well SK? I have your package set the way it arrives as recommended. It is worth taking the rear down a little??

Thanks!

The 2wd set up is rather different than the 4wd set up. You should never get corner exit understeer in a 2wd, the right foot usually fixes that problem.

cheers

[hrd-hr30]

I'm not trying to be a smart-arse, but just thought we should check you have got the full soft and full hard swaybar settings right. full soft is using the holes at the end of the bar and full hard is the holes furtherest from the end.

personally, for track use, I'd be running toe out on the front as suggested, and you could also toe out the rear a little too - try zero rear toe for starters.

another thing you could try is changing the pineapple setup. If you went for the traction based setup, try going to a neutral setup.

are the shocks adjustable in the whiteline kit? and does it start understeering the moment you get on the gas when exiting a corner?

[djr81]

I'm not trying to be a smart-arse, but just thought we should check you have got the full soft and full hard swaybar settings right. full soft is using the holes at the end of the bar and full hard is the holes furtherest from the end.

personally, for track use, I'd be running toe out on the front as suggested, and you could also toe out the rear a little too - try zero rear toe for starters.

another thing you could try is changing the pineapple setup. If you went for the traction based setup, try going to a neutral setup.

are the shocks adjustable in the whiteline kit? and does it start understeering the moment you get on the gas when exiting a corner?

Despite all available evidence being to the contrary I still maintain that I am not a complete idiot. So, yes I have checked.

For track use I would like to run toe out, unfortunately the only two tracks available are quite a way from home, respectively 300 kms for Wanneroo and 80kms for Collie - each way. If the SES runs at Northam next month make it closer to 400kms for that. So I have to run a set up that is manageable for the road. Rear is bugger all anyway. The local shops don't calibrate their wheel alignment equipment, so playing around with 0.5mm increments is largely a waste of time.

Pineapples I don't have huge amount of faith in, but are on the list for adjustments - from neutral to less squat.

Shocks aren't adjustable - they have been matched to the spring rates. For one I wouldn't mind seeing a histogram from the shock dyno, as I reckon it would be illuminating.....

As the post said it has mid corner understeer & push understeer on corner exit. If I can fix the mid corner issue the amount of push being shown will become less of an issue.

[Sydneykid]

Despite all available evidence being to the contrary I still maintain that I am not a complete idiot. So, yes I have checked.

For track use I would like to run toe out, unfortunately the only two tracks available are quite a way from home, respectively 300 kms for Wanneroo and 80kms for Collie - each way. If the SES runs at Northam next month make it closer to 400kms for that. So I have to run a set up that is manageable for the road. Rear is bugger all anyway. The local shops don't calibrate their wheel alignment equipment, so playing around with 0.5mm increments is largely a waste of time.

Pineapples I don't have huge amount of faith in, but are on the list for adjustments - from neutral to less squat.

Shocks aren't adjustable - they have been matched to the spring rates. For one I wouldn't mind seeing a histogram from the shock dyno, as I reckon it would be illuminating.....

As the post said it has mid corner understeer & push understeer on corner exit. If I can fix the mid corner issue the amount of push being shown will become less of an issue.

What I used to do when I drove cars to circuits was to adjust the toe while it was jacked up for fitting the sticky tyres and adjusting the stabiliser bars. From memory 1 complete turn of the toe adjuster is around 1 mm. If you do both sides the same amount, you should be easily able to return them to zero to drive home.

Only takes a few seconds while the car is jacked up. Check the 1mm = 1 turn with the wheel aligner next time it is there.

There are 3 settings on the rear subframe alignment kit, I usually go for the neutral setting, except in the continuous rain where we go for the squat setting. I never use the drift setting.

cheers

[Adrian Knack]

Terminal understeer & damn near terminal frustration.

I have fitted the Whiteline suspension kit to my R32 GT-R & unfortunately with the rear sway bar on full hard & the front on full soft the thing still doesn't want to turn. It rides the bumps beautifully (Now that the workshop trimmed the bump stops properly) & puts its power down wonderfully (maybe too well), but as I said it won't turn (HICAS is locked). I have some questions:

1. Can I reasonably revert to the standard front bar (ie 20mm instead of 22 which is about 2/3rds the stiffness assuming both are solid)

2. What (in % terms) is the approximate change in stiffness between the pick up points on the lever arms on the sway bars?

3. Does anyone else supply a softer, adjustable front bar?

Anyone running the Whiteline kit on the track (with R compounds) able to help?

The part numbers are

Springs 73157 front 70191 rear

Bars BNF27Z front & BNR26XZ rear.

Hey djr81,

This may have been covered already (but I didn't see it in my quick skim read) but you say you have the

REAR: Full Hard

FRONT: Full Soft

Which I would say would promote understeer...

I was under the impression that to promote a more neutral feel or even oversteer you need to set the FRONT to full hard and the REAR to full soft. You can then modify modify them a touch to get your prefered handling characteristic.

Now I might have this completely wrong (in which case someone can tell me how the theory works...) or you might have made a typo... but anyway just my thoughts.

[hrd-hr30]

no Adrian, you've got it arse about. going harder/stiffer at one end will increase the slip angle at that end, and prompt that end to slide earlier. so going stiffer at the front will change the balance towards understeer. stiffer at the rear will change the balance towards oversteer.

As the post said it has mid corner understeer & push understeer on corner exit. If I can fix the mid corner issue the amount of push being shown will become less of an issue.

I think you're really not going to get rid of it until you get the camber/castor happening. either that or more power!