Hi all, I am just putting my rear suspension together, having renewed with poly bushes. What toe settings do you guys use / suggest? It is a DAX, but I expect settings for other cars would be similar.
regards
Dave
regards
Dave
Rear Toe Setting
- Thread starter wolodymyr
- Start date
Thanks Goran, as you can see from my picture the back end is not very stable, and I had to be really careful on the track. I have used poly bushes, and gone from 200/250 which I felt were too soft, to 300/350 springs. Now I have put the suspension back together, I will set up the suspension with the help of some experienced single seater people and hopefully improve on the setup. I am sure I will improve it, as the rear seems to have lots of camber and unequal toe in at the moment. I have also replaced the top arm outer bolts with the correct size. They were 11.75mm shank in a 1/2" rose joint! Seems to me that cars with fully adjustable suspension can be dangerous if not set up properly, particularly mid engined with heavy engines like this.
regards
Dave
regards
Dave
Dave,
Just got done re-aligning my car. My initial settings were quite good and the car seemed fairly well balanced. The initial settings are listed on this page: ERA specs
I don't want to let out all my chassis tuning techniques but these initial settings worked well and I only have made minor adjustments from the original settings.
Hope this helps.
Mark
Just got done re-aligning my car. My initial settings were quite good and the car seemed fairly well balanced. The initial settings are listed on this page: ERA specs
I don't want to let out all my chassis tuning techniques but these initial settings worked well and I only have made minor adjustments from the original settings.
Hope this helps.
Mark
IMHO. Your car could be giving you a toe out condition at the rear on bump. As a guide, Rear toe in 10-15 Minutes per side, caster 7 deg. Check toe in on full bump and rebound. Ideally there should be no change or toe in should increase slightly (10 min). Depending on your suspension configuration Caster adjustment should alter bump steer and reduce change to a minimum. I note that you are using poly bushes in your suspension. The dynamic deflection in those bushes will alter bump steer as you round a corner. When setting up the rear in a static condition log the bump steer change versus caster change. On the track you can then make known adjustments to get the balance right. Then start on camber, (initially zero) Camber is best done by recording temp across the tread and adjusting to get temps even. You may then need to revisit the bump steer and play more if need be. Log all the changes and adjustments you have made for future reference. Once you have done this then check the settings in the static condition. Settings and balance of the car is a personal issue as to what suits your driving style. It is the car and driver as a package that produces the best results.
Trevor
Trevor
JP
Checkout daves 3 second video, the car exhibits oversteer,
" Your car COULD be giving you a toe out condition at the rear on bump" is a correct statement. He COULD have been going to fast, he COULD have applied the throttle to early. Read all of the post, it goes on to say 10 minutes of toe In, and I am not talking about time.
Checkout daves 3 second video, the car exhibits oversteer,
" Your car COULD be giving you a toe out condition at the rear on bump" is a correct statement. He COULD have been going to fast, he COULD have applied the throttle to early. Read all of the post, it goes on to say 10 minutes of toe In, and I am not talking about time.
Hi JP and Trevor, regarding the 3 second video. That incident was on my first lap coming out of the hairpin at knockhill. I have driven single seaters, and my Subaru many times here. I took the hairpin at what I felt was a comfortable and cautious pace for a first time car, and the result was what you see, getting the steering wheel ripped out of my hands in the process. /ubbthreads/images/graemlins/blush.gif On subsequent laps as I explored the handling, I found that when cornering it felt very stable up to a point, but under only slightly harder cornering a little opposite lock was needed, and I knew that I was on the limit at a very moderate, even slow pace. So sorry guys, I had to let the Ferrari past, and the Lambo, GT3, Noble and TVR. /ubbthreads/images/graemlins/blush.gif But I enjoyed it anyway as a first time out. /ubbthreads/images/graemlins/grin.gif So that was when I knew that I needed to do some work in this department.
I went to the local chassis set up shop to determine the suspension setup, I will post the full horror of these figures soon, suffice it to say that I have a bit of realignment to do. /ubbthreads/images/graemlins/wink.gif
regards
Dave
I went to the local chassis set up shop to determine the suspension setup, I will post the full horror of these figures soon, suffice it to say that I have a bit of realignment to do. /ubbthreads/images/graemlins/wink.gif
regards
Dave
Ross Nicol
GT40s Supporter
Seems to me nobody has mentioned tyres or the fluids that may have been dropped on the track.Don't be too quick to conclude you have a suspension problem Dave however if you have the classic 60's suspension ie reversed lower control arm'top link and 2 trailing arms you must check your rear bump steer.Don't worry about initial settings at ride height, you are interested in what Toe change occurs between
ride height and full bump. To do this sit the car on jack stands, take the springs/shocks out and jack the wheel from ride height to full bump in small increments, while checking the toe change.You do not want to see any toe out
I agree with trevor on using temp across the tread for camber adjustment but it's easier to monitor tread wear after a few hard laps.I put more neg camber on until the wear is even across the tread.It's taken me 12 months to get a handle on the GT40 handling (no pun intended) and the car is very fast through corners with stability the Porsche guys would kill for.I really love passing them when they have brakes locked up in a corner.In my opinion all these factors come into play with the GT40's handling - Tyres,springs,suspension settings, power/torque and the Driver.Check the bump steer Dave and work on things as you go nice and steady it should improve but only change one thing at a time and test at the track.Oh yes when you have overcome any toe out at the rear, you can then set an initial toe setting of 0 degrees or maybe a little toe in.
Ross
ride height and full bump. To do this sit the car on jack stands, take the springs/shocks out and jack the wheel from ride height to full bump in small increments, while checking the toe change.You do not want to see any toe out
I agree with trevor on using temp across the tread for camber adjustment but it's easier to monitor tread wear after a few hard laps.I put more neg camber on until the wear is even across the tread.It's taken me 12 months to get a handle on the GT40 handling (no pun intended) and the car is very fast through corners with stability the Porsche guys would kill for.I really love passing them when they have brakes locked up in a corner.In my opinion all these factors come into play with the GT40's handling - Tyres,springs,suspension settings, power/torque and the Driver.Check the bump steer Dave and work on things as you go nice and steady it should improve but only change one thing at a time and test at the track.Oh yes when you have overcome any toe out at the rear, you can then set an initial toe setting of 0 degrees or maybe a little toe in.
Ross
[ QUOTE ]
it's easier to monitor tread wear after a few hard laps.(quote)
Ross, it is not wear thats important, its the temperature and there is no guesswork with a sub surface temp probe
Trevor
it's easier to monitor tread wear after a few hard laps.(quote)
Ross, it is not wear thats important, its the temperature and there is no guesswork with a sub surface temp probe
Trevor
flatchat(Chris)
Supporter
You're on the money guys ,all this talk about fancy items on a stroked motor etc is wasted unless the car handles.
40s have plenty of options for correct "pointing".
Then you can go flat around the circuit instead of flat on the straights and nursing it through corners.
Ooops no more coaching!
/ubbthreads/images/graemlins/cool.gif
40s have plenty of options for correct "pointing".
Then you can go flat around the circuit instead of flat on the straights and nursing it through corners.
Ooops no more coaching!
/ubbthreads/images/graemlins/cool.gif
My settings measured with a Pro-Align SPACE 800
Front Camber L -2deg52' R -2deg42'
Caster L 4deg46' R 4deg42'
Toe L -0deg42' R +0deg43'
Rear Camber L -2deg23' R -1deg47'
Toe (in) L +1deg38' R +0deg18'
Thrust angle 0deg40'
based on these figures and back in my garage I adjusted the toe on the Left Rear and the Camber on the Left and RightRear by extending rose joints the appropriate distance.
With the car set back down and measuring camber with my high technology spirit level /ubbthreads/images/graemlins/wink.gif, and Toe in with my even higher technology pieces of string /ubbthreads/images/graemlins/grin.gif, I got
Camber L +0deg15' R -0deg08'
Toe (in) L +0deg45' R +0deg45'
Before I set the car down I checked Camber and Toe at 3 positions.
Full bump Camber +1deg0' Toe (in) 2deg30'
Top arm level Camber 0deg0' Toe (in) 0deg35'
Full droop Camber -2deg48' Toe (in) 0deg52'
Any comments or questions welcome.
I will pay another visit to the garage when I have time, but I guess these are much better than before and Goodwood enough if you get my four wheel drift /ubbthreads/images/graemlins/grin.gif.
Regards
Dave
Front Camber L -2deg52' R -2deg42'
Caster L 4deg46' R 4deg42'
Toe L -0deg42' R +0deg43'
Rear Camber L -2deg23' R -1deg47'
Toe (in) L +1deg38' R +0deg18'
Thrust angle 0deg40'
based on these figures and back in my garage I adjusted the toe on the Left Rear and the Camber on the Left and RightRear by extending rose joints the appropriate distance.
With the car set back down and measuring camber with my high technology spirit level /ubbthreads/images/graemlins/wink.gif, and Toe in with my even higher technology pieces of string /ubbthreads/images/graemlins/grin.gif, I got
Camber L +0deg15' R -0deg08'
Toe (in) L +0deg45' R +0deg45'
Before I set the car down I checked Camber and Toe at 3 positions.
Full bump Camber +1deg0' Toe (in) 2deg30'
Top arm level Camber 0deg0' Toe (in) 0deg35'
Full droop Camber -2deg48' Toe (in) 0deg52'
Any comments or questions welcome.
I will pay another visit to the garage when I have time, but I guess these are much better than before and Goodwood enough if you get my four wheel drift /ubbthreads/images/graemlins/grin.gif.
Regards
Dave
Ross Nicol
GT40s Supporter
Dave
Are you reading that level correctly? Rear suspension should crank on neg camber at bump.
Ross
Are you reading that level correctly? Rear suspension should crank on neg camber at bump.
Ross
Dave,
Front toe in is too much, 0-10 min(per side) is more likely, or approx 1mm ( ea side) at tire dia. It is also not uncommon to run toe out at the front but this can lead to directional instability under braking. depends on the car and driver.
There is something awry with your rear suspension. Toe in is way too much and the change from bump to droop is yuk!!
2 deg 30' on a 600 dia tire equates to 26mm toe in. Note comment by Ross N, camber should go more neg on bump. Check your rear caster, The forward lower pivot on the rear upright should be higher than the rearward lower pivot. The angular difference is your rear castor, should be around 7 deg as a starting point. When checking rear toe in statically, camber should set at 0 deg at ride height then adjust camber on track. ( and dont forget to calibrate your piece of string!!
Front toe in is too much, 0-10 min(per side) is more likely, or approx 1mm ( ea side) at tire dia. It is also not uncommon to run toe out at the front but this can lead to directional instability under braking. depends on the car and driver.
There is something awry with your rear suspension. Toe in is way too much and the change from bump to droop is yuk!!
2 deg 30' on a 600 dia tire equates to 26mm toe in. Note comment by Ross N, camber should go more neg on bump. Check your rear caster, The forward lower pivot on the rear upright should be higher than the rearward lower pivot. The angular difference is your rear castor, should be around 7 deg as a starting point. When checking rear toe in statically, camber should set at 0 deg at ride height then adjust camber on track. ( and dont forget to calibrate your piece of string!!
Similar threads
