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Suspension question????
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NASA Rocky Mountain Region

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TOPIC: Suspension question????

Suspension question???? 12 years, 3 months ago #1035

  • Skimr2
  • OFFLINE
  • Drivers Ed
  • Posts: 16
So I have had the understeer problem for a while, I have a rear weltmeister bar in the garage that I am going to install tonight, but I was thinking that I needed to reindex the rear torsion bars on the car to get a little more ride height.
Current setup is as follows....
-2 camber Front
350 springs front
koni yellow full soft
Weltmeister front bar, full soft

30 mm torsion bar (suspected, not confirmed)
Noticeable rear camber, needs to be confirmed with a good alignment.

The car came up from AZ and is running pretty low in the rear. Check out the following pic...

and this one...

Re:Suspension question???? 12 years, 3 months ago #1042

You have an understeering set-up in that car and alot of it.

Here are a few things to take out understeer

Front
Camber -2.0 -> go to -3.5 --- reason is that -2 is just not enough.

Rear
Ride height Level front to rear at the rockers - Rear end low is no right for 350lbs front springs you need the car level front to rear.

Add in welt bars. - If you run 350's and the front welt you will need the rear welt even at a soft setting. Otherwise too much understeer.


Now what is interesting is that a rear end low set-up can work, but not with front spring you have. With 250lbs front springs you could make all that work. The reaons is that 250lbs front and 30 mm rear t-bars produce an oversteering set-up, but no rear bar and low rear end tend to balance this out. With 350lbs fronts the car will push like a pig. However when you have 350lbs fronts you can get all the balance back by doing what I stated above.
Joe Paluch
944 Spec #94 Gina Marie Paper Designs
Arizona Regional 944 Spec Director, National Rules Coordinator
2006 Az Champion - 944 Spec Racer Since 2002

Re:Suspension question???? 12 years, 3 months ago #1046

  • Skimr2
  • OFFLINE
  • Drivers Ed
  • Posts: 16
The car previously had 400 spings on it, and I went to the 350 trying to soften the front end up.
The camber setting in the front was determined and set using a good tire pyrometer, and so, I know the tire is being used all across the surface area, and they are wearing evenly.
The car did have a rear sway bar, it was an 18mm non adjustable unit.

Re:Suspension question???? 12 years, 3 months ago #1047

Skimr2 wrote:
The car previously had 400 spings on it, and I went to the 350 trying to soften the front end up.
The camber setting in the front was determined and set using a good tire pyrometer, and so, I know the tire is being used all across the surface area, and they are wearing evenly.
The car did have a rear sway bar, it was an 18mm non adjustable unit.


Well you can put those 400's back on if you put the rear welt on there and raise the rear end. Plus add backs some negative camber. I tried to reduce my front camber from 3.5 to 3.0. Well turns out the car had too much understeer like that and worked better at -3.5. I also lowerd the front end by 1/4" and stiffened the rebound on the front shocks. Result was my corner exit full throttle understeer was gone and I picked up 0.5 seconds on a 1:14 lap.

Right now the -2.0 might be ok since the rear is too low and not causeing the nose to dive alot in the corners. As such you can run -2.0 and not wear the outside of the tire. Either that or you are not pushing the car hard enough to roll it over. Even so with 350/30 you will want a level front to rear ride height and welts front and rear.

I think the issue is that the set-up on Billy's old car was just not very good. When he was running I don't believe he got enough track time to really see where it was off. Now this is not a big deal in that all you need to do tweak some stuff to get it where it needs to be.
Joe Paluch
944 Spec #94 Gina Marie Paper Designs
Arizona Regional 944 Spec Director, National Rules Coordinator
2006 Az Champion - 944 Spec Racer Since 2002
Last Edit: 12 years, 3 months ago by joepaluch.

Re:Suspension question???? 12 years, 2 months ago #1524

  • Skimr2
  • OFFLINE
  • Drivers Ed
  • Posts: 16
Suspension update!
I have the ride heiht adjusted, it was time consuming, but really not that hard. So now I can make sure the car is level. BUT, I found out that my T-bars were not 30mm as I had believed (why I don't know) but they are actually 24mm. Quite a drop in stiffness. I am worried that after all this it will still understeer. Anyway,
what springs are people running with 24mm torsion bars?
I am also taking the car in for an alignment tomorrow, does anyone have a good setup for 350lb springs, 24mm Tbars, and welt sways front and rear? I was going to start at -2degrees camber all around, and play with the front ones with temp gauge from there. Toe? 0 front and rear?
Thanks, looking forward to some action Saturday!

Re:Suspension question???? 12 years, 2 months ago #1529

The 24 mm bars are a bit softer than most of us run but with the right set up front to rear they would be very fast ! I would say lets swap out those 350lb springs for some 300# springs and see how you like them. I have a spare set and will bring them to Miller. If you like them i will trade you for those 400# springs.

As for setup ...
My starting guess is

rear
1/8 to 3/16 total toe in
neg 2.5 camber

front
0 toe (Easy to adjust at the track)
neg 3.0 camber (agian easy to adjust at the track)
max equal positive caster

Look for my green van and we can put your car right up on the open pit trailer. we can Swap those springs in no time !
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