High speed instability issue
#231245
02/21/09 01:05 PM
02/21/09 01:05 PM
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Joined: Jan 2003
Posts: 686 Houston, Texas
FastOrange
OP
mopar
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OP
mopar
Joined: Jan 2003
Posts: 686
Houston, Texas
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70 challenger. ladder bar/coil over car with front shocks on 90/10 setting. Strange double adjustables in back. Extension set at max, rebound set in the middle. Big Block torsion bars. 35 psi air pressure in radial tires. Stock suspension. Car hooks nice and straight but gets unstable at high speed. Ran 129 mph twice last night but it was all I could do to finish the run. I had to lift on a 3rd run because it started getting sideways. My front end is aligned but it is mechanically limited on caster degrees and is set at around zero. I'm not sure if the shocks are keeping the front end nosed up unloading the tires or more positive caster will fix the issue. Any suggestions? Also, what front shocks and settings are usually good with a ladder bar car?
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Re: High speed instability issue
[Re: FastOrange]
#231246
02/21/09 01:32 PM
02/21/09 01:32 PM
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Joined: Sep 2005
Posts: 2,442 LOWELL IN
QWK_ENUF
top fuel
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top fuel
Joined: Sep 2005
Posts: 2,442
LOWELL IN
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no caster means big trouble get adjustable upper control arms and put 6 degrees in it , it will be like you are on rails
WAXER
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Re: High speed instability issue
[Re: QWK_ENUF]
#231247
02/21/09 01:37 PM
02/21/09 01:37 PM
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Joined: Feb 2006
Posts: 698 Alberta Canada
Edge
mopar
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mopar
Joined: Feb 2006
Posts: 698
Alberta Canada
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I agree aftermarket tubular upper control arm can give you the caster you need to to help the car self center, zero caster could be pretty dangerous IMHO
good luck
76 Duster
work in progress
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Re: High speed instability issue
[Re: QWK_ENUF]
#231248
02/21/09 01:38 PM
02/21/09 01:38 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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0 caster or negitive will mess you up. On the front shock, run them just loose enough to get the front to rise on the launch. Also make sure there's no binding in the front end EDIT also make sure your not toed out with the body up 1"(1" up is where the alignment should be done at)
Last edited by MR_P_BODY; 02/21/09 01:40 PM.
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Re: High speed instability issue
[Re: MR_P_BODY]
#231249
02/21/09 02:43 PM
02/21/09 02:43 PM
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Joined: Jan 2003
Posts: 686 Houston, Texas
FastOrange
OP
mopar
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OP
mopar
Joined: Jan 2003
Posts: 686
Houston, Texas
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Thanks fellas. The alignment was done at 1" raised. About Tubular A arms. What choices do I have? Pros/Cons? I would prefer a simple Bolt-in if possible. Sounds like I need to try another shock setting too.
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Re: High speed instability issue
[Re: dvw]
#231257
02/22/09 10:19 AM
02/22/09 10:19 AM
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Joined: Jan 2003
Posts: 686 Houston, Texas
FastOrange
OP
mopar
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OP
mopar
Joined: Jan 2003
Posts: 686
Houston, Texas
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That is some good info to consider. I already have the offset bushings in the upper arms and the strut rods are tight and have poly bushings. I'm still questioning the shock settings at 90/10. I wonder if the front end is maybe higher than one inch raised at the end of the track which changes the toe setting?. I have had the car aligned twice with the same results.
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