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Registered
Join Date: Jul 2006
Location: Daytona Beach, FL
Posts: 310
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Bad Shake HELP!!!
So I have a 1989 Turbo S that is built for club racing (PCA G Prepared class). I am having trouble figuring out a problem. When on track I have a shake in the front end. When I brake it gets worse. When normal driving there is still a slight shake but braking makes it way worse. I feel the shake in the steering wheel vs the brake pedal.
I have brand new rotors and pads that are not warped. I have checked the hubs to see if they are loose and they are tight. The shake feels like a warped rotor but the rotors are dead straight. I have checked the balance on the wheels and they are good. I cant figure out what it could be as everything seems tight. The car has koni double adjustable shocks with 800# springs up front and I believe #600 in the rear. I have removed the camber eccentric bolt upfront and welded in plates so there is not movement in the strut. I adjust camber with camber plates. I run 993TT front brakes, Pagid black pads and 245 Hoosiers upfront. The motor is stock. Hub bearings were replaced over the winter as well as tie rod ends. I also just replaced the control arms with the fabcar arms. I have probably 7 track days on all the new stuff. Any thoughts on what it could be would be appreciated as I need some paths to diagnose. Thanks in advance Brian
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1989 944 Turbo Cup Replica PCA Space Coast Region #44 |
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08-14-2009, 08:17 PM
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Registered
Join Date: Feb 2000
Location: Kingsport, TN
Posts: 2,935
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How did you check your wheel balancing? Whenever I get a tire mounted, I put it on the rear, raise the rear of the car with a floor jack under the tranny and spin the wheels. Lean out the door to see if they are shaking.
With a open rear end, I leave one rear on the ground and spin at 2X speed. Occasionally, one has to go back for rebalance.
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Lawrence 1986 951 2002 SLK32 AMG 1987 328GTS 2011 528i |
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08-15-2009, 06:11 AM
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Automotive Necromancer
Join Date: Nov 2006
Location: Beantown, MA
Posts: 1,544
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little things
remove the wheels and clean the nuts, studs, and mating surfaces. (all of them!) clean and grease the threads. hand tighten the lugs back on and torque the lugs to spec. Drive for a bit and then re torque the lugs. Better?
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There may be nothing quite as expensive as a cheap Porsche: Ruby Red 84 928S : White 87 924s 2.5L NA (Blinky) M44/07-43H10676 spoiler delete - 046/2B - Belts 9/12, Clutch and OC seals 8/08 andd Red 94 Del Sol: Please put your Make, Model and Year in Sig. Try not to break more than you fix. |
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08-15-2009, 12:56 PM
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Back from Beyond
Join Date: Nov 2004
Location: Alberta, Canada
Posts: 2,697
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Are you sure the tires are round? Not kidding. These cars HATE imperfect tires.
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'88 944 Auto - project, kinda '87 944 Auto - died saving my wife '84 944 5SP - crushed under shop roof during snow storm All others GONE! |
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08-17-2009, 10:34 AM
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Automotive Necromancer
Join Date: Nov 2006
Location: Beantown, MA
Posts: 1,544
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flat spot?
Sometimes when a car is sitting for a bit the tires will develop flat spots. These can present some serious shaking. Check the tires for round and that the bead is set evenly all around. Just to be safe, lift up the front of the car and give the front wheels and suspension a check for excessive play.
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There may be nothing quite as expensive as a cheap Porsche: Ruby Red 84 928S : White 87 924s 2.5L NA (Blinky) M44/07-43H10676 spoiler delete - 046/2B - Belts 9/12, Clutch and OC seals 8/08 andd Red 94 Del Sol: Please put your Make, Model and Year in Sig. Try not to break more than you fix. |
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08-17-2009, 11:16 AM
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Registered
Join Date: Jun 2006
Location: O.C. CA
Posts: 4,587
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check the castor blocks
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08-17-2009, 01:41 PM
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