Jolt and Shake Issue

Tiny
RMOORE09
  • MEMBER
  • 1984 CHEVROLET CELEBRITY
  • 6 CYL
  • 2WD
  • AUTOMATIC
What would cause a car to jolt when put into drive or reverse? Also, what would cause it to shake especially the steering wheel when driving highway speeds?
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Sunday, July 24th, 2011 AT 5:55 AM

4 Replies

Tiny
CARADIODOC
  • EXPERT
The jolting problem could be worn engine mounts or worn suspension parts. The shaking most commonly is an out-of-balance wheel but could also be caused by a bent wheel, broken tire belt, bent hub, even a warped brake rotor. Worn lower control arm bushings or struts could cause both problems. The best approach is to have the steering and suspension systems inspected at a tire and alignment shop.
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Sunday, July 24th, 2011 AT 6:34 AM
Tiny
RMOORE09
  • MEMBER
Thank you. My car has three motor mounts. One mount has been replaced and the other two are fine. Every now and then the car will bang when you put it into gear. I was going to ask what suspension part it could be? Also, is this problem serious and can it get worse? Thank you for answering my question.
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Sunday, July 24th, 2011 AT 6:47 AM
Tiny
CARADIODOC
  • EXPERT
For starters, watch the engine while a helper shifts between drive and reverse to see if it's rocking back and forth a lot. GM likes to use a "dog bone" mount on the top front. It isn't really a mount; it's to control engine movement. The rubber bushings in it can deteriorate. Idle speed that's too high can cause harsh engagement too.

Without knowing if other parts are related to the problem it's impossible to say if it will get worse. Instead, other parts could be damaged from the banging. In particular, exhaust parts are designed to shift position gradually as the engine rocks. If there's too much movement, that can stress those exhaust parts and hangers. Wire harnesses will be flexing a lot which leads to rubbed through wires and loose connector terminals. Fuel and emissions hoses will be flexing more than normal.

If engine movement appears to be normal, watch the two front wheels to see if they move when switching between forward and reverse. If one does, suspect the lower control arm bushings or strut. If idle speed is too high, suspect a vacuum leak. Use a spray bottle to spray water on the vacuum hoses and intake manifold gasket while the engine is still cold. If you see water get sucked in or the engine slows down momentarily, check that area for a leak. You can also pinch off vacuum hoses to try to identify one that's leaking.
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Sunday, July 24th, 2011 AT 7:13 AM
Tiny
RMOORE09
  • MEMBER
Thanks. When I put it into gear, The block shakes back and forth once. It shifts just fine driving. I dont think the wheels move when in gear although it will move a little bit when put into park. I believe my idle could be turned up too high. Also, sorry but I was mistaken earlier on the drivetrain, the car is a front wheel drive.
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Sunday, July 24th, 2011 AT 7:21 AM

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