Suspension Bottoming Out

Tiny
DEE DEATHERAGE
  • MEMBER
  • 1999 PONTIAC TRANS AM
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 103,000 MILES
I recently purchased this car. It seems to have problems bottoming out or dragging underneath when hitting small dips or bumps. I have a 1999 Z28 Camaro and did not have this issue. Any ideas or suggestions on how to fix this? I have replaced shocks and struts all the way around the vehicle and still have this problem. Wonder if this is a common issue with this model vehicle since it sits so low to the ground?
Monday, July 11th, 2016 AT 9:05 AM

3 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Has the car been lowered? It may have prior to you getting it and nothing was said about it. Bounce the suspension three times by hand on front end then take measurement in pictures. The Trans Am will sit lower than the Camaro.
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Monday, July 11th, 2016 AT 9:45 AM
Tiny
DEE DEATHERAGE
  • MEMBER
  • 2 POSTS
Okay, thank you! Anything that may help this? Taller tires?
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Monday, July 11th, 2016 AT 9:55 AM
Tiny
CARADIODOC
  • MECHANIC
  • 33,922 POSTS
Hi guys. You mentioned the struts and shocks. Those have nothing to do with ride height. It's sagged coil springs that must be replaced. That's where measuring ride height is important. Along with that, even though the numbers on an alignment computer might show everything is in perfect alignment, that is only for a car that is sitting still on the hoist. For a car in motion, the suspension geometry must be correct, and for that to be true, ride height must be correct. A conscientious alignment specialist will not align a car that is sitting too low because there IS going to be accelerated tire wear and poor handling. Only new springs will solve that. Many mechanics save their customers money today by installing new struts with the new springs already installed. Parts cost more but installation time is cut a lot.

Taller tires will add all kinds of new problems including rubbing, especially if the car is already sitting too low. The speedometer will be wrong. You'll also affect an alignment angle called "steering axis inclination", (SAI). That will adversely affect handling, steering response, braking distance, and comfort. Your steering is already very tiring on long drives because it is "busy" by responding to every twig and pebble on the road. Changing SAI will aggravate that to the point you won't want to drive the car.
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Monday, July 11th, 2016 AT 11:18 PM

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