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Q: Shudder or bounce after hitting bump

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My truck is 2wd with rack and pinion steering, I have a shudder or fast bounce only when I hit a bump at any speed and a slight vibration from 40-50mph. I believe the shudder is coming from the rear. I have installed new quality Moog components in the front: upper control arms, lower control arms, wheel hubs, outer tie rods, sway bar end links, and sway bar bushings. I ve also installed new Bilstein shocks all around. I am a part-time mechanic myself, am stumped by what it could be. I assumed the shocks at first then thought it was the front end. What else could cause this? All part numbers are correct. Please help!

My car has 112000 miles.
My car has an automatic transmission.

A: Hello there, thank you for writing in. Base...

Hello there, thank you for writing in. Based off of your details, you may first want to concentrate on diagnosing the speed sensitive vibration at 40-50 MPH because that will be easier to resolve. I would place wireless chassis ears at all 4 corners of the car, probably attaching to the hub/spindle area. Run vehicle at speed necessary to generate the vibration and try to isolate a corner (i.e., switch between the channels and listen at each corner).

If a corner(s) stands out as noisier than the others, see if you have an issue with that wheel/tire assembly. "Imbalance" can easily be hidden (i.e., tire will check out perfectly on balancer but vibrate noticeably) if the issue is a tire defect, abnormal wear or road force related "variation". Resolve that first and see if the symptoms when hitting a bump are reduced or eliminated.

If not, you can use chassis ears as well to diagnose that, although you will have to make many "passes" over a known bump in the road that will create the necessary signal, while switching between the channels on the chassis ears. If you'd like YourMechanic can assist you with this diagnostic by coming to your home or office to inspect the issue.

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