Thump/shudder above 50

Live Fee or Die RT4WD · February 2015

1991 RT4WD..shudders above 50 mph. It started on the way home from work. Below 50 it's fine, anything above that it shudders. It feels like something is slamming the front right tire. The shudder does not change if the car is in gear or neutral. IIRC, the shudder lessens when accelerating... I will test that out again just to be sure. I jacked up the car and looked for any wheel movement/slop. None. The CV axle boots were not torn. I did notice when I twisted the axle there was some kind of play but the axle looked fairly new. The Axles and half shaft on the other side were solid. No issues there. I looked at the other various suspension linkages and did not find any movement (the suspension is complicated!).

I did have new tires put on recently and I changed an outer tie rod end. The car does not pull. I will recheck my work.

Any suggestions or tips? I've read that an out of balance wheel may cause this...

civtec350 · February 2015

it does sound like it could be an out of balance wheel. you could try rotating the tires to see if it moves the shudder to another corner of the car.

Live Fee or Die RT4WD · February 2015

Thanks for the tip. I rotated the front tires. Problem persists and shudder doesn't seem to have move. I can say for sure that putting the car under load decreases or eliminates the shudder. I'll try moving the fronts to the rear and see what happens. I'm going to check the back wheels/suspension and see if something is loose there too.

Because the shudder changes under load, I question the CV axle. They "look" good but there was some shaft play if I pushed up.

Ryanthegreat1 · February 2015

Loose CV joints will most definitely cause vibrations at speed. Inner joints will vibrate harder with load and outer joints get worse with speed and turning.

I have only gone through 6 half shafts now. Learning really quick what sort of failure causes certain vibrations. Yay for junk chinese half shafts!

TheBarber · February 2015

I'll second that. Usually worn inner CV's will give you a bad vibration under accel/load and the outers will give you a general vibration although in my experience it is not as intense. It's a pretty common failure now days as most are aftermarket and are total crap. Just keep the receipt and keep changing them out. It still could be another issue like bad u-joints, diff mounts, bent wheel or separating tire. Rotate the tires front to back, and make sure to check all drive-train components. I check front CV joints by lifting the car completely in the air, blocking one wheel and accelerating. It tends to work pretty good when one is especially bad as the vibration will disappear when the bad one is blocked. But its not so effective if they are both bad or if other drive-train components are shot. Obviously don't try this with locking differential.

Live Fee or Die RT4WD · February 2015

Thanks for the advice on the CV's! The shudder was very bad, like someone was hitting my car. I called the tire shop and they recommended cleaning my tire of snow (we've been hit with 3 or 4 feet of snow in just a couple of weeks). That helped but it was still bad. So I had the shop re-balance my wheels and now the shudder is gone. But, in the meantime it sounds like the unbalance wheel killed the front two CV axles (I switched the front two wheels). Darn. Autozone has axles... is their "gold" set worth it?

MrJayDM · February 2015

I have never had problems with Autozone axles, now their upper and lower ball joints are SHIT!!
I would get them, Plus they are lifetime warranty...
if the boot rips take it back!!

Live Fee or Die RT4WD · February 2015

Thanks MrJayDm. Ordered a set of axles from autozone. Now, just waiting for them to come in.

Thump/shudder above 50

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