Okay, so the old threads about this are all mostly closed without conclusions which is why I'm starting this one.

I've got a shake in my truck, and am trying to find the cluprit; please read on:

The shaking becomes noticeable around 65mph, and gets worse and worse the faster I go. I think i can notice it even below 65, but it's hard to tell.

Thinking it was from the front end, where I had other problems, I replaced the hub bearings and cv shaft on the passenger side front wheel. The problem is still there, tho that did fix another problem. It is worth mentioning I've since had new wheels installed with the old tires, but the shake was there before and the intensity is still the same. New rotors and pads on all wheels, but there is no change with the shake.

It is hard to tell if it is from the front or back, but since it makes the whole car shake, I think it's from the rear. Another reason why I suspect this is because the rear right side wheel sticks out about 0.5-0.75" further than the passenger side rear wheel. This winter, probably around the same time I noticed this shaking, I slid in the snow and the back wheel slid sideways into a bank -- which could have caused that offset, but I'm not sure. I have since replaced the rear shackles, though the old ones didn't really look bent. Could I have bent the stabilizer bar which is keeping the rear end crooked and maybe causing this wobble?

The drive shaft is tight, I can't wobble it or feel any looseness, but I can wiggle the transmission a little bit. Is that odd? It looks to me like it has 2 bolts connecting it to the frame with a rubber pad between the two. If that is supposed to be rigidly held in place maybe this is the reason for the shaking?

I don't think the e-brake drum brakes are sticking. I've pulled the wheels off the back and there is no side to side play in the hubs, tho I can pull them in and out a few millimeters.

Yes, I've had the wheels balanced when installed and the tires aligned, but it didn not change the shaking. My theory right now is that whatever is causing the wheels ot be out of center is causing the driveshaft to be unbalanced, and making things shake. If the shackles are straight, what else could control rear wheel alignment?

Thanks in advance, I know I just wrote a novel up there but hopefully it's clear.

 

The rear axle should be centered. The roll bar should not cause the rear to be pushed to one side. I would start there. You may have bent an axle in your collision.

 

Thanks, I think that's a good place to start as well...

I had thought I may have bent an axle, but talking to some coworkers who are car savvy, they all seemed to think that if I'd have bent the axle, there would be fluid from the axle or differential all over the place. I am learning cars as I go with the truck, so while I've looked high and low on the internet, I have never seen firsthand how they fail and can only believe the things I hear.

How could I tell if the axle was bent? Since it only happens at high speeds, I assume the bend, if any, is small and not visible to the eye. I've had an alignment done, and they didn't say anything about it either. But unless the frame is bent, which I doubt, SOMEthing in there is not right.

Thanks for the reply and tips. Hopefully I can resolve this soon because a speed cap of 65 mph sucks haha

 

A bent axle flange (end of axle) may not cause the axle to leak. This can be checked with a dial indicator fixed to the axle tube with the point on the inside of the rim. Spin the tire and note the deflection.

The fact that the tires stick out more on one side than the other means things are tweaked somewhere.

 

tires any need to be balanced

 

even though the drive shaft seems to be snug, it still may be out of balance. Thats the same problem I had with mine. Just something I thought might help

 

Hello I currently have a 1996 GMC Jimmy 4x4 and it is doing the exact same thing. It starts around 50-55 just a little but by the time I get to 65 it is horrible and it does it to about 80 then it slacks off a little. I have new tires that are balanced, and I needed a new idler arm but that did not solve the problem. My boyfriend is a mechanic and builds engines and trucks all the time and works on big cranes like what are at the mines and he cant figure it out. Help any one!!!!

 

This is still plaguing me! Since my old wheels did it and so do the new, balanced, wheels, I think it is safe to say it isn't a balancing issue.

I did a rough look at the straightness of the outer edge of the rim on all four wheels and they look pretty much straight.


I think I'm going to take it on the highway and have a friend follow and see if he notices any wheel that looks to be shaking, so I can find which wheel is the culprit, if any.

 

The cause is more than likely related to the accident you had. But there are other things that can cause this as well. Toe out increases with speed, and if it gets excessive, will cause shaking. Pop your tie rods and screw them in a few turns, then drive it to check. Its worth a shot.

 

I fought this with the wife's 4x4 Jimmy, front hubs, new tires, re balance tires, balance them again, u-joints, swap rotors, new rotors, back in for a balance, new tires, finally I bought a rear end off a blazer and threw it on one night. Smooth and quite.

I suspected that it might have been curbed, but I think the rear outer bearings were the reason (it was a ton quieter after the swap too).

Justin