Well, here's the situation. Between about 40 - 46 MPH when I'm accelerating, coasting, braking or cruising the rear end of my truck will bounce up and down like a tire is severely out of balance. I have had the tires rotated and balanced with no resolution. I replaced the rear shoes and had the drums turned with no resolution as well. I took the truck to a local tire and brake shop that I trust, they drove test it and inspected front and rear brakes. They had no idea and suggested I take it to the dealer. I then took the truck to the dealer, they called back and said it could be faulty U-Joints in the drive shaft (although I hear no noise that they could be failing). I asked specifically if it could be due to faulty rear axle seals or rear bearing going bad, they did not think so advising that if it were bearings that the truck would bounce all the time and not at just one speed. I have seen other posts say that replacing the bearings will fix the problem but have not seen where anyone has actually tried this to fix it. If anyone has any idea what might be causing this or how to fix it, it would save me about $325 for the dealer to try replacing the u-joints.

Thanks!

Shawn

 

What year truck?

4wheel drive or 2 wheel drive?


phox

 

Sorry, having troubles with my profile.

1999 2500 extended cab, 4X4, Auto. Stock

 

I had the same problem, but only when braking. I replaced the rear brake shoes and had the drums turned. Solved the problem for me. I say it's the universals or something in the drive line. It is happening all the time not just braking so something is binding if you have balanced the tires.

 

325 bucks to replace your u joints......holy crap..... even if you use spicer u joints you are only looking at maybe 60 bucks in parts. they are taking you for a ride..i would go somewhere else....my truck did the same thing just came out of nowhere and only did it for a day.

 

Well, I didn't let the dealer replce the U-joints. I didn't think that was the problem. If anything I still think it might be the rear bearings. Anyway, The dealer did do a rotate and balance, today I had to take the truck back to them for the 3rd time becuase the weights keep coming off (stock steel wheels). At this point I'm thinking about trying the antifreeze and water mix in the wheels or ceramic beads to keep my 285/75's balanced.

 

May be a long shot, but how are your rear shocks? My old chevy's bounced like crazy when the rear shocks were bad.

 

Ya Know....You could take Hoss's course of action....CAll The concret company...have them lay 3inches of concret into your bed...

 

it could still be your tires (belt slip radial pull) had that with one ov mine .new tire problem fixed

 

Would the ceramic beads or antifreeze help if it is a tire problem like rebal mentioned? I like the antifreeze idea. I've read were some people swear by it and have had no problems at all with it. How many oz. should I use in each tire?

 

out of round/unballanced rear drums

 

How do you balance a drum? I had them turned, helped just a bit but not much at all.

 

I have the EXACT same problem with my truck. It has been driving me crazy for almost two years!!!!

This is what I have done so far:
Installed new U-joints- Did not improve
Had drive shaft balanced-No improvement
Had wheels aligned- No improvement
Rotated wheels over and over again- No improvement
Removed 6" lift kit from truck, installed new tires with Dyna Beads (balancing beads), installed new Bilstein shocks-No Improvement
Had wheels aligned-No improvement
Replaced one brake drum since it seemed to be warped-Some improvement
Replaced same brake drum again as it was out of balance. I know this by raising the truck up from the frame and letting rear axle hang free while letting the rear wheels turn with the engine at idle and trans in 5th gear. The side of the axle with this drum installed bounced up and down. New drum improved ride some. Bed still bounces.

I am still scratching my head on this one. I hope you can figure it out for me
The new drums I installed are aftermarket ones from Advance Auto. I know these are not balanced since there is no grinding marks or a weight added to balance. I added additional balancing beads as this should compensate for a slightly out of balance drum. But, if the drum is out of balance enough it could flex and cause it to hit the brake shoes.

Did you replace your brake drums with aftermarket ones?

 

I've never been in a 3/4 ton-up Dodge P/U that didn't bounce some, not sure how bad your problem is though. Personally, I have (2) concrete slabs that they use for putting outside Air Conditioner units on (weigh about 90-100 lbs/each) and it makes a world of difference in the ride...no more bounce.

 

my truck doesn't bounce...

I'll happily keep it that way.