rear wheel bearings or U-joints?

[rob21]

I have searched this topic and have not found exactly what im looking for. I had a gear swap done and should have had them replace the bearings while they were in there since they have to pull the axle out anyway. Anyways, im chasing a washboard like rumble at highway speeds. between 55 and 70mph i have this faint washboard like effect while going down the highway, and ive narrowed it to either rear wheel bearings, or U-joints. Tires are new and i have ruled out the torque converter. It does it when i let off the gas pedal and shift into neutral, so i dont believe its the engine shuddering. What are some symptoms of a wheel bearing going bad? U-Joint? What are some checks I can do to either diagnose it as being the problem or rule it out? Anything else im missing? I know it is not the rear gears, as it was doing this before the gear swap. Does the driveshaft have weights somewhere I can check also?

 

[mindgame]

Before going back into the rear, I would change the U joints since it is a easy and less man hours of work..

 

[Yudaman]

Could also be pinion bearings and/or gear mesh.
If the gearset was shimmed wrong, that could cause all sorts of issues. You could be feeling gearbind on deceleration.
Please tell us you had a reputable shop do your gearchange and not your buddy Phil for a case of beer.

 

[rob21]

Before going back into the rear, I would change the U joints since it is a easy and less man hours of work..

Yea i think im going to start with this. Done it before on my F250 so I know it wont take too long or be labor intensive.

Could also be pinion bearings and/or gear mesh.
If the gearset was shimmed wrong, that could cause all sorts of issues. You could be feeling gearbind on deceleration.
Please tell us you had a reputable shop do your gear change and not your buddy Phil for a case of beer.

it was doing this before the gear swap. Swap was done by a gear guy who is well reviewed over on LS1 Tech. He does a lot of GM rears and GM trans gears. No whine/chatter during acceleration/decel. He did the work right. Im going to start with the U-Joints and take a look around the drive shaft.

 

[GAINMOB]

and alignment isn't an issue?

 

[rob21]

and alignment isn't an issue?

Freeway whats up man!

Although I have not had it checked, the alignment does not seem like an issue. She tracks pretty much straight down the road.

 

[superexpy]

If the rumble doesnt change when under a load or coasting I would thing its wheel bearings. Can you tell if its coming from one side or the other.

 

[rob21]

If the rumble doesnt change when under a load or coasting I would thing its wheel bearings. Can you tell if its coming from one side or the other.

I want to say its coming from the passenger rear. I guess I could jack up the rear of the truck, spin the wheels and listen?

 

[superexpy]

I want to say its coming from the passenger rear. I guess I could jack up the rear of the truck, spin the wheels and listen?

Feel for roughness while spinning and also try wiggling it too see if there is any movement. another thing you can do is go drive it at 55mph + for a few minutes and then feel your wheels. If you feel one hotter then the rest, Then that will probably be your trouble wheel. It could also be your brakes too.

 

[tonydiv]

The guy who did the gear swap would have to be a real door knob not to notice bad driveshaft u-joints when he was doing the gear swap. I mean he had the driveshaft in his hands at one point during the swap.

Wheel bearings will rumble and make get louder the faster you go. When they really get bad, you will sometimes hear a knocking when you hit bumps.

Often times the noise will also change if you swerve left and right at speed (this usually only happens when the front bearings are bad).

 

[rob21]

Feel for roughness while spinning and also try wiggling it too see if there is any movement. another thing you can do is go drive it at 55mph + for a few minutes and then feel your wheels. If you feel one hotter then the rest, Then that will probably be your trouble wheel. It could also be your brakes too.

I will try this tomorrow. Interesting technique.

The guy who did the gear swap would have to be a real door knob not to notice bad driveshaft u-joints when he was doing the gear swap. I mean he had the driveshaft in his hands at one point during the swap.

Wheel bearings will rumble and make get louder the faster you go. When they really get bad, you will sometimes hear a knocking when you hit bumps.

Often times the noise will also change if you swerve left and right at speed (this usually only happens when the front bearings are bad).

He told me that "the u-joints look good, but you never know." He said nothing with the drive shaft looked out of the ordinary. I will focus my attention to the U-joints and bearings and post back over the next few days. Thanks for the help.

 

[JUST4FUN]

if you want to kill to birds find a drive shaft place to balance and replace the u joints.