Front Driveline Problem... Please Help!

DSN46 · October 9, 2009

Hello,

I have been throwing parts and money at a noise, and am at my wits end. Almost went today and traded my Tahoe in for an Expedition EL.

Here is exactly what I am hearing in the best way I can describe it:

A "slow throbbing" wuuump, wuuump, wuump from somewhere under the truck while going at highway speeds, quiets down when foot off-throttle. Then a short "rub, rub, rub" noise in time with the wheels when going slow. Neither is very loud, but you notice it.

What I have done: Had the rear axle rebuilt. This took care of the pinion bearing noises I had. Replaced all U-joints with Spicer joints and had both driveshafts straightened and balanced at Florida Powertrain (great shop by the way).

What I have since found: Put it on a lift with tranny in Neutral. Spinning rear tires by hand, I hear rear brake pads rubbing slightly, I think this is normal? I hear TC parts moving inside of it. I can jiggle both front and rear output shafts on TC up and down just a little, BUT I can hear the chain moving inside when I do. Normal? Remove front tires / wheels. Spinning the front hubs by hand, I can hear (and see) the rotors are just slightly warped.... meaning that each time the wheel rotates, I can watch the rotors barely contact pads then be free of them... makes a slight rub sound "swish, swish, swish".

Here is the biggee: When I rotate the front, driver's side wheel, I hear "click, click, click" noises coming from the front differential. The clicking is faster than the rotation of the wheel. Passanger side is quiet. Not sure but is sounds like it is right where the CV shaft enters the diff housing.

No play or noise from the front Hubs themselves.. and they are not overly hot after highway miles.

I have been to the shop that rebuilt my rear axle again, but they want to throw parts at it and take more money. I don't have much more to give! Can someone PLEASE tell me if they have heard any of this before in their experience and let me know what it was? Or give me the right part to throw at it next?

Thank you for your patience in this long post. I appreciate any advice.

James

jimc · October 9, 2009

James,

My truck makes the exact same "whump-whump" noise from the front of the vehicle at highway speeds it's very noticeable. Has been for a long time. I attributed it to the tires wearing funny since when i get the tires rotated, the noise changes and is not as noticeable. After miles are put on the tires again, the noise re-appears. Try swapping your tires front to back and see if the noise changes or disappears.

I've notices that my rear tires are very flat and square across the bottom, fronts tend to wear a little different. Once i rotate them, it's only a matter of time before the relocated rears wear like the fronts were. The rears, of course, tend to flatten back out. I've got BFG AT's, which have about 55-60,000 miles on them. Still have decent rubber left, so they'll probably last till next year. I only put about 3-4,000 miles a year on my truck since it's no longer a daily driver.

I'm due for an alignment, so I'll have them rotate the tires at the same time. I'll make sure to check to see what the noise does.

Jim

DSN46 · October 10, 2009

Thank you Jim!

I dont think it is tires though. The tires on it are 5-Day-Old, brand new Firestone Destination AT's. I wish it was that easy brother...

Thanks again,

James

jimc · October 10, 2009

Did your truck make this noise prior to the new tires, or I guess maybe the reason you bought them, to eliminate the noise? I was going to suggest that maybe they hadn't balanced them properly and was causing them to make the noise.

If this is in the 4X4 Tahoe in your sig, it seems that the only thing in common with our trucks is the 4X4. I would suggest that it's got to have something to do with the front CV's or the way the suspension is handled. Though, I doubt your Tahoe has torsion bars.

Wish I could be more help. Always pegged my noise as tire related. If you figure it out, let me know.

Jim C.

DSN46 · October 10, 2009

Jim,

I removed the front driveshaft and drove today. The sound was quieter. This leads me to believe that it is in the front Diff.

My Tahoe does have the Torsion bars up front just like yours. But I think I have at least isolated the noise to the front differential.

By the way.. I DO have one tire that needs attention... it is going "whup whup whup" at slow speeds. Can feel it in the steering wheel. Gonna go out and move it to the back/right side and see if the noise moves with it.

I'll let you know if a front diff rebuild does the trick.

Thanks again,

James