Thump when taking off... HELP!

Zembonez · April 2, 2006

UPDATE - Problem solved! Spline in driveshaft was dry and needed lubed. Quiet as a mouse now! WOO HOO!

Well... here is one for you. I have an 01 Silverado 4.3 AT regular cab and when you pull away stop you get a thump in the trans/rear end area just when you start to move. It doesn't happen every time but does it quite often. All services have been done... any ideas?

RyanZ71 · April 2, 2006

If it's a 4X4, then it's probably the Slip Yoke. VERY common problem on the 99-2003 models. Solution:: replacement with a nickle plated Slip Yoke.

sonjaab · April 2, 2006

Many times what your hearing (after you check out you slip

yoke for excessive play) is "axle wrap"and involves axle

preload upon acceleration from a dead stop.

This is the ends of the leaf springs hitting against each other.

In older trucks the rubber? spacers between the springs are worn

or are missing...........geo

asilverblazer · April 3, 2006

That bump feeling like some one tapped into your rear bumper is definatley different from the slip yoke, I've had both, and cured the slip yoke.

Zembonez · April 4, 2006

That bump feeling like some one tapped into your rear bumper is definatley different from the slip yoke, I've had both, and cured the slip yoke.

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I agree... I will certainly check the slip yoke as well. I thought it might somehow be "dry" and not moving freely. This truck has a Fabtech 3" Lift on it which would make the yoke not insert as far as stock. The lift has been on the truck for 3 years. Leaf springs are in good shape. I have aftermarket rear shackles with urethane bushings but they seem to be moving freely. The noise is more felt than heard and it doesn't feel like worn Ujoints or driveline play. Feels like it is originating around the pinion / rear axle area to me. I like the fact that it never gets worse but I sure am looking forward to solving it.

Thanks for the input everybody... I'll let you know if I get it fixed.

nalineeds24s · April 10, 2006

I had that problem with my 2000 Escalade, my problem was when the transfer case fluid was changed the GM blue fluid was not used. I drained the transfer case and put in the GM stuff in that took care of the problem. Has something to do with the clutch in the auto transfer case needed the GM blue fluid.

torx · April 10, 2006

I had that problem with my 2000 Escalade, my problem was when the transfer case fluid was changed the GM blue fluid was not used. I drained the transfer case and put in the GM stuff in that took care of the problem. Has something to do with the clutch in the auto transfer case needed the GM blue fluid.

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I believe GM's fluid is mineral based and the aftermarket synthetic is all petroleum based. Anyone here confirm this?

bajakid2 · April 11, 2006

hey i have the same exact problem with my 2000 silverado z71...and it feels like its coming from the back end sometimes then sometimes the front...would things should i check out?it kinda sounded like my shocks but then i looked into it and i guess not any ideas of wat i would look for?Thanks

nalineeds24s · April 11, 2006

hey i have the same exact problem with my 2000 silverado z71...and it feels like its coming from the back end sometimes then sometimes the front...would things should i check out?it kinda sounded like my shocks but then i looked into it and i guess not any ideas of wat i would look for?Thanks

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I thought mine was in the rear end at first, sometimes it would clunk, sometimes it would honk / squeak, sometimes both. I checked over everything and it all looked good, so I started with $10 on the Blue Fluid, and 30min to change it. After reading some of the forums it was the most inexpensive thing to try for this problem, and luckily for me that was the fix.

Black-Z71 · April 11, 2006

Mine was more of a squeak/chirp...it was the slip yoke. I had the new nickel plated one installed, and fixed the problem...drives great now.

bajakid2 · April 11, 2006

hey thanks for the help,ill get some of the blue fluid and change it and see how it does from there...thanks for the help

Zembonez · April 22, 2006

If it's a 4X4, then it's probably the Slip Yoke. VERY common problem on the 99-2003 models. Solution:: replacement with a nickle plated Slip Yoke.

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UPDATE - I pulled my driveshaft and lubed the slip yoke internally with high quality synthetic wheel bearing grease (the green stuff) and the problem is gone. It was bone dry inside except for the factory grease way down in the end of the cavity. I cleaned it all out and replaced it... There isn't any danger of it contaminating my tranny fluid since it is inside the splines and was dry when I pulled it out.

I'll see how long it works! Thanks for the tips guys. I am just glad to have the noise and "bump" gone!

ken1mod · April 22, 2006

this is a really common problem with leaf spring suspensions, that is why they are only used on trucks, I guess we are tougher.

I read a post here that mentioned replacing the rubber bumpers between leaves with rubber cut from rad hoses. the guy said it worked great. I'm fixin' to do this as mine is getting really clunky.

Ken