Slam when decelerating and reapplying gas at lower speeds

Donvan514 · November 15, 2015

Hello,

I don't know if I'm noticing a tranny issue or a drive line issue. My truck will "slam" on occasion when decelerating and reapplying the gas. This happens at lower speeds. The tranny doesn't slip from what have noticed... Does anyone have a similar slam when at lower speeds and transitioning off and on the gas pedal? I cannot quite pinpoint if it's a slip yoke, u-joint, tranny or other issue.

Thanks,

Matt

tnchevy · November 15, 2015

Several threads already talking about this. Mine does it as well but not all the time, did it twice today on me and has since I bought it. My 2002 always had a clunk when taking off but never when decelerating like my 2014 does.

Donvan514 · November 15, 2015

Thank you... I am just unsure if my issue relates to the other posts. What is the issue directly linked to?

Ltz73 · November 16, 2015

Mine does it and my 2009 did it. Sadly I have accepted this as normal with Chevy trucks.

Donvan514 · November 16, 2015

Thank you

fondupot · November 16, 2015

Slip Yoke. Pretty much every GM truck I have ever driven has done this. Dating back to my Grandfathers 97 GMC Sierra, My old 2002 Silverado, some 2007-2008 work trucks I drove, and even my old 2008 Suburban. Now my 2014 GMC sierra.

You can add straps to your leaf springs to tighten things up. Like in this thread here:

http://www.gm-trucks.com/forums/topic/172777-clunkthud-while-acceleratingslowing-down/page-3

Front Runner · November 16, 2015

I've driven some Ford's that do it too.

waumo1 · November 16, 2015

I've experienced the same with every GM truck (and Yukon) we have owned since 1998. Some other vehicles also. I guess I have just learned to drive in a manner that prevents it from happening except very rarely.

Ltz73 · November 16, 2015

I've experienced the same with every GM truck (and Yukon) we have owned since 1998. Some other vehicles also. I guess I have just learned to drive in a manner that prevents it from happening except very rarely.

My 1967 Chevy truck does not do it.

Donvan514 · November 17, 2015

Thanks everyone. I'm just happy it's not a Tranny issue.

waumo1 · November 17, 2015

My 1967 Chevy truck does not do it.

Does it have coil spring rear suspension?

pm26 · November 17, 2015

Does it have coil spring rear suspension?

i do not think any pickups used coil springs in the back in 1967. Even most passenger cars had leaf springs in the back.

EPIC CAJUN · November 17, 2015

Mine does this also between 1200-1500 rpm when you get off then back on the gas. Sometimes its worst than others. I've had it happen with people in my truck and they thought we got rear ended the bang was so loud and abrupt.

BuyAmericanIron · November 17, 2015

My truck does it all the time. It is one of the reasons GM is buying it back. At steady speeds, mostly around 30 mph if you go up a gentle incline and let off the gas as you crest the top, it will upshift as you let off the gas and give you a clunk along with a slight nudge forward. It was much more pronounced with the first transmission. Not so much with the second. Believing the problem was further back, I pulled the cover off of the rear differential and found a lot of clearance between the center shaft and housing. With the ring gear held firmly, it is possible to turn the driveshaft 1/8 ~ less than 1/4 turn. That is a lot of play in a differential. When you add that much clearance and an upshift at the wrong time, you get a nice clunk that echo's up the long and large aluminum driveshaft and into the transmission.

Back when I was a tech I worked on a lot of police cars. Many had high miles and years of abuse. I can only remember ever seeing one rear end with as much free play as my truck had at 3000 miles. With a tight differential, I am fairly certain the clunk would be much less noticeable and could possibly stop the clunk all together. But this is just my opinion. When I told the dealer about my findings, they said nothing could be done unless it was broken or made a significant whining noise. All I requested was a new center section, but it would only happen if I paid for it. Very disappointing. Hopefully the new truck won't have the same problems.

Donovan, I hope your truck is fixed the first time and you have no more problems. These are great trucks, but if you have the driveline clunk, it takes something away.