Clunk/thud while accelerating/slowing down

sugarjohnson · June 9, 2015

Got it....I may give this a try

towerrigger · June 9, 2015

Give it a shot. Did this on the weekend and took away all the clunking I had going on. Initially thought it was the tranny, had the update done for the 8 speed. The update made it worse if anything. Installed the shackle brackets on the springs like pic posted and it's gone for now.

ToesonTheNose · June 9, 2015

how much did you torque the bolts?

nadrojcote · June 9, 2015

I didn't torque them I just tightened them really tight. With the shackel straps you have to tighten really tight because the bolts have splines that have to squish into the strap holes.

nadrojcote · June 15, 2015

I just had my service tech check for tsb's and recalls associated with this on my truck and the only one he could find was TSB 010730042. I can't find any information on it online, but he read it to me and it describes the problem perfectly. It said that there was a clunk in the rear driveline during 1-2 up shift and 2-3 down shift. There is no fix for the TSB and it says the issue is normal. So it looks like the only fix at this time is the clamps. This is also only on 2014's. This TSB doesn't exist for 2015's he said.

towerrigger · June 15, 2015

Ha! Typical. "Perfectly normal". The clamps have definitely got rid of the clunk. I find now if I brake really hard I will get the clunk. May have to try the clamps on the other side of the springs.

GMC-AT · June 15, 2015

I put the clamps on last week - overall improvement

sugarjohnson · June 15, 2015

I'm going to try the clamps as well. This is really the only annoying thing about my truck...ok maybe a few other things but the clunk drives me nuts. I was actually looking at other options like traction bars but they are $$$$.

nadrojcote · June 15, 2015

I'm going to try the clamps as well. This is really the only annoying thing about my truck...ok maybe a few other things but the clunk drives me nuts. I was actually looking at other options like traction bars but they are $$$$.

Originally I was too, but in reality a stock height vehicle shouldn't need traction bars. It's bad enough we have to clamp our leaf springs.

BOOMER119 · June 15, 2015

Got the clamp kit at Autozone. $16.99 for the set of 2, 1 for each leaf spring. Put 'em on after work. Maybe a slight improvement in trans response??? Truck didn't seem like it was trying to figure out what to do when accelerating out of a turn so much. Did feel more "planted" overall. We'll see how it goes over next few days.

BTW - Is there any advantage to putting clamps on both sides of the leaf spring (front & back of axle)?

sugarjohnson · June 15, 2015

Got the clamp kit at Autozone. $16.99 for the set of 2, 1 for each axle. Put 'em on after work. Maybe a slight improvement in trans response??? Truck didn't seem like it was trying to figure out what to do when accelerating out of a turn so much. Did feel more "planted" overall. We'll see how it goes over next few days.

BTW - Is there any advantage to putting clamps on both sides of the axle (front & back)?

+1 on this question

nadrojcote · June 16, 2015

+1 on this question

Others have said it will make the ride really stiff, if anyone tries it let us know how it goes.

fondupot · June 16, 2015

BTW - Is there any advantage to putting clamps on both sides of the axle (front & back)?

It might help to make the leaf pack tighter, but it will probably ride rougher with both sides done.

sugarjohnson · June 17, 2015

Well I'll be damned...the clamps did fix my clunk issue! Any long-term issues leaving them clamped on?

nadrojcote · June 17, 2015

Well I'll be damned...the clamps did fix my clunk issue! Any long-term issues leaving them clamped on?

gmt900 owners didn't have any long term complaints that I know of. If anything I would say it should make your leafs last longer because they aren't flexing as much