Clunk/thud while accelerating/slowing down

nadrojcote · May 22, 2015

OK ProjectSummit, I've got questions.

How many miles did you have on your truck when you put the shackles on?

How many do you have now?

Any wear problems or downsides to doing this?

Was the main/only reason for doing this the clunking on shifts?

How long are leaf springs supposed to last? I've never heard of them being worn out or replaced before your post. Well, aside from people doing stupid things like pulling 15,000lbs trailers with light duty trucks or something like that.

Thanks! :-)

1. 78,000kms

2. 79,000kms

3. If you clamp too tight you could crack the leaf springs, probably highly unlikely

4. My main reason for for clunking, not that I've done it I notice that I have less body roll and more planted feeling

5. I'm not sure how long they're supposed to last, but my truck was owned by a farmer who has stuff in the back all the time and I would assume towed a lot. The leafs are fairly worn out and are now warped and w-shaped where they mount to the axle.

If anyone is noticing clunky shifting due to axle wrap its worth trying. Just clamp them on and drive for a couple days, if you don't like it take them off.

nadrojcote · May 22, 2015

I just called a local spring shop and they said these springs are way too soft. They add a leaf and re-arch about three of these trucks a week and this is a small town. They also said its common for our leafs to be w-shaped and also for them to sit lower on the drivers side.

CounterMeasure · May 22, 2015

My plan this weekend is to apply rubber sheets between the leafs per another thread and clamp to see if that solves my problem. Anything worth doing is worth doing overkill. After the dealer tightened them down, they only clunk/thud/pop when its wet, which this has been Texas year for that. I believe the water is acting as a lubricant just enough to allow them to have play. Will report back on how that goes.

nadrojcote · May 22, 2015

I've seen people shim them, but I thought they were using flat stock metal not rubber.

CounterMeasure · May 22, 2015

I've seen people shim them, but I thought they were using flat stock metal not rubber.

My plan was to do something like http://www.gm-trucks.com/forums/topic/140196-if-anyone-has-a-clunk-from-leaf-springs-when-moving-laterally-i-hav

Kerrslight · May 28, 2015

I just called a local spring shop and they said these springs are way too soft. They add a leaf and re-arch about three of these trucks a week and this is a small town. They also said its common for our leafs to be w-shaped and also for them to sit lower on the drivers side.

It's funny that you say that. I've always wondered why it looked like the rear of my truck was slightly lower on the drivers side. I swear I make myself crazy about it sometimes. I tell myself its not leaning, its just the driveway, it's just the parking lot, that tire has a little bit less air in it than the rest.....is this a fact? I wonder if replacement leafs would solve this problem

nadrojcote · May 28, 2015

It's funny that you say that. I've always wondered why it looked like the rear of my truck was slightly lower on the drivers side. I swear I make myself crazy about it sometimes. I tell myself its not leaning, its just the driveway, it's just the parking lot, that tire has a little bit less air in it than the rest.....is this a fact? I wonder if replacement leafs would solve this problem

It's pretty common on all vehicles, you can measure to see. even if you did fix the rear with stiffer leafs, the front will still be unlevel. I wouldn't let it bug you. Next time youre driving and you see a bagged out old vehicle with the rear end sitting really low, or one side leaning really bad just tell yourself it could be worse!

Kerrslight · May 28, 2015

It's pretty common on all vehicles, you can measure to see. even if you did fix the rear with stiffer leafs, the front will still be unlevel. I wouldn't let it bug you. Next time youre driving and you see a bagged out old vehicle with the rear end sitting really low, or one side leaning really bad just tell yourself it could be worse!

Yea I have measured in the past. If i remember the truck was pretty level minus the driver side rear. I was 3/4" lower than other corners. Took it to the dealer and they took the stress off the leafs, bounced it and re-assembled. Left the dealership with 1/4" lower than other corners. By the time I got back home it was at 1/2". It's only the driver side rear tho. Front is level. I do see other trucks, not just chevy/gmc, but also ford, dodge that have a slight lean, some worse than others. What annoys me though, is when I see a perfectly level sierra or silverado when i know mine is unlevel. Who knows. I'm just really anal about the smallest things.

nadrojcote · May 28, 2015

Yea I have measured in the past. If i remember the truck was pretty level minus the driver side rear. I was 3/4" lower than other corners. Took it to the dealer and they took the stress off the leafs, bounced it and re-assembled. Left the dealership with 1/4" lower than other corners. By the time I got back home it was at 1/2". It's only the driver side rear tho. Front is level. I do see other trucks, not just chevy/gmc, but also ford, dodge that have a slight lean, some worse than others. What annoys me though, is when I see a perfectly level sierra or silverado when i know mine is unlevel. Who knows. I'm just really anal about the smallest things.

I hear ya! I'm very picky about every little thing. I just had to leave work to set my tire pressure different and go for a drive to make sure it rode better afterwards. I'm also about to spend $30 on some UHMW tape to reduce the friction of my door seals so they dont creak and squeak.

CounterMeasure · May 28, 2015

I didn't clamp mine after all. What I found out is that while the leafspring ubolts were tight, they still were not torqued to the 78ft/lbs the spec I was given calls for. The driver side nuts were around 60ft/lbs, while the passenger was around 70ft/lbs. So I loosened them all on both sides to relieve the load and allow the leaves to settle, and then retorqued the nuts to 78ft/lbs in the correct pattern. No more clunking/popping. Need to recheck the nuts tonight, but so far, so good!

Silverado-Hareek · May 29, 2015

I just called a local spring shop and they said these springs are way too soft. They add a leaf and re-arch about three of these trucks a week and this is a small town. They also said its common for our leafs to be w-shaped and also for them to sit lower on the drivers side.

I thought they're supposed to be stiffer on these trucks than the GMT900's?

But yes both my 2007 and my 2014 lean slightly lower on the driver's side. I too used to think I was crazy and say it was just the driveway. Although on completely level/flat ground, I don't notice any lean.

pm26 · May 31, 2015

I feel like ATF is too viscous. It would just all come out right away.

Lol, I remember back on my 2002 GMT800 silverado I dropped the drive shaft to pack the splines with grease. But I forgot to put the parking brake on the truck. As soon as I got the drive shaft out of the truck, it started to slowly roll out of my garage. Luckily my garage is not too sloped and it moved slow enough for me to crawl out and hop into the truck and stop it from rolling.

Too viscous? No, not viscous enough. The thicker the stuff, the higher the viscosity, i.e. resistance to flow.

Pat Grant · May 31, 2015

I noticed it this morning for the first time (I finally drove with the radio off...lol). But once I drove several miles and got all of the driveline nice and warmed up, it went away. My guess is the sound I heard in mine was due to the increased drag in the driveline from a cold engine, tranny and diff.

fondupot · May 31, 2015

Too viscous? No, not viscous enough. The thicker the stuff, the higher the viscosity, i.e. resistance to flow.

Thats what I meant yea..

sugarjohnson · June 1, 2015

I didn't clamp mine after all. What I found out is that while the leafspring ubolts were tight, they still were not torqued to the 78ft/lbs the spec I was given calls for. The driver side nuts were around 60ft/lbs, while the passenger was around 70ft/lbs. So I loosened them all on both sides to relieve the load and allow the leaves to settle, and then retorqued the nuts to 78ft/lbs in the correct pattern. No more clunking/popping. Need to recheck the nuts tonight, but so far, so good!

78 is the correct torque spec on those ubolt nuts?