Clunk/thud while accelerating/slowing down

CounterMeasure · June 21, 2015

I finally gave in and clamped mine. Haven't driven it enough to see what difference it makes though as the weather hasn't been conducive to running it hard. For those with Denalis, you'll have to clamp out at least 5 inches. Otherwise, you risk hitting the magnaride sensors on the frame when the springs deflect up.

nadrojcote · June 21, 2015

I finally gave in and clamped mine. Haven't driven it enough to see what difference it makes though as the weather hasn't been conducive to running it hard. For those with Denalis, you'll have to clamp out at least 5 inches. Otherwise, you risk hitting the magnaride sensors on the frame when the springs deflect up.

looking forward to your update. I think you might be the first to do this on a denali.

CounterMeasure · June 21, 2015

looking forward to your update. I think you might be the first to do this on a denali.

I did put about 15 miles on it a few hours ago running errands. The results were unexpected. The truck isn't as bouncy or jolting as before. I don't know if the magnaride dampening just happens to work out nicely with the change in spring rate or what. I didn't notice any clunking, although it was already infrequent. The commute to work tomorrow will give some good data, as it has about 10 miles of 80mph concrete tollway. So far, so good.

stevev · June 22, 2015

amazing, this mod does work, my clunks have been greatly reduced. I got the kit from Autozone (for 2.5" wide leaf springs - watch because they also sell one for 3" wide leafs). I installed them about 5 inches in front of the axle like suggested on here, and did it without removing the rear tires. I just crawled under the truck and attached the plate/nuts on the bottom of the leafs.

edit: after more driving tonight, I say this mod got rid of 75% of my clunks. I still get them occasionally, but when I do, they seem less severe and less noisy (bang sound) than before.

SouthernSilveradoGuy85 · June 22, 2015

Well if anyone is interested to know I installed some clamps on my leafs and it helped a lot, the clunking is still there but its very minor compared to before. It shifts nice, fast and smooth now with my diablosport.. I think I will still replace my old leafs to improve the ride. I couldnt find leaf clamps anywhere at this time of night so I bought shackle straps and bolts. They seem to hold in really well.

Do you have any kind of part #s or anything because I can't find them anywhere and I don't like the ones from the auto parts store like Autozone and O'Reillys because they look cheaply made where the Rockwell American ones you have look heavier duty.

nadrojcote · June 22, 2015

I don't have part numbers, I think fondupot has an extra set of the kit I used. Lots of guys have used the cheaper kits on other truck forums and had no issues.

SouthernSilveradoGuy85 · June 23, 2015

I checked the u-bolt nuts that hold the axle to the leaf springs and every since one was out of TQ specs. I ended up doing at least 1 full turn on all of them to put them into spec. I hope that was the problem. I didn't hear or fell the clunk a lot, but did once in awhile.

JCJ · June 24, 2015

Has anyone tried to put a help spring on to help this issue or just using the leaf or shackle clamp?

BOOMER119 · June 25, 2015

It may be all in my head, but I think this mod has helped slightly with the transmission issues as well.

Driveability has cleaned up quite a bit ... almost like the transmission knows what to do now :-)

I still have acceleration issues when getting on it coming out of a turn. Seems like I'm in too high of a gear and tranny wants to downshift several times. After all the downshifting and clunking around it finally moves out, but I've NEVER had a car or truck do this before.

nadrojcote · June 25, 2015

It may be all in my head, but I think this mod has helped slightly with the transmission issues as well.

Driveability has cleaned up quite a bit ... almost like the transmission knows what to do now :-)

I still have acceleration issues when getting on it coming out of a turn. Seems like I'm in too high of a gear and tranny wants to downshift several times. After all the downshifting and clunking around it finally moves out, but I've NEVER had a car or truck do this before.

Its quite possible the truck knows that the yoke isn't moving around as much and doesn't have to think as much to shift.

Has anyone tried to put a help spring on to help this issue or just using the leaf or shackle clamp?

It will stiffen it up quite a bit, but in theory should do the same thing.

bdbake01 · June 28, 2015

Been thinking about this more lately. Springs have definitely loosened up since new. I do like the ride, but it gets dis-shoveled over pavement breaks, etc. And the pinion clunk of course.

But, I think I'm gonna go traction bar. Theoretically this should reduce the wrap to virtually nothing without any impact on spring rate. The clamps, while they do stiffen the springs by virtue of increasing the "solid" area in the middle, seems like it would transfer more of the work during movement to a slightly smaller area of the springs which, over time, could maybe cause those areas to deteriorate faster? I may be over thinking that. It's kinda like having a spinal fusion. Sure, helps the trouble spot, but now the vertebrae above and below have to bend even further than OEM spec to allow for full movement of the back.

Never made a traction bar before. Doesn't look too hard

[email protected] · June 28, 2015

I bought the clamps but they didn't have the bolts in...can I get away with an grade 8 or black steel, rated bolts??

Sent from my SM-N900W8 using Tapatalk

nadrojcote · June 28, 2015

I bought the clamps but they didn't have the bolts in...can I get away with an grade 8 or black steel, rated bolts??

Sent from my SM-N900W8 using Tapatalk

it should be fine. I'm sure the clamp just bolta really aren't that high rated.

Kerrslight · June 30, 2015

Installed the leaf clamps from auto zone today. From the short distance I've driven since installing them, I don't think ride has stiffened up much at all. I will say like others have stated I do feel more planted to the ground. Transmission feels smoother for sure. Not as jolty as before and smoother shifts. Seems less confused. I can't comment on the clunking as I didn't have that issue before, but cheap, quick, and easy mod that makes a good difference

stevev · July 1, 2015

I just took my clamps back off temporarily. My truck has always shifted fine, but I just had the clunks. The clamps only got rid of some of the clunks. But to me, I think it did stiffen the ride and it seemed like I could feel more vibrations (just slightly) in my seat when driving locally. Since I took the camps off, I don't feel the slight vibration in the seat anymore.