Clunk on take off

pickupman87 · March 18, 2016

Hello,

2014 Silverado CC 6.5box. Sometimes when I'm fully stopped and go to take off I get a quick clunk before the truck starts moving (reminds me a lot of my old 99 w/ slip yoke issues). When I hook my boat up to the truck (small 16ft, 1000lbs) it does it at every take off and sometimes when I stop.

Any thoughts?

I brought it to the dealer and they 'could not replicate'... They inspected the slip yoke and said it all looks good. Frustrating. Short of bringing it to the dealer with my boat in tow - any thoughts on what would be causing this?

Thanks,

Pete

CounterMeasure · March 18, 2016

Check torque on leaf spring bolts. There's been many reports (me included) that these bolts were not torqued to spec of 85ft/lbs, and there's a bulletin on it. As such, it caused a clunk on launch and sometimes at stop. I could replicate it by power braking the truck to load up the rear end or if I had a bunch of weight in the bed or towing. Once retorqued, problem solved.

pickupman87 · March 18, 2016

Sorry, I should have noted that. I've tightened the leafspring / Axle U-Bolts to 78ft/lbs. Played around with clamps on the springs - if I put the clamp behind the axle it happens more frequently (most stop/starts w/o trailer), in front of the axle I haven't given a fair shake because it seems to make the truck vibrate more.

SouthernSilveradoGuy85 · March 18, 2016

Ya the U-bolts aren't tight enough. I had the same problem and torqued them to the right specs and haven't heard a clunk since.

scottl1346 · March 18, 2016

i second the u bolts i found mine torqued 15 - 30 ft lbs it seems a fair amount of clunkieness went away

GMCSierra4x4 · March 19, 2016

pickupman87, on 18 Mar 2016 - 10:18 AM, said:

Hello,

2014 Silverado CC 6.5box. Sometimes when I'm fully stopped and go to take off I get a quick clunk before the truck starts moving (reminds me a lot of my old 99 w/ slip yoke issues). When I hook my boat up to the truck (small 16ft, 1000lbs) it does it at every take off and sometimes when I stop.

Any thoughts?

I brought it to the dealer and they 'could not replicate'... They inspected the slip yoke and said it all looks good. Frustrating. Short of bringing it to the dealer with my boat in tow - any thoughts on what would be causing this?

Thanks,

Pete

Do you have the 6 speed or 8 speed transmission? My transmission was replaced under PI1450 (clunk on launch). The diagnostic step in the PI is straight forward. Built prior to December 1, 2014.

Warm transmission to at least 140F

Place transfer case in 2WD

Drive vehicle up to about 40 mph

Release throttle and bring vehicle to a stop

Launch vehicle and listen for snap or clunk

Repeat several times to confirm

If the test confirms the noise, replace the transmission. Anyone can do the diagnostic steps. Also, see PIP5200.

pickupman87 · March 21, 2016

Do you have the 6 speed or 8 speed transmission? My transmission was replaced under PI1450 (clunk on launch). The diagnostic step in the PI is straight forward. Built prior to December 1, 2014.

Warm transmission to at least 140F

Place transfer case in 2WD

Drive vehicle up to about 40 mph

Release throttle and bring vehicle to a stop

Launch vehicle and listen for snap or clunk

Repeat several times to confirm

If the test confirms the noise, replace the transmission. Anyone can do the diagnostic steps. Also, see PIP5200.

6spd.

I've torqued my U Bolts to 78 and then some. Doesn't do it without a trailer. Put a little boat behind it and it happens at every stop.

hirdlej · March 21, 2016

Do you have the Z82 suspension? There's a recall on the hitches due to cracking. Perhaps the receiver is shifting or moving? Have you checked to make sure it's tight or that it's not cracked anywhere?

HondaHawkGT · March 21, 2016

The spare tire will clunk too. Mine had loosened up and made a lot of clunking. I also went around torqing every bolt on the rear suspension. Even the bed mounts could make a noise if they're lose enough.

The plastic pads on the ends on the leaf clamped to the main leaf can get dirt under them that will create friction that causes them to make creaking and clunking noises.

pickupman87 · March 21, 2016

Do you have the Z82 suspension? There's a recall on the hitches due to cracking. Perhaps the receiver is shifting or moving? Have you checked to make sure it's tight or that it's not cracked anywhere?

I do, but the recall doesn't affect my VIN. I guess I didn't look close enough at the hitch but I don't believe that's it. I get the same clunk on take off w/o a trailer if I put the spring clamps 6" behind my axle.

harveyfamily · March 21, 2016

Mine does it but I assume it's due to the Torque Management.

As much as I'm afraid of getting a tune done before the warranty is out I may end up doing it just because my truck feels sluggish no matter what I do. It acts like an 18-wheeler: slow upon takeoff but cruises just fine.

GMCSierra4x4 · March 21, 2016

The transmission replacement fixed my clunking and almost all of my driveline vibration is gone at lower speeds. I will check highway speeds later this week.

oburgtiger · March 22, 2016

I've noticed the same thing on my truck. It seems to be coming from the front end, not the leaf springs. It's on the list for the dealer to check out next time in the shop. My truck is a November 2013 build, but I bought it new from the dealer in July of 2015 and it still only had 470 miles on it. Who knows what happened from it sitting around for so long, though.

pickupman87 · March 23, 2016

I ordered some Blisten rear shocks - I'm going to give that a shot first before I bring it to the dealer again. Each trip to the dealer ends up costing me about what it would for the rear shocks so I might as well rule that out.

sk · March 23, 2016

I ordered some Blisten rear shocks - I'm going to give that a shot first before I bring it to the dealer again. Each trip to the dealer ends up costing me about what it would for the rear shocks so I might as well rule that out.

Why do the trips to the dealer end up costing you? If your truck is a 2014 it should still be under B2B warranty and if that is expired the powertrain warranty should still be good. It shouldn't cost you anything to have it checked!!