Hard jerk coming from drivetrain

[hockeymanam]

I have an 06 H3 that when traveling at hwy speeds and let off the gas and get back on it, I get a solid jerk and a clunk sound coming from the back of it.

So if I'm in the O/D gear and let off to coast or whatever then go back to the gas pedal thats when it feels like there is slack in the driveshaft and by letting off it lets it slides forward and getting back on the gas sends the driveshaft back making the noise i hear and feel....

I do not know if this makes since but if someone can decipher this description please let me now what you think could be the problem

 

[SuperBuickGuy]

your best bet is to put it in the air and look for looseness

set the emergency brake and try to turn the driveshafts and half shafts. wiggle everything.

if the driveshafts check out, put the vehicle in neutral then check the backlash.

you say "a noise" what noise? whine? clunk? rattling?...

 

[hockeymanam]

its a solid clunk that happens when i get back on the gas after a brief let off only at 50+ mph

 

[Best4x4]

If the drive shafts check out it kinda sounds to me like slack in the transfer case.

 

[amrg]

Check ur front diff cross member bushing. I had a similar thing and turned out to be that.

 

[SuperBuickGuy]

Check ur front diff cross member bushing. I had a similar thing and turned out to be that.

that's a great place to start - problem is, you'll never see it wobble. To find out, put some wide washers between the bolt and the rubber bushing. If the noise goes away, bingo, your problem. I took pictures of replacing mine - it's on my SAR H3 build thread. The other one, could be the CV in the driveshaft - apparently those are pretty common to fail... if you catch it soon enough, it won't take out your transmission (wiggle it, it shouldn't wiggle).

 

[alrock]

For some of the crossmember bushing failures, you can watch the failure. One person in the truck, another watching the diff and crossmember. Putting it in/out of gear or reverse, you can see the diff rise up away from the crossmember and crash back down.