Re: Lurching 40 to 50 mph slight hill
 

Unfortunately, not the same problem. Mine bucks like poor gas or cylinder misfire, but neither are occurring, and the engine rpm is rock solid. Got a call yesterday that an engineer thinks it is caused by the exhaust system... but I think the front differential carrier bushings sounds more like what is happening. Time will tell as the dealer will look at it more next week.

And again to all, the local Hummer dealer is trying everything and is being responsive - it is a GM design problem that appears endemic to all H3s, more in some than others.

Re: Lurching 40 to 50 mph slight hill
 

I'm sure your dealer's service dept. is doing all that they can. After all, it's in their best interest to keep you as a returning, satisfied customer. The guys (and gals) at my dealer's service dept. are also good people. The service mgrs appeared almost as frustrated as I was over my H3 issues. But what the GM/Hummer Corp Customer Service person had told me was true ... another dealer's service dept MAY have come across a similar problem to mine and know what to do. I think that my H3 may have been the first one in with the problem and they (first dealer) didn't know what to think of it after trying different fixes. The 2nd dealer obviously had another H3 with a similar problem like mine, so it was a quick fix for them. If your dealer can't locate your problem, then going to another for THIS concern may be your answer. Good luck and keep us posted. :)

Re: Lurching 40 to 50 mph slight hill
 

Dealer has put on Toyo AT Load D tires and I would say about 70% of the shuddering is gone. Can someone explain why new tires would do this?

Kinda ties in with the problem first being noticeable at around 7000 miles, and getting worse with more miles.

Re: Lurching 40 to 50 mph slight hill
 

Sounds like a good question for Goodyear tire!!

Re: Lurching 40 to 50 mph slight hill
 

Maybe the wheels weren't balanced right.

Re: Lurching 40 to 50 mph slight hill
 

Goodyears were balanced twice by Discount Tire and three times by Hummer dealer. Made no difference.

Perhaps the thicker tread allowed the tire to absorb more the rotational jerkiness?

Or perhaps the tire is much heavier and the rotational inertia damps out the drivetrain? Hmmm. How to ADD weight to a wheel is something I have never seen written up before.

Re: Lurching 40 to 50 mph slight hill
 

So Dave The Tires. That was it?:confused:

Re: Lurching 40 to 50 mph slight hill
 

Unfortunately, the new tires after a few hours of driving really only reduced shuddering maybe 40%. Helped to have heavier ones, but not the cure. Still has the driveline shuddering enough to be annoying, particularly once you are tuned into it. Plus, LT tires ride harsher than P tires due to the higher air pressure.

Re: Lurching 40 to 50 mph slight hill
 

Dave, did you ever get your shuddering/lurching problems completely resolved, or, are you just going to live with it?

Re: Lurching 40 to 50 mph slight hill
 

Buy back in progress....

Re: Lurching 40 to 50 mph slight hill
 

Ohhhhh mannnnn! Ok .. this could be good. Are you going to go for an H2 this time??? :beerchug: