45 MPH Hop / Vibration...anyone had this too?

[Vincent]

Well my tranny seems to be good to go now...no leaks, nice and quiet. Long story, dont ask.

Anyway, the only problem I seem to have left with the truck now at 15,780 miles is a hop from the rear end at around 45 to 50 mph. Its not a vibration, but a harmonic tremor...you could almost swear you can see the tailgate going up and down in the rear view mirror. It will literally shake your innards up.

The dealership has been real good trying to troubleshoot it, but they frankly are running out of options.

They replaced both rear Firestones with new ones after the tech took 4 off a new truck as a test and said the hop went away (although I didnt go on the test ride with him so I cant verify it fixed anything). He said he could visibly see the rise and fall of the old tires while re-balancing them.

Well, that didnt fix anything. I noticed my one piece driveshaft had a significant rise and fall to it as it rotates. This is a very new shaft, installed after the tech bulletin for the 2 piece replacement bulletin.

I had them order a new one piece and am getting it installed tomorrow. We'll see if that fixes anything. If not the service manager says he's going to start a case file ith GM regarding the problem.

I sure hope I dont have to go into buy-back litigation over this. I finally have most of the bugs worked out of the truck (I hope anyway!).

Has anyone run into this problem on their rig and if so, what did you (or your dealer) do to fix the problem??

Thanks...Im at my wits end!!!! :confused:

[mark45678]

with the wheels off and the rear end up off the ground turning the shaft in 1st or 2nd I would not expect any more then 1/8 run out in the center of the drive shaft!

[mcfly]

It's either the driveshaft or the wheels are AFU. When they gave you the new tires, did they replace the wheels as well?


-Rick

[Vincent]

Well the new, new driveshaft didn't get rid of the hop either.

I dropped the truck off tonight and told them do whatever they have to to troubleshoot it and make it right.

I have an all week class next week and I'll be out of town, so it's all theirs. I mentioned buy-back proceedings today and the service manager cringed, saying "Please give us the chance, we'll get it".

I think... no.... I know, I've been more than patient, but this is getting ridiculous.

They are going to check the runout on the rims, maybe change the front tires, etc... We shall see.

I sure hope they can make it work, the truck goes on vacation with me and the family, towing the travel trailer as soon as I get back!!

Any other ideas/suggestions folks??

Thanks so far.

[Vincent]

Well I got my truck back today after a week at the dealership. I let them have at it all week while I was away at school in Salt Lake.

Anyways...the service manager worked it all week and said by friday he was panicking since he was no further than the beginning of the week.

Finally he tried different combos of tires and the vibration/hop all but went away. He said took two fairly new ones off a truck on the lot and put them on mine.

I got home tonight and discovered I have a brand new tire on the left rear and a very worn one on the right rear. Wouldn't a combo like that play hell on the rear locker??

I asked him before I left the dealership "What will I do in the future about roating my tires?"

He said that shouldn't be necessary! Since when??

I have all but given up...I have to take it on vacation. If the rear end goes south I know who to turn to!

[SoMnDMAX]

I've had the dreaded bounce. Started when I installed my 285's last spring, and my 265's did it all last winter as well. My symptoms were identical to yours.

Cause: Tire imbalance. I had a different shop rebalance my 285's this spring, and the bounce is gone. Hasn't come back in the 3,000 miles I have put on since I reinstalled my 285's. Needless to say, I'm happy. smile.gif I'll get my winter skins balanced at the same shop when the time comes.

[ 06-11-2002: Message edited by: SoMnDMAX ]</p>

[Nevada Hauler]

Vincent, You might want to give this a try, have your tires balanced on a Hunter 9700GSP tire balancing machine. These machines are owned by Discount Tire Co. Not every Discount Tire store has the machines so I would suggest you call their regional office at 505.797.7100 to get the location of the nearest store with one these balancers. They call this a "Road Force" balance and what this does is match the tire to the rim and then the balance is completed using any kind of weights you want and where you want the weights(i.e. wieghts all on the inside or behind the spokes-you have to see it!). What this results in is the best rolling unit possible for that tire and rim. This will set you back about $15 or $20 per tire but I think you will agree it worth when you get back on the road with your truck. I saw these machines at the SEMA show in Las Vegas NV a few years ago and was considering buying one myself until I found out that Discount had them. I did the tires on my old '89F350-7.3 this way and could not believe how much better it was.( a Duramax is a whole order of magnitude better though) Good luck with it!

[Searay90]

I went thru this same issue with my wifes suburban. The tires were out of round. Any electronic balance machine can "balance" them for a given speed, but at any other speed, they hop! The people at Discount tire don't even look at the tire when they balance it.. they just put the cover over the tire and press the balance button. Then put the weights where it tells them to. Anyway, I was out there watching them and could easily see the tires were out of round. The first set were kelly springfields. Then I told them I wanted Michelns.. They didn't have th size I wanted in stock so they put a set of goodyears on it. Well in less than 2000 miles I was back in the store and 2 of the 4 tires were out of round. They replaced them and while I watched them balance the new tires, I saw that one of them was out of round. I raised hell with the manager of the store and I got a set of Michilens LTX's put on the truck and they were so smooth on the road. They had 45K miles on them with plenty of tread left when we sold it last year. I have put michilens on everything I have owned over the past 25 years and have never had a problem with them.

I was so frustrated with the hop, that I was ready to buy new rims thinking that they were the problem. Have them put on the tire balancer, and start up the machine, then watch the tire as it slows down. You can see if the tire is out of round.

[odoh]

Vincent ~ In your orig statement, you alluded to previous transmission issues? (we were admonished not to ask) You commented re the driveline?

You have some very good input from experienced DuraMax owners. I've not that experience but recall on my '84 Toyota that if the driveline was removed and not replaced in the exact same location, it would have those horrid vibration. Particularly the driveline from the transfer case to the front differential. Its been too many years to recall why but it made a believer of us to chalk mark locations when R/R, universal joint changeout etc.

Just something to think about if the other suggestions don't work out. ~ odoh

[ 06-12-2002: Message edited by: odoh ]</p>

[Nevada Hauler]

Vincent, The issues raised by Searay90 are the types of problems the "Road Force" balance is used to correct. If it can't be made to run smoothly at all speeds this will show up on this machine. Try it.

[Vincent]

Thanks for the advice folks...I'll hunt down one of those Road Force balancers and give that a shot.

The dealership tried and tried all week to get the hop out of my truck and I'd say they were maybe 60% successful. It is better, but it still has tremors depending upon the load, road surface, etc.

They ended up swapping out several sets of tires with trucks on the sales lot until they finally found a set that would smooth it out somewhat.

I dont really want to litigate over this, and I have to take off on vacation with the truck tomorrow so I'll see how it goes.

Maybe I'll go with a set of Michelins or BF Goodrichs somewhere in the near future. Even that is an expensive gamble on getting rid of the problem though, unfortunately.