New gears/truetracs..return of the vibrations

[RS Warburton]

Problem solved. Here's the story:

I gave up. After doing everything I could to driveshafts, runout, angles, etc. I took the thirds out, had them checked by a gear shop. Everything checked out fine. Traded the thirds and the driveshaft to a guy for his stock thirds, rotoflex driveshaft, plus some cash. We install them in his D2 last Sunday. He gets the same vibrations. He indexes the driveshaft, checks runout, etc. No improvement. He's at the dealer doing some checking with the head tech, who suggests he try the old rear driveshaft out of his D1, which was removed while the tech chases down vibrations in it. He puts the u-jointed-at-both-ends driveshaft in his D2. No more vibrations.

Dang! If I had only known. Of course, I already had a rear GBR u-jointed driveshaft when I put the 4:11's in, had it rebuilt/rebalanced, didn't make a difference. We are assuming that the factory shaft may have smaller u-joints, and less overall mass, so that might be why it works.

Turns out there's another guy in town who went through the same thing we did, he had his 4:11's and truetracs installed a couple of weeks after I did and had bad vibrations. Ended up with a D1 u-jointed driveshaft and solved his problems.

I'm going to miss those 4:11's.

 

[RS Warburton]

On the road again Saturday evening. 3:54's, truetracs, original rotoflex. Smooth as silk, at least up to 75. Life is good.

But I still miss those 4:11's. So does my transmission.

 

[Disco Mike]

Richard,
I have been sitting back and watching how this thread turned out before tossing in my 2 cents worth. I also have a 99D2 that I had 4:11 gears, rear Detroit with hd axles and a front TT installed, all of which was supplied thru Bill at Great Basin.
I have a 3" lift with stock drive shafts, the rear being a roto flex. I had this lift for about a year prior to having the diffs rebuilt and never experienced any problems with vibrations or noises of any kind.
The day I got the truck back from the shop it started shaking, vibrating, making droaning noises and I initiall thought it was just needing to break in. At 1000 milesa I changed the fluid, using a GL6 rated 140wt oil hoping it would go away, and it never did.
After 6 months and a number of visits to different axle shops I bought another set of Bill's 4:11's and had them installed by the same shop, Drive Line Direct, and all my problems went away for about 3000 miles and then it came back, just not as bad but at 55 to 60 the vibrations is there. Again we rechecked everything including the drive shafts and everything is perfect, BUT what we did find is a very uneven wear patter on the first 4:11 ring gear that 2 different drive line shops say caused the problem.
I also spoke to Bill a number of times looking for some help with this problem, even sent him the first set of bad gears and only received a letter back from him stating that his diff man said they were OK, even though 2 drive line shops in Calif. say they are bad. It was mention that Bills supplier could have turned out some bad gear set and others may be having the same problems.
Maybe we should talk, if you're interested and see what we can do to get some help.
Mike J.

 

[RS Warburton]

After having the third members checked out, I had to rule out the gears. I'm not 100% positive that they aren't contributing to the problem, but the fact that Sean and Joe both eliminated their vibrations with a factory driveshaft tells it was/is a driveline issue. It's been a very frustrating ordeal, and I'm keeping tabs on what develops with Sean and his driveshaft issue to see if he can eliminate the problem. I know Joe has, and he had the exact same symptoms. I can live with 3:54's, but if I keep the D2 for more than another year, I will seriously consider trying 4:11's again.