New gears/truetracs..return of the vibrations

[RS Warburton]

Like a few others here, I got my GBR 4.11's in a few weeks ago. Had the complete third members sent with truetracs front and rear (99 D2). Replaced them two weeks ago and had a new set of vibrations at 55 and 65 indicated speed. More of a rumble than a vibration. Switched driveshafts around: no improvement without the front, a little improvement with the rear removed. Ran without the e-brake drum, no change. Took the driveshafts to get rebuilt and rebalanced. Installed last night, no change. Knowing that the driveshafts are spinning at a faster speed, I have to assume it's something in the driveline. I had a tolerable rumbling before, but this is very noticeable.

My question is, does anyone have any experience with the truetracs causing this? Maybe they need a break-in period? CV joints - they seemed to be in good shape when I pulled the axles, but are the truetrac exposing any issues with them that weren't apparent with the stock open diffs and the 3.54 gearing?

Last fall and spring, in order to eliminate the vibrations I had before, I rebuilt the front driveshaft (GBR), installed the GBR rear driveshaft, and replaced the transfer case. All was okay until the new third members.

Any ideas?

 

[LostInBoston]

I have a TT up front and have no vibration issues. Im currently intalling my GBR 4.10 gears, so far the rear is dont with no vibration. I have a slight vibration issue with my TW front drive shaft which i will eventually get balanced. Are you sure that you installed the 3rd members correctly?

 

[GregH]

Did you damage a pinion bearing upon install? I'm assuming you had Bill install new bearings and I'm also assuming you properly filled diffs with diff lube also. Are those new U-joints being kept lubed as well? Did you install driveshafts in phase?

 

[Snwbord24]

Maybe a stupid question but did you maybe lose a wheel weight or somehow lose the balance in your tires?

 

[Sergei]

Rumble is ok - you got lower gears - they are more loud than 3.54. Also there is break-in time for gears, when they are actually experiencing load and getting used, and you will get some lovely metal shaving in your first diff oil change (which you should do at the end of break-in period). You shouldnt drive at fast speeds for long distance till that period is ended, btw.

However vibration shall not be there is differential is set up properly.You may have to contact Bill to clarify that part, as it his product (seeing you got complete 3rd members).

Only thing i can think of, if everything was done correctly , is that for some reason crown ring or pinion got some high point which isnt got grinded off at set up b/c of some mistery... Is it oscilating rumble or just constant sound? Is it increasing with acceleration? & etc.

Can of course be something like not properly bolted shafts - are you sure all bolts torqued equally?

I got front TT and have no issues with it whatsoever. Apart from occasional funny sounds when its engaging/disengaging.

 

[RS Warburton]

The third members were built by GBR and sent as a complete unit, so the only installation involved was removing the old and bolting in the new. Maybe I missed something, but it was just a matter of bolting the new ones back in place. I don't know of any alignment that is required for mounting the diff to the axle housing. Pulling the hubs and axles shouldn't have changed anything to cause vibration, besides they're still rotating at the same rpm's as they were before the switch, so I discount them as a cause.

Yes, I did fill with diff fluid. The u-joints were greased, and now there are new ones, so that is eliminated. Driveshaft phasing? Do you mean driveshaft u-joint yoke orientation? I didn't pull the slip yoke out, so the driveshaft alignment wouldn't have changed. As for re-bolting the driveshaft in the same position, I didn't match mark the t-case flanges because with a new complete third member it would be pointless. At least I think it would be pointless.

I am going to try to check the runout on the pinion flanges, and possibly the mating of the driveshaft flange to the pinion flange.

Wheels aren't an issue since they were just a remove and re-install process.

LostinBoston: What was the reason for going with a Tom Woods driveshaft? I ask because I had tried one last fall to see if that would correct the vibration issues back then, but it only made it worse, since it was a bigger/heavier driveshaft. But that was caused by a t-case output shaft with too much run-out. How much lift do you have? I'm running OME heavy duty with a winch/RTE bumper in front, and 3/4" spacers on the rears. Nothing radical, so I've discounted that as the root cause.

Thanks for the input. I'm still open for suggestions.........

 

[RS Warburton]

It is an oscillating rumble that increases from 65 and up. I had talked to Bill a couple of days ago, but we didn't reach any conclusion. I'm trying to eliminate the obvious before targeting the diffs. After all, I did have a faint rumble before the install, but not enough to worry about. I'm still thinking the higher driveshaft rpm and the tighter diffs are making a pre-existing condition become more apparent.

Break-in was one of the things I first thought about. I've read or was told though that a break-in period was not required. What kind of break-in are we talking about?

Just keep feeding it money, it will be happy.........

 

[Sergei]

Here is good article on break-in
http://www.randysringandpinion.com/tech/techg0698.html

 

[Randy]

Richard, mine do it too, and a friend has the same issue. I have TT front, Detroit rear, same vibrations. I'm told it is all about the angle of the drive shaft because of lift. I guess technically the third and the output from the xfer case are supposed to be pn a parellel plane. when you lift, you change the angle slightly. Custom radius arms that change the angle of the third are supposed to help.....

 

[RS Warburton]

I keep pondering the lift factor myself. I've heard the lift causes it, I've heard the 2" lift isn't enough to make it do that, etc. I know several D2 owners with more lift that don't have any vibration issues, so it's hard to pinpoint it. Have you done anything to try to correct the vibration? I almost bought a multiple double-cardan front shaft from Tom Woods, but they and many others said that I didn't really have enough lift to warrant it. Plus, if the vibrations are caused by run-out of some other component, the vibrations would be worse with that kind of shaft.

..........Randy Maynard.......... - didn't you buy something from me a while back?

 

[Ron L]

Generally on gear swaps the mildest of vibrations pre-installation, will increase substantially. Generally it has nothing to do with break in. Every time I have seen it has been a balance issue on the drive shafts or a u joint that is on its way out. On my Toyota, I had bad harmonic vibes from 70-100 mph, at a 100 they would go away completely. Come to find a slight balance problem completely wore the u-joint on the rear shaft.

 

[LostInBoston]

I put a TW drive shaft up front becasue i wanted a multiple DC. im runnign a 3.5" lift. The lift alone shouldnt cause a lot of vibrations untill the ujoints start wearing out. I had stock drive shafts for about a year with my lift with no vibrations until my front one blew up suddenly on the highway.

 

[Sergei]

Ahemm.. thats not quite true.

Any kind of lift will cause vibration with stock shafts, b/c they are simply not designed to handle drive angle change.
You may be lucky to not notice that, but its there.

Simple u-jointed driveshafts on D1 is totally way off for lift. DC shaft on later D2 (i think its stock there, is it not?) is better b/c it can
transform angle a bit.

However - lift always changing angle. Even slightest change of angle cause shafts to produce vibration. No matter how good they are. Only real solution is "double double " type on both shafts, but its pricey.. Double joined end can compensate angle of driveshaft..

In very simplistic picture:
--]t-case[-- at normal "stock" condition
/]t=case[\ with lift and stock shaft ends
/*-]t-case[-*\ shafts with double jointed ends

Also lift compromizing how well pinion bearings are lubricated in both differentials. Due change of angle they arent getting as much oil as they used too. And that angle causing some vibrations too btw. Fix for pinion angle is to get some hacky corrected arms.

As you go lower in gears driveshafts has to rotate faster, so whatever before was noticeable at higher speeds - wll now appear at lower...
With lower gears its very important to keep checking your driveline every now and then, making sure its all well lubricated ans tight..

 

[marc olivares]

richard,
this is a symptom of an out of balance tire. (don't completely rule it out)
i was building up a D1 last winter (gears lockers links d/s etc...)
while moving the tires around the shop, i lost a weight on one of the tires.
the vibe drove me crazy, i rechecked everything only to find that after i had exhausted my possibilities, that one of the tires was a bit out of balance.
the 4.1 gears are louder than the 3.54 but should not "rumble" as Sergie states.
if the vibe wasn't there before you started i would look at tires, then diff set-up.

 

[scrover]

Yeah, I agree with Marc. Try swapping your tires front to back (don't forget to adjust the pressure) and see if there's any change in the rumble.

SC

 

[RS Warburton]

Keep the info coming, all good ideas. I switched to my mud tires last week, no difference. Even the extra noise from the tires didn't help. So I'm going to rule out the tires for the time being. I've got someone checking the runout on all the driveline flanges, but his opinion is that it's break-in on the new gears. He said he's seen this before in D2's and they will require several thousand miles before their settled. This seconds Sergei's comments, but is contradictory to other's comments.

I'm seriously thinking of switching to a multiple DC front driveshaft, and adding a DC rear driveshaft, even though I don't have more than 2" of lift. But that's a hard decision to reach due to the expense and the unkowns of the effects. It may not make a difference, or it may make it worse. So, jury's still out.

Thanks for the info, guys.

 

[marc olivares]

don't waste your money on a Multi double cardon D/S. they are very expensive and typically do not correct your issues. M/D D/S are not a fix all, i've got one on my D1 and it DID NOT correct all of the pinion angle related vibes. if the vibes are coming from the drive shafts, correct the pinion angle (that's what i had to do w/ mine).
and NO, you will not get vibes during "breakin" with those gears. i've set up tons of them and they have never growled or rumbled during break in. if it's making noise then there is something wrong. if you have ruled out the tires, then its the setup or the pinion angle.
but if you did not have this issue before you put in the thirds, then chances are it's the thirds not the pinion angle.
did you pull off the Harmonic Dampering weight on your axles, that would make your vibes more noticable. contrary to popular belief, those weights do help dampen noise and vibes, that's why LR spent the money to put them there. just a thought.

i know the noise you are talking about and i'm still gonna go with tires.?

 

[p m]

Any kind of lift will cause vibration with stock shafts, b/c they are simply not designed to handle drive angle change.
You may be lucky to not notice that, but its there.

actually, Sergei, driveline vibrations, like wheel shimmy, are a nonlinear dynamic process - they have a distinct threshold of onset. Both in speed and in load. It isn't just a matter of being noticeable or not - although, most vehicles seem to have structural vibrations near 80mph (with stock tires), which adds low-pitch rumble to vibrations.

 

[RS Warburton]

Not sure about the pinion angle, based on the results of running with one or the other driveshaft - no change without the front driveshaft, slight change without the rear driveshaft. Besides, pinion angle problems with only about a 2" lift?

I did, a couple months ago, remove the rear diff weights when I removed the skidplate (to go ahead and have that off when the new diffs arrived to save that step) and drive without. The rumble that I had been experiencing was even more noticeable. I'd hate to think what it would be like now.

The only thing I haven't done is get towed at 65 with no driveshafts. That would be an interesting trip..........

 

[p m]

Richard,
let me sum it up - there's no change when you remove the front driveshaft, and very little change if you remove the rear driveshaft.

Have you completely ruled out the wheels? (you need to both balance them and check if the wheels are truly round, with no repeated contact patch pattern. One annoying way of doing it is to replace the wheels one at a time with the spare, it it's any good).

If the tires/wheels are ruled out, it almost sounds like some of the diffs wasn't set up right (e.g., ring gear has significant runout). This may become more annoying - you'd have to pull the axleshafts and driveshaft out and drive it in 2WD to verify that, on both ends.