Drive line vibration

[Ed Z]

94 Disco with a vibration... It appears to be load related as it is worse with heavier acceleration... Flex coupler replaced last summer... Front drive shaft U-joints replaced a month ago... Completely stock truck... It feels like some kind of clutch chatter... There is little noise that I can tell from inside...
I read up on the rear diff issues with cross pins, but they seem to make noises when they go up... If I had to make a guess at it I would think something in the torq convertor... Any ideas of what to check ???

Thanks,

 

[geoff]

I got my driveshaft rebalanced after replacing the ujoints. All the previous weights were removed and new ones added.

 

[p m]

Check oil/lube in the swivel balls (make sure CV joints are lubricated), and gear oil in the transfer case.
Also, check the engine and transfer case mounts.

 

[Ed Z]

Thanks, will advise on findings...

 

[Ed Z]

Put it up on jack stands and did some testing... Foot on the brake to create a load and the other foot on the gas pedal produced the vibration... My friend was under the vehicle and said that the transfer case seemed to be the source... He touched the rear diff and watched the drive shaft ... There was some vibration felt in the rear diff, but nothing like what was felt when touching the transfer case... I put the emergency brake on (causing the front wheels to turn... With the foot brake to create a load the front wheels now turned... In this config I did hear some very undesirable noise from the transfer case area... So, it appears that the case is the source of the problems... I didn't have enough time to try draining the oil to see if there is any metal bits... At this point I have to ask, is the truck really worth replacing the case (got a head gasket job in the near future as well)... Almost 20 years old and rusty... From what I have read, the case is a real pain to remove from the vehicle as well… I guess, I’m just feeling sad and depressed about it right now…

 

[stu454]

Fix your post. I'm too old and crabby to even begin to attempt to read that.

 

[barefoot]

agree with above.

my bet is on the rotoflex. the fact that it is worse with heavy load and chatter bring me back to my first discovery part failure. check the bolts on the rotoflex, you will see wear on them where they hit the meatl thinggy there and cause the chattering when you get on the gas or go uphill.

yes i know you replaced it last year but they will eat them, especially the generics and especially if installed backwards which is easy to do.

it is an easy thing to rule out anyway...look for the wear on the bolts.

if it is bad, quit wasting money and get the u-joint conversion.

another thing to check is that ebrake drum...mine self destructed once and sounded like that a bit. there should be no wobble in it.

one way to trouble shoot vibes is to lock the transfercase, remove one driveshaft at a time until you can determine which is causing probs...front or back.

 

[Ed Z]

Thanks Barefoot, but that does not explain the bad noise when we had the emergency brake on (locking the rear drive shaft) and then just letting the front wheels spin... After reviewing the exploded diagrams of the transfer case, I'm leaning towards the cross pins in the transfer case being at fault... Once I get to draining the oil, I should be able to confirm the issue is in the transfer case... I will dismantle the flex coupler and inspect it but it showed no signs of wobble when we were inches away from it while testing (causing the vibration)...

 

[Ed Z]

I got to lookin for a replacement transfer case and ran into a question... Some have em listed as fitting 94 and 95 while others list em to fit 94 to 99... I have a 94 Disco, what years can I use in there ??? Also is there some years of Range Rover that use the same case ??? It apears that for around $350 I can get a used one... I'm a bit leary of used parts as I can't be sure it's any better than mine unless I rebuild it first... Any advise on this is most welcomed...

Thanks,

 

[JohnC]

I got to lookin for a replacement transfer case and ran into a question... Some have em listed as fitting 94 and 95 while others list em to fit 94 to 99... I have a 94 Disco, what years can I use in there ??? Also is there some years of Range Rover that use the same case ??? It apears that for around $350 I can get a used one... I'm a bit leary of used parts as I can't be sure it's any better than mine unless I rebuild it first... Any advise on this is most welcomed...

Thanks,

I have one from a 95 DI for $250. I also have one from a 96 DI. I've replaced Transfer Cases by myself using a motorcycle lift and it's not to hard to do.

Here is a post from Paul Grant on the subject:

"Actually, with regard to the transmission coupler, the issue is in the length of the splines on said coupler. The Range Rover Classics and '94/'95 DI's had the same size coupler but the length of the splines on that coupler were not as long as the ones on later DI's. That's why, if you use a '96 or later LT230 with an earlier DI or RRC you need to use the later style, long spline coupler. Otherwise, the transfer case won't meet the back of the transmission."

Paul might also have some LT230s in stock.

 

[p m]

There's chance the center diff is about to go in your t-case - but I'd try checking how much oil is in it, and topping it off. Also, have you checked if there is no play in the front yoke of the t-case when you replaced the front U-joints?

 

[barefoot]

yeah, i didnt read your post that was blacked out.

you dont have to remove the flex coupler to check. if it is collapsing on itself there will be marks on the bolt heads visible.

 

[Ed Z]

Thanks for the replies folks... I did not check for play in the front yoke, but I did check that the flange bearing was tight... I didn't think to check for drive line lash at the time though... When we tested the other day we did have vibration with the front wheels not spinning (brakes applied) and we had a unpleasant noise when we locked the emergency brake (no rear wheel spinning) and the front wheels turning... Will decide over this weekend as to what action I'll proceed with...