Okay, I recently rebuilt my front and rear drive shafts last year, but after a day of off roading and messing up a diff I replaced both diffs. Now in havE the typical 40-50 mph vibration that stops when I let off of the gas. So I decided to replace the front drive shaft with a tadd hd drive shaft with serviceable centering bearing, u joints and slip yoke, thinking that would fix it, as i had already replaced the rotoflex. That didn't fix it so I decided to get the lucky 8 u joint conversion since I had got the terrafirma 3 inch lift from lucky 8 along with 265 75 16 treadwright claw tires. That didn't seem to fix it either, so I have brand new front and rear drive shafts and the vibration persists. Now if I get to 70mph or above the vibration gets bad and remains when I let off of the gas. Could my alignment be off? I replaced the motor mounts, ad one was bad, and also replaced the trans/transfer case mounts a's one of those was ruined. So I have new motor mounts, new transfer case mounts and new drive shafts front and rear and the drive line vibration continues. What else could it be?

 

Check your front and rear hubs/wheel-bearing assemblies. Had a slight vibration on my 01 that peaked at about 55/60 mile an hour, then smoothed out a bit...but kind of was still there. Turned out being right front hub.

Also, have you checked the transfer case fluid level lately?

Good luck,

Brian.

 

Recently changed all fluids a couple months ago. Quieted down the transfer case. When I looked at the rotoflex it appeared out of shape so could it be an alignment issue? It's definitely a drive line issue because it is a high speed vibration, and it gets really bad after 70 mph so I stay below 70.

 

1) Make sure you installed the rear 4-bolt flange properly.

2) Could be a bad output bearing on the t-case.

 

You mention messing up one of your differentials, was it the front? Wondering if maybe you damaged a CV joint (axle shaft), too?

You also mentioned replacing both driveshafts, were both of them "clocked" properly (u-joint flanges aligned with one another)? Not trying to question your repair abilities, just need to rule certain things out before moving forward.

As far as alignment goes, if you are talking about steering components, l'd consider this the least-likely culprit. "Usually", a front end alignment issue will create a shaking or wobble...not a vibration.

4X4's are one of the most difficult vehicles to track down a vibration, even experts cringe at the subject. Just the nature of the beast, so many rotating parts involved in the system. So, keep looking...it will show itself. Also, if you were 4-wheeling hard enough to damage a diff...the transfer case would be subject, too.

What year Discovery are we talking about, anyway?

Brian.

 

This will be hard to believe. I've suffered from a vibration for sometime, whilst I had the front end jacked up on axle stands I checked the wheels for ovality, hmmm, hard to believe eh, the tire isn't completely circular, there's about a 5mm (1/4") ovality. The tires are reasonably old now and probably need replacement soon so I'll get some new tires fitted and balanced asap. In the meantime I think I'll checkout all the tires for similar problems as it gives similar vibes to bad wheel balancing. It would be worth checking with a dial gauge on the rims and then with an indicator wire or similar on the tire width in about 4 places.

 

1/4 inch would be extreme, especially on stock tires...wow. Good info about the out-of-round tires.

Usually, I jack the vehicle up and put a jack stand directly in front of the center of the tire, so it is barely touching...then spin the wheel slowly looking for spots that stop the wheel from moving...highest spot of out-of-round...then set the jack stand at the point...spin to lowest spot (largest gap) and take measurement.

Like I said before...there are so many things that cause vibrations...so every detail has to be examined.

Brian.

 

no worries, the drive shaft was clocked and bolted right up without having to turn anything. Torqued the flange to spec, the vibrationis exactly the same as be free when I had the rotoflex. One thing I did notic was that the rotoflex seemed kind of out of round. The front diffwas damaged and I replaced both of them as a precaution. Guess I'll be changing the transfer case. I have a CDL transfer case I was going to put in anyway so I guess I'll go ahead and do that and report back what I find. Obviously it wasn't the drive shafts lol.

 

Like Offroadfrance mentioned about the tires. There is much possibility also with those as well especially the front tires. Did you have any balance issues? I had it before winter and all tires were good and found out one of the inner part had a gaping hole not sure what to call it .

 

It's not uncommon for tires take a permanent set on a vehicle that's parked for long periods of time. A standard spin balance won't uncover the problem.