Vibration Search Continues...

[Hltoppr]

Ok ya'll. The old school on this site (and SOR) may remember that I've been chasing a certain low, cyclical, feel it in the seat vibration at highway speeds since I picked up my 1992 80 a couple of years ago. Since I still haven't been able to quite get it fixed, I'm testing a new theory on you guys, with the hope that you may have some opinions.

That being said, here's the beta...

Low, cyclical vibration at 60+ mph. You feel it in the seat of your pants, and it's enough to shake the dashboard. Varies somewhat with speed, but not with engine rpms.

I've done the following all following the FSM for torque, etc.:

New 31x10.5 tires, rotated and balanced 3x since new.
Birfield job, including new bearings
New front driveshaft, OEM
New OEM rear U joints, Rear shaft spin balanced
New front rotors and pads
New rear pads, turned drums


Here's the kicker. When I got it, I had the local dealer (pre-CDan ) put new U-Joints in, and was told that the front driveshaft was "bent" so it was replaced with a new OEM unit.

I know the previous owner's wife was involved in an accident where she rear ended another vehicle; however, the receipt only involved the replacement of the front bumper, A/C dryer, and some other small parts.

If the front ds was bent in that accident; could force have been transferred to the Transfer case, bending the front input shaft? Could the transmission mount have been torn, causing the vibrations?

Thanks for your thoughts!


-H-

 

[landtank]

How about some mileage numbers.

Sounds alot like what I was getting just after the gear swap. Turns out some of the yukon gear sets where a little noisey and I might have gotten one. But 2 oil changes and 50k later they are much better now.

 

[LandCruiserPhil]

Have you tried pulling one driveline at a time in order to narrow it down some?

 

[Hltoppr]

193K

Yup Phil, I've pulled the front and run with just the rear, and I've pulled the rear and run with just the front...no real difference...

-H-

 

[Cruiserdrew]

Here is another guess-How about a bent wheel from this accident you mention? They can be pretty subtle and only appearent if you test the wheel itself for run-out with a dial indicator.

 

[Hltoppr]

I was thinking about the wheel scenario; however, with several 5 wheel/tire rotations, I'd think that it would eventually place the bad wheel in the spare position, and the vibration would go away....no luck.

Tomorrow it looks like I'll pull both ds's and check the T-fer case output shafts for out of round as well as the t-case mount and engine mounts....

-H-

 

[PHAEDRUS]

-H-
as far as the theory of the axle driving back into the transfer case somehow I highly doubt it. it would have to go through the control arms before it can get into the transfer case. any wreck that could bentd the lower control arms would likely do a lot of frame damage and you shoulld be able to see it. realistically the weakest point in the lower control arm set up is the brackets on the axle tube itself. I would expect to see these bend or break before the LCA will bend at all. they are pretty stout.
My WAG based on what you are saying is that there is a possible bend at the lower control arm mount to the axle. this will make the toe and camber angles read out on any alignment you have gotten. I am curious how far if any the toe was out after this accident. would be interesting to see. you could be in spec as to toe on the alignment but out on camber. since there is no adjusting the camber if it is off the toe could have been over corrected to compensate for it. hence you will have a slight dog track on the front axle but no real tire scrub due to the toe compensation.
remember this is a WAG I have never seen anything form an accident do something like this to an 80 series axle in 3.5 years of looking at wrecked cars but hey it is a WAG.
Dave

 

[97 FZJ80]

It could also be an alignment issue. My 97 was vibrating at 65MPH and ceases at 85MPH until I had the alignment checked. The toe-in (the only thing that is adjustable) was out by a little bit and realigning the front end made the vibration go away.

John