GOCOUGSWSU

That's unfortunate, looks like I'm going to living with the vibration. Does anyone know if this will cause the transfer case to fail?

hankinid

I'd guess 99.9% of transfer case failures are from never changing the fluid. Every 30K for "severe driving or towing", every 60K for "regular". Toyota recommends 75W synthetic, pricing around $80/L.

The only other synthetic 75W that meets Toyota's specs is from Ravenol...you'll need a little over 1.5 qts. If you don't have a dealer nearby, they ship 2 qts. for ~ $40 including shipping. Good stuff, made in Germany. The plastic bottles have an elegant fill hose built in. You will not need a funnel. Stupid simple.

Ravenol Trans Case Oil

Prior to the 2010, Toyota recommended synthetic 75W-90, available anyplace from anybody. Some anecdotal complaints of truck not shifting or hard to shift out of hi/lo range using that viscosity. I don't see cause and effect. I think the change was to squeeze another 0.0001 mpg for CAFE standards...a lot like the factory recommendation to use premium v. regular gas.

GOCOUGSWSU

After a computer diagnosis today, it turns out cylinder #7 is misfiring! Recommended that I replace the coil, the big question is, do I replace 1 or all 8... I hope this solves the problem.

z32

Misfiring should trigger CEL / MIL. The CEL / MIL wasn't on ?

GOCOUGSWSU

What I was told is sometimes the coil will only cause a misfire at certain speeds and loads. He was able to see the misfire on the computer during the test drive.

I'm changing out the coil this morning, so I will keep you updated on what happens.

hankinid

I'd definitely replace #7, and buy an additional spare or 2.

z32

Maybe if you have time, swap the coil from cyn 7 to another cyn and go for a road test and see if the misfire jumps to another cyn. If that does, then it's the coil... if cyn #7 is still misfiring after swapping coils, then chk the spark plug...if not then check fuel injectors.... compression test (less likely imo)....ettc

GOCOUGSWSU

138k miles

Finally went to a shop with a mechanic that was willing to drive around with me so I could let him feel the vibration. Unfortunately, it's almost the worst-case scenario; the technician thinks it's the torque converter.

I called a few transmission shops to ask for some advice and my next step. Most of them suggest that when you do the torque converter, you rebuild the transmission also.

Any advice would be appreciated.

hankinid

Changing the trans fluid back in February improved the vibration according to your post.

I know this might sound like a radical idea, but have you driven the truck to a Lexus or Toyota or good independent shop for a diagnosis??

samosuv

Here’s a long shot. And I second hankinid’s suggestion about taking it to good independent shop (or a dealer) that should be able to help with a diagnosis.

Anyway, an experience of mine long, long ago. I bought a new set of Goodyear tires for a ‘69 Z28. At a certain speed on the freeway, there would be a vibration that I could feel. I can’t recall if it was both through the floor and the steering wheel too. First attempt to fix was dynamically balancing the tires (fronts while still mounted on the car). No dice. Next attempt was actually putting all 4 tires on a lathe to insure perfect “roundness”. This was at a particular Goodyear dealer. I’d never heard of a tire lathe before. Again, no dice.

After being told that it must be the Camaro (and not the tires), something that didn’t make any sense sice this issue appeared with the change to the new tires, I went to another Goodyear dealer and they simply replaced all 4 tires under warranty. Problem solved.

If your wheels were OEM and with say, Michelin LTX tires or similar, I wouldn’t suspect your boots on the ground. But since they are not, I thought I’d chime in with one long shot possibility.

Best bet is to have someone experienced with your make and model, that you can trust, to take a look. End of ramble. Good luck.

PS, do you feel this vibration at 2000 rpm if in 5th gear (in addition to 2000 rpm in 6th)?

z32

Take tires out and put on a road force balancer - check for runouts (out of round.... some can even dismount tires from rims, put back on the balancer and check for out of round on the rim too... so check these first...

Check tranny / drive shaft / engine / diff (basically all drive train mounts

this probably will be rare...check drive shaft / axles if bent

i don't anticipate cv boots / shocks / control arm for causing noise / vibration... there will more result in a clunk noise

I am leaning more towards diff / tranny / transfer case area (internal). When was the last time fluids were replaced in these 3 areas? Replacing fluids may help and probably the cheapest way (process of elimination) - after performing a visual inspection...

Do not keep replacing parts hoping for the best..

Was the misfire consistent? again if consistent, then check for coil and spark plug condition / failure...swap coils and see if the misfire shifts to another cylinder.... I anticipate Check engine light should lit up if Misfire happens (enough). a few random misfire should not result in a consistent vibration at 2000 rpm while in motion.

Another way will be to put chassis ears on each drive train area, have someone go on a road test and record the noise (which ear has the loudest noise). Then raise the car up in air, have someone slowly engage the car forward, wheels spinning, have someone else listen to the area where the chassis ear recorded the loudest noise. that will be the ideal way imo.

good luck