Topic: Pretty bad driveline noise....

[Jared88]

When im cruising on the freeway in 4th or 5th gear..( way worse in 5th) and let off the gas so everything is unloaded, i get a very bad noise coming from the trans, driveline and /or rear diff. I installed a locker, and kinda hoped it was just spider gears...but nope. The backlash in the R/P is nice and tight....so i don't think it's the third.

Is it my trans..maybe driveline splines or a U joint?? I'd like to get this figured out before i start making alot of trips this season.

thanks guys.

[junya92toy]

Maybe the carrier bearing, if you have one

[2manytoys]

This sounds crazy but bang on your cat and muffler to see if it's busted loose inside. I had what I thought was a trans noise. It ended up being the exhaust.

I swore it was the trans or t-case. I found no particles in the oil, it shifted great, checked the diff oil, crawled all over my truck and finally found the cat and muffler both putting out nasty sounds. Most noticeable when letting off the gas, especially at highway speeds. Not noticeable when cold either.

I have also had siezed bearings in a u-joint. I thought they were good because they were not sloppy. That caused more of a vibration than noise though.

Just thought I'd throw the odd ball stuff out there in case you already checked the common stuff.

Good luck, let us know what you find.

[Mnmstoy]

I had that same problem a few years ago. my problem was the drive shaft. After a 4" lift and the the DS being a little to short.
specs 1980 LWB 20R/W56/dual cases. A 93 4runner (non CV) DS bolted right up.
Check the play at the splines. If it is lose in that area. That may be your problem. Great when power is applied but vibrated bad letting off the gas.
My local DS shop suggest 2" of compression. I was happy at 1.5" compression.
Hope that helps.

[Jared88 [OP]]

Thanks for the ideas guys. Cat is off the truck, and it is definately in the drivetrain. Ill check the splines and u joints. no carrier bearing, its a std cab, short bed. Thanks again guys!

[Dingman.]

It started doing this when you installed the diff?

Whats the backlash? its supposed to be set to spec.

[zack.carter]

im having this same problem. 63 inch chevys and moved back 2 inches driveline is barely long enough. that was my guess for the problem.

[Slolyfe]

Shake your rear driveline and see if your pinion or tcase output flange move. Could be a pinion nut backed off.

[dare44]

I have this same problem, it started when i took my dual case skid plate off to put the front driveline on, when i put it back together it vibrates. 

[Jared88 [OP]]

problem started right before i did my SAS about a year ago, and hasnt gone away. ( not that noises like that ever do!) pinion nut is tight. no after market skids.

I'll be checking all of this out today. Should have an answer by the weekend or so.

[Jagdverband44]

I had this problem in my 82' LB and it was the U-joint. It was in 4th but worse in 5th because of higher rotation speed. It was associated with a lot of vibration. Did you bang your driveshaft on anything, forget to lube, etc.. Is your noise also associated with vibration like mine was? Open up the drain plug on the diff and dip it in solvent, take the metal "fuzz" and rub it between your fingers. If there is any "sand" in it you have a gearing issue. Do the same with the trans. Good luck!

[79coyotefrg]

your driveshaft is out of phase.  you slipped the shaft apart instead of pulling the other end off right??  you didnt get it splined together right

[superyota]

Shake your rear driveline and see if your pinion or tcase output flange move. Could be a pinion nut backed off.

i had this happen.  made a dry bearing rumbleing sound.  it was the nut on the tcase flange starting to back off.  put the inpact on it and now its gone.

[sas_yota91]

not sure of what truck your driving, single or dual cases? but its pretty common for dual cased trucks and single cased 4 runnners to get a little driveline vibes. my truck gets it a little, at the point of throttle just past the freeplay in the peddle. Mines a 91 std cab, dual cased, no cv on rear driveline. 

[Zs Confederate Toy]

My buddy had this problem on his 84 but instead of addressing the problem he let it go. After so long the T-case end of the rear drive shaft broke loose and hit the pavement. It jammed the pinion into the carrier and ring gear. He had to replace not only the driveshaft but also the third. It was all caused by a seized u joint.

[Jared88 [OP]]

79 coyote, I did f*** up last time and let it slip apart. I tried getting it back together, and had no luck.

I got under it today, and the output of the transfer case ( single case) is moving up and down. the U joints seem nice and tight.

Is there a bushing or bearing that would make the whole output move if it took a crap??

This is all the details i have right now.....so what is next?!

[Dingman.]

Pull the driveline off and see if the nut backed off tthe tcase output

[Jared88 [OP]]

I'll do it tomorrow on my lunch. Had to pull an engine after work for a customer, and had it in my truck tonight to take to work tomorrow, and the driveline noise was alot less. It's way quieter. I dont know. Ill check that flange tomorrow.