Topic: help weird t-case sound

[mikestoyokrawler]

i have a grinding sound coming from my rear t-case... everytime im slowing down off the gas theres a grinding sound that sounds like the gears are rubbing up to eachother does anybody know what it could be??

[84pickup]

 are you sure it's from the tcase? i thought maybe mine was doing the same thing but it turned out to be the front axle. i still need to figure out just what in the front axle is making the noise but it's either the birfields or the ring and pinion. what year is your truck, how many miles does it have? we need more info to really help you.

[82juguete]

I actually think im in the same boat, today I disco'd my front driveshaft, drove around in 2hi with the hubs locked and didnt hear the rattling.  In 4hi, however, the tcase does have a distinct noise that increases when I let off the gas..so..gotta be the tcase.  Does it only happen to you in 4wd though??

[Marlin]

This is a very common problem.
Do you have a cv joint on the rear driveshaft?

Remember that the pinion must be pointer in a straight line with the t/case when you run a cv joint on the rear driveshaft.

Marlin

[bkubisht]

Did it start immediately when you added the crawl box?

I'm in the same boat but with a single case.  I should start a thread.

[mikestoyokrawler [OP]]

i dont know what it is its an 88 toyota the sound is like gears grinding together it happens in 2wd drivin down the road only when i let off the gas

[Duffil]

i dont know what it is its an 88 toyota the sound is like gears grinding together it happens in 2wd drivin down the road only when i let off the gas

how many miles are on it? mine was noisy for a while.

[mikestoyokrawler [OP]]

it sounds like it is comin from the rear t case and that case has over 200,000 miles on it... a tech i talked to told me it was the thrust bearing but i dont know if thats it or not

[bkubisht]

Do you have a CV driveshaft in the rear, with the pinion pointed at the CV?  Do you have 4.7 gears in the rear case?

There's no thrust bearing in the tcase.  Not my definition of it at least, where it takes an axial load like front wheel bearings or the thrust bearing in an engine.

[88_Pathy]

All of the dual cased Toys that I have ridden in make the same noise. It is normal as far as I'm concerned.

[Slolyfe]

my cases are really loud also. but make sure your hubs are unlocked I had one hub locked and it made some ugly noises. Alos if you put in an Allpro style tcase crossmember that will cause alot more vibration cause of the solid mounts

[jimbo74]

i dont know what it is its an 88 toyota the sound is like gears grinding together it happens in 2wd drivin down the road only when i let off the gas

sure you dont have a problem with the rear end gears? like damage to teh coast side?

[blackdiamond]

This is a very common problem.
Do you have a cv joint on the rear driveshaft?

Remember that the pinion must be pointer in a straight line with the t/case when you run a cv joint on the rear driveshaft.

Marlin

Respond to the man! 

[mikestoyokrawler [OP]]

theres no cv joint on my rear driveshaft just u joints

[blackdiamond]

theres no cv joint on my rear driveshaft just u joints

What do your angles look like?  The angles should be essentially the same between the t-case and shaft & rear pinion and flange.  Any lift?

[germ]

not to throw a whole new problem into the mix, but I had a similar sound in my 85. Turned out the rear bearing on the Tranny was going, and as I let off the gas it would allow the mainshaft to shift just enough to make a wierd noise. It eventually popped a ball from the bearing which meandered thru the tranny and ate 4 of the 6 gears.

Drop the rear d-shaft, and see how much play you have at the rear out-put shaft. Should move only minimally if at all. Also, while your there, look for any signs of leaks, which would suggest a bad seal, which in turn would suggest you may be low on 90w, and just need to top it off.

You could also play around a bit and take the rear d-shaft out all together, drive only on the front for a short distance and see if it still makes the same noise. If not, I'd look at my rear ring and pinion (check gear oil level there too).
gotta play with it some to try and isolate the noise.

Erik

[bkubisht]

Erik is pointing you in the right direction:  start doing some diagnostics.

I have the same problem.  I was able to narrow it down to either the Tcase main bearing, or the lack of a CV driveshaft by removing the front driveshaft.  Then getting up to speed with the rear case in 4-hi where it makes the noise, I shifted the case into neutral.  The noise kept going as I coasted, which ruled out the tranny and tcase input.

[mikestoyokrawler [OP]]

ya ill try some diagnostics on it but i noticed that the driveshaft u joint is goin out and the driveshaft has some play in it... im thinkin that the vibration is causing the gears to move around and grind together