Transfer Case Problem

[DanB]

I have a 91 Sport 5 spd with man t-case and hubs. Last week, the t-case started to make a grinding noise (not real loud) when I shifted into 4 hi going down the road. Afraid to try 4 lo. Today with it up on jackstands, it's still noisy in 4 hi, but I found out new things. If I shift into 4 hi while in gear with wheels turning, I get noise and the front driveshaft doesn't turn. If I shift into 4 hi while in gear but with brakes on, the t-case is quiet and the drive shaft turns. Neutral and 4 lo don't seem to be affected. I'm going to pull it this weekend I guess, but does anyone have any ideas what to look for?

 

[yob_yeknom]

Shifted into hi going down the road? 4wd isn't for use on pavement.

Shifting into 4 hi with the vehicle up on stands, the rear wheels turning, and the front ones not is very bad. That's making it try to suddenly turn the front wheels as fast as the rear. If you read in your manual, you'll notice it says NOT to shift into 4wd with the rear wheels spinning faster than the front ones.

Since everything does work with the brakes on, I doubt you have a problem. You were trying to shift into 4wd during situations the system is not designed to work in. This is why you heard the noises and it did not work.

 

[yob_yeknom]

I just remembered you said you have a manual t-case. That makes what I said even more correct. With a manual t-case, you need to have the clutch pushed in (out of gear) to shift into 4wd. You're also supposed to be going rather slow when you make the shift, not at speeds traveling down the road.

 

[mrboyle]

The 1345 can be shifted into 4hi while moving. There is a sincro in the transfer case that is identical to thoes found in a manual tranny. This allows the case to be shifted in to 4hi while moving without causing any damage. My guess is that the sincro is going out and causing the noise. Check the fluid in the case, if it has a lot of brass shavings in it, your sincro is bad.

 

[DanB]

You guys are mostly right about what happened, however I did have a problem and think that I still do have one. Yes, I shouldn't have tried shifting into 4wd on jackstands with the front wheels not turning. However, when I first noticed this problem, I had just shifted into 4hi at about 20mph on the snow. I've had my rig for 5 years and 65k miles. It's lifted, ARB'd, 4:56s, and I probably have 10k off road. In the past, I've shifted into 4hi at speeds up to 45mph (the shop and owners manuals both say okay to 50), and never had a problem. I've used synthetic ATF since I've had it and drained the fluid this weekend and it's clear with no particles and doesn't smell burned. I did readjust the linkage and that seemed to help a bit. It ground just a little going in the first time I tried it, and then was okay afterwards. I live in south central oregon at 4100' so I drive on snow and lots of ice 6 months a year. I've gone two months without taking my hubs out. I'm hoping to go to Death Valley on vacation in march and am going to try and do an Atlas this summer, so let's hope it lasts until then. Thanks for your comments.