Transfer case leak

Hi Guys,

This is something I noticed when I looked underneath my car for the first time, but i’ve put off fixing it as it seems like a big job.
The issue is that the transfer case appears to be leaking from its output seal, where it connects to the driveshaft. It isn’t dripping but the driveshaft is quite wet from the leak.
Does anyone know what kind of job it would be to fix this? Is it just a case of removing the TC, pulling the old seals out and tapping new ones in with a big enough socket, or is some kind of special installation tool required?

Car is a 1992 GTO NA, 5 speed manual.


1 Like

I’m assuming you’re talking about the all wheel drive version ? Drain the gear oil out of the transfer case. Match mark the flange on the front section of the prop shaft(so it goes back in the same position as it’s balanced) Remove the 4 bolts n nuts on the flange of the rear end of the FRONT section of the prop shaft, lowering it and slide the splined shaft out of the rear end of the transfer box. This gives access to the rear seal. No need to remove the transfer case.

1 Like

Sounds pretty simple to do it like that, though i’ve also got an input seal since I might as well change both while i’m at it, so definitely will have to remove the TC.

I don’t know if its possible to push the new seals in by hand accurately enough (ive never done this before).

I think there used to be a 2.5mm spacer for the input seal to push it in far enough but i cant find one for sale anywhere.

Just use a large socket to cover the outer rim of the seal (32mm on the input shaft seal). Make sure you use some grease on the shaft surfaces and on the inner lip of the seal. Tap the seal in gently with a rubber mallet and gradually drift it into position making sure it goes in square and even. You’ll need to drain the gear oil, remove the front pipe section of the exhaust and unbolt the 5 bolts from the transfer case (17mm). 4 of them are easy to get at but the 5th is difficult to access. It’s towards the top and tight against the body. torque on those is about 27Nm or 20ftlbs. Once you’ve loosened the bolts use a long screw driver or lever to edge the case away from the gearbox BUT be ready to catch it as it comes away (after you’ve moved it about an inch or so) The case has 2 locator studs which help to align the case when it goes back on. Place something under it as it’s quite heavy. Take care as you slide it off the end of the prop shaft. (support the prop shaft with a bungie or axle stand. Take care removing the old seals and try not to scratch the contact surfaces where the seals sit. As you are lightly tapping in the seal you will feel when it has reached home. Don’t forget to refill the case with gear oil. Have fun and work safely.

ps … the hardest part for me was getting the front pipe off. 19mm socket, power bar and extension bars. Spray some release fluid beforehand eg plusgas or something. Don’t forget to put the gaskets back on during reassembly.

To put the case back on I used a jack and some wood to ease it up into position onto the prop shaft and align it up with the input shaft. Then nudge it sideways onto the input shaft. If it struggles to line up you may need to rotate the shaft a bit or turn the wheel to line up the splines

1 Like