Transfer Case / Clutch Pack Shot

[Pezhead]

I have searched a bit and can't find anyone with my exact symptoms. So I'm seeking comments from you experienced folks.

I just had my R33 GTR out at the NSW SAU dyno day. Also had it at powercruise where it was so back end squirly wasn't even funny, couldn't get any traction at all. So as soon as it went on the 4WD dyno the car stalled as they tried to release the clutch. The shop said the clutch pack in the transfer case is shot.

I drove it home and it does drive ok. The 4WD and ABS lights do not come on at all. It drives fine and even the torque gauge reads. Although I'm sure it isn't transferring any torque at all.

I lifted all four wheels on stands and even free wheeling as I try to release the clutch the car stalls with the wheels off the ground, no resistance on them at all. So I know that when the Atessa does try to kick in something in the front drive train is "locked up" and thus bogging down the power.

So is it just the transfer case or is there a problem in the diff or something else. To me it is really strange that the wheels won't spin even with zero resistance. If it were clutches wouldn't it just engage but not spin the wheels? Since it bogs the car down I'm concerned might be something else in the front drive train.

For instance, if the front diff was blown then as it tried to engage the front diff and couldn't spin it wouldn't it drag down the motor. Then only the transfer clutches would allow the back wheels to spin as they slip during ramp up engagement. Basically reverse of what the shop said e.g. clutches OK but front diff/something in the front drive train is stuffed.

I'm not having a go at the knowledge of the guys at the shop. They really know their skylines and were really helpful given that I was only supposed to do a $50 dyno run.

I'm really interested in the experience from you folks.

So Godzilla is back in its den hibernating until I can save the funds for this next fix. Sometimes I think a drug addiction would be cheaper than owning a GTR.

Edited March 2, 2008 by Pezhead

[giant]

thats a bit weird! if your transfer case is shot, i dont see how it would cause that issue.

you dont have two different size sets of wheels or tyres on the car do you?

[Pezhead]

Nope the tyres are new but same size all around. I've read all the threads on people trying to stagger them or even uneven wear. The tyres have less than 1000 km's so know that isn't the problem.

It is really strange that the car will drive ok but on freewheel it bogs down. I really makes me think I broke something at Powercruise as that is really the first time I did any power on starts where the wheels spun. But it didn't make any sounds there and didn't feel funny just a hard launch. The power did really hit a boost at like 4.5-5 grand, maybe that is where the 4wd finally kicked out causing the surge in power.

I'm a bit stumped.

[Duncan]

ahh interesting I was wondering why it kept stalling on the dyno too. Have you noticed it is hard to move off the line?

I would try the same test after taking the front intermediate shaft out. if you don't have the same problem that would suggest front diff. Is there anything visually wrong with the front driveshafts? what happens if you turn a front wheel by hand when it is in the air (does the other turn the same way, different way or is it hard to turn? Is one side harder to turn than the other?

[Pezhead]

I'm going to have to get underneath it to have a closer look.

It is also funny that when I drove it home it is ok. Even at the track earlier in the day when I stood on it the rears spun loose while the fronts didn't, but it didn't stall then. Of course I was really into it so maybe it was just making enough power to overcome the stall.

Off the line there isn't any sign of trouble either. I would expect hesitation or some noise or something, but it drives ok with no real hint that anything is wrong.

This weekend I'll pull the drive shaft and check the front axles. At this point I'm thinking it is something to do with the diff since it only really acts up when the transfer case tries to apply power to the diff.

Although I've wondered about the 4WD since I bought the car back in August. Sometimes when I pull out of my driveway the back tyres loose traction on the dirt but the fronts are on pavement. Shouldn't the fronts pull me out? They don't and I end up spitting up a big dust cloud until the rears push me out. Then on the road as I turn it us up hill tight turn. Again the torque gauge indicates that a lot of power (30-40%) is going to the front but the backs are spinning slightly as I make the turn - but can't feel the fronts grabbing. It's always been like that.

Unfortuantely spoke to the CFO last night and she says I can't carve any money out of the budget to fix it for a couple months

Can I just pull the front drive shaft and drive it 2wd for a while? Is that going to do any damage?

Appreciate the input folks.

[EDIT]

A new theory here folks. Could this be something wrong with the pinion of the diff? Here is my thought process:

If the pinion bearings are totally shot, it would just free spin when there is no power but wouldn't hold thrust pressure against the ring gear. When the Atessa engages it tries to spin the pinion but the pinion pitches and locks against the ring gear - mesh angle being totally wrong. Thus the front diff locks up and the clutches then are trying to drive but the torque is lost as the pinion mesh doesn't transfer it efficiently to the ring.

This might also explain how it works ok when the wheels turn as the ring is then turning so the pinion is spun just a bit so it doesn't have the chance to lock up.

This is the only theory I can come up with that fits the symptoms I'm experiencing. It would also explain why the power isn't getting to the front.

(to those that have made it this far, thanks for reading - I know it is a lot)

Edited March 2, 2008 by Pezhead

[Pezhead]

Update #1 folks.

I pulled the front drive shaft and spun up the wheels. The rears go fine and the atessa says 50% torque at the front. So doesn't look to be a transfer case problem.

I don't have the proper 3/4" drive to drain the oil out of the front diff but I'm now pretty convinced that it is the problem. When I grab the drive yoke and turn it does clunk around a bit, maybe 5 degrees or so but makes an audible clunk clunk sound.

I guess it is time to have the front diff rebuilt. Can that be done in the car or is it a motor out operation?

[ali-turko]

you can pull the front diff withe motor in as iv done it,

and if it your pinion gear iv got one laying round although it may have surface rust on it, u can have if you want

but when my front diff let go i didnt have any problems with my car stalling, but when the 4wd engaged it woould pull to one side, then it completly got shagged and the 4wd didnt work at all

[Pezhead]

Update folks.

I pulled the inspection plate today to see what condition the diff was in. I was first surprised that very little oil came out - maybe only 100-150 ml! Then I looked at the inspection plate there wasn't any gasket - wasn't on the diff housing either. Somebody took the thing apart and didn't put a gasket back in! There was a little silicone stuff but it was all out the sides so was pretty much just bare metal trying to hold the oil in the case.

So then I expected the worse as I inspected the gears. To my surprise there are no scoring marks and no signs of heat. No broken teeth. Wow - did I get lucky? Went out and bought some gasket material, cut a new gasket and filled 'er up with diff oil. To my surprise it passed the free wheel test up on jacks - all the way to 80k's. No vibration or noise.

Here are a couple of pictures inside the diff - do you think it looks OK?

I'll probably have it checked out by the shop when I free up some funds. Just seems weird to have such a severe problem add oil and all ok.

[Duncan]

I've got no idea how to check its OK, but you might have been bloody lucky. We killed one within about 100k after an oil problem. I would get a diff shop to check it properly.

from the look of the seal they used liquid gasket - you can see the remains on the edge of the casing. only takes about 1l but 200ml is nowhere near enough. had you noticed a leak? is the drain plug tight?