Olds witb the Fulltime AWD Bound Up

[jsawduste]

Searched the net and have found quite a bit of information about the TB and Bav viscous transfercases,. Often though the subject gets muddy when describing the differences between the push button vs FT AWD.

Daughter has an `02 Olds Bav that is bound up. Have found references to a factory bulletin that speaks of a new improved fluid. Since her`s has just shy of 100,000 and has never been changed I am hoping a fluid change will solve the issue.

Any other advice or things to look for ?

Thanks

[fishsticks]

"Bound Up" can mean a lot of things. Can you explain further?

[The Roadie]

The fluid change interval is a very important 50K miles. I think the fluid has always been Auto Trak II. At 100K without even the level being checked, you will be lucky if the clutches are OK. Good luck!

[jsawduste]

"Bound Up" can mean a lot of things. Can you explain further?

Best way to describe it is like when I run my Jeep with locking hubs on the street. The difference in wheel travel between the front/rear axles causes the ride to bind up. Of course unlocking the hubs or shifting the TC into neutral allows the two axles to release the "tension" between them.

As I understand, the Bav has a viscous coupling TC with clutch packs that allows for the difference between the F/R axles automatically. Slippage if you will.

A GM service bulletin speaks of an oil change to replace the factory fill that is supposed to address this issue. Further research talks of an encoder/motor asm. that could also be a suspect. But the subject gets confusing between the push button system used in the TB vs the full time AWD that the Bav has. Some sources are suggesting the Bav does not have an encoder/motor but is electronically controlled via wheel speed sensors.

As a father I am trying to help the kid out and get her back on the road.

Thanks for the interest and I welcome any comments and suggestions to a system that I am a bit unfamiliar with.

[jsawduste]

The fluid change interval is a very important 50K miles. I think the fluid has always been Auto Trak II. At 100K without even the level being checked, you will be lucky if the clutches are OK. Good luck!

Ouch, while I have to admit the vehicle has been well maintained in the general sense.......We purchased it from my father..........I can say that the TC fluid has never been touched. Regular engine oil changes and small things like filters have always been addressed in a timely manner.

The rear axle fluid was recently changed and at a 100K it was pretty clumpy. Finding out about the TC oil now makes me aware of shortcomings in our maintenance schedule. Hoping that the God of friction material will have mercy on us.

Again, I am a Jeep guy whom runs an Atlas TC with front and rear shafts. Perhaps a dumb question but is there a front drive-shaft on the Bav that could be disconnected ? This would at least make it drivable with only RWD.

[fishsticks]

The fluid change interval is a very important 50K miles. I think the fluid has always been Auto Trak II. At 100K without even the level being checked, you will be lucky if the clutches are OK. Good luck!

Ouch, while I have to admit the vehicle has been well maintained in the general sense.......We purchased it from my father..........I can say that the TC fluid has never been touched. Regular engine oil changes and small things like filters have always been addressed in a timely manner.

The rear axle fluid was recently changed and at a 100K it was pretty clumpy. Finding out about the TC oil now makes me aware of shortcomings in our maintenance schedule. Hoping that the God of friction material will have mercy on us.

Since you're in a bind situation it's unlikely that the clutches have worn themselves out....yet. The NVG 126 (what your Brav has for a TC) DOES have an encoder motor. I believe it is, in fact, the same encoder motor as the NVG226 (What TBs/Envoys etc have).

Again, I am a Jeep guy whom runs an Atlas TC with front and rear shafts. Perhaps a dumb question but is there a front drive-shaft on the Bav that could be disconnected ? This would at least make it drivable with only RWD.

The front DS has a yoke at the front diff and a slip CV joint on the TC end. The TC part of this slip joint is male and sealed. So you can safely remove the front DS.

I would just change the fluid and see what happens. $8/liter at the dealer for Autotrak II (You'll need 2 bottles). I believe Royal Purple Synchromax also has the proper rating.

http://royalpurpleconsumer.com/product- ... sion-fluid

[jsawduste]

Since you're in a bind situation it's unlikely that the clutches have worn themselves out....yet. The NVG 126 (what your Brav has for a TC) DOES have an encoder motor. I believe it is, in fact, the same encoder motor as the NVG226 (What TBs/Envoys etc have).


The front DS has a yoke at the front diff and a slip CV joint on the TC end. The TC part of this slip joint is male and sealed. So you can safely remove the front DS.

I would just change the fluid and see what happens. $8/liter at the dealer for Autotrak II (You'll need 2 bottles). I believe Royal Purple Synchromax also has the proper rating.

http://royalpurpleconsumer.com/product- ... sion-fluid[/quote]


Thanks for the help. I will get a couple bottles of lube from the dealer and do an oil change. Now that I understand how the front DS mates to the TC. It is an option to remove it if all else fails. A last resort option though.

[The Roadie]

It's possible to physically remove the front driveshaft, but there is no electrical or mechanical disconnect unit to stop the AWD functionality short of removing the driveshaft.

The encoder motor is the same except on the AWD NVG126, there is no brake. It's always available to move freely under control of the TCCM (Transfer case control module) which is the electronic box always looking for wheel slippage.

The clutch packs are engaged by the encoder motor to send more or less torque forward as wheel slippage is detected. Normal minimum torque sent to the front differential is 5%. It's not "viscous" in the way other vehicles are designed. It's a set of clutches, and they are always rotating.

When you drain the TC, measure how much comes out. That will be an indication how much damage is already done.

Also check the level and refill the front diff. At 100K, ALL fluids and the spark plugs are due.

We have an article here on the NP (NVG) 226 that the on-demand 4WD system uses. Our A4WD mode is mostly what the NVG126 uses all the time.

http://www.offroadtb.com/articles/tech- ... -operation

[Trail X]

If its in a constant bind, I'm pretty sure its going to end up being your encoder motor. Do you have a service 4WD light on the dash by chance? As the other guys said though, fluid change, then take it from there.