C4inLA

A suggestion was made to diagnose a drivetrain issue, that the clamp at torque tube to C4 transfer case shaft can be loosened and slipped forward towards front diff essentially having no drive to front axles. Has anyone done this ? Sounds easy. What happens to abs or PDAs fault code wise or on dash lights? If I were to try this, it would only occur in driveway at a crawl speed.

Vandit

I think the car won't move. It'll be like an open differential with one tire in the air. All the drive will be transfered to the output with least resistance.

C4inLA

Not sure we're talking same thing? Where shaft out from c4 PTU and enters torque tube to drive front diff 31% would then be spinning freely, front axles essentially dead. All drive would be to rear axles and front wheels would just roll with open front diff? Explain why you think the rear drive would not function?

P-daddy

I'm sure 964 and 993 AWD systems are very similar. A friend of mine did this on his 993 C4 with no issues at all. Slide the collar forward and you've disengage awd. The car becomes rwd. He's been driving this way for several thousand miles zero issues. No codes/lights.

Vandit

The 993 and 964 AWD transaxles are not similar in this regard.

NineMeister

You can disconnect the drive on a 993 because the vehicle is permanent rear wheel drive with front axle only driven through a viscous coupling when a speed differential is detected.

You cannot disconnect the drive on a 964C4 because the vehicle is a permanent 4WD system with nominally 69% to the rear and 31% to the front, adjusted by hydraulic servo control of the forward differential. If you do choose to disconnect it you will burn out the forward differential and have no drive to front and rear in no time at all.

C4inLA

Appreciate the feedback... I was looking at as a diagnostic to rule out grunch coming from front diff part of drivetrain under load in my driveway test. I'll table that for now.

Thanks!

P-daddy

Thanks for the info, Colin!

-nick

And Vandit...