Is my front differential working?
09-12-2011, 02:16 PM
#16
Race Director
Direct experience? As in for instance have I experienced a drive train failure with my Turbo?
No.
But I have some direct experience in some things, indirect experience in others, and sometimes something comes up that piques my curiosity -- like this drive train thing -- since I own a Turbo and wondered how to tell if all is well -- and I consult with some who do have experience and share what I learn if my sources give me permission to share.
Sincerely,
Macster.
No.
But I have some direct experience in some things, indirect experience in others, and sometimes something comes up that piques my curiosity -- like this drive train thing -- since I own a Turbo and wondered how to tell if all is well -- and I consult with some who do have experience and share what I learn if my sources give me permission to share.
Sincerely,
Macster.
09-14-2011, 06:44 AM
#17
Allow me to share my limited experience with you gurus.
When I bought my old 993Turbo (without a PPI, long story), the first thing my workshop (staffed by ex Porsche Malaysia technicians. I am in Malaysia) did was to put it up on a jack with the car in neutral and the mechanics proceeded to rotate the rear wheels. The front wheels did not rotate at all and they concluded that the VC was shot because if it worked, it would transfer some of the torque to the front wheels and they would also rotate (diff rotational speed between front and back wheels?). They opined that with a working Viscous Coupling, the front wheels rotated.
Since I was replacing the clutch and flywheel then as well as servicing the gearbox, I also replaced the VC which when dismantled was found to be totally shot on the inside. Now I wish I had documented the whole experience.
Subsequent to the replacement, when entering a corner too fast (on track) and the tail began to slide, I could actually feel the car correcting when the front began to pull with torque being transferred to the front. This never happened in the old 993C2.
Sincerely,
4th911
When I bought my old 993Turbo (without a PPI, long story), the first thing my workshop (staffed by ex Porsche Malaysia technicians. I am in Malaysia) did was to put it up on a jack with the car in neutral and the mechanics proceeded to rotate the rear wheels. The front wheels did not rotate at all and they concluded that the VC was shot because if it worked, it would transfer some of the torque to the front wheels and they would also rotate (diff rotational speed between front and back wheels?). They opined that with a working Viscous Coupling, the front wheels rotated.
Since I was replacing the clutch and flywheel then as well as servicing the gearbox, I also replaced the VC which when dismantled was found to be totally shot on the inside. Now I wish I had documented the whole experience.
Subsequent to the replacement, when entering a corner too fast (on track) and the tail began to slide, I could actually feel the car correcting when the front began to pull with torque being transferred to the front. This never happened in the old 993C2.
Sincerely,
4th911
09-14-2011, 01:54 PM
#18
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Porsche recommends a mechanically linked 4wd dyno. This can be done with a belt or a chain. It CANNOT be done electronically. The safest dyno run is done with the cardon shaft removed.
There are You tube vids showing the front diff puking oil after a run. Sharkster has a vid of his first 996TT being dyno'd with it puking oil right on the dyno. Lucky for him it was replaced under warranty.
The damage usually is done right after the operator lifts off the gas. The rear wheels will spin down slower vs the front wheels. This inbalance heats up the diff and you knock out viscous coupler. It is common to see the front diff casing CRACK.
Beware, if you want to be safe, dyno in 2wd.
There are You tube vids showing the front diff puking oil after a run. Sharkster has a vid of his first 996TT being dyno'd with it puking oil right on the dyno. Lucky for him it was replaced under warranty.
The damage usually is done right after the operator lifts off the gas. The rear wheels will spin down slower vs the front wheels. This inbalance heats up the diff and you knock out viscous coupler. It is common to see the front diff casing CRACK.
Beware, if you want to be safe, dyno in 2wd.
