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      10-24-2012, 12:47 PM   #133
Jack M.
New Member

Drives: E39, M5, rebuilt by me ;)
Join Date: Sep 2012
Location: Colorado Springs, CO.

iTrader: (0)

This t-case works in a completely different way than the Japanese units we upgrade and service. The Japanese t-cases use a ring and pinion, and a hydraulic pump to push a piston in order to actuate the clutches.

This unit has 3 helical gears and a mechanism which uses a motor that directly drives the system to actuate the clutches.

I would gather from the posts in this thread that the t-case is not the problem, but that cog interface which drives the gear and moves the clutches. In the picture below, you can see how the Limited Slip Diff (LSD) works. To the right, you can see a small incomplete gear on top of a larger gear which the cog unit attaches to and moves. When that gear is turned, the scissor looking unit to the left is moved and applies pressure to the clutches. The more the scissors are moved outward, the more LSD action as the clutches have more pressure applied to them. You can see by the shape of the wheel that it will move the scissors apart and inward depending on the position.

So when the cog unit turns the gear clockwise, it creates more friction at the clutches. When it turns counterclockwise, less friction, so you get less LSD action.

The cog unit is a separate assembly from the t-case, so I'll try to get one of those and see what the deal is with it. I would imagine that it is always moving around and doing something, especially in high powered applications where the unit needs to work harder in order to keep traction at the wheels.

I see no plastic parts in this t-case, so the cog unit must contain those weaker parts.

For some reason, I was supposed to get 2 different t-cases, but only this one showed up. I'm trying to figure out where the 2nd t-case went and I'll also work on getting the cog unit.

If someone could please break this t-case and share some pictures of the damage, it would help greatly. Carl, you're local, just break it already!!

Thanks again all!


Originally Posted by pits200 View Post
Jack, awesome pics but stop being such a pansy, it's only a piece of metal going through your hand.

Just kidding! Hope you're doing better.

As for the t-case, I thought the people with failures said it was something to do with a worm mechanism. Overall, I agree that all those pieces seem to look pretty heavy duty.

Your work on this is fantastic. Maybe you can relate some t-case failures that you've seen with other platforms and see how those weak points relate to the specific xi parts.
Successful E39, M5, s62 engine rebuild. She's still going strong