Background: Car is an M6 swap and just received a Strange 12 bolt last weekend.

Figure it's time I addressed these. First up, clutch:

After I installed the rear end last weekend, I ran the tranny/clutch through a series of engagements and disengagements with the rear wheels in the air. It seems like the clutch is disengaging, as the wheels aren't turning, but upon initial gear engagement the tires spin over about 1/2 turn then stop. I'm thinking an adjustable master cylinder is in the immediate future for the car to safe the life of the clutch, but wanted some opinions on the matter.

Second, piggybacking above making me thing the clutch isn't fully disengaging, when trying to shift from gear to gear if you aren't nice and slow with it you get a solid resounding thud from the tranny when you hit the gate for each gear. Same issue as above I think.

Lastly, and this one has me stumped. There seems to be a lot of slack in the driveline. Say you're rolling down the highway in sixth, and you are holding the gas and lift to slow or just maintain. When you get back on the gas there's a healthy clunk from the drivetrain. Same thing when shifting gears unless you're being agressive with it. Just feels like there's slack somewhere, but I've got everything tight down there. I tightened all the suspension and everything with it pre-loaded (rear end supported at ride height on jack). *Edit* The rear and drivetrain are completely silent when accelerating, getting on it, and deceleration. The clunk only happens when you're transitioning between gears or of then back onto the throttle.

Thoughts?? FWIW the car seems to LOVE the 3.73's. I ran through first through fourth, and for the first time the car barked third. Didn't even do that with the 4.10's for some reason. Can't wait to track test it now!!

 

Well......found out what the clunking was. Had the car in the air today to get two new tires put on and was poking around under there. There's somewhere between 1/8 to 1/4 driveshaft turn play in the backlash of the gears. I had the E-Brake on, tranny in neutral, and could turn the driveshaft between 1/8 but more like closer to 1/4 turn (if not more) either way. That's a really wide backlash......

So what's the possible downside to that besides just a lot of clunking around??? The rear is whisper quiet right now and I and my wife would prefer to keep it that way.

 

I wouldn't think that a new rear end would have that much play in it. A high mileage stocker, you expect that, but a new 12-bolt?