Thread: Rebuilding Differential?

Tweet

I have the feeling I'm going to regret asking this, but does anyone have instructions on rebuilding an 8" rear differential to a limited-slip? How heinous of a job is it? I see the kits for sale on eBay, I have access to a machine shop at my job, and the prices on 8" diffs are ridiculous. I tried Googling it and couldn't find any instructions online. Which oughta tell me something, I guess. . ..

8" are third member diffs, so just getting a new limated slip third member, might be an easy way out.

Yeah, that's the problem. A limited slip 3rd member costs more than I paid for the car. I'm just looking for another way out -- and a way to learn something in the process -- that isn't quite so hard on the pocketbook. Does a rebuild entail advanced machining?

Here's an alternative we used to use. Install an air shock on the right rear only and adjust the pressure higher and higher until both tires slip, or grip, equally. It works and you still have the smooth driving characteristics of an open differential.

Now we're talkin'!

Would that give a similar (or additional) result to adding slapper bars?

No, it does nothing to prevent spring windup, it merely equalizes the weight on each rear tire so that each has the same grip. On a front-motor, rear-drive car, the right rear gets light on acceleration due to the way the chassis twists, so putting additional weight there will equalize the grip. You'll want to use Caltrac bars or slapper bars or some other arrangement to prevent spring windup.

Yep, that's why you see the right rear tire always worn out first on a one legger differential with some young squirrel driving, cause the right rear is light and lets the tire spin.

That's also why you see the left front in the air as compared to the right front at the street drags. The left front and the right rear get light on acceleration, the right front and the left rear get heavy. It's just the way the chassis twists on a front motor, rear drive car.