What is the internal differences between a 9 bolt and 10 bolt rears?

 

Everything. They are as close as any GM & Ford rearend. They all go in the same place & do the same function, but zero parts are shared between the two.

 

I was wondering about the strength of the 9 bolt versus the 10 bolt. I have a bone stock LB9 motor and the '90 IROC has the 10 bolt in it now with drum brakes.

I have come across 2 9 bolt disc brake rears and wondering if I should go that route to make the swap simple to get the disc brakes on the rear?

 

The 9-bolt is a bit stronger, but parts to get for it are a bit harder to locate & may cost you a little more when you need them. But that being said.....Unless you REALLY lean on a 9-bolt with slicks at the dragstrip, they are "less likely" to have failures on the street.

 

Check to make sure the 9-bolt posi cones are not worn when you look at them. And you WILL need to look at them. There is a window in the case. The cone should not be all the way to the side of the case towards the wheel on that side. There should be a gap at the wheel side of the window, and opposite side of the window towards the center of the carrier, there will be the cone. If they are bottomed out MOVE ON TO THE NEXT ONE.



This is a bottomed out cone, note there is no gap:



You can see this easily by just removing the cover and taking a gander at it.

Avoid the cast iron disc brakes (came on most all 9-bolts). They will have the same caliper on the left and right side of the car, just one caliper is on the front of the rotor, the other on the back of the rotor. Those are the "Delco Moraine" calipers. Avoid those. You want the PBR calipers.

I got my 9-bolt with the PBR calipers because it was just what I could find at the time... but if I were you I would look for 89-92 10-bolts. A 1989 9-bolt will have the PBR's though.



Those brake calipers (aluminum with fins) are the PBR brakes. Look for those.



These are the ones you want to avoid. Notice the left caliper is removed, but you can still see the mounting tabs. These brakes arent terrible as they can be "fixed", but they're not as good, and if you're gonna go through the trouble of buying a whole new rear end and installing it, you may as well get something worth the cost and hassle of installing.

 

I picked up a 9 bolt rear end with the cast iron calipers. I have a 1992 B4c car with the 1LE brakes. Am I able to swap and put the 1LE's on the 9 bolt BW?

 

Yes. Replied to your PM.

JamesC