Final Drive and SIR

[mr. black]

Well, I did the spin check and found out that the diffs are mis-labled. I had 4.10s in and my back up is the 3.73. That should solve my problems. But I learned a lot. I'm running 225/50 R16's right now. What kind of 16" tire would put me on par with ITR on 17's?

I can't imagine changing this rear in 30 minutes. The Bentley manual says to remove the A-Arms before pulling the carrier with the diff. When I tried to do that, the bolt backs out against the diff. which won't allow you to remove the arms and the diff is tucked in front of the tank so it doesn't look like you can pull the diff and leave the carrier. I pulled the whole thing, a-arms and all without fully removing the half-shafts. Let's see if I can get it back in. Any suggestions for now and the future swaps? Thanks again for all the 411.

[robits325is]

All you should remove is the rear sway bar, drive shaft nuts, aves bolts and the three mounting bolts. No need to remove the carrier or rear control arms. I've seen them swapped in 20 minutes.

[JoshS]

I'm running 225/50 R16's right now. What kind of 16" tire would put me on par with ITR on 17's?

That's about the same diameter as the 245/40-17 I use.

[mr. black]

Thanks guyz. I will start putting it back together tonight. One last question. The book also says to have the car realined. Is that necessary? Especially if I did not remove the half shafts from the hubs? This is my first independent rear that I've taken out.

[robits325is]

If you pulled the entire sub-frame out of the car you will need to do an alignment.

[mr. black]

By subframe, you mean the carrier that the a-arms bolt to?

[mr. black]

If anyone is out there, especially in the NE division. I spoke with the previous owner and it turns out that both rears had been changed and not relabled. One diff has 4.27s and the other is 3.91. I will most likely never need the 4.27s. I'm going to try the 3.91s while looking for a back up 3.73. Both my diffs have 70% lock. Hard to find, but willing to do partial trade or sell. I would need 70% lock on the 3.73s to consider even trade.

[ed325its]

I run a 3.91 Quaiffe at the short tracks (NHMS & LRP) and a 3.64 for longer tracks (WGI & M-O). Need lower yet for Pocono, possible to the stock 3.15. I am running 225/50-16 tires. The 4.11 is certainly too much for any track.

My crew chief changes the diff in 20 minutes at the track, just pull the half shafts and drive shaft and drop it out. Since no suspension points are moved there is no need for a realignment. Hope that helps your planning.