I am getting ready to have the rear end of my LX checked. The previous owner installed 3.73 gears and there is some clunking going on back there. My question is should I go ahead and replace the differential and axles while it is apart? If so, what differential should I be looking at? This is not a track car. It is one that a drive around every now and then either to work or out cruising. I have talked to the guy who will be doing the rear end and he explained some of the different diffs out there. As I understood it, some have carbon fiber clutch discs and some have gears in them. He suggested that I go with the ones that use gears but I wanted to know if this would be overkill in my situation. He said that the clutches wear out but this is not a daily driven car. Any help?

 

Assuming you're talking about which carrier to go with, and by the one with gear assuming you mean something like a detroit locker? If that's what you're talking about DO NOT get it. The mechanic you are dealing with is apparently very in-experienced when it comes to differentials, as no mechanic with any experience will ever recommend a detroit. They are ABSOLUTELY terrible. They are extremely weak compared to other choices, they chatter like a bastard around corners, and they are noisy as hell. You might as well put a spool in your car if you want to put a detroit in and save yourself a few hundred dollars. Just get a regular posi unit, a factory one, unless you're putting out a lot more power than factory. If your car already has a posi in it, just get a new set of clutches for it, cheap cheap cheap.

In summary, if you're driving it on the street, stick with a clutch operated posi-unit.

 

Detroit lockers aren't that bad, I've got one in my dana 60 in my chevelle and have no issues with it.

I just got a 31 spline eaton posi unit along with axles, its a clutch style differential and these first 1000 miles have been fantastic. With the exception of a different gear ratio, you wouldn't know it's a different rear end, it performs the same but is stronger.

 

The car is pushing 350 hp at the crank, so a little more than stock. I figured the type of differential this guy was talking about would not exactly be what I wanted for my car. I just wanted to upgrade my rear end to something a little more stouter than factory since I am having the rear checked anyways. My initial plan was to replace the stock unit with a beefier unit with carbon fiber clutches, heavy duty 31 spline axles and a rear end cover with bearing cap support studs. Back to the differential, which is recommended? Eaton, Auburn or Ford Traction-Lok?

 

Eaton all the way, I got mine through Strange Engineering as well as my strange 31 spline axles. I'm pretty sure they sell 31 spline 4 lug axles, but the axles I run are 94-95 design as my car has a 5 lug conversion. They sell two different types, the spring style differential which cannot be rebuilt but does not have clutches, and they sell the clutch style differential which can be rebuilt. I went with the clutch style.