I have had a bit of a roaring sound coming from the rear of my car and in my efforts to diagnose it, I replaced the rear diff oil. What came out was thick, gray and sparkley, like fine pieces of metal in it. Quite a thick sludge. The car still makes the noise and I am going to replace the gear oil again and get it all cleaned out. Does this sound like it is going to need replacing? How hard would it be to remove the diff and open it up to check for damage? If it needs to be replaced, are there aftermarket units I should look at? Price is a concern so cheaper is better as long as quality isnt lower.
thanks

 

G'day Tom,

I have for sale on the parts trader a Manual diff from a J-Spec RHD '93 Type R that had approx 53 K miles on it (88K kms). (see pic) The diff is in excellent condition, oil was clean when drained. I'm asking $400 + shipping which will be a $$ pain because these diffs are bloody heavy, but it can be done ! I sure don't want to take it back to Oz in March !

Let me know if your interested.

Mac
Ft.Lauderdale

 

What's the gear ratio on that diff? 4.1 or 4.3?

 

Hi Mac, I am interested. I haven't really started looking for diffs so I don't know what is out there yet, If you can get some kind of an estimate what shipping it will cost I will let you know in a day or 2. Oh yes, ditto on the ratio question.
thanks,
Tom

 

I also have a complete unit with a new Torsen LSD installed less than 5K miles ago. Changed to a KAAZ diff so I have an entire assembly available and also just a diff available. I'll sell the whole assy for 400 and the shipping should be around 60bucks or so, the unit weighs about 80lbs. The differential itself I'll sell for 175plus shipping and can be bolted back in place with minimal effort and weighs about 22lbs. The whole assy is the stock 5 speed manual setup with 4.10gears. The diff alone has no ring gear on it, you'll have to use yours provided it's not destroyed. PM me if you're interested.
art

 

Tom93R1 and jr,

I guess it is stock 4.10. Is there an easy way of telling for sure without opening it up ?

Thanks

Mac

 

If it's from a 5 speed it's a 4.10 unless you or someone has put the 4.3 gears in it. If it's from an automatic it's a 3.90 gear.
Art

 

J-Spec cars had the 4.3 rear gears as an option and he said it was a JSpec diff so that's why I asked.

 

Thanks Jr, you learn something new every day. I wasn't aware of that option.. But I still have a whole assembly for sale and a "spool" for sale if anyones interested.
art

 

To RTS3GEN and jr.

So, if the auto diff actually uses a 43 tooth ring gear with an 11 tooth pinion to get the 3.909 ratio and the 5 speed diff uses a 41 tooth ring gear with a 10 tooth pinion to get the 4.100 ratio, then could you use an auto diff 43 ring gear with a 5 speed 10 pinion to get a 4.300 diff ?

or vice a versa, take the auto ring gear and put it in the 5 speed diff.

Is it correct that the end result would be higher revs across all gears for the same speed and therefore a more usable rev range in 5th ?

Thanks for your insight.

Mac

 

Yes and no. 5th will be more useful as a track gear as opposed to an "overdrive", but it's still not as effective as getting a shorter 5th gear. I think the true value of the 4.3's would be better acceleration.

 

I've been out of town so I haven't been able to figure out what I need yet. I guess I will have to pull off my diff and open it up to see what I need to replace? Is the limited slip something that may go bad on its own and the rest of the diff is OK, or vice versa? I don't really understand how the limited slip works, is it just something exrta inside the diff? All I know so far is that I have alot of noise from the rear of my car and the oil was a thick, silver sludge when I replaced it. Any thoughts if the whole assembly will need replacing, or just the limited slip, or just the diff?

 

Most limited slip diff failures that I've seen can be attributed to bad clutches, but the diff in our cars does not have any clutches. Check out this article from howstuffworks.com:

http://www.howstuffworks.com/differential.htm

Page 8 explains the Torsen diff which is what the FD has. I'm not too sure what the main failure points are, but if your seeing a lot of metal particles in the fluid I guess you could have stripped the teeth off one of the gears.

 

The spider gears are usually what fail, usually due to excessive torque applied that the hardened gears just cant handle. The car will still drive straight, but when you apply excess torque, such as a launch or hard corner the broken gears will break more. The spider gears are the gears that transfer the torque split from axle to axle. When you dissassemble your diff, you'll see the gears in the center of the assembly, and how they are situated, you'll see how they transfer the torque from one wheel to the other.
Art

 

On My Diff. early this year. I changed the oil and gound a couple metal pieces stuck to the magnetic rear end oil drain plug. About 1/2"
long and 1/4" thick.

I'm sure it was from the spider gears. At that time I had no $$$ to change it. I figured it was from wheel hop during 5 yrs of drag racing.
I took a chance at it. And took it to the track. I launched hard w/drag radials and it lasted only 2 runs and broke. I did not know what was all involved when changing the diff. I cracked the entire Diff casing and needed new ring and pinion and LSD unit. Labour + Shims...more $$$.

Canadian funds: New Diff. case: $500
Kazz Lsd unit : $1300
Ring and pinion: $750
Shims and Labour: $800

So if you're drag racing. Change to the Kazz before you break something. And really pay. Really hurts since I also went thru an
engine and turbo earlier this year. Now I need axles...
best wishes jc.