Link

When putting the diff back together I put the disks in the most logical order. Some sides of the disks are worn more than others so I put the most worn sides where the least worn sides used to be etc. There were no unusual grooves or wear marks in any of my disks so there wouldn't have been any benefit to putting them back exactly where they came from.

You are correct about the backlash. It's the amount of travel in the ring gear when the pinion is held steady. This is measured with a dial indicator set up perpendicular to the ring gear teeth. You set the dial indicator up, hold the pinion steady, and rock the ring gear back and forth, the amount it moves is your backlash. You tighten and loosen the adjusting nuts to get the backlash within spec. I believe there are quite a few tutorials on this site that show how to do this. It's not difficult to do, just tedious and you have to take your time to get it right.

As far as my project goes, my differential is leaking from the driver's side axle.





It's leaking and spraying gear oil on my hot exhaust, which makes for some awesome smells!

It's not leaking a TON, but it's about a dime to quarter sized drop every time I drive the car. I've tried everything I can think of to fix the leak. I've replaced the oil seals twice, replaced the axle clips twice, and tried a few other things with the breather and I even tried modifying the axles. But it's still leaking.

My guess is that because the problem is because the axles don't really lock into place. This unit is from an 85 solid axle vehicle, so there are no grooves in the side gears for the axle clips to lock into. Even though the axles are held in there tight, they can slide in and out a little bit during hard cornering, which is enough to make them leak.

My only option is to either find a differential from an 86-88 NA RX7 and rebuild it with the disks in my current unit, or I will have to bite the bullet and buy a Kaaz.

I am going to keep my eyes open for an 86-88 unit and hopefully I'll get lucky, but they are getting harder and harder to find. I love the way this differential drives, it's currently at 85 lbs/ft and it feels amazing. I just wish it didn't leak!

mpk490p

thanks for the info i have the new pumpkin now, i'm only swapping in the lsd unit so it shouldn't be too much hassle

Mark

Link

Alright fellas! We are back in business!

I came up big time on this deal and couldn't pass it up. I found this thing listed as a "carrier" which I never search for, at a local wrecking yard. Best of all, they wanted $50 for it. I drove straight there from work and sure enough I walked away with this complete assembly for $50.







So I brought it home and started pulling it apart. Pulled the axles out, looks good so far...







And here she is...





I haven't taken it apart farther than that yet, but already I can tell the side gears are totally different from the 84-85 gears. They are way more beveled and the axles fit tighter than they do in the 84-85 diff.

I will complete the disassembly next week and measure out the disks. Then hopefully I will be able to find some time to pull my rear end, rebuild it AGAIN with the new disks and correct side gears. Then hopefully this whole project will be over and I can move onto something else!

I'm crossing my fingers, but so far nothing about this project has gone as planned, so we'll see.

Link

I finally had some time to get this thing apart last night. Before I took it apart I checked the backlash and bearing preload just to see. The preload was spot on, but the backlash was all over the place, it varied from .0032 to .0060. Which isn't completely within spec but the gears looked perfect. In my experience it's nearly impossible to get the backlash perfectly in spec all the way around the ring gear. I suppose it doesn't matter that much as long as it's not too out of whack.

Surprisingly this diff was in awesome shape! The disks measured out almost perfect, better than the previous two that I purchased. I don't know if this one was rebuilt sometime along the way but you'd think that a differential out of a car that's 23 years old would have at least a little wear. I'm not complaining though.

The order of the disks was somewhat weird, it was different from the previous two diffs I took apart. The way this one was assembled left 3 of the friction surfaces completely untouched because they weren't sliding against anything. Which is great because those disks are pretty much brand new still.

Here's the case, the bearings seem to be in good shape, I'll have to compare this one to the one that's already in my car to see which one to use, I'm not sure it will matter thought since they both seem to be in great shape.



Here are all the measurements in mm. Brand new the disks should be 2.00mm and the lower wear limit is 1.90, so as you can see, these are pretty much brand new.



The spider gears look great as well, no burs, cracks, or unusual wear.



And here's the reason that the 86-88 diffs work and the 84-85 diffs don't. The side gears on this 86 are beveled and there's a place for the axle clips to lock into.



Compare that to the side gears from the 85:



So far so good. I'm confident that using this diff is going to work for me and that the axles won't leak anymore. Unfortunately I won't have time to pull my rear end and rebuild the diff this weekend so I'll have to wait until next weekend. This project has gone well over 6 months now so I'm sooooo ready to be done!

Link

Tomorrow is the day! I'm planning on rebuilding the rear end with the 86 diff internals!

I'm hoping that it will be fixed after tomorrow, I'm so sick of this stupid thing leaking!

jinxed4dub

iTrader: (7)

so if your doing away with the 1st gen lsd. you should sell it to me. I've bought some parts from you before I beleve. I'm the guy with the 10 tone paint on the beater FB.

pfsantos

iTrader: (1)

Excellent thread for us 2nd gen. guys/gals too. Subscribed.

LongDuck

Don't forget the GM LSD additive that's recommended for these. I don't know if everybody's in the habit of adding it, but for the small cost and effort when changing diff oil, it's cheap insurance nonetheless. HTH,