We're going to replace the third member (old one has a blown diff) with another '83 drum/open diff from a local wrecking yard ($150). We are not interested in moving up to a SE third member at this time.
Any advice for a couple of noobs? I remember reading somewhere about a suspension upgrade/retrofit - we would like to try to do that at the same time.
Any useful help appreciated...

 

Is there any possibility that you could get a 3rd member from a GSL? That way, you get the LSD and disc brakes, but you keep your bolt pattern. This is a very simple sway, one that I performed a couple of years ago. The LSD alone makes this worthwhile, but its also a lot easier working on disc brakes than drum brakes.

But either way you go, you should get a set of bushings for the rear, and for the rear swaybar (bushings and endlinks). You're going to have everything out anyway, so this is the best time to do it. You should also consider rear shocks. www.re-speed.com is a good source for any of these items.

Soak all of the nuts and bolts in something like PB Blaster as soon as you can. The longer it can soak, the easier your task will be.

Best way to get the old bushings out is to light a small fire in the grill and burn them out. An actual fire works great, trying to use a torch just doesn't seem to do the job so well.

Other than that, there are no real surprises or anything. Use the right tools, try not to break any bolts off, and remember to bleed the brakes when you're finished.

Good luck.


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I just pulled and replaced my 3rd member a month ago to install my new gears... pretty simple job.... you'll have to pull the axles first, then drop the driveshaft from the pinion... leave it inside the tranny tailshaft... unless you want to change your gear case fluid b/c it will go everywhere.. lastly just loosen the 10 bolts that secure the 3rd member to the rear axle. As Kentetsu said a GSL diff would be a nice upgrade and they can be found for cheap. Just out of curiosity what makes you think your diff is bad? Most open diffs don't go bad as there are no friction surfaces to wear out. More than likely you've got some differential bearings that are going bad. Either way you should replace them if you're going through the trouble of dropping the diff.... axle bearings would be a great idea too. I have a full set of differential bearings that I ended up not needing when I tore mine apart. I paid $150 shipped for the set but I'd sell them to you for $75 plus shipping. If bearings are the cause of your issues this would be a cheaper fix for you. You can PM me if you're interested.

 

I believe the diff is fragged - the PO tried to "do a burnout" (in reverse) in his driveway and it went BOOM. I believe it is the original third member.
I do not know if it is a GSL or what (how do you know?).
When we roll it (difficult), it clunks. When it's off the ground and I spin one wheel, the other wants to go in the same direction. When one wheel is held, it's locked solid.
Unfortunately, we live in the boonies (central WA) and there are precious few sources for first gen RX7 bits without making it a day trip.
This is a project on the cheap - my son's - he is learning how to be resourceful and frugal. He and I object to the notion that the wallet is the most valuable tool in one's kit

 

it sounds like a gsl if it has disk breaks in the rear its for sure a gsl and as to the wallet being the best tool lol ...yes the wallet is the best tool with an RX-7

 

I have drum brakes...

 

Before anything, using your 3/8 ratchet, unscrew the diffy filler plug. THis is a must coz if the filler plug wont budge after draining the fluid, you will be in deep ****.

 

well then im thinkin it is a welded diff by how your explaining its behavior and ya it sounds toasted

 

We got that old bugger out yesterday the PB Blaster/impact gun combo made it easy. The pumpkin rattles inside - pieces of something bouncing around in there...
Sadly, we unknowingly got an '81 third member from a wrecking yard - of course, once we had it almost all back together, we realized:

1. The pinion flange was too small (sigh) for his '83.
2. The '83 driveshaft seems to be too short :-/
3. The Watt Link bracket stud is pointed (bent) downward a lot

Yes, it was a frustrating but educational day. So, it goes back to the wrecking yard in hopes of finding a good pumpkin instead (at least we'll save some money). We would love to find a GSL third member, but where we are located, that's pretty unlikely.