OK I tried searching for info about this. I found some but nothing specific about what i'm looking for. So I apologize if this has been covered before. I'm curious about installing a LSD in my 78 RX-7 but keeping the same bolt pattern, and even rear brakes if I could? I don't want to do the complete change-over because I want to keep the wheels I have...unless I've misread and there is a way to do the complete changeover rear axle, brakes and everything and keep the same old bolt pattern that it's almost impossible to find wheels for lol. Someone please enlighten me here!

Thanks,
Colin

 

im assuming you have a gs? what kind of lsd do you want to swap, cause if you go with a gsl, you would also get rear disc brakes, but the same bolt patter, which would be easy, then all you would need is some brake line. but with the gsl-se you would have a diferent bolt pattern

 

are you sure bout the year of your rex? I wasn't aware of any differences in the bolt pattern, a long as it's 4 bolt and came off a rex, it should fit, but feel free to correct me if I'm wrong. As far as a rear end swap it's pretty straight foward, provided that the '82 suspension is the same as a '78 or '79. I would find a junk, wrecked would be best, 1st gen with the GS or GSL options, and use that rear end. That's what I did this summer to swap my rear to LSD and disc brakes, I bought the whole GSL for $100, not a bad deal. I would recommend you swap brakes and all, unless your trying to keep the stock brakes. The only difference between the LSD rear and the drum rear is the brake line, other than that identical. Alll that's required to fix difference in the rubber line that hooks up to the rear end itself is a $20 brake line

Good Luck

 

Let's take my car's year (1984) as a good example.

I have a GS. It has rear drum brakes and Open Diff, with 4x110mm bolt pattern

There are two other models in my year. GSL and GSL-SE

If I take the rear end from a GSL, it will have LSD and rear discs, and will have the same bolt pattern (4x110mm) and the same rear end gear ratio

If I take the rear end from a GSL-SE, it will also have LSD and rear discs, but have a different bolt pattern (4x4.5") and a different rear gear ratio. On the plus side however, the rear discs are vented like the front ones, for better brake cooling. The GSL only had solid rear discs.

So If you have good mags on a GS, switch a GSL rear end into your car. You'll keep the bolt pattern, get a brake upgrade from drums to discs, and it won't cause you much hassel. Make sure you get it from the same year car or there might be some differences on how the driveshaft mounts IIRC.

If you have good mags on a GSL, you've already got what you want and you can stop here.

If you have crappy mags on a GS or GSL, then switching to a GSL-SE rear end can open up *tons* of mag options, since the 4x4.5" bolt pattern is much more common, and easier to find rims for. Of course you'd also have to switch the spindles out in front. On the '84-'85 cars (any model), you can just put GSL-SE discs and bearings in front and be done with it. On pre-'84 cars you need to swap the spindles out too, since they're a smaller diameter.

Jon

 

If you want to keep your rear drum brakes just get an LSD (center section only) from an 83 Gsl. Or you can get the whole rear end from an 83 Gsl wich will give you a lsd and disc brakes and you get to keep the same bolt pattern.

If you can't find an 83 Gsl you can use an 84-85 GSL Rear end but you have to swap the whole rear end you cant use your old rear end. And you also have to get any 84-85 drive shaft the modle does not matter for the drive shaft as long as its from an 84-85.

 

Edit:

Just noticed you had a '78. The good news is you can still swap in a GSL rear end for a disc brake and differential upgrade. The only thing is that they didn't have GSL model cars in 78. I *believe* (don't take my word, but I'm pretty sure) that GSL started appearing in '81. They weren't badged, but you could tell because they're the only cars from '81-'83 that had rear discs.

Grab a rear end off one of those. I don't know if it will swap in easily. I vaguely remember that from one year to another they changed the mounting points of the rear end, and someone mentioning differences in how the driveshaft mounted......

If you have a victoria british handy, check that. It should have the info on when the control arms were moved.

Anyone else want to chime in? Potential problems with putting an '81 GSL rear end into a '78?

Jon

Side note to Tatterjuice
Just thought I'd notice/mention that you list your '82 as a "G".
There is no G. It goes S, GS, GSL, GSL-SE

You probably have an S

 

Here is a prtty good right up and it will tell you everything that you need.

http://www.wankel.net/~krwright/cars...ds/brakes.html

This one has other modifications that you might want to do to your car

http://www.wankel.net/~krwright/cars/rx7/mods.html

 

If you want to only put in the lsd diff then you have to use an 81-83 lsd. All you have to change the flange from your old diff to your new one. 84 and up diffs used bigger axles so you would have to swap the whole rear end.

 

i have an 82 lsd for sale. if you are interested pm me.

 

I have a 1978 Savanna GT...no GSL or SE or any of that stuff...it's a japanese import...for simplicity sake and for keeping almost everything original i'd prefer just swapping a rear LSD in and not changing much else? Sorry I should have been more clear about that before. Thanks for the TON of info. My main concern is keeping the 4x100 bolt pattern which is what I think mine is...

Thanks,
Colin