rxtuner79

iTrader: (1)

i am planning on doing a T2 swap in the near future, and heard the 84-85 differentials were the strongest of the first gens. i was wondering if a differential from an '85 gsl would bolt onto my '79, or if it would involve some sort of modification.

Rotor13B

No.

rxtuner79

iTrader: (1)

that was a pm sent to me by wackyracer. so does that mean it will work if i get the full disk to disk assembly? or should i just get the 81-83 differential? would the 81-83 be stonger than the one i have now?

EDIT: are the 81-85 differentials limited slip? and for the 81-83, would i need to swap anything other than the differential? for the 84-85, will i need anything other than whats included with the disk to disk assembly?

peejay

You need the entire rearend assembly, not just the differential.

People who make enough power to test the limits find that the series 2 rearend is the strongest overall. Series 3's have beefier axles and larger axle bearings but the housings seem to be weaker and allow more flex, and a flexing housing will break axles too.

The gearsets/differentials are the same S1/2/3 save for the difference in axle sise and therefore the side gears in the diff. S1's also obviously never had a limited slip.

Midwest 7's

iTrader: (4)

a plus to the s2 limited slip, is that it is lighter.

rxtuner79

iTrader: (1)

so youre saying i should get an s2? and will i need the entire assembly for the s2 as well, or just the s3? did they all come with an LSD or will i have to find one that came with it? thanks for your help.

Midwest 7's

iTrader: (4)

find a 81-83 GSL parts car.

Siraniko

iTrader: (13)

can you elaborate more? what kind of power are we talking about here as in XXX HP? street/bridge? Im asking as I have been running streetported motors for almost 20 years and I havent broken any axles. My driving habit includes daily driving and occassiional drag...and thats with puck clutches. In fact, everything in my blue FB is original factory stuff except the motor. Im the 2nd owner and I have owned it for almost 10 years.

MosesX605

The '79-'80 axle housing only has one use:

Greasy paperweight.

You can't swap in any new bits, you have to take the entire assembly out, brake to brake and swap in a new S2 assembly. If you get a rear end out of an '81 or '82, you don't have to swap driveshafts, for the '83 you do. All disc brake equipped cars came with LSD from the factory, but that's no guarentee, because alot can happen in 20 years.

I scored a complete assembly from an '81 and it installed really easily. You should rebuild the calipers, install new rotors and make sure the brake lines are in good shape. Speaking of brake lines, you will have to contend with a different thread pitch on the later model brake hardware. What I ended up doing was purchasing a short length of hard brake line and making an adaptor, with one coarse threaded end and one fine threaded end. That was then used to connect the hardlines on the axle to the flexible line going to the body.

Good Luck.

rxtuner79

iTrader: (1)

ok, i found a complete rear from an '83 gsl including the driveshaft. what exactly will i have to do to make this work with my car? everyone says it will bolt right on, but will i need to change the master cylinder? anything else i need to know before i drive over and buy this? thanks.

Fire85GSLSE

iTrader: (29)

I think the brake master cyl. might be ok but I believe the vale assy next to the brake master will have to be swapped.
I will be doing this same swap in a few months.
83 gsl LSD into a 79sa

Midwest 7's

iTrader: (4)

when you buy the rear end make sure and get the e- brake cables also. im pretty sure they are different for the disc brakes. some people say you need the proportioning valve, some dont. i think it is kindove a controversial subject since the rear brakes dont do all that much anyway.

peejay

But the '79-80 axlehousing has the best rear brakes of any 1st-gen. It's drum, so it is pretty much foolproofly effective instead of the continually requiring rebuilt calipers, and it's a non-self-adjusting type, so *you* set how the brakes are adjusted, and they *stay* that way.

MosesX605

Repeating this over and over doesn't make it so.

The rear discs are infinately better than the drum setup, with improved stopping power for street and race applications.

I've only had to rebuild the calipers once, when I installed them, and your perennial complaint about the parking brake has never affected me.

In short, on this issue, you're full of it.

Yark79

Drums on the '79 are teh_suck. I think I adjust my rears like two times a year (maybe only once, but still more than I'd care to). I wish I had disks in the rear since they are self adjusting. Drums will never be as good as disks.

jays83gsl

Now, I disagree with you, Moses.

My 83.5 GSL has the rear discs, and I recently replaced the pads on them after my 323 brake disaster

I test drove an 83 GS with drums. The GS stops quicker, hands down.

Midwest 7's

iTrader: (4)

whats up with the 83.5? does that have the 84-85 big axle?

Rotor13B

Your gsl brakes must not be adjusted right then. When I had my SA along with my current gsl (83 btw), The gsl would win hands down in braking distance. This is with both cars having new brakes and drums/rotors.

Siraniko

iTrader: (13)

There is no adjustment on front and rear disk brakes...For the rear, its only E-Brakes.

jays83gsl

Yeah, we're talking discs here, bud.
I mean, think about it. SOLID REAR DISCS certainly aren't all to hot for performance

MosesX605

I've owned two disc/drum cars and one disc/disc car. The disc/disc car had the best braking by far, especially during Solo II events.

That's just my .02. It is worth noting that I haven't changed either the proportioning valve or the master cylinder on my '79 that I swapped the '81 disc axle into. Perhaps that has something to do with it.

stilettoman

iTrader: (1)

I recommend the following steps to improve your braking:

1. Remove all personal effects from the 79 RX-7.

2. Buy a 1984-85 GSL.

3. Put you personal effects in the new car.

This will give you a limited slip, the larger diameter axles, 4 wheel disc brakes, not to mention MUCH NICER interior, heating and ventilation, instruments,etc.

As an alternative, find a complete 84-85 GSL rear axle housing assembly, as someone already suggested, but there will be some conversion issue with hoses, fittings having different threads, etc.

I have been running my V8 powered 84 GSl for a couple of years as a daily driver, no problems with the diff. Your turbo rotary will not be likely to have as much torque as my V8.

Pen_Two

I agree.

Fire85GSLSE

iTrader: (29)

I guess to each his own! I would rather have the 81-83 dash anyday as long as I got the 120 speedo and the front mount oil cooler. I hate the 84-85 dash! Nothing beats a 81-83 black interior 1st gen! Nothing!!!

Plus not to mention you chose a v-8 over a rotary! come on dude you must be loosing your mind. I have to agree I would like to drive a V-8 rx7 every now and then but if I wanted a v-8 I would have used a nissan. But again everyone has a different outlook.

Midwest 7's

iTrader: (4)

the 79 is WAY tighter than some heavy *** GSL with blocky interior. dont get me wrong, the GSL is tight too, but if i had a choice i would chose the SA.
anyway i thought this thread was settled? you find a S2 rearend, pretty much bolt in. sounds like he alreay even found one. **** and if you tell him to put a 84-85 rearend in his car, ( which i dont recommend ) at least tell him to get the se rear! i mean if he's gona go to all that trouble im sure he could swap the front and get some cool rims as well.

also i think more people would like the older interior if it was always so shitty.