black79

I'm sorry if this has been covered a million times a;ready, I did try searching but couldn't find exactely what I'm looking for. I have the rear-end pulled out of my 80 SA doing some suspension work. I have a 1983 rear-end with the disc braked and LSD in my garage that I had ploanned on putting into the car. What I'm wondering id can I just take the parts from the rear-end of the LSD and put them into my open diff or do I need to swap the entire rear-end? If this is possible how much work is involved. Thanks in advance.

Rx-7Doctor

iTrader: (13)

Yes you are correct. It has been covered a million times. :-)

If you just want to put the LSD in your SA then it is just a bolt in.

If you want the benefit of rear disc brakes then you need to swap the complete rear end and you can find the info on that by searching with the terms diff interchange or rear end interchange.

Here is one such thread.

https://www.rx7club.com/showthread.p...nd+interchange

Rogue_Wulff

I hope you also have the driveshaft for the 83. Aside from the flange on the front, the pumpkin is a direct swap.

Greaper_ca

Rogue, What do you mean when you say "pumpkin"

Few questions for all. As the first poster mentioned, it's getting cold up here and the city is giving me warnings about parking on the street. Rather than doing a search on this topic and reading through all the threads (call it laziness), I would rather just ask the questions and get responses. I seems faster this way.

I have an 81 and an 83, which I want to swap the rear ends from the 83 (w/ disk brakes) to the 81 (drum brakes). This is the only reason why I want to swap them. I'm thinking the easiest way to do this is to swap the entire thing - axle and all. Here are my questions:

For those who have done this job before. Were there any obstacles that might get in the way of a smooth swap?

What adapters do I need to swap the brake lines?

Are there any extra parts that are needed for the swap.

Does the driveshaft also need to be swapped?

How long should this take me? I want to schedule and allocate time for this project. I'm hoping just a full weekend would do it.

Knowledge and advice would be greatly appreciated.

Thanks all.

trochoid

iTrader: (6)

Hardest part is usually getting the bolts out of the control arms/watts link. You will need the rear brake cable for both sides and maybe the driveshaft, depending on if your car is an early/late 83. Small flange driveshafts have bolts, large flange have bolts and nuts, difference is in the pinion flange. Hand tighten all suspension bolts, do not torque them until the full weight of the car is on the ground. Allow for a full day for the swap, in case things get stubborn, soak all bolts, nuts and brake lines with PB Blaster a day or 2 before you start.

Pumpkin is the diff gears. Don't expect this kind of generosity, reading is your friend.
.
.
.
..
.
.
.

black79

So back to my original question. I tried searching the suggestions you gave me doc, but did not find anything. What I'm trying to find is someone that has done this before with an SA, that can kind of give me some insight on actually how to do it. I now know that you can do it, but now I need to know how to do it.

Sgt.Stinkfist

iTrader: (6)

i swapped an '83+ rearend into my '82 (same requirements as a '79) and it is essentially a direct swap. you will need the driveshaft from an '83-'85, and the rubber brake line that goes from the chassis hardline to the metering block on the rearend (chances are its still attached to the rear end) and youre good to go. if you are gonna just swap the diff. from one rearend to another, there was a change of axle size (im not sure which year) that may cause complications. either way ide suggest just swapping the entire axle

trochoid

iTrader: (6)

If you only plan on swapping the diff gearset, you may or may not need the driveshaft, as noted above. If the pinion flange is different, rear end may have the larger axles. I'm not sure if that when they went to the later 83 flange that they also came with the large diameter axles. If so, swap the entire unit. You will need adapters for the difference in the brake line thread pitch between the soft brake lines and calipers. RB sells them. You could have new SS flex brake lines made up with course thread pitch on one end, fine on other. Contact ReSpeed for those.

Diff only swap, jack up the rear, place jack stands under the axle, remove the brakes/backing plate bolts so you pull the axles out approximately 3". Unbolt the driveshaft, leave the other end still interted in the tranny unless you plan of changing the fluid. Shouldn't need to crack open the brake lines. DO NOT loosen the diff flange or change it unless you want to buy a new crush tube and have the lash reset in the diff.

As far as amount of work involved, you're past the hard part of it. There is no gasket between the diff and housing. Clean the mating surfaces with brake cleaner, use a good RTV sealant and don't forget the LSD additive for the diff lube, unless you use Royal Purple.

black79

Thanks, I have the entire rear-end out of the car now so it's all easy to get to. I haven't opened up either rear-end yet so I'm not sure what shape either is in. I'm still not really clear on what all I need to do to swap the gear sets. I take it everything will fit but what all do I take out and what all do I leave in? I am doing a TII swap and already have the TII tranny mounted in the car, so I'm going to have to get a driveshaft made anyway, so the flange shouldn't be an issue. I guess I'm just looking for a little more detail on changing out just the gear set. Thanks in advance for any help.

Rogue_Wulff

The only item that you really need to pay attention to, is the axle shafts themselves. The 80 model should have the small axles, assuming the rearend hasn't been changed. Once you have the axles pulled out of the housings enough to allow the center pumpkin to to be removed, you should be able to determine if the the disc rearend has the large or small axles. The large axles are noticeably larger where the bearing goes.
If the bearing appears to be the same size, just swap the entire center unit. If the bearings are noticeably different, you will have to swap the entire rearend housing, and get the special hose fitting or chassis to axle hose, and the disc brake cables for the park brake.
As for the driveshaft flange. 4 threaded holes is the small flange. 4 non-threaded holes is the large flange.
If the disc brake rearend has the small flange, it likely has the small axles.

Greaper_ca

Thanks everyone

black79

Thanks a lot Rouge Wolf for the information, I'll have to look at the 83 rear-end and see if it is the bigger axel or smaller ones.

black79

Ok so I have all of the bolts out of the center pumpkin section now. I also have the brakes and backing plates all unblted. I can't seem to get the axels to pull out. I'm assuming that these rear-ends are similar to a ford 8.8 as they would have to have a c-clip holding the axels into the tubes. To get to these i would also assume that that I need to get the pinion nut off. My problem now is that the entire unit is out of the car and I can't figure out how to get the pinion to stop rotating while i try to get the nut off. Anyone have any ideas?

black79

nobody has any ideas?

trochoid

iTrader: (6)

No clips and do not touch the pinion nut, unless you want to take the diff somewhere and have it reset. Axles simply pull out. You can put an old rim on and hammer on it or loosely bolt s wheel on and jerk on it.

black79

ok so just so I completly understand. I have the 7 or 8 bolts out of the rear-end where it bolts together, and I have the brakes and backing plates removed. Now all there is to do is to pull the axels out? There is nothing else holding them in there? Will this let me completly seperate the 2 parts of the diff?

boricua65

Hello everyone. I just have a question as far as to whats required to convert my 1980 GS to rear disc brakes? Thanks in advance....Harry