83 rear end swap
03-12-02 | 04:52 PM
#1
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From: North Jersey
83 rear end swap
I have a 83 S with an open differential and drum brakes. I want to put a GSL rear end (LSD, disk preferably out of the same year) in my car. What is involved in doing this? Will I have to change the master cylinder? anything else? Will it just bolt right in? Thanks 
03-12-02 | 06:23 PM
#2
smog nazi destroyer
Joined: Jul 2001
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From: california
i am looking into doing the same swap in my 79.
i think it is just a matter of droping your current rear axel and putting the new one in. the break lines will have to be changes , and also the emercency break line.
hopefully someone esle can give more detailed information, as i need it too
i think it is just a matter of droping your current rear axel and putting the new one in. the break lines will have to be changes , and also the emercency break line.
hopefully someone esle can give more detailed information, as i need it too
03-12-02 | 06:45 PM
#3
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From: North Jersey
Yea the main thing I'm concerned with is whether the master cylinder is the same for disk and drum brakes. I'd assume it isn't becuase disk and drum have very different requirements to power them. I know there are probably a ton of you guys out there that have already done this. Any pictures, and/or detialed info would be greatly appreciated. Thanks
03-12-02 | 11:52 PM
#4
Passenger
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YES!!! YOU NEED TO CHANGE THE MASTER CLYINDER!!!
this is what can happen if you have to spike the brakes and do not change the master cylinder!!!! trust me, i know!!!!
the following info i am not 100% sure on since i've only toyed with '84-'85's.
82transam: the '83 is kind of an oddball. it is the first year for the larger flange and last year with smaller axles. you could stick with the '83 rear or you could go with the '84-'85 rear to get the bigger axles. i THINK it is a bolt in.
riffraff: i think the '79's and '80's had different threads then the '81-'85's on the brake lines. to the best of my knowledge the 79-80's did not have the good stuff. so you will have to do some mods. sorry i can't be anymore help then that.
this is what can happen if you have to spike the brakes and do not change the master cylinder!!!! trust me, i know!!!!
the following info i am not 100% sure on since i've only toyed with '84-'85's.
82transam: the '83 is kind of an oddball. it is the first year for the larger flange and last year with smaller axles. you could stick with the '83 rear or you could go with the '84-'85 rear to get the bigger axles. i THINK it is a bolt in.
riffraff: i think the '79's and '80's had different threads then the '81-'85's on the brake lines. to the best of my knowledge the 79-80's did not have the good stuff. so you will have to do some mods. sorry i can't be anymore help then that.
03-12-02 | 11:57 PM
#6
smog nazi destroyer
Joined: Jul 2001
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From: california
rb and rp both have ss braided break lines for 79/80 with rear disks, so i would imagine that that then incorporates the different threads...
who knows. i will figure it out soon enough. i will probably find a used 81/82 gsl rear end in may and do it then (get my new suspension at the same time too)
who knows. i will figure it out soon enough. i will probably find a used 81/82 gsl rear end in may and do it then (get my new suspension at the same time too)
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dude that sucks , that was the master cylinder...
03-13-02 | 10:30 AM
#10
Senior Member
Joined: Apr 2001
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From: indiana
actually, i did the swap with my 82 about 3 years ago. i've had 3 years of trouble free braking too. and i'm VERY rough on the brakes. it was a fairly easy swap, especially considering i'm not much of a mechanic. bolt comes off... bolt goes on. very straightforward swap. not sure what could've caused the problem that 'brake' had, but damn! that really sux! hope nobody got seriously injured in that shiznit!
03-13-02 | 11:53 AM
#12
Tennis, anyone
Joined: Jun 2001
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From: SoCal.
One of the first things i did to my car, was the rearend
swap,i'm 82 GS, i went to the junkyard and from different year cars i put together a rearend with disk's
and LSD,i don't know the years, but i used my same
drive shaft,,,what i did was go through all the rearends
at the boneyard and put together MY rearend on the
side out of the best parts i could find. it took a while
to do that but hey,,why not,,it was a direct bolt in project that took 1 person about 2 hours,,i did not
change the master cycl. and have had no problems at all
make sure to use LSD oil when you install the new rearend,,the gearing and LSD are better then what was
in the GS,,,oh and the disks too
swap,i'm 82 GS, i went to the junkyard and from different year cars i put together a rearend with disk's
and LSD,i don't know the years, but i used my same
drive shaft,,,what i did was go through all the rearends
at the boneyard and put together MY rearend on the
side out of the best parts i could find. it took a while
to do that but hey,,why not,,it was a direct bolt in project that took 1 person about 2 hours,,i did not
change the master cycl. and have had no problems at all
make sure to use LSD oil when you install the new rearend,,the gearing and LSD are better then what was
in the GS,,,oh and the disks too
03-13-02 | 02:06 PM
#13
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From: North Jersey
yea man sorry to see yer car like that. So you're saying that an 84/85 rearend has the same flange as 83 right? So it should thoretically just bolt in. And after seeing that pic I'll be sure to change the master cylinder as well. While I'm at it I might as well go with ss brake lines too. 
Thanks for the info
Thanks for the info
03-13-02 | 03:14 PM
#17
Passenger
Posts: n/a
with drums in the rear the front tires always locked up first. i would have to really jam on the brakes to get the rears locked up.
after i swapped in the disk rear i did some brake tests and noticed the rears got pretty damn hot. i never did a panic test though. the master cylinders have different part numbers and i was planning on swapping them. well, before i got around to it i had an unexpected panic stop. the rears promptly locked up and i spun the car into an embankment. jumped the 6-foot hill and landed on the pass side door/roof (thank God there wasn't a passanger) it landed hard enough that the door hinge dug into the pavement about an inch. the car rolled about 5 times. i walked away with some minor cuts and pulled muscles in my back... and a real bad headache.. Rx-7's are tough little cars! when i got the car back i put in a new battery (old one was smashed) put the dist. cap back on and the thing started right up and i drove it into my garage.
don't feel sorry for me though, i was being really stupid when i did it.
that same rearend is back in the car that donated it with the proper master cylinder... the same front rotors and brake pads for that matter too. the only thing different is the master clyinder. it stops like it should, i made damn sure of that.
changing the rears isn't very hard at all. jack it up from the 3rd member, put some jackstands under the rear trailing arm brace (they are good and sturdy for this). lower the jack so it's just suporting the rear and unbolt. the only trouble i had was getting the e-brake cable loose. aluminum and steel don't mix well. it took 2 days of soaking it with PB blaster and a heat gun. oh ya, grab the rear e-brake cables off the doner car as they are different. careful not to bust a gut lifting the rearend, they are not light.
after i swapped in the disk rear i did some brake tests and noticed the rears got pretty damn hot. i never did a panic test though. the master cylinders have different part numbers and i was planning on swapping them. well, before i got around to it i had an unexpected panic stop. the rears promptly locked up and i spun the car into an embankment. jumped the 6-foot hill and landed on the pass side door/roof (thank God there wasn't a passanger) it landed hard enough that the door hinge dug into the pavement about an inch. the car rolled about 5 times. i walked away with some minor cuts and pulled muscles in my back... and a real bad headache.. Rx-7's are tough little cars! when i got the car back i put in a new battery (old one was smashed) put the dist. cap back on and the thing started right up and i drove it into my garage.
don't feel sorry for me though, i was being really stupid when i did it.
that same rearend is back in the car that donated it with the proper master cylinder... the same front rotors and brake pads for that matter too. the only thing different is the master clyinder. it stops like it should, i made damn sure of that.
changing the rears isn't very hard at all. jack it up from the 3rd member, put some jackstands under the rear trailing arm brace (they are good and sturdy for this). lower the jack so it's just suporting the rear and unbolt. the only trouble i had was getting the e-brake cable loose. aluminum and steel don't mix well. it took 2 days of soaking it with PB blaster and a heat gun. oh ya, grab the rear e-brake cables off the doner car as they are different. careful not to bust a gut lifting the rearend, they are not light.
03-14-02 | 02:52 AM
#20
Full Member
Joined: Feb 2002
Posts: 146
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From: Germany
Originally posted by mark perez
of any disk brake system,isn't 70 % allways front rotors. 70% of stoping power is front, 30% rear.
of any disk brake system,isn't 70 % allways front rotors. 70% of stoping power is front, 30% rear.
The more weight towards the back of the car, the more the rear brakes take care of things (unless your suspension sucks and the car takes a nosedive when you stab the brake pedal). Example: BMW tests show that their new M3's weight balance is 49/51 still, and 43/57 under braking.
Not trying to be nit-picky, just accurate.
03-14-02 | 03:25 AM
#21
Rotary Freak
Joined: Apr 2001
Posts: 2,441
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From: Troy,Mi
my fronts are not currently working at all right now,
and ill say you would be amazed how much those back brakes actuall work,
not to mention my car is gutted in the back.
i do wics i had my front though,
i pray everyday someone in front of doesnt lock em up.
id be screwed
if i hit the brakes to hard the rears just lock and i slide,
there worthless in the rain,
oh and i also have drums
84 gs welded diff
and ill say you would be amazed how much those back brakes actuall work,
not to mention my car is gutted in the back.
i do wics i had my front though,
i pray everyday someone in front of doesnt lock em up.
id be screwed
if i hit the brakes to hard the rears just lock and i slide,
there worthless in the rain,
oh and i also have drums
84 gs welded diff
03-14-02 | 07:34 PM
#23
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From: North Jersey
hey riffraff **** paying someone to do it. I do all my own **** and not only is it satisfying to know that your riding on something you put together but youy also learn a lot in the process. I'm definatly gonna swap my rear this summer when school is out. Peace
03-14-02 | 09:19 PM
#24
smog nazi destroyer
Joined: Jul 2001
Posts: 1,681
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From: california
i definatly know about satisfaction with the car. i more or less put mine together.. i just didnot know if the rear end would be more involved than i could do with limited knowhow and limited knowledge... but i will probably give it a shot.. do that and the suspension upgrade at the same time
