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So I've come across a 78 to 82 lsd. I believe Carl is no longer selling the adapter plates to install this into a later model car. Since I have the whole early model diff. can I just take the side plates from that and install it into my S4 diff? will that take up the difference?
So I've come across a 78 to 82 lsd. I believe Carl is no longer selling the adapter plates to install this into a later model car. Since I have the whole early model diff. can I just take the side plates from that and install it into my S4 diff? will that take up the difference?
Another incredibly poor idea, by Carl.
This ends up being all screwed up, dimensionally.
One axle ends up being too short and the other axle ends up being too long....by 5mm.
Some people, who don't understand how C/V joints work, will say that the joint has enough movement to allow for 5mm design difference,
but in reality, a C/V joint is designed to run perfectly in the center and will constantly attempt to reach this.
This is why badly worn C/V joints will allow the axle to thrust and pound on the flanges....they no longer have the ability to return to center.
Look, if you have a street car and think you need a limited slip, get the '85-'90 one:
There's probably not two people, on this entire forum, that could tell you what version limited slip is in the car (or if there is one.)
If you've got a dedicated track car....and enough talent to actually be able to tell what limited slip is in the car (probably less people than above), find an '83-'84 unit.
Can you tell me what stops one from installing the early year LSD in the later year car. I need details if you have them. Also could one just change out the complete diff housing to solve the problem?
Can you tell me what stops one from installing the early year LSD in the later year car. I need details if you have them. Also could one just change out the complete diff housing to solve the problem?
Just very basic engineering problem:
Because the late ring gear is thicker than the ring gear on the 78-82 transmission, the entire differential needs to shift 5mm to the driver's side of the car to be able to set-up the backlash.
The part that Carl sold was a 5mm shim that fit under the driver's side bearing flange.....simple and cheap to make.
It all fits and functions.......
Except, because the entire differential moved 5mm, the passenger axle is 5mm too short.
And the driver's side axle is 5mm too long.
The C/V joints can no longer function as designed and suffer from the misalignment.
i bought years ago such a LSD kit from Carl....and installed it in the "rally" car.
It is indeed a 5 (? ) mm shim for one side and a machined side bearing for the other side. So i suppose that one was machined down 5 mm. ( didn't take dimensions )
But it worked and backlash was again the same as before.
Don't know how bad it is for the axles.....
Greg , i just doubt now that it is as you wrote.... but the opposite , so 5 mm towards the passenger side. That i suspect as we had to bevel the alu ring ( with the speedo magnets) a bit so that it did not touch the pinion. ( as in Carl's manual described) In that case the late rings are smaller then the old ones ??
i bought years ago such a LSD kit from Carl....and installed it in the "rally" car.
It is indeed a 5 (? ) mm shim for one side and a machined side bearing for the other side. So i suppose that one was machined down 5 mm. ( didn't take dimensions )
But it worked and backlash was again the same as before.
Don't know how bad it is for the axles.....
Greg , i just doubt now that it is as you wrote.... but the opposite , so 5 mm towards the passenger side. That i suspect as we had to bevel the alu ring ( with the speedo magnets) a bit so that it did not touch the pinion. ( as in Carl's manual described) In that case the late rings are smaller then the old ones ??
Could be....just going from memory of the different pieces.
However, the speedo magnet is on the passenger side. If you had to bevel it to clear the pinion, it would have moved towards the pinion...towards the driver's side.
(BTW....I'm talking about left hand drive vehicles.)
You want to know how much the C/V joints hate this? Go drive the car and touch them, after you stop....carefully.
That crazy heat is energy, stolen, before it gets to the tires.
Worth noting, In the "US off road world", they make axles with very long splines on the ends, which allow the axles to "float" in the C/V joints. This allows the C/V joints to remain centered as the suspension travels, dramatically reducing heat and wear. Without doing this, C/V joints will overheat and fail in a few hours.
Ok fellas work with me in this one. Since I already have the complete diff. Could I used the 78 shafts and bearings in the 87 housing to make it work? Or possibly have a machine shop Mill 5 mm off of my 87 ring gear?
must have been drunk ... Greg is correct. Diff has to move (5) mm to the drivers side. ( LHD ) Thats why the alu ring with magnets almost touches the pinion and has to be machined .
So this means that the S4 ring gear , which you want to reuse as partner of the pinion , is thicker then the early types .
so i suppose "yes" , machining the ring could let you keep it at backlash as was. But is this possible in hardenend steel as i assume those gears are made of ?
Could the diff flange be machined the (5) mm ??
By what I'm hearing. It Sounds more like you could have a spacer make to shift the ring gear further out towards the driver side. But without a 87 diff lined up side by side it's hard for me to tell.
you make it now more complicated
If you want to keep the bearings in the same place ( and so also cup holders and axles ) you must reduce the pinion-ring gear distance by (5) mm. Either machine ring gear ... or diff house. ??
Carl's kit was shifting the hole diff ( and so the bearings etc ) (5) mm towards the drivers side.
So he made a (5 ) mm spacer for the bearing cup holder at the drivers side and machined the passenger side cup holder (5) mm down. But indeed doing so , the axles are 5mm to long and one 5mm to short if really needed to work on exact design length.
That's also why we needed to reuse the same spacers as was in the diff housing each side ..... and got the same backlash. We just moved the complete diff the extra thickness of the ring gear.
So it sounds like to me that one needs to move the ring gear out towards the driver's side. If that's so. Then a spacer between the ring gear and the diff is in order, correct????
no , was it that simple.
Ring gear is bolted over de diff house at the inside of the flange .... so only possibilty is removing (5) mm. Or move the hole thing (5) mm.
But wouldn't removing 5 mm from the ring gear bring it in closer to the pinion gear? Where as a shim between the ring and diff may move it further out towards the driver side?
But wouldn't removing 5 mm from the ring gear bring it in closer to the pinion gear? Where as a shim between the ring and diff may move it further out towards the driver side?
No....
You're all messed up, because you've never seen what you are trying to figure out, or had the various pieces in your hands. If you could remove 5mm from the ring gear and possibly keep the surface in the exact perfect plane, so there is no run-out on the backlash (virtually impossible to do and would cost more than any other approach you could dream up), your early limited slip would fit right in, you could simply adjust the preload and backlash, and be done.
01-02-2022, 07:39 PM
PLACING EARLY LSD IN A 87 S4
... Greg is correct. Diff has to move (5) mm to the drivers side. ( LHD ) Thats why the alu ring with magnets almost touches the pinion and has to be machined .