Please a FAST HELP on LSD

[rei99]

Hi everyone.
I\'ve a Euro and USA 1980 model, so  w/o LSD.
I\'ve found this:
http://cgi.ebay.com/ebaymotors/ws/eB...5000&viewitem=
I\'m a not great expert, better a noob, so someone say if I could put it in my rear differential swapping just this parts and have so finally the differential LSD?
Thanks a lot!       :cheers

[David Nock (RIP)]

Mark on here did something similar, changed the diff unit on his \'85 car. He was fitting the LSD into a crown wheel and pinion set from somewhere else because his set was poor.
This seems to be the smaller (fewer) spline LSD which I imagine fits the earlier car like yours.
I\'ve never done this Davide - I think you need more advice from people on here or even perhaps the seller.

[rei99]

I ask also outside, from Rx7club:

I think that\'s all you would need to get lsd, but that auction has ended. In my opinion, it would probably be a better move to find an entire rear end from an 83-85 GSL. That will give you the lsd, disc brakes, and you\'ll keep the same lug pattern for the wheels. I don\'t know how available used parts are in Italy though...

As usual, it\'b better an entire swap, but for no knowing Rx7 car mechanics here, and not very good my English, It\'s more easy for me a simple swap, like just this differential clutch seems to be.
Also if I could found the rear axle it will be expensive to ship in Italy from USA I think...

By the seller:

Hello Davide:  The differential clutch-pack units I sold would not have fit into  your 1980.  I do have another unit, but it is from a rotary Mazda earlier than  1978, so I have no idea if it would fit your car.
 As to your last  question - No.  If you want to do anything with an Rx-7 differential, you would  have to dismantle the brakes and other parts.  No shortcuts available.
 

I had read the rack/pinion it will be smaller in Sa22C car until 1983, so why he must doesn\'t fit?
I\'ve an Haynes manual, I try to see if I could learn something...
:cheers

[David Nock (RIP)]

To summarise Davide, you want to fit an LSD into a 1980 USA car that you\'ve got. I know that the number of splines on the half shafts was different between the earlier cars and the very late 1st Gens. I don\'t know whether your car needs an LSD that takes 24 splines or one that takes 26 splines, but I imagine that your 1980 is 24 splines (guessing here).

To fit the LSD then first of all you take out your existing diff. You do this (the only way) by taking the brakes apart and pulling the 2 half shafts out of the axle tube. Then you can unbolt the diff from under the car and take it out.

Then on your diff you would have to unbolt the gear cage part, leaving just the crown wheel and the pinion assembled, but don\'t unbolt them because they\'re are pre-loaded - a specialist job.

You then replace the gear cage with the LSD and reassemble.
I\'ve changed my Series 3 diff so I know all about that but I don\'t know about LSDs. You need Mark (MPK 490P) or another wizard to tell you about that bit.

I think that adds up to what you are trying to do but you need to know the number of splines, as said. Have I got it right?

[David Nock (RIP)]

Not quite right when I read the diff section in my manual - the crown wheel (ring gear) comes away with the gear cage when you dismantle. It\'s the setting up of backlash and adjustment of the side bearings that\'s a specialist job when you reassemble.

[rei99]

Mumble, this things came every day more difficult
I\'ve read the Haynes manual, nothings about LSD and difference between the different model, this could be a jump in the dark...
I think to take otherwise the spare parts, on Ebay it was sold very fast, if it doesn\'t work or I caould not fit it (hope in my mechanics) I relisten it...
What you think David?

[David Nock (RIP)]

I can take a spare 1985 axle apart and count the splines on the half shaft if you like. Then if mine is 26 splines, yours should be 24. The trouble with that idea is that it is not your axle - the one you truly need to know the number of splines for.
If you are really serious for an LSD I would suggest that you practice part of the job. Take out 1 half shaft (doesn\'t matter which) and count the splines. I can tell you how to do that - it\'s very easy and usually on RX7 you do not have to use a hub puller tool or anything special. Then replace and you are back on the road until you can find your ideal LSD.
It is maybe 20 minutes for me to check mine, maybe 3 hours (working slow) for you to check your own car. What do you think?

[rei99]

I think it\'s an a good Idea David I must change for the italian MOT the handbrake cables, so on those days I take the car to mechanic. Until the car is under work, I try to take out one shaft, if it\'s the 24pinion, I take he LSD on Ebay.
If it\'s 24 mine like this, you think I don\'t need any other parts?

[David Nock (RIP)]

I haven\'t taken my diff apart so I don\'t really know but if you look at Mark\'s post \'a bit more on the project\', you will see that in the last few pages he was planning to do the same as you but with his 1985 car. There are pictures of his LSD in pieces as well.
I think that once the diff is out you only need the LSD fitting in place of the usual differential gears but I honestly don\'t know. As said earlier I was always concerned about setting up the correct backlash and necessary play in the differential. I suggest check with rx7.com club what is involved with setting up, because LSD\'s are the kind of thing they\'re used to doing. Perhaps you could find out the number of splines then ask advice of rx7.com?

[mpk490p]

yours should be a 24 spline being the earlier diff, you can just swap the unit over, i am going to set the backlash then get a shop to check it (dont like doing things twice!)
Mark

[rei99]

Thx Mark.
I also read this in the Rx7club, so I take it. I\'m waiting, hope to (can) drift soon with my Black 13B :3gears-rh