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Recently I found an 84 rx7 solid axle differential in a junkyard with the clutch type lsd in it. I picked it up and swapped it in my 1.8 open per some forum posts saying it was bolt in. Setting the lash and going about as normal. Both axle seals were replaced less than a month before this because I had swapped an open diff in from a welded and damaged both sides unknowingly causing them to leak. the seals held well after swapping them in, and i THINK they held for a while after i swapped in that lsd. However after taking a glance under the car for some unrelated reason i noticed both seals were leaking. The breather is not plugged and bleeds pressure fine. I saw a post from 2007 saying they were a direct swap in, and then after swapping in and googling the issue, a post in this forum in 2013 saying they wont hold the axle circlips. Should i replace the diff, or the seals?
You probably saw my post from back then. I was able to swap the clutch type LSD into the 1.8 housing and it worked well. I was meticulous and did a lot of research, and learned a lot in the process. It has been a long time now, but if you have any questions, I'll do my best to answer them.
Btw, I seem to recall making shims out of soda cans to get increase preload. Sounds ghetto, but it worked fine.
they dont seem loose at all, I pulled on side out and checked everything, seal looks intact and axle snaps in as it should, I also cant pull them out by hand. Just curious as to wether i should replace the seals. I used oem mazda seals from the dealer.
If everything feels right, maybe the seals got installed a bit off, or got damaged somehow on reinstall. Could there have been some dirt or rust on the axle? Also any scratches or deformity on the shaft could cause a problem.
If everything feels right, maybe the seals got installed a bit off, or got damaged somehow on reinstall. Could there have been some dirt or rust on the axle? Also any scratches or deformity on the shaft could cause a problem.
I'll take a look tomorrow, remove, clean, regrease, and see if the seals are intact. my main worry is that it has to do with rx7 differential and it ultimately being a problem i cannot fix and have to get rid of it. On that note if anyone wants a clutch type rx7 lsd with good clutches for a torsen if thats a good trade lmk!
I spent a bit of time refreshing my memory. I don't know why older threads on this are so confusing, but basically, the LSD "gits" are a direct swap for all 1.8 NA & NB (except MSM maybe?). Some find they need the rx7 clip on the stub for it to slide in, but many dont (myself included). If your axles are miata. seals should be likewise. Rx7 stub shafts are apparantly compatible, but in that case, IDK.
If you installed like above, then I am inclined to think it's got to be damage to the sealing surface or the seals, or poorly seated seals.
BTW, if you didnt see this thread. It has sone good discussion, and a nice video about the internals :
I spent a bit of time refreshing my memory. I don't know why older threads on this are so confusing, but basically, the LSD "gits" are a direct swap for all 1.8 NA & NB (except MSM maybe?). Some find they need the rx7 clip on the stub for it to slide in, but many dont (myself included). If your axles are miata. seals should be likewise. Rx7 stub shafts are apparantly compatible, but in that case, IDK.
If you installed like above, then I am inclined to think it's got to be damage to the sealing surface or the seals, or poorly seated seals.
BTW, if you didnt see this thread. It has sone good discussion, and a nice video about the internals :
I hadnt seen that thread, would have provided some peace of mind. As with my last reply. I removed both axles and cleaned them, this time, i was able to pull them out with one hand from the differential. not much struggle at all. I know I had gotten them in the same way i always do, holding the slack and hammering the end of the axle. The seals looked fine, maybe a little dirty but i cleaned them up. I regreased and put the axles back in, and checked to see if i could pull them out whenever i had set them in properly, sure enough they are not a struggle to pull out by hand. even without prying them out dropping the hub down was enough to pull them free. guess thats my issue. I had a lot of wear and chewing on the clips on both axles, the one with worse chewing seemed to be the one that leaked more but that could be all in my head. I added some photos. I called the dealership and had them order some oem 2002 miata clips to replace these. should i go ahead and grab some rx7 clips at the same time? What part number or year should i specify if so. worse leak side
The problem is with the area next to the splines, with the spiral grooves. That area is supposed to ride inside the diff carrier and is load bearing. The early "big axle" rx7 diffs have the same spline, but the area where the spiral groves ride is slightly larger diameter, maybe .040" or so IIRC. So the Miata axles are sloppy in the early rx7 diffs, which were meant to have the outer end of the axles supported by a bearing in a solid axle housing. Might be able to stuff some .018 shim stock in there or something? Maybe...
The problem is with the area next to the splines, with the spiral grooves. That area is supposed to ride inside the diff carrier and is load bearing. The early "big axle" rx7 diffs have the same spline, but the area where the spiral groves ride is slightly larger diameter, maybe .040" or so IIRC. So the Miata axles are sloppy in the early rx7 diffs, which were meant to have the outer end of the axles supported by a bearing in a solid axle housing. Might be able to stuff some .018 shim stock in there or something? Maybe...
So should i grab the axles from that car too? Side note the posts i had seen were from @Braineack
I've heard the axle stubs are compatible with early 1.8 outer halves, but no 1st hand experience. Not sure if the seals are different, but AFAIK they are different part #. Will they seal better, will they work with miata seals? If the shaft, where it seals, is slightly larger, maybe it would work. I haven't heard of anyone doing it, but may be the best combo.
If what bloop said is true, it would explain why some have issues, while others dont. I cant remember what year mine came from ...
Hopefully you get the leak sorted. Not sure I can help more, but I think you have a good starting point now.
Looked back at old posts, and braineack used the older 84-85 LSD, and had issues with leaking as well as needing to use rx7 circlips. My setup was the later 86-88. I had no leaks and used miata circlips. So, yeah there may be a slight difference there. If you already have two piece shafts, and the rx7 stubs aren't too $$, it may be the way.
Yes, 86-88 rx7 diffs had independent rear suspension like our cars. 84-85 rx7's had solid axle rear ends. So unless the spiral area is built up somehow, or the rx7 stubs have a slightly larger diameter there, the seals will have a short life as they get beat up by the axles wobbling around. I am not talking about the sealing area of the stubs, I am talking about the machined spiral bearing surface.
Looked back at old posts, and braineack used the older 84-85 LSD, and had issues with leaking as well as needing to use rx7 circlips. My setup was the later 86-88. I had no leaks and used miata circlips. So, yeah there may be a slight difference there. If you already have two piece shafts, and the rx7 stubs aren't too $$, it may be the way.
I think ill go ahead and change out the clips for science, 84 rx7 solid axle lsd with 2002 miata full axles, oem circlips and seals. If i finally find a combination that works out and doesnt leak, ill post here for anyone else in the future.
I'm telling you. I have first hand experience with this. The stub axles need support at 2 points, the spline is 1 point. If you don't address the the slop in the other point, you will be using the seal as the other point. The best solution I came up with would be to weld/build up the machined spiral area and turn it down to the correct diameter for the inside of the 84-85 rx7 diff carrier.
But feel free to keep buying seals and using them as bearings. I am done commenting on this thread, do as you please and let us know how it goes.
Looked back at old posts, and braineack used the older 84-85 LSD, and had issues with leaking as well as needing to use rx7 circlips. My setup was the later 86-88. I had no leaks and used miata circlips. So, yeah there may be a slight difference there. If you already have two piece shafts, and the rx7 stubs aren't too $$, it may be the way.
it been too long for me to remember, and i just replaced it with a cheap $200 torsen and called it a day.
i wish i measured and tried to document the actual differences, but alas. torsens were cheap and plentiful at the time, it didn't matter. i did like that clutch diff though.
I'd prefer a torsen too, ive found a few, but would rather sell this clutch type first, that being said if anyone wants the chunk ill gladly sell it and ship at buyers expense
I've researched this quite a bit the last few days. I know it was brushed upon above, but the issue is that the axle gears in the 84-85 do not have provision for the circlip to lock into place, so the axle will slide out a bit while in use. One solution would be swapping to the later style side gears, but good luck finding any. Another solution that MAY work is to machine grooves for the circlips.
I found a few more excellent discussions on other forums about this:
In the 1st pic, you see the side gears from the 86 - 88 lsd. Notice the cut-away at the end, which is not present in the earlier version (2nd pic). Honestly, it looks like it could be modified at home with a Dremel, or a lathe would be even better.
04-02-2024, 02:46 PM
84 RX-7 LSD swap
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