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Old 05-14-2017, 04:08 PM
adamdrives adamdrives is offline
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Question Locking diff

Let's talk about options for locking diffs. Anybody running one in their diesel? Talking to dad today, who said there weren't any (or many) factory solid rear axle cars sold with a limited slip, and that the majority of LSD cars were IRS, and have a larger pumpkin which wouldn't fit in 1030/1031 casing (nevermind axle differences). He used to have a detroit locker in his 740t, I still remember how that thing would bang backing up into parking spaces. He said that he had to clutch in around corners etc to keep the back from jumping around. They also aren't particularly cheap (400-500 new). I watched a youtube jeep guy put a lunchbox locker in his front axle (a dana 30 like ours) but I don't know much about this type of diff or how it it with drivability, I think he was mainly off-roading. I'm not so picky about how it behaves, I'd just like to be able to get sideways once in awhile and not have to worry too too much about how I drive it. What would you use?

New car features greenbook for 85 shows that some automatic cars came with a 1041, which looks to be an LSD. Anyone know of this rear end? I'm also not sure how durable the clutch packs are or if replacements are available.
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Old 05-15-2017, 11:11 PM
ngoma ngoma is offline
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Not sure they are that rare. The other info may also be incorrect. Check over on turbobricks. I kind of remember something about maybe G80 type on 7/9 series turbo gassers with live axle.

This might be attractive to you:
https://www.summitracing.com/parts/dtl-912a588
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Old 05-16-2017, 01:33 PM
v8volvo v8volvo is offline
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Late 940/960 came with the Eaton G80 locker mentioned above so that is the bolt-in option, but not everyone likes them for a couple of reasons, they only operate up to 25mph or so without modification, and their lockup action is fairly abrupt so not ideal for maintaining traction in snow. The other consideration with getting one out of a later car is that the later axles use a different tone ring with more teeth for the speedo pickup, so speedometer drive will not work on an earlier car. Probably wouldn't be a major challenge to retrofit other late style parts to an early car, might just need to change the speedometer head and use the late style pickup, but it would be more involved than just swapping the rearend and gains you the G80 which is arguably not much of a prize depending on what you want it to do.

Rear end ratio choices may be limited as well, though from what I recall the early 960 wagons all had the lockers and also had the tall 3.31 gear set, which I think would be an improvement over the stock 3.54 gearing with the M46. From your original post it sounds like the locker might have been available as an option in earlier cars too but I don't think many of them had it, probably would take a long time to find. They are common in the later ones though.

The truetrac linked above seems to be the favorite alternative for good performance. Again the challenge is getting the speedo drive working but there are solutions out there, either cutting off the stock ring and tacking it onto the truetrac, or a few folks sell precut strips that can be wrapped around the unit. Someone on turbobricks had some of these available recently. The pickup may need to be spaced outward to clear the chopper wheel too. It can all be done though.

I want to get one of these in this year too, since even with good tires the cars are helpless putting down power on uneven ground. Keep us posted on what you find out.
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Old 05-17-2017, 07:59 PM
adamdrives adamdrives is offline
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Thanks for the replies. A 900 g80 with 3.31 gearing would certainly suit my needs. I'm not so familiar with all the rwd families, I didn't think they were still using solid rear axles in 900s or that the subframes were compatible. Ideally, I'd like to just rebuild the diff and not deal with replacing the entire rear end. Unless I can find a used truetrac I think that's out of my (do it as cheaply as possible) budget, but it does seem like the best option.
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