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I got a '87 z31 LSD (w/ some questions)


Phyxius

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Also in looking over the whole thread again I see that you never got the side gears out. There is LOTS of surface tension from the oil behind the side gear' date=' but tap it with a hammer and you should be able to get the side gears out. You really want to inspect the surface behind to make sure that there is no galling behind the gear.[/quote']

 

One of the side gears and it's mating surface on the pressure plate has some small scoring and pitting. I can rub my finger around it in a circular motion and it feels smooth, but if i drag my fingernail across it axially, I can feel the scoring. What do I do about this if anything? BTW, the other side gear and pressure plate look great.

 

Also, do you think it would be okay to run a spacer on one side but not on the other? 2 friction disks are about = one spacer, and that would make installing 2 extras a snap. Otherwise, I'd have to mill both spacers down to the desired thickness.

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Can you clean the surfaces on the side gear and the pressure ring up with some Scotch Brite or something like that? The pitting sounds pretty minor from your description. You might be able to buy the pressure ring and side gear from Nissan if it is worse than it sounds, but seeing as how we figured out that they aren't all the same during the course of this thread that might be a little risky. Might get the wrong parts...

 

You might be able to run the spacer on one side only, but I can see two potential issues. You'd want to run disks on both sides, so the side gears would be shifted in the case 1.625mm to one side. I don't think this would be a problem as long as the CVs or stub shafts can click in with the circlip, and they didn't drag on the side seals. The other problem is that the back end of the side gear might hit the case, as BJ's was designed to do. If that happened on ours there is no thrust washer or machined surface there, so that might not be too good. We don't know the difference in the size of the gears. Maybe his is longer to set against the case. Then again...

 

As far as the functioning of the LSD unit goes it wouldn't lock up the left wheel more than the right or anything funky like that. You want the same number and size clutches on both sides, but any shims or spacers you put in will just shift the whole middle assy with the side gears, pressure rings, pinions and cross pin over to one side, but won't affect the way they function. I shimmed mine all on one side, but that was only .020" shim, so not quite the same as what you're talking about.

 

I'd make 4 disks and completely get rid of the spacers. The safe, sure fire way to use the spacers would be to use one on each side.

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Some of the pits appear to be too deep to get out with just scotchbrite. maybe .1-.2mm deep at the most.

 

I'm starting to back out of making them because they are still available, and it wouldn't make much sense to build something that you could buy for a comparable price to what you could build it for. So my options are only the 1.75mm disks.

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  • 2 months later...
ugh...this is starting to make my head hurt. I just talked to Nissan Motorsports again, and after the 12 that they have onhand are gone, there will be no more. So I'm not sure what to do.

 

Looks like this thread has been dead for a while, but does anyone know what happened with Nissan Motorsports?Can anyone get these clutches anymore?

 

Phyxius, are you still considering making these?

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I've got so bogged down with school that this project has ground to a halt. I am still planning on making these, but I was only going to make enough for myself using the CNC machine where I work. I've nearly got the cut file finished, and all i have to is put the stuff in the machine.

 

If you guys can stir up enough interest, I may consider having a batch of 50 or so made by an outside source. I can't make a lot at work or I'll get in trouble...hehe

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I hate to keep draggin this to the top, but we got a mass spectrometer at work, so I just had to put a clutch plate in there to see what it was made of. Best I can tell, it is a high-carbon 1000 series steel. Something like a 1080. Now I know what to make it out of, so it's just a matter of getting the material. I'd like to use 1092 just to be better than stock.

 

 

Now that school is out, I actually have time to work on this again... so

 

If anyone is willing to buy and ship enough material for my six and theirs, I'd consider cutting it for free :) (Satisfaction guaranteed...lol)

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What other metals would be suitable? Would this work?

http://www.onlinemetals.com/merchant.cfm?pid=9663&step=4&showunits=inches

 

Or this?

http://www.onlinemetals.com/merchant.cfm?pid=12782&step=4&showunits=inches

 

The 4130 is almost exactly the right thickness, if we used the 1008 then it might require a shim or two. Nice thing is these guys are mail order so I can just have the material shipped to you.

 

I only checked this place because they're local and I've bought from them before, but they didn't have the exact steel you mentioned, and I don't know what would substitute. Maybe we should do a group buy also...

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4130 is a good metal, and would probably work, but I think the 1095 (i said 1092 earlier...my mistake) would be much harder and resist shearing off the ears a little more. 1008 is way too soft. You can get 1095 from mcmaster.com for sure. I'd link it, but their website won't let me. If you really want to order from online metals, we can try 4130. Honestly though, I think 1095 is a better choice.

 

A single discs will require a 4" x 4" square of material. anything over .070" thickness should leave plenty of room to mill to the proper size.

 

Also keep in mind that I have only set up to cut discs (ears on the inside)... not plates... since those are the only ones I need.

 

The problem with a group buy is that I can't be making too many at work. They won't mind me using the machine, but I don't want to wear out my welcome. I feel save making enough for 3 or 4 people, but not much more than that... not all at once anyway. I could take the cutting file to a local cnc shop and see what they would charge to do a large run or something...i don't know...

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OK, mcmaster is usually a little high on price. I'll see if I can't find someone esle who sells the 1095. So I think this is mostly going to benefit people who have the spacers on the sides. We'll need 4 clutches per unit. I was thinking that the full thickness of the washer was 3.25mm, so divide by two and you want 1.625, which is .0639". If we could get close to that thickness then it wouldn't be necessary to mill the clutches. If we went with .070, then you'd effectivly be adding .016" shim to the the stack, which in my case puts it at about ~50 lbs breakaway, but I don't know that this would be the correct figure with all the new clutches in the stack. I think we're going to have to try a thickness and see what we get with it, but I'd still rather err on the conservative side and add shims later if need be than put them in and find out we've made a spool. What do you think?

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McMaster is a little high, but that was the only place I looked besides online metals. Online metals has it, but they have it in rolls. I couldn't figure out how to straighten it to make the parts we want with the equipment that's available.

 

I was thinking make them on the large side first, and then mill them to the desired thickness. Sometimes when you get raw metal you get some surface inperfections that need to be milled away, so it's always a good idea to mill the surfaces. It's only one more step in the process and about 3 lines of code to do, so it's not that much more trouble.

 

Deciding what thickness to end up with is another issue all together. I think you may have forgotten that I am wanting enough clutches to replace ALL of the disks. So you have to add the thickness of the 1.75mm disks in with the washers. You'd have 6 disks, 4 plates , and 4 spring plates when it was all said and done if I'm thinking right. The order I'm thinking from the outside of the diff in is:

 

spring x 2, disk, plate, disk, plate, disk::center

 

It is also feasible to replace one spring per side with an appropriately sized disk and having 8 disks total and haveing the spring act like a plate would make 6 plates total. I'm not sure if that's a really good idea from and even wear standpoint. It may be that the spring gets completely flat when compressed, or it may only touch at two points. I suppose the same is true with the first arrangement that I listed. So it may be better to go with 4 disks as you suggested with the extra disk near the center, leave the spacers in, and replace one spring per side. I guess it really just depends on what you want to do.

 

It wouldn't be a really big deal to make 4 disks that were the 1.625 and 2 that were 1.75 to replace the old disks or whatever.

 

It may be necessary for you to remove some flashing when the parts get do you depending on how cleanly I can cut this stuff. The same thing that makes 1095 good for this application makes it tough to cut. :lol: I can't immagine sitting and cleaning the flashing off of 30 some disks, so I think I'll let you guys do it with the method of your choice. I'd recomment a circular file or a dremel with a grinding stone. Also, my work may say that I have to buy the end mills to do this with since there are so many, and the material is so hard.

 

I'm starting to think that it may be easier if this is gonna happen for more than myself and jon that I should buy all the material and tools and just charge everyone some price per clutch. I need to know exactly who wants some and how many they want.

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You're right I did forget about your broken disks. Not sure that it matters too much though. The 1.75 = .068" and the 1.65 = .064" so your really talking about a .004" difference. Not hard to add .008" shim to make up that difference if it's needed. I am a little concerned though that with all the increased surface area from all the new disks that it may not be needed at all. If milling is that easy then great. I assumed it would be a big PITA to do on such a thin piece, but still, we don't know if it is even necessary yet. At some point we're going to just have to try it and see what the result is.

 

You can definitely replace one of the spring washers with another clutch if you want, that shouldn't cause a problem at all, other than it takes some of the progressiveness out of the lockup. Some of the other Datsun LSDs have no springs whatsoever, so I'm sure that this isn't a problem. My reason for pursuing this is that I think the reason you (and others) stripped all the tabs off of your disks was because there is only one per side. I think 3 per side would be sufficient, but 4 per side wouldn't hurt I suppose.

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Nah, I don't think I need spares. The ones in there look pretty good and they've been through 8 seasons of autox and a bunch of track days. If I blow this thing up, which I highly doubt, I'll spring for a KAAZ with their better design and more, bigger clutches.

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This 1095 spring steel is just about the hardest stuff around. I didn't realize exactly how tough it was until I started looking at the numbers for the tempered stuff. It will be ordered heat treated, tempered, and polished at .062" (1.58mm). After heat treating, tempering, and polishing, the Rockwell Hardness is about C50 where it was about C30 to begin with. That is getting into the tool steel realm. Being polished, it won't require removal of inperfections like I was worried about. I think they will be at least half again as tough as stock clutches if not twice as tough.

 

What do you think would be a fair price for these? It looks like the material and tools would cost around $90 for about 14 clutches. I'm not trying to get rich off of this, but I would like a free set of clutches out of the deal, so if you split the cost among the remaining 8, it would be about $12 per disc for just tools and material. If you have no objections, I'll set the price at about 12 per, but you can send more if you feel so inclined ;).

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Well I'd rather another buyer stepped in and split the cost, but if I have to spend $90 and sell the extra clutches myself I'm OK with that I guess. You wanted 6 I think, so that leaves 8 left, which basically means 4 for me and 4 for somebody else. If they're $12 each, that means basically someone else has to come up with $48 for their set.

 

The only other thing that concerns me is that if the material is too hard it might shear the teeth off but I'm no metallurgist so I'll leave that part to you and anyone else who may want to comment on it.

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Matt73GNZ said that he'd like a set, but hasn't said how many yet. I'd assumer 4-6. So if he takes 4 and you take 4 that would be perfect.

 

As far as hardness and shearing goes, I don't think that will happen. My clutches look like the ears were cut off -- Like the material yielded at the edge and was slowly cut off by the corner of the slot. It's a nice and smooth. The way that I understand it is that when a material fails due to being too hard, it's due to an impact and the part cracks...kinda like glass. Even though a hard launch is sudden, I wouldn't call it an impact. The yield strength on this material is over 100,000psi. With 6 clutches to distribute the forces over, I wouldn't worry too much about the ears coming off.

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