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JMortensen

R200 LSD's and breakaway SHIMMING DONE!

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Hoping maybe Savage 42 or someone else with more experience than me can help:

 

I just got off the phone with Nissan Comp, and they faxed me a parts

list for the R200 LSD with both 45 lbs and 75 lbs (street and comp)

versions of the clutch packs. Here's the parts lists:

 

45 lbs:

Qty Part #

4 38432-N3210 friction plate 1.70mm

4 38433-N3210 friction disk 1.75mm

1 38433-N3211 friction disk 1.85mm

2 38435-N3210 spring plate 1.75mm

2 38436-N3210 spring disk 1.75mm

 

75 lbs:

2 38432-N3210 friction plate 1.70mm

4 38433-N3210 friction disk 1.75mm

1 38433-N3211 friction disk 1.85mm

4 38435-N3210 spring plate 1.75mm

2 38436-N3210 spring disk 1.75mm

 

For anyone familiar with the usual American lingo, friction plate =

driven clutch and friction disk = drive clutch.

 

So it would appear that the 75 lb version uses 4 spring plates and 5

friction disks (4 thin 1 thick), where the standard version uses the

same 5 friction disks and only 2 spring plates. This seems like a

strange way to get more breakaway.

 

Do you think that it would be better to use the 2 spring setup and use

a combination of thicker friction disks or maybe add another thin disk

to get the increased preload and breakaway? Seems weird to me to use

more springs rather than more clutches.

 

I'm looking for about 100 lbs breakaway and want this to be as

bulletproof as I can make it.

 

I've already spent time looking here:

http://www.gordon-glasgow.org/lsd1.asp but he just says to test it and

see what it does. If anyone already has this experience it would be

helpful.

 

Jon

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I emailed this question to Gordon, and he responded, saying basically that it's probably the thickness of the clutch pack that makes the difference, rather than the additional spring.

 

If you add up the clutch pack thicknesses, the 45 lb = 22.65 mm and the 75lb = 22.75 mm, so the difference is .1 mm or .004 inch. So my first attempt will be to run 3 thick friction disks, remove one thin disk, and leave everything else alone. This should get me .010 over the regular 45 lb clutch pack. Now I need to order parts and give it a try. I'll let you all know how it turns out.

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It's obvious that there are several ways to get the desired affect and I don't think any is "so much better" than another. I always ran the street stuff and just had it shimmed for additional breakaway torque. If your car is primarily a track car, then I'd go for the 100 lbs. If you want it to be "civil" for the street, I recommend the 75 lbs. It's amazing how much difference that can make. When you get at 100 lbs, it's darn near locked unless you have sticky tires that grip enough to get the diff to slip. With street rubber, you'll get the "chunk, chunk, chunk" type behavior that you get from a locked diff. If you've ever experienced that, you know it's not nice for a street car. Also, tighter diff will make for more understeer and more stress on the chassis. You want it tight enough to keep the inside wheel from spinning, but not locked. Hope that helps.

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Yeah, I'm aware of the chattering clutch problem that I am going to have, but I'm not too worried about street driving. I think I've got about 500 miles on the street in the last 2 years.

 

It will be 50/50 autox and track day, so I figure 100 lbs is about right. Do you agree, or do you think I should just build it to 75 lbs?

 

Thanks.

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I guess it depends on how dialed in your handling is, as I'm sure you'll need to play with bars a bit to get it back the way you like. If that's not a huge concern, then you can go either way. Ideally, you don't want the tires fighting each other in the corners and a more locked diff will certainly get you some serious push on an autocross course. I ran mine at 60 lbs and the one and only time I ever got any kind of inside wheelspin was with slicks on some very tight, slow corners w/ steep incline at a hillclimb. With the weight of your car and what you are doing, especially with autocross action, I would lean toward the 75 lbs. If that's not enough, you can add a shim. It's not quite that easy to change if you go the other way. Just my 2 cents.

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Finally getting around to ordering parts for this, and guess what? $30 EACH for the clutches thru Nissan. There are 13 clutches in there!!! I think I'd just buy a new LSD before I bought clutches.

 

The alternative is to buy shim stock and do it that way, so that's what I'll be doing. $10 in shim cost vs $390 for all new clutches...:weird:

 

So I'm thinking I'll get .004 stock and do one shim, if that's not enough do another on the other side. Not sure how much wear I had before, but I can always just shim it tighter...

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Guest Jason84NA-T
Finally getting around to ordering parts for this, and guess what? $30 EACH for the clutches thru Nissan. There are 13 clutches in there!!! I think I'd just buy a new LSD before I bought clutches.

 

Yup, and guess how long it takes to actually get them? I had to wait OVER 6 WEEKS for 6 spring plates and 4 discs.

 

Personally I think 100 is too much for the street, and autoX. I noticed more understeer when I put mine in, which is to be expected.

 

Let us know how that turns out.

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Personally I think 100 is too much for the street, and autoX. I noticed more understeer when I put mine in, which is to be expected.

 

For a street/auto-x car, I'd not go more than 75 lbs. Any more works great on a road course, but will tend to push in an auto-x. Shoot, even with a good 50 lbs, you'll be hard pressed to get any severe inside tire spin, as you'll go sideways first! :-D

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I'm with Gary on this one. In ITS we saw no advantage to going over about 65 ft-lbs of breakaway, and usually just ended up increasing our operating temps. Plus, in the rain it sucks at 100 ft-lbs, and sometimes us non-NASCAR types have to drive in it. Expecially for auto-X where you want to avoid understeer at all costs, I'd stick with the lower breakaway.

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That's funny. Part of the reason why I wanted to up the breakaway was so that it would run cooler. The theory I'd read was that the clutches only generate heat when they slip, so the more worn the LSD gets the hotter it will run. If they're too tight to slip than no gears inside the diff move but the ring and pinion. Interesting that you would have higher temps with the higher breakaway. Not sure what to make of that.

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OK, finally got into the diff, and I have some unexpected stuff going on. The clutch parts don't fit the description of EITHER the 45 lb build or the 75 lb build.

 

The number of clutches doesn't match either the 45 lb or the 75. The type of clutches doesn't match. The thickness of the clutch stacks doesn't match. Weird.

 

So here's what I've got:

Here is the entire clutch stack from one side gear

normal_oneside.jpg

Here is the drive clutch or the clutch disk in Nissan terms. Gets driven by the side gear. As you can see, only ONE per side... surprising.

normal_drive.jpg

There are 2 of these driven clutches or clutch plates per side

normal_driven.jpg

There are 2 of these spring plates per side

normal_spring.jpg

And there is and "end plate" or an end washer that is over 3mm thick per side.

 

Here's a picture of the LSD crosspin and case shape. It would appear that the Nissan LSD is a 2 way LSD. Compare the photo to this: http://www.club4ag.com/faq%20and%20tech_pages/limited_slips_differential_101.htm

normal_xpin.jpg

 

If you run a couple bolts through the carrier you can relieve the preload on the little phillips machine screws that hold it together. Once that is done it still takes an impact driver to remove the screws. I figured out that if you can get an extension on it, an impact GUN works a hell of a lot better than an impact driver for getting the little screws out. :D

normal_impacts.jpg

 

Everything looks peachy inside, no chipped teeth or worn gears or anything. The clutches don't look very worn either, surprisingly. So my plan is to lube and reassemble and test the breakaway and see where it is at now and shim if necessary.

 

I don't think that the shim will hold up if I install it all the way against the side gear. I don't want to install it between the drive and driven clutches either. I could install it between the end washer and the spring plates, but I think it would wear out really fast. I'm thinking I'll put the shims between the case and the thick end washer. It will have the same effect and should be safer there. I can tell from the wear on the end washers that they did not move previously.

 

Anyone have a reason not to do what I'm planning on doing?

 

Thanks, that was a long haul.

 

Jon

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Odd combination in your LSD carrier. All my friction plates, friction disks, spring plates, and spring disks are smooth. Yours seem to have ribs and lines?

 

Here is what I have starting from one side and going to the other.

 

Spring plate - 1.75mm

Spring disk - 1.74mm

Friction plate - 1.75mm

Friction disk - 1.74mm

Friction plate - 1.74mm

Friction disk - 1.74mm

Pressure Ring

Side Gear

Pinion Shaft with Pinion Gears

Side Gear

Pressure Ring

Friction disk - 1.74mm

Friction plate - 1.75mm

Friction disk - 1.74mm

Friction plate - 1.74mm

Spring disk - 1.71mm

Spring plate - 1.74mm

 

This gives me a total of 20.88mm which is nowhere near what you have specified at the begining of your post for a 45lb. breakaway LSD. Is mine in need of a rebuild?

 

!M!

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Wow, that is weird. I honestly don't know what to think about yours or mine. They just don't follow the parts list from Nissan in either case. Thanks for the info Mat, and just for the record my clutch stacks measure 20.1mm thick total including the big fat washers. Another question for you Mat: on yours were the springs facing the same direction so that they got stacked like plates, or were they facing opposite so that they increased the preload? Mine were facing the same direction, so that when I got the screws out and undid the bolts, the two halves only separated by ~1/8" or ~3/16. I'm sure if I put them in opposing each other the case halves would be ~1/2" apart.

 

I've seen ribbed clutches and wavy metal clutches in domestic LSDs, but this is the first Nissan unit I've had apart, so I was hoping to follow right along with the info that Nissan Comp sent me. Unfortunately nothing seems to be going to plan.

 

I'd really rather see 8 clutches at work in the diff than 6, but I am thinking that the ribbed clutches are probably intended to be more aggressive than smooth clutches, which might explain why there are fewer. Probably one of those "use fewer and put a big spacer in to save money" things. Mine came out of an '87 300ZX Turbo and I got it from a jy, so I really don't have any history on mine, but it does have the numbers C4D4 stamped on the carrier itself.

 

I'm not sure that any of this really matters so much. I wanted to shim it up a little tighter, nothing I've found would prevent me from continuing on with my plan. Would be nice if Nissan knew what was in these things though...

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Another question for you Mat: on yours were the springs facing the same direction so that they got stacked like plates, or were they facing opposite so that they increased the preload? Mine were facing the same direction, so that when I got the screws out and undid the bolts, the two halves only separated by ~1/8" or ~3/16. I'm sure if I put them in opposing each other the case halves would be ~1/2" apart.

Mine were the same as yours, they were both facing the same direction. I would think if you flipped the Spring disk around, so the inside diameter of the Spring disk and the inside diameter of the Spring plate were touching, it would wear much faster in that area. Probably not the best idea.

 

I'd really rather see 8 clutches at work in the diff than 6, but I am thinking that the ribbed clutches are probably intended to be more aggressive than smooth clutches, which might explain why there are fewer. Probably one of those "use fewer and put a big spacer in to save money" things. Mine came out of an '87 300ZX Turbo and I got it from a jy, so I really don't have any history on mine, but it does have the numbers C4D4 stamped on the carrier itself.

My carrier has C9D9 stamped on it. Also, on the other end, it has LOM59 cast into the carrier along with N2 stamped right next to LOM59

 

I'm not sure that any of this really matters so much. I wanted to shim it up a little tighter, nothing I've found would prevent me from continuing on with my plan. Would be nice if Nissan knew what was in these things though...

Has anyone else taken thier LSD carrier apart? Would be interesting to have at least one more to compare with.

 

!M!

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Mine were the same as yours, they were both facing the same direction. I would think if you flipped the Spring disk around, so the inside diameter of the Spring disk and the inside diameter of the Spring plate were touching, it would wear much faster in that area. Probably not the best idea.

 

I was thinking that too in your case. In my case I could flip them around since I only have plates and no disks, but the more I think about it the more I think I don't want to. It would give more preload and more breakaway, but wouldn't increase the overall lockup, so it'd probably just make the car understeer worse and not have any benefit whatsoever.

 

One idea I did have is I could get 2 friction disks and install one on each side and remove a spring plate from each side, that way I would have 2 plates, 2 disks, and the one spring all working as friction surfaces. That should decrease my preload and increase the total lockup.

 

Still not wanting to spend $60 for 2 disks though. Seems like a waste. Wonder if anyone has some old ones laying around...

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I don't know about that. I've been running it for ~8 years and have no complaints about the lockup on decel. Might explain my rear toe-in preference though... I can tell you that the R200s have springs and the R180s don't. I don't know if the R180s are 2 way also, I would imagine they are, and that 4ag link seems to say that they are, along with R160s, TuRDs, pretty much anything made by Fuji. Lots of racers running around in Jap cars with Fuji LSDs...

 

Here's the quote from the 4ag site:

The 1.5 way can provide more forgiving balance when braking than a full 2 way setup, although it is less effective for true racing applications, it provides easier operation for beginners in throttle off conditions. It is also effective for front drive cars which need extra stability during braking.

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Yeh I don't have personal experience of a two way -v- one point five way LSD comparison JM, however drifters like the two way so if they do I don't :)

 

But if you don't have any off throttle handling problems then no worries eh.

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More confusion... Tried some shims today. Figured that one shim was going to get me where I needed to be, so that's what I started with. (EDIT--stuff I wrote previously was wrong) WITH the shim, breakaway was a whopping 24 lbs. Added another .004" shim, up to 32 lbs. Went to 4 shims, total of .016", got 45 lbs.

 

I'm going to keep adding until I get in the general vicinity of where I wanna be, but it seems strange to have that little change from the shim I did add.

 

One thing I'm doing, and I can't imagine that this is anything other than the right way to do it, is I'm testing the clutches wet. I've added a tube of LSD additive to the oil I'm using to test. So it's probably 50/50 oil and additive. I can't imagine that the concentration of additive would be a problem, but I just thought I'd throw that out there. I would test with the SWEPCO 201 I plan on using in the diff, but I just don't have any right now... :?

 

This project is kinda pissing me off, because NOTHING is what it is supposed to be with the LSD.

 

I'm cutting up some more shims, I guess unless someone advises me to do otherwise I'll just keep shimming it until I get it where I want it.

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I cut it back to 5 shims, and that got me 100 lbs. 4 shims = 40 lbs. I think I'm gonna run it in several months when the rest of the project is done and see what it does.

 

I'm not too scared of 100 lbs breakaway, because a lot of the posis I sold for Randys were 150 and better supposedly (they didn't really rate them that way).

 

I have a feeling it will really affect my turn in, seeing as how I was running 20 something lbs before, but I've got adjustable everything so I should be able to tune out any push.

 

I can't believe this thing required .020 shim to get up to 100 lbs. The clutches were not really worn, so I can only imagine that they tuned them down in later years??? Having been in a car with a clutch style LSD with no additive I can see why they would want to do that.

 

Anyway with the rate that I get things done I'll let you all know how it works next June... :D

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Got an interesting email from Gordon Glasgow, thought it would be nice to share with everyone here who was interested in this:

 

Hi, Jon. A friend of mine who is vintage-racing his 2000 brought over his

new Nismo limited-slip unit so we could test it. He'd run it a few times

already and was getting lots of wheelspin.

 

We tested it and it was only about 10 lb/ft of breakaway, so we pulled it

apart. Guess what: it had two spring plates on each side and no spring

disks, and each side had three clutch plates and only one clutch disk. So

all the work was being done by that one clutch disk on each side. BTW, it

was a 4-pinion unit.

 

I threw a .010" shim in it just for starters and that brought it up only to

about 20-25 lb/ft. So I threw in another .010" shim and it measured 90

lb/ft. I talked to him after the next race and he said it worked great.

 

I have no idea what Nismo is doing putting them together like that. It just

doesn't make sense. But it does sound similar to the setup you found, so I'm

thinking it maybe wasn't a PO issue after all. Interesting.

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