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R200 LSD's and breakaway SHIMMING DONE!


JMortensen

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The problem with the stock config is that you've only got the two clutches, one per side, driving the wheels. The ones with the outer tabs ride with the case. The reason that the clutches were made in the first place is because these diffs had a reputation for stripping the clutches at about 300whp. With your usage I think you're going to need the extra clutches to make it last. I'd suggest you take it apart and put the extra clutches back in. You can see some pics of stripped clutches here: http://forums.hybridz.org/topic/46653-cncd-lsd-clutches/page-2

 

I went and looked it up, and the stock clutch is .070" thick, and the replacements that were made in the original group buy were .063". So if people were getting about 45 lbs breakaway with 4 aftermarket clutches, that means they had .014" less total thickness than you have with the 4 stockers and 2 aftermarket clutches config that you PM'd me about. I'd just get a couple more from Gary if you need them and swap them in.

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I guess if I strip 'em, I strip 'em. I tried using all six new clutch discs and stacked it all up as described and it was a spool. I can't imagine what I did that was wrong. If each big spacer is the same thickness of two clutches, it should work, but for some reason it didn't. It was fine on my other diff. Maybe I was drinking beer on the first one do I was better lubricated.

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Ok, Jon, I'm gonna spend some more money and time on this. I got spme good sleep last night, so im re-motivated. Can you send a photo to my email pkeiththompson@yahoo.com of the best style gauge for measuring the clutches and plates and ill go buy one and take some measurements. Maybe ill have some thousandths milled off the inside of the carrier lid then shim back up. Let me get one thing straight on the clutch stack up: a driven clutch goes directly against the center section, then friction plate-clutch-plate-clutch-friction plate-spring plate-spring plate-shims(if needed) then the lid. Mirror stack up on the other side. I don't like the idea of having a driven clutch right up against the center section, but if that is correct, I'm game. That is how I've been stacking them up. That is the way I'm reading the instructions in the early posts. Maybe there is something I'm just stacking wrong?

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The stack sounds right. As to a measuring device for the clutches, I'd suggest a micrometer. It doesn't have to be super accurate, Harbor Freight would be fine on that one. http://www.harborfreight.com/0-to-1-inch-range-digital-micrometer-895.html

 

You could mill the case, but really, I have to wonder if something else is going on. If everyone else (including you on your other diff) gets basically the same result, and on this one you get something totally different, it makes me think there is some other problem. I don't know what that problem might be off the top of my head, but seems like something is wrong there.

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I would just shim it to what is the "best" recommended stack for your powerlevel and then install it and drive it around a bit. I had the same problem assembling my obx and I just said eff it and installed it. A drive later and I could move the tires with my hand. Weird but true.

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There is a harbor freight nearby where I'm visiting for the holidays so the plan is to get one tomorrow. Kaito I was tempted to do that, but it has kind of sucked driving with an intermittent spool with the diff currently in my car. I just got an email from duragg (this forum and its members are great). His clutch stack is quite a bit different. It looks from his pictures that he put a clutch between his spring plates. Is it ok to put a clutch between or even directly against the two spring plates? Also, is there no problem having the inside driven clutch riding directly on the center section (dissimilar metals)? Duragg appears to have three driven clutches, and only three plates with tabs on the outside (can't tell if they atre spring plates or friction plates). I have 3 clutches, 2 grooved plates with tabs on the outside and 2 springs plates with tabs on the outside.

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Cross checked this thread and the clutch thread along with some photos from duragg. Comparing pictures, it looks like duragg has a power brute just like bjhines. The spring plates in the power brute look to be wavey looking at the wear pattern in the pictures. Apples and oranges again.

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Tore Z31 diff carrier down again.  Started by measuring all the discs and plates with my new Harbor Freight micrometer.

 

Savage42 clutch discs:  4 were 0.0623", 2 were 0.0633".

Stock clutch discs:  varied between 0.0685 and 0.0691" (I have 4 stock discs, 2 from this diff and 2 from my other one).

Stock clutch plates: varied between 0.0666 and 0.0695" (there are 4 clutch plates in the stock diff)

Stock spring plates: varied from 0.0688 and 0.0690" (there are 4 spring plates in the stock diff)

Stock spacer: 0.1275 and 0.1280" (there are two).

 

I inspected the clutch discs from Savage42.  Three of the 4 had some burs that looked like weld splatter on the "gear teeth."  I had previously judged these to be in a position that made the burs inconsequential.  That is true, unless the burred discs is placed directly on the "center section."  I cleanned all the burs off with a dremel tool.

 

Put it all together with all 6 new clutches and no shims. Dipped each clutch part in diff oil.  Wet test in the vice was 45# with both a breaking-style torque wrench and a wand-style torque wrench.  Breakaway was 45 both with and without the ring gear on and torqued.  Slapped it into the case, added 2 tubes of Trans-X and a quart of synthetic 75W-140 oil.  Put an Energy Suspension insulator on the front awaiting a new RT mount.  Diff cover is tapped for an NPT 3/8" fitting for external venting to a puke tank.  I think the problem was a combination of using too many stock discs to the point that there was more added total clutch thickness than the thickness removed by removing the spacers, and possibly burs on the clutch discs. Thanks everybody, especially for encouraging me to not give up.  Mission Accomplished. 

post-5903-0-76742800-1357099682_thumb.jpg

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  • 1 year later...

Power Brute was the name of the aftermarket version of the Nissan LSD. It's a two way with more clutches and more aggressive ramps than the 87 ZX diff. I believe it's built the same as the more aggressive Nissan diff like bjhines has.

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If you have the one with more clutches it also has more springs in it. Kind of a mystery to me why some people are getting chatter with the less aggressive setup, unless the more aggressive just locks up and doesn't chatter because it's essentially a spool, but then you'd hear people complain that it was chirping inside tires in parking lots and you don't.

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  • 2 weeks later...

I was in the local z boneyard owned by a friend of mine. I hadn't been out there in a couple years and I wanted to look around before the chiggers wake up and the weeds green up. There were three Z31 turbos with 4-bolt CV axles and diffs in place, but the year models were '84, 85, and '86. Rats. Well, at least I know where to get more CVs if I start going thru them. Now I have that itchy junkyard feeling that we all know and love. Is that a spider in my hair?

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JMortensen, I don't know why my CLSDs bang around so much. I really think it is clutch "stiction." But the 3.90, 6-clutch, shimmed to 65 does it and the 3.54, 6-clutch with no shims at 45 breakaway does it exactly the same. I think for the 3.36 I'm still hoping to get I will not do the clutch upgrade at all and see how it behaves. I will just change ring gears and throw it together. The other two have 3 tubes of modifier and it hasn't changed anything. Duragg, if you had as much banging as I do, you would know it. It loves to give a couple of good bangs right after exiting the track turning into the paddock. Low-power loafing around parking lot speeds. Feels and sounds like a driveshaft breaking or a wheel falling off! A little tire chirping would be an improvement. If I ever settle on a ratio, maybe I will pony up for an OS Giken. Although I'd rather save my pennies for a dog-ring mod to my T56.

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