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verification, is this an r180?


beaniam

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Went to swap in my welded r200 3.54 rear today and to my suprise it looks like there's an r180 in the car.  At least I think it is.  Maybe it was originally an automatic car?

 

NCM_0066.jpg

 

NCM_0065.jpg

 

Guess I've gotta find some more unexpected parts before I dig back into this.

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I cant tell from photos, but that might even be an R160 from a Subaru... to be sure, take some measurements between two measurable points on the diff and post them, then somebody can measure their R180 and let you know.  I only have R200s in my shop and that is not an R200.  I'm also bothered by the bolts attaching the cover to the mustache bar.  Those should be studs with nuts-the threads in the diff cover are very coarse-not fine enough to handle a standard machined bolt.

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The narrow width and bolts holding the stub axles in made me think r180. It looks like the rear transverse in the car is already curved like the r200 cars. I've also read the front diff mount is the same? I haven't been able to find much info on 77-78 r200 swaps, just swaps into 240z's. I've also read all halfshafts are the same length. Such a mixed bag of info is floating around. Makes me think I could get away with just finding an r200 mustache bar and using my halfshafts. If the shorter side shaft bottoms out then I should be able to cut a little off and use it. Just really don't feel like tearing the car apart and finding I need something I'm missing and have to put it back together. Yes you're right about the threaded studs. The r200 I have has them.

Edited by beaniam
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I'm pretty sure I'm using my R180 axles on my R200. My understanding is that there is no difference, which is why the wider R200 can cause one side to bind.

 

Someone definitely has been under there with the bolts instead of the studs. Once the unit is removed a picture of the unit would be much more telling. It does look like an R180 from the size (more rectangular rear cover then square), but other then that it's a little hard to tell.

 

^blu beat me to it lol.

Edited by seattlejester
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I would read jmortensen's diff thread in the FAQ section.  You might have some changes from stock.  A welded R200 might be going backward.  Or maybe Nissan converted to clip-in axles with the 280Z R180's.  Edit - actually that picture I posted is from the 77 FSM. So what you have doesn't match.  

 

http://forums.hybridz.org/topic/49194-differential-cv-lsd-hp-torque-r160-r180-r200-r230-diff-mount/

Edited by NewZed
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Having read that link I'm still a little in the dark. Seeing as this is a 280 and not a 240 that means my mustache bar will work as it's not a flat 240? I don't have to address moving the diff forward as it's already in the same place as the r200 280z's. The mounting holes for the diff cover on the mustache bar are in the same spots in the 280 r200 and r180 cars?

R180 and R200 280z's share the same front diff mount? Now as far as I can tell all I need to possibly address is the short side half shaft. It may bottom out as I'm about 2" lower than stock and they are basically straight out from the diff at right height, no angle taking up some width.

 

edit: looks like the front diff mounts are the same judging from http://www.geocities.com/jasonparuta/diffswap.html

Edited by beaniam
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If it is an R180 unit, then the mustache bar should be flat, the R200 units have a little curve in them to push it backwards. You would need to source an R200 mustache bar if memory serves as the front diff mounts do not change.

 

I think the consensus is that it makes a difference when you are going around a right hand corner and shifting weight to the left which is the short side? Or it might be the other way around. No real way to address it other then changing to different axles, lengthening LCA's, or running the R180 diff.

 

Newzed brings up a good point. If you don't need the R200, the R180 may be preferable. It's substantially lighter and you won't run into the binding problem.

 

This is all still guessing though. Easiest way to determine for sure would be to take a tape measure and measure the width of the cover and compare it to the r200 you have.

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On http://www.zhome.com/ZCMnL/tech/R200.htm it states there are 3 mustache bars, a flat, an offset and a more offset one. The bar in my car is not flat but I don't know if it's offset enough for the r200. I have also read you can flip them around for the r200 to fit. The internet is such a crap shoot of all kinds of misinformation and threads that never get resolved. I'm just going to have to get under it and try it myself and see what I need.

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r200.jpg

 

it's in. I don't know about bolt spacing being different. The r200 bolted right up in place. Someone must have swapped the r180 in. There were spacers between the mustache bar and diff cover. The only thing I had to address was shortening the driver side halfshaft by about an inch. Turns out the r180 was a 4.11. Guess someone got it cheap. The turbo likes the 3.54 a lot better. Double win for me.

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