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Old 08-30-2002, 05:39 PM   #1
iBlueVirus
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Default open diff to LSD conversion!!

okay, i don't even know if this will ever happen (the conversion). I've been search and posting on the club and can't get what I want. So I did my own research on Google.com.. If I don't do it, this might be good info for those who are considering....

I started off with knowing that big piece of metal in the back inside my rear diff protector is the rear diff.

I knew the difference between LSD and Open diff and how they look like (the actual inside of the diff). I see LSD here and there.

But I wasn't able to see how the pinion shaft-> pinion gear -> ring gear ->LSD or Open Diff -> axles

I see a lot of pics of the inside of the LSD or Open diff, but not the WHOLE setup.... after half an hour of search (yeah, should have done this first) on google.com (using the image search). I got the following...
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Old 08-30-2002, 05:40 PM   #2
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this is the complete pic. drive line to axles
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Old 08-30-2002, 05:41 PM   #3
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this is hard to see and somewhat different from what we have I believe... but it's another version
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Old 08-30-2002, 05:43 PM   #4
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this is just the LSD, rign gear, and the pinion gear. the dark ones are the gears and the silver piece is the LSD. For me, at first I didn't even know which way the LSD suppose to point because I couldn't figure out where the ring gear suppose to go. I thought it was suppose to be inside the LSD, but don't know how it could work. Now it explains why there are bunch of wholes on the LSD.
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Old 08-30-2002, 05:46 PM   #5
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if you don't know how the inside of an LSD looks like. Here is one version of it. I believe this is the viscous version.... I think this is from a GSR.. I looked at so many and don't remember which is which.
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Old 08-30-2002, 05:47 PM   #6
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this is just a paper diagram of the pinion gear, ring gear, and a viscous LSD...
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Old 08-30-2002, 05:48 PM   #7
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another look of the inside of a LSD
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Old 08-30-2002, 05:50 PM   #8
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this is another good pic of the whole diff system... now you know how to convert!
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Old 08-30-2002, 05:50 PM   #9
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That inside pic is of a clutch type diff. Notice all the tiny little clutchplates in there?
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Old 08-30-2002, 05:50 PM   #10
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this is a LSD by itself
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Old 08-30-2002, 05:51 PM   #11
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this pic
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Old 08-30-2002, 05:53 PM   #12
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so that's all I have. what do you people think? helpful? BS? worthless? They sure helped me!!
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Old 08-30-2002, 05:55 PM   #13
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Old 08-30-2002, 05:56 PM   #14
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Old 08-30-2002, 05:58 PM   #15
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so after reading and looking at the pics, still a little confuse between clutch and viscous type diff.
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Old 08-31-2002, 12:43 AM   #16
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SO! would the 02WRX LSD or 00-01RS LSD match with 02RS ring gear? Anyone?
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Old 08-31-2002, 07:50 PM   #17
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Default an alternative

car-part.com
Use this link to search around the country for either a used LSD from a WRX or older 2.5RS that had a rear LSD. Search for either "carrier or differential assembly" and then lsd. I think you can usually get a used one for less hassle and less money than trying to swap out ring and pinion sets. The guts of the rear diff in most cars is not something a shadetree mechanic should be messing around with. It needs to be balanced and weighted so it does not rip itself apart.
The only other factor to consider would be the halfshafts and driveshaft. See if they are direct bolt on or if you need different half shafts, etc. This all seems like a lot of work, but it is considerably easier than trying to modify your existing open diff. That is of course unless you regularly repair rear diffs for a living.
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Old 08-31-2002, 09:08 PM   #18
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Quote:
SO! would the 02WRX LSD or 00-01RS LSD match with 02RS ring gear? Anyone?
There's no guarantee that the pinion bolts will match up. I found out the hard way when trying to mate up a 1990 Legacy Turbo rear LSD to my OBS driveshaft. However, it should be possible to pull the pinion flange off your existing open diff and transfer it to the LSD. You will need either an air wrench or pin vise for the operation.

FYI, this is what the inside of a Legacy Turbo LSD looks like:


Furthermore, you cannot use a WRX 5MT LSD on your MY02 2.5RS. AFAIK, the WRX has a 3.90 final drive, while the 2.5RS uses a 4.11 final drive. I'm not sure about the WRX 4EAT though. You will, however, be able to use a MY00-01 2.5RS LSD, which has a 4.11 final drive.

-WaC
Wayne

Last edited by wac; 08-31-2002 at 09:15 PM.
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Old 09-01-2002, 01:26 AM   #19
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I'm using a 92 legacy turbo rear diff in my 2001 RS.I had to swap pinion gears because I didn't feel like buying new half shafts because the splines on the 92 are just like the ones in the picture above.The MY01 has c-clips holding the shafts in.All in all it was a pretty easy sway..I know most of you are asking why I'm using a 92 legacy rear...Well I'm using a upgraded legacy tranny in my car when I did the EJ20 swap..Also I need the pull type clutch so I could use the exedy twin plate clutch.Also from what I heard and read the 92 Legacy tranny is the same tranny in the WRX now,,Gerry
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Old 09-01-2002, 02:05 AM   #20
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Wayne, thanks for the info.... yeah I know about the gear ratio and that is also one of the reason why I am considering of taking the diff apart. 02WRX4EAT has the same gear ratio as 02RSMT, 4.111. I've been calling around and CANNOT find a wreck 02WRX4EAT and the parts dept selle it for $1400!!

But it's good to know that I could use 00-01RS LSD. So you are saying I could the take the whole piece of the rear diff from 00-01RS and do a direct swap with my 02RS right? Thanks!

Leo
Quote:
Originally posted by wac
Furthermore, you cannot use a WRX 5MT LSD on your MY02 2.5RS. AFAIK, the WRX has a 3.90 final drive, while the 2.5RS uses a 4.11 final drive. I'm not sure about the WRX 4EAT though. You will, however, be able to use a MY00-01 2.5RS LSD, which has a 4.11 final drive.

-WaC
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Old 09-01-2002, 11:37 AM   #21
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Quote:
Originally posted by wac
Furthermore, you cannot use a WRX 5MT LSD on your MY02 2.5RS. AFAIK, the WRX has a 3.90 final drive, while the 2.5RS uses a 4.11 final drive. I'm not sure about the WRX 4EAT though. You will, however, be able to use a MY00-01 2.5RS LSD, which has a 4.11 final drive.

-WaC
Wayne
Couldnt you just take the ring gear off the 02 WRX LSD and put on the RS Ring gear? and then just drop the sucker into the diff?
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Old 09-01-2002, 01:04 PM   #22
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Yup..It will work..Gerry
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Old 09-01-2002, 01:20 PM   #23
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Quote:
Originally posted by Clegg


Couldnt you just take the ring gear off the 02 WRX LSD and put on the RS Ring gear? and then just drop the sucker into the diff?
If you know how to shim the diff you will be fine, but if you don't... don't try it yourself. Shimming the diff is VERY important and will be costly if you don't do it. That is why just replacing the pumpkin is easier as long as it bolts right in and as someone else clarified -the final drive ratio is similar. Actually for those 2.5RS turbo guys out there, I would think the WRX pumpkin would be helpful as it is higher geared (lower numerically). 4.11 (2.5RS)vs. 3.9(WRX). Keep in mind that the R180 diff in the WRX, 2.5RS is also used in a few different years of Nissans. I don't know if it is the same exact version, but that info may be available from someone else.


edit:


^
|
|
misinformation...
The WRX and 2.5RS apparently have the R160 diff stock. The Sti apparently has the R180 and that is what many Nissans have. My old 240sx had an R200v the v designation means viscous if you look up the diffs. I don't know if that was a Nissan designation or it was for all R160, R200, R180 diffs...
R200 on the left, R180 on the right


I guess many older 280z guys perform this swap all the time... does anyone know if that is viable for WRX/ 2.5RS people? The drive ratio is either 3.9, 4.08, or 4.11 for those diffs....It would seem that if the R160 and R180 could be swapped out, and the R180 and R200 could be swapped out, then the R160 should be able to be swapped with the R200...or R180. I remember hearing on Nissan boards about 200sx (RWD) guys talking about swapping out the R180 from another year vehicle Subaru....not sure on exact procedures or specs... Anyone else have any info on this?

Last edited by Scoobie Snack; 09-01-2002 at 01:56 PM.
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Old 09-04-2002, 05:54 PM   #24
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As you can see, I am pretty new to the diff world. What is shimming? So if I take the 'pumpkin' off of a 02WRX MT and change the ring gear and final pinion. Before I could swap the pumpkin, I have to shim the diff? Also, I would need the axles too correct? Thanks!

Leo

Quote:
Originally posted by Scoobie Snack

If you know how to shim the diff you will be fine, but if you don't... don't try it yourself. Shimming the diff is VERY important and will be costly if you don't do it. That is why just replacing the pumpkin is easier as long as it bolts right in and as someone else clarified -the final drive ratio is similar.
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Old 09-06-2002, 01:04 AM   #25
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Quote:
Originally posted by iBlueVirus
As you can see, I am pretty new to the diff world. What is shimming? So if I take the 'pumpkin' off of a 02WRX MT and change the ring gear and final pinion. Before I could swap the pumpkin, I have to shim the diff? Also, I would need the axles too correct? Thanks!

Leo

I am not sure what parts you need to swap in a WRX diff. First though you need to realize that you can swap the whole pumpkin from another subaru w/ LSD without doing any internal work to the differential. The pumpkin is the whole rear differential casing and internals. You wouldn't buy a pumpkin to open it up and replace stuff inside, unless you wanted your stock one as a spare. If you have never heard of shimming the differential, then you cannot do it. Shimming the diff is balancing it and then putting shims inside the diff so it doesn't start a rotational whip effect and rip itself apart. I am sorry I can't explain it any better than that. I was hoping someone else on here would know more about the exact parts that are needed for the swap you need and would be able to say the exact parts. I think that the easiest thing to do is look for a 2000 or 2001 RS and swap the diff off of it and onto your car. The 2000 and 2001's have LSD stock and would bolt right into your car. The only thing to worry about would be the output shafts from the diff. Sometimes they have different bolt patterns or more importantly they do not have the correct splines on the end to mate up with the inside of an LSD instead of an open diff. If this is the case, whatever car you get the pumpkin from, make sure you get the output shafts also... problem solved. I hope this helps.
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