36 replies to this topic

[JMortensen]

I think you're charting new territory. Good luck and keep us posted!

[Sparky]

I also look forward to more info on your progress....sounds like it could pay off.

[rudypoochris]

Sounds great! I thought that the output splines of the subaru R180's were a different diameter than the 280z's. I could be wrong though, but that is cool!

[BRAAP]

Thread has been subscribed to, and if this works at all, I prematurely vote it for sticky…

BRAAP… out!

[Sven]

You've got my attention! I've been too busy moving cross-country to devote any real time to working on my diff swap. Keep us posted.

[Tony D]

Wait till the 2007 Legacy Turbo Differential (Helical ATB R-200) becomes available in the wrecking yards...

That would be nice if they stuck with the 27 spline input. That would make my conversion easier...

[NZeder]

Wait till the 2007 Legacy Turbo Differential (Helical ATB R-200) becomes available in the wrecking yards...

That would be nice if they stuck with the 27 spline input. That would make my conversion easier...

27 spline count? I thought the R200 used a 29 spline count - that is what all the R200 long noses I have take, the 300zx turbo shafts are 29 spline count? I would only assume the Helical ATB R-200 fitted to the Legacy would be the same as the S15 Helical ATB R-200 center (I know you guys in the US did not get the S15 but we have a lots here in NZ - so it should not be too long before these start to get wrecked) and these ATB R-200 use a 30 spline count on a 31mm shaft. So we need to find a shaft solution for the S15 ATB so the same would apply to the Subi ATB R-200.

[NZeder]

Any update on this R180 Helical install? ie CV shafts what have you found out. I am thinking of doing something sim on my new 240z (factory R180, the 260z has the R200 in it already so I have done the normal R200 cv conversion stuff) but with the 240z I am thinking I might pickup a Subie R180 and go down this path.

What brand is the Helical R180? I thought all Subie used CLSD or VLSD in the rear with only the newer cars using ATB/Torsen/Helical in the front and centre.

[Nizzan]

Hey guys, I think this is possibly my second post I've written on Hybrid. Although I am often on this forum looking to you guys for answers. I've been paying close attention to this thread because around the time that this thread started I too purchased a 2004 Subaru STI differential. In addition to the diff, I also pick up two STI axles.

Before spending any money I made sure that this setup was even remotely possible. Because I planned on using the STI axles with the STI Diff, I knew there were no issues on the axles-to-Diff side, with splines and what not. I also noticed that the input flange on the differential was a different bolt pattern. But that problem was easily resolved by simpley swapping the r200/r180 (from the datsun's) with that of the Subi.

Now there were two big issues that I came across. One: Is that the subaru axles are about 4-6 inches to long. Two: Is that the hub side of the subi axle has splines that go into the STI's wheel hub assembly. And I needed to somehow modify it to a flange.




So...

For the length issue, I thought, there had to be a place that made a shorter center shaft for an STI. Sure enough, the Driveshaft shop make a shorter center shaft for the STI. The stock shafts are 20 1/2". And after measuring and calculating I determined that the ideal length would be 15 1/4" to 15 1/2". As a bonus the shorter center shafts I ordered were made to handle 400 Hp +. Now I'm just running a L30 stroker, so there is no chance I will break them. Oh I should mention the two stronger shorter shafts were about $400. That also includes: 4 New CV boots, 4 Tubes of CV grease, and 12 clamps. (6 small, 6 large).

Here the stock shaft and new shaft are side by side:




For the other issue, the problem with not having a flange. I took the outside axle case and the 280z stub axle flange to a machinist. I told him that I wanted the spline section removed and a flange welded on to match the 280z flange. This was a little difficult because I also wanted a center circle sticking out from the flange to match the inboard circle of the stub axle. It's hard to describe. But to your luck I have photos.

This is the planning:



And this is the outcome, all painted and looking good:



These are the axles in pieces and ready to be assembled:







Well, thats my setup. I'm kicking myself that i didn't take any pictures of it in the car after install. But I just took a picture of them now. It's a little dirty because I've done about 2000 miles on the setup.



Works flawlessly though. The axles fit perfectly so it isn't a pain in the ass to take out, like it was with the z31 axles. But best thing about this setup is that I got Limited Slip, the 3.90:1 gears that I wanted, and both my axles and Differential have less then 20,000 miles on them.

Price wise:

-The 2004 STI LSD differential with 3.90 gears. (16,000 miles) cost me about $400.

-Both the axles (18,000 miles) cost about $250.

-The new center shafts, and boots. etc. cost $400

-Welding/machining on outer CV case cost about $100

-Some POR paint and Redline gear oil. Under $100

Well, I think I marked new territory here. While it cost a little over $1,200. Spending $700-$900 on z31 r200 LSD is sort of ridicules. Considering how many miles there are on a 1987-1989 differential. Maybe a couple of years ago the r200's ran for a lot less than that. But I am very please with my setup. And I would recommend it.

[NZeder]

Excellent work and thanks for the pics and update/post. You also have the bonus of less weight in the rear due to the R180 vs R200 so that will be worth a bit and I am sure this centre and axles will be more than strong enough for a lot of the engines we hybridz'er run.

[fastzcars]

$100 for machining and welding? That's cheap! Machine shops around here won't even consider doing things like this for less than $200! Thanks for keeping us informed! It's great that we have other options.

[Nizzan]

You also have the bonus of less weight in the rear due to the R180 vs R200 so that will be worth a bit and I am sure this centre and axles will be more than strong enough for a lot of the engines we hybridz'er run.

You are correct. So I benefit from using he lighter differential AND because I went to a newer (2004) "K" type r180, the differential is a 4 pinion diff as compare to the older r180's which are 2 pinion.

$100 for machining and welding? That's cheap!

Yeah it was more like $65 for each CV case. And that's also because I've done business with the guy before. I also had my 280z bellhousing machined out to fit my 240sx 5 speed gearbox. I think he charged me $100 alone for that. So in total it was about $220-$240.

I'll wash the car sometime this week and take some good photos of the setup in the car.

[JMortensen]

You are correct. So I benefit from using he lighter differential AND because I went to a newer (2004) "K" type r180, the differential is a 4 pinion diff as compare to the older r180's which are 2 pinion.

I thought this was a helical diff. If that's the case, it doesn't have typical pinion gears.

Regardless, kudos to you for doing what it takes to get it done. I really like this solution.

[Nizzan]

Jon...

I too thought this diff was a helical differential. But before I installed the diff, I had the LSD assembly out to set the breakaway torque to about 50-60 Ft/lbs. What I discovered was that it did indeed have 4 pinion gears. (6 total gears)

This is exactly what the Subi LSD pinion gears looked like:



Note: This isn't a photo of the subi LSD. I found it on google, infact it came from the thread you started Jon.

[jeffer949]

Whats also nice about that is that you now can get new cv axles that arent "rebuilt" and arent 20 some years old.

[JMortensen]

Jon...

I too thought this diff was a helical differential. But before I installed the diff, I had the LSD assembly out to set the breakaway torque to about 50-60 Ft/lbs. What I discovered was that it did indeed have 4 pinion gears. (6 total gears)

This is exactly what the Subi LSD pinion gears looked like:



Note: This isn't a photo of the subi LSD. I found it on google, infact it came from the thread you started Jon.

OK, good to know. For what it's worth, I'd prefer the clutch style anyway.