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Subaru STI R180 LSD into 240Z


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Hi Guys, I have recently bought a STI diff for my 240 and now I'm trying to work out the most cost effective way of sorting out the output shafts.

The STI runs a 27 spline, circlip hold-in CV style shaft, whereas my 240 has the original 25 spline bolt-in UJ style shafts.

 

I figure I have 3 options.

 

1.) I have been told that from about '80-82 the 4wd 720 King Cab front diff ran a 27 spline R180 diff with a bolt-in 4 bolt flange uni joints (same as the 240), but I haven't been able to find any conclusive evidence of this. If they do exist and I could find some of these ouptut flanges, this would be the cheapest and simplest option, just have to get a button inside the STI diff to bolt the flanges in and run my original half shafts

 

2.) Use the STI inner CV that matches the diff, and a 260z outer CV to match the 240 wheel hub, then get a shaft made up to suit the CV's. Now my problem with this option is, I am not sure about the 260 CV shafts, are they a straight swap between the 240 UJ type and the 260 CV type at the wheel hub? If so, I think this would be the next cheapest option with not too much messing about, with the added bonus of having CV's.

 

3.) Buy a ready made kit from the States. http://www.betamotorsports.com/products/products_main.php?cat=11&scat1=46&scat2=31

This option is probably fool proof but also most probably the most expensive and considering it would still leave me with UJ's, not sure it is the best option.

 

How have other people done this conversion? Someone please tell me you got some output flanges from a 720 front diff and you have a spare set in your shed that you want to sell!!  :D

 

Please chime in and give me some ideas guys. Other options or info regarding above would be greatly appreciated.

 

Cheers

Mick

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Yeah thats where all the Google searches send me. Havent been able to confirm the 27 spline 720 diff thing though.

Hey Jase what do you get your 4.4, 4.6 etc. ratio diffs out of? I assume they are from the deisel 720?

Hamilton strikes again!

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It's not just  a 720. Any K series R180 stubs should work. S12 Gazelle came with a K series off the top of my head.

I'm in the process of making axels that will be clip on STi one side and S30 outter. I have Wolf Creek CVs which i am going to see what's involved in putting and STi inner on and take it from there.

 

There are stacks of threads on Hybridz.org on how to do this:

https://www.google.com.au/search?q=hybridz+240Z+stub+axels+STi&sourceid=ie7&rls=com.microsoft:en-au:IE-Address&ie=&oe=&rlz=&redir_esc=&ei=kg4WULfXAq2WiQf-2ICAAw#hl=en&rls=com.microsoft:en-au:IE-Address&q=+site:forums.hybridz.org+hybridz+240Z+stub+axles+STi&sa=X&ei=kg4WUPj-LObYigeUwYCIDw&ved=0CHMQrQIwAA&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&fp=d9be7a9c80e97857&biw=1440&bih=805

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So all R180's with the K marking have the 27 spline?

I like the idea of the sti inner and wolf creek outer CV setup. Are you still using the 4 bolt companion flange at the wheel hub? or have you gone to 3x2 flange (I think that's what they are called?) from the 260z / 280zx CV's?

Thanks for the links.

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No, the WC axle outters bolt straight up to stock 240Z stub axel as far as i know as they are for Datto 1600 too.

If we can put the STi inner on the WC axel for under $500 we are onto a winner.

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So I contacted betamotorsports who says his shafts are not available at the moment and he will do another run of them in the fall. He has put me on the waiting list, So that means I've got 3 or 4 months to come up with another plan.

I'm thinking the wolf creek cv's are probably over engineering my car (NA L28) as well as blowing my budget.

Can I fit 280zx CV type stub axles straight into my 240 hubs? Or is there more to it than a straight bolt in?

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This is what i am looking at,

 

http://forums.hybridz.org/index.php/topic/73182-subaru-sti-r180-differential-and-axle-conversion-revised/

 

http://i270.photobucket.com/albums/jj106/itzgoten/240z%20project/IMG00144-20110512-1630.jpg

 

Rather than getting the BMS stub axel ($500 US) and the WC Axel kit ($900 US).

 

The response has been very swift from driveshaftshop.com and they have quoted $1100 for the kit (300HP not the 700hp kit) not sure if this is including postage yet.

 

John

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Yeah sorry should have been more clear, not EXACTLY the same.

I want to make one with a porsche outter and an STi inner so no adapter in the middle, lighter and cheaper.

Aim is a bolt in LSD kit for $1500.

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Spoke with SW Motorsport today, he has told me that because my STi diff is a mechanical centre, it is not possible to put the buttons in the centre and use the bolt in stub axles, and I have to find a stub axle that uses the circlip as a hold-in method. This is now pushing me along the route of CV's as I don't think I can get the 27 spline stubs with the circlip to suit the 240z half shafts, unless I do some other welding/machining of stub axles, or wait till fall for Betamotorsports stub axles.

Stewart also warned me about the WC shafts, suggesting he has seen a few of them break.

Any other suggestions would be appreciated.

Cheers

Mick

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I wonder what sort of setup that S13 R180 short nose diffs use. They have stub axles?

 

--Edit--

 

Ok i did some more research turns out S12 Gazelle and probably 720 / S30 / S130 are 25 spline.

 

As far as i can tell short nose R180 is 27 spline (cant confirm) and might give another axle option.

 

--Further Edit--

 

Looks like S13 are all 29 spline  >:(

 

--More Edit--

 

This is too hard - i just emailed the drive shaft shop if they can do the 240Z axle with an STi inner CV. AND to me those Driveshaft Shop 240Z axles look the same as the wolf creek ones.

 

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This is too hard - i just emailed the drive shaft shop if they can do the 240Z axle with an STi inner CV. AND to me those Driveshaft Shop 240Z axles look the same as the wolf creek ones.

 

Hi d3c0y,

 

Did you get a response from the driveshaft shop?

 

Johnboy

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Yeah they just need the measurement from the CV seal on the diff to the stub axel flange on the strut. They said that the cost wouldn't be much different to their standard model which is good. Maybe if enough of us want these we could get a good price on them too.

They said they wanted the diff mounted in the car for the measurement.

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So are 280z and late 260z diff axles 27spline? Can you get the required circlip groove machined into these to suit Subaru diff and then you can use standard half shafts?

Not sure about the spline count from the 260 and 280 diffs but unfortunately the bolt in stub axle is not long enough to machine in the circlip groove.

 

My 'k' series gazelle diff had cv's not half shafts.

Is that diff out of the car, can you count the splines and tell me the hold in method?

 

I am led to believe the NA S13 Silvia has the 27 spline stub axle with the circlip but has the 3x2 flange plate. Supposively the S13 also uses a 25 spline wheel hub which is the same as the 240z. Maybe, just maybe it is possible to use the whole drive shaft setup from diff to wheel hub from a NA S13.

 

Any ideas?

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  • 2 weeks later...

N/A S13 CA18DE cars were the only ones that had R180s from what i read. There are also different diameter shafts and i think this is LSD vs open diff (different axles).

 

I think S13 axels are longer as the S13 has a wider rear track than the S30. FWIW i found some things saying 27 spline for S13 but i found more saying 29 spline so i gave up.

 

280Z and 260Z are all 25 spline from what i have read and i think K series S12 diffs are 25 as well.

 

Cozza is your STi diff in your car? TDS just need that measurement and i think it's one of those things where you just have to pay the money. At least you are saving $500 but no having to buy stub axles.

 

 

 

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Not sure about the spline count from the 260 and 280 diffs but unfortunately the bolt in stub axle is not long enough to machine in the circlip groove.

Is that diff out of the car, can you count the splines and tell me the hold in method?

Sorry Cozza missed your post. I run the Amax torsen diff centre which requires the late 'k' series diff and uses the r180 bolt in flanges. The cv's were useless to me so I didn't take them when I bought the diff. I'm not much help  :-\

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Short nose R180's from NA S13's and the front diff's from Navara's, Pathfinders and terrano's have 27 spline output flanges. They are bolt in style though and 6x2 bolt flange pattern. Only the short one from the 4wd's is useful though, as one is around 2 foot long as the diff is offset a long way to one side. The S13's output flanges are 27 spline and are circlip style, but the flange pokes out from the diff about 2 inches each side which will impact on what shafts you can use.

 

I have put a long nose R180 from a 720 4wd with a NA s13 short nose Tomei 2 way LSD into my C210 Skyline.

 

What I did was use  2 short output flanges from a Terrano front short nose R180. I had the tips of 2 NA S13 output flanges cut off at the circlip groove. I had them drilled and tapped to suit the Terrano flange's bolts, and bolted them to the end of Terrano output flanges. I had the Terrano flanges tips machined  prior so that the circlip groove would be in exactly the right place.

 

I used the Terrano output flanges instead of the NA S13 ones because they are flush with the diff and don't poke out as much. This makes finding factory shafts a lot easier. You get around 2 inches extra length of shaft to play with on each side with the Terrano flanges.

 

I then used NA S13 cv joints on the inside end of the axles.

 

The shafts you use will obviously depend on the car it's going into, but I used R30 shafts with R30 cv's on the outside as it's all mounted in an R30 cradle. I have a different setup in my 240z so I can't be sure what shafts would suit, but I think 2 x R30 short side shafts may be close to fitting. From memory I think they were 390mm and 400mm.  NA S13 cv's and R30 cv's share the same shaft spline size and count.

 

I'm not sure about the flange on the wheel end, but I think R30 flanges may fit in place of the 240z flange so that it can bolt up to the R30 cv. If not the you may be able to squeeze an adapter flange inbetween.

 

Alternatively You may be able to use subaru r180 inner cv's with R30 short shafts. I have not measured this idea, but It would be worth looking into if you can get the cv's with a subaru diff.

 

Getting custom shafts made is not overly expensive though. I had a pair shortened and resplined for $360. I was told I could have a pair made from 4140 for not much more, about $400.

 

 

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Awesome info! Any idea what sort of HP this set up could hold?

How much was the total all up, Machining + Parts?

I'm thinking (in regard to my application anyway (350hp)) if 4140 axles are $400 + New CVs + Machining it's going to have to come in close to $1000 anyway?

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Not sure about what power it could handle, but it would be the same as whatever an STI Subaru, R30 Skyline or NA S13 could handle. I would think 300hp @ the wheels would be fine and probably around 400hp @ the wheels would be pushing its limits. And that would depend on what type of driving you do to. Drags and drofting would be on the lower end and circuit racing on the upper.

 

Costs can vary greatly as it's all 2nd hand parts. But, the machining etc for the output flanges was $80. The NA S13 shafts with cv's and output flanges was $40. The Terrano output flanges were $20. The 720 diff was $200. The S13 Tomei LSD was $400 from importmonster. The complete R30 car with shafts and diff was $200. R30 shafts alone would have been $40. So $940 total.

 

You wouldn't need the complete cradle though and maybe not even need a diff, so the parts and machining alone was $180. This leaves out the diff, which you may already have and the LSD center which can vary in price.

 

My machinist may be cheaper than your average city machinist as he is a very small business who does a lot of smaller one off jobs. Big machining shops often don't like these types of jobs and charge accordingly. If you're in S.E QLD I can recommend my guy from Ipswich, If you're interstate, look for smaller machinists on the outskirts for better prices.

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If you're looking at NEW cv's then I probably wouldn't bother cutting costs with the rest of it though. If you're willing to pay for new cv's then just go the whole hog and do the lot custom. Once you're willing to go down the custom axle shaft route it makes the whole process a lot easier.

 

With custom shafts you can use any cv you want and keep the standard circlip NA S13 output flanges and whatever flange you like on the outside end. The prices I quoted for parts were the prices quoted to me to buy these parts locally and not necessarily what I paid, as I had a few of them in the shed already from previous projects.

 

After all this though, the weak link would still be the 240z stub axle on the wheel end anyway. So unless you're upgrading this area then I think this collection of 2nd hand bits and pieces would be sufficient if you can get them for the right price.

 

Custom axles would be a lot less work and headaches and wouldn't cost much more, if any. But the info is there for those that like a challenge like me.

 

For my 240z I had a custom hub carrier made to suit r32 skyline hubs and cv's. It uses r32 GTR brakes and S13 front coilovers. It has a short nose r200 skyline diff with 4.6 ratio gears from a Pathfinder front diff, which some are r200's. It has standard r200 output flanges and inner cv's. It has a Cusco MZ 1 way LSD center and uses Z31 axle shafts.

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  • 4 months later...

I know it's been a while but I have finally received a pair of side axles from Beta Motorsports. I can plug these side axles straight in to the diff and use all the original 240z half shafts in keeping an original theme. I think others on here have the same setup.

Heres a link

http://forums.hybridz.org/topic/78123-subaru-wrx-sti-r180-side-axles/

 

Now before I put the diff in I have 2 questions.

1. Where can I find a new front diff mount (mythe 1 in the car at the moment is welded up, I figure a bit of movement would be good)

2. What type of oil should I use, I have done a bit of googling and as usual a came up with a wide range of opinions.

 

Anyway the diff is a Torsen type LSD out of a 2008 WRX STI.

Any suggestions or info on what others use would be appreciated.

 

Cheers

Mick

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