Subaru WRX STi R180 Side Axles

[FlatBlack]

Do you have to ask? Definitely!

 

I would also love to see the process!

[Racer Z]

The rear cover shows the mustache bar mounting bolts are longer on the STi unit. Did you swap the differential covers or is this not necessary? They seem nearly identical aside from the bolt length.

 

We R&R'd our stock rear-end recently to do the suspension bushings. Although we did not try to fit our STi LSD, I don't think the longer studs will be an issue.

 

It will be easy to double-nut the studs and change them out if push comes to shove.

 

Now that I think about it, our unit is missing the studs, how much longer are the STi studs vs the 240z studs?

[BrandenZ]

I've already pulled both of my 240z studs out and intend to install them in the WRX STi diff myself. Once I pull the STi studs I'll measure the exact difference for you if no one else has chimed in by then.

 

BTW -- Did you order the front cover gasket from Kragen also? I couldn't find the gasket on there, and was hoping to order all of the seals and the gasket at the same time.

[proxlamus©]

Just trying to piece together some info.. please correct me if I'm wrong

 

We will need the 27 spline differential.. which can be pulled from a

2004-2005 Subaru WRX STi - these are clutch type CLSD with a 3.9 ratio

2006 Subaru WRX STi - Viscous VLSD with a 3.54 ratio

 

shucks.. I really want a 3.54... but I want a clutch type =/

 

Is there a 3.54 CLSD option?

[Cobra_Tim]

Just trying to piece together some info.. please correct me if I'm wrong

 

We will need the 27 spline differential.. which can be pulled from a

2004-2005 Subaru WRX STi - these are clutch type CLSD with a 3.9 ratio

2006 Subaru WRX STi - Viscous VLSD with a 3.54 ratio

 

shucks.. I really want a 3.54... but I want a clutch type =/

 

Is there a 3.54 CLSD option?

 

You SHOULD be able to use a 115mm ring gear with this diff... so you should be able to swap out the 3.9

[RebekahsZ]

I'm afraid that you guys are making this too complicated. Here is how the swap goes. Your Subaru rearend (call it whatever you like) is relatively new. The seals are probably fine. The rear cover is the same. Leave the thing alone. Pull the output flanges with a puller or two leavers (screwdrivers work). Put John's new output flanges in - light tap with hammer and block of wood. Take your Z input flange off with an impact wrench, a 27mm socket and a gear puller. Do the same with the Subaru flange. Put the Z input flange on the Subaru input shaft and torque it as best you can (spec is 125 ftlbs). Put oil and LSD lube in the Subaru differential (1 quart). Put the differential in the car and hook up the half-shafts and drive shaft with the original hardware. Go racing. The rear cover studs are longer on the Subaru diff. Swap them if you can - mine were in too tight. I left them. It made for a bit more wrestling, but I still got it in. This is a 1-day job tops - a couple of hours if you are good and have the tools I listed.

[mrcheeze36]

2006 Subaru WRX STi - Viscous VLSD with a 3.54 ratio

 

shucks.. I really want a 3.54... but I want a clutch type =/

 

Is there a 3.54 CLSD option?

 

I forgot to include what the 2006 STI came with...I updated my post:

 

Just remember ratios and LSD type differ depending on the year (which may affect pricing):

 

3.9 ratio:

2004, 2005, 2008

 

3.54 ratio:

2006, 2007

 

CLSD:

2004, 2005, 2006

 

Torsen LSD:

2007, 2008

 

I'm not sure what came in 2009 and 2010 STIs (that's why I didn't list them above).

[Racer Z]

I've already pulled both of my 240z studs out and intend to install them in the WRX STi diff myself. Once I pull the STi studs I'll measure the exact difference for you if no one else has chimed in by then.

 

BTW -- Did you order the front cover gasket from Kragen also? I couldn't find the gasket on there, and was hoping to order all of the seals and the gasket at the same time.

We haven't ordered anything yet. My brother says he will...

 

 

I'm afraid that you guys are making this too complicated. Here is how the swap goes. Your Subaru rearend (call it whatever you like) is relatively new. The seals are probably fine. The rear cover is the same. Leave the thing alone. Pull the output flanges with a puller or two leavers (screwdrivers work). Put John's new output flanges in - light tap with hammer and block of wood. Take your Z input flange off with an impact wrench, a 27mm socket and a gear puller. Do the same with the Subaru flange. Put the Z input flange on the Subaru input shaft and torque it as best you can (spec is 125 ftlbs). Put oil and LSD lube in the Subaru differential (1 quart). Put the differential in the car and hook up the half-shafts and drive shaft with the original hardware. Go racing. The rear cover studs are longer on the Subaru diff. Swap them if you can - mine were in too tight. I left them. It made for a bit more wrestling, but I still got it in. This is a 1-day job tops - a couple of hours if you are good and have the tools I listed.

That's pretty much what I figured. My brother and I have a different view here. I say it's new enough that the seals are probably good.

He says,

1) It's too much trouble to remove the diffy if the seals fail shortly.

2) Everything else we thought we could get away without replacing has been wrong. (We did not replace the diffy mount when we did the suspension bushings and it failed before we got to the sidewalk. LMAO it was only 40 years old.)

3) Since it's only $40 bucks, let's do it and be done.

 

I don't disagree with his logic, but...

[datrod]

O.K. here ya go. The slugs ready to go to the lathe.

17 Lbs to start.

Making chips.

A little code for you techie types.

 

I'll be sending them off to H.T. next week. Then a little more lathe work and spline cut. then off to beta motorsports for shipping to you guys.

[Sven]

I'm afraid that you guys are making this too complicated. Here is how the swap goes. Your Subaru rearend (call it whatever you like) is relatively new. The seals are probably fine. The rear cover is the same. Leave the thing alone. Pull the output flanges with a puller or two leavers (screwdrivers work). Put John's new output flanges in - light tap with hammer and block of wood. Take your Z input flange off with an impact wrench, a 27mm socket and a gear puller. Do the same with the Subaru flange. Put the Z input flange on the Subaru input shaft and torque it as best you can (spec is 125 ftlbs). Put oil and LSD lube in the Subaru differential (1 quart). Put the differential in the car and hook up the half-shafts and drive shaft with the original hardware. Go racing. The rear cover studs are longer on the Subaru diff. Swap them if you can - mine were in too tight. I left them. It made for a bit more wrestling, but I still got it in. This is a 1-day job tops - a couple of hours if you are good and have the tools I listed.

 

You deserve something for that post! To the point and simple. It was pretty much what I initially suspected, but this thread and the endless dialogue made me start believing there was going to be more involved in the swap.

[garvice]

Always interesting seeing the manufacturing sequence. That seems like a lot of wasted material. What ever happens to all the shavings?

Do you send it to a scrap metal place for beer money?

[datrod]

Always interesting seeing the manufacturing sequence. That seems like a lot of wasted material. What ever happens to all the shavings?

Do you send it to a scrap metal place for beer money?

 

Yea I fill up a 4X4X6 bin with chips at least once a month when I'm busy. about 3K #. Not much money there but it has to be done.

[V8INtheZ]

So datrod do you have any rough idea of when all the pieces will be finished and shipped off to Johnc? I know things happen, but I just want to plan ahead. Do you think it will be a week or a month is the answer Im looking for.

 

They look awesome and I cant wait!

 

Thanks

[datrod]

So datrod do you have any rough idea of when all the pieces will be finished and shipped off to Johnc? I know things happen, but I just want to plan ahead. Do you think it will be a week or a month is the answer Im looking for.

 

They look awesome and I cant wait!

 

Thanks

 

More like a month than a week. I have to heat treat and spline them. That can take a couple of weeks.

[V8INtheZ]

Awesome, thanks for responding quickly.

[BrandenZ]

A couple of points of interest from my working session last night:

 

1) The pinion seal appears to be a straight pull and replace. I pulled the input flange (have to swap them anyway!) and the seal is directly accessible once the 27mm nut and input flange (I used a punch + light tapping as opposed to a puller) are removed.

 

2) The studs are _not_ interchangeable between the rear covers. The covers themselves appear to be identically cast, but they're tapped differently. Unfortunately I did not receive studs with my Subi diff, so I'll personally be cleaning up the Z's rear cover and bolting it up. I'll probably pick up a diff cover gasket for the Z as opposed to the subi also. Just wanted to give everyone a heads up -- again, my 73 diff studs did not fit into the 2005 subi diff, slightly different thread pitch.

[datrod]

A little more work on the stubs today.

Should send to heat treat tomorrow.

[Racer Z]

datrod -

 

Those are some interesting pictures of the process. I think you said heat treating next then cut the splines. How are you going to cut the splines? One at a time in an end-mill? 27 x 40 is more than I can count. Surely there must be a better way.

[Racer Z]

A couple of points of interest from my working session last night:

 

1) The pinion seal appears to be a straight pull and replace. I pulled the input flange (have to swap them anyway!) and the seal is directly accessible once the 27mm nut and input flange (I used a punch + light tapping as opposed to a puller) are removed.

 

2) The studs are _not_ interchangeable between the rear covers. The covers themselves appear to be identically cast, but they're tapped differently. Unfortunately I did not receive studs with my Subi diff, so I'll personally be cleaning up the Z's rear cover and bolting it up. I'll probably pick up a diff cover gasket for the Z as opposed to the subi also. Just wanted to give everyone a heads up -- again, my 73 diff studs did not fit into the 2005 subi diff, slightly different thread pitch.

 

Ok. We also have a 73 240z and our STi LSD is missing it's studs. Thanks for the heads-up.

[datrod]

datrod -

 

Those are some interesting pictures of the process. I think you said heat treating next then cut the splines. How are you going to cut the splines? One at a time in an end-mill? 27 x 40 is more than I can count. Surely there must be a better way.

 

I send them out to a gear house and they cut the splines. Top quality stuff.