N/A to TII rear end swap

[My5ABaby]

I have a turboed 6 port and I'm looking at swapping in the more reliable TII diff/half-shafts. I've found some conflicting information on this.

I get the diff/half-shafts/driveshaft/tranny matching scenario. However, does the subframe (carrier?) have to match the diff/half-shafts? In other words, if I bought a TII diff/HSs, I could keep my existing N/A subframe and it would all go together like Legos?

I'd love for this to be yes as that will save a ton of hassle with shipping or what not.

[JustJeff]

I believe the answer is that you can use any subframe. Many years ago I had a shop in Indy do my JDM TII swap. With that swap, I had them put a S4 TII diff and half-shafts in. More recently I swapped the same drivetrain into a different n/a convertible. At that time I swapped subframes and differentials as complete units.

[TitaniumTT]

The subframes and rear hubs are all the same, swap shafts and go.

If I may add a suggestion, ditch the S4 clutch pack diff in lieu of an S5 or better yet, a Torsen....

[My5ABaby]

I'm probably going to go with whatever TII diff/shafts I can get a hold of... Stupid overpriced diffs. People want too much money for a used 25 year old differential.

[RETed]

I wouldn't run that viscous LSD either...
The viscous LSD basically mimics and open diff at very low deltas.

http://fc3spro.com/TECH/MODS/DT/lsd.htm

The stock clutch-type LSD's are all basically worn out by now.
Most of them operate like an open diff due to the high mileage.
I believe the clutch discs are all "NLA" from Mazda?


-Ted

[My5ABaby]

What would be a good recommendation for road racing/auto cross? I think what I'm seeing from you guys is the clutch is better but worn out, and the viscous is not worn out but sucks.

P.S. I can't get your site to work Ted.

[TitaniumTT]

My choice from least favorite to favorite is as follows.... S4, S5, Torsen.... Most FD guys will trade thier torsen plus cash for your S4 TII clutch type diff. You don't want a clutch pack for auto-x, Torsen is the way to go IMNSHO

[My5ABaby]

So I can put the FD torsen into the FC housing?

[TitaniumTT]

You can put the FD Torsen into the TII housing. You need S4 stub shafts though and Turbo shafts.

[My5ABaby]

Good to know. Anyone know if I need the early 87 or mid 87-88 stub shafts to do the FD swap? Apparently Mazda decided to change things... :-/ http://www.mazdatrix.com/G8DiffMnt.HTM

[RETed]

Sorry, just keep trying...
My ISP has only a 90% uptime rate. :P

For the beginners...
It's advantageous to go with a Torsen cause it's predictable.
The other advantage is that there is nothing to wear, so it's maintenance-free.
Downside for a Torsen is that it's relatively delicate - due to it's design and all the little spider gears.
The FD Torsen LSD is good to about 300hp or so - above 400hp is pushing it.
This is also very dependent on your driving style.
You could run 500hp through a Torsen if you're very delicate with your throttle control.
I'm talking worst case which is drag-style launches.

Clutch-pack LSD's can be a handful, because beginners will have hard time with the on / off engagement; this is where the Torsen is superior.
The clutch LSD is stronger by design.
This is why your drag "posi's" and aftermarket LSD's are almost always clutch-type.
For advance drivers, you can use the on / off point of the LSD engagement to your advantage.
Also, the clutch packs can be tuned to change on / off engagement points and also the rate of engagement...
Last, but not least, one big disadvantage is that the clutch discs will wear.

Viscous LSD's only advantage is that they are basically maintenance-free.

Yes, the FD stock Torsen LSD will swap into any FC turbo rear diff with the right stub shafts.
This is basically what the Infini VI FC3S in Japan was running...


-Ted

[My5ABaby]

Good info, thanks Ted. It looks like I'll try to get my hands on a low mileage clutch, or just swap a torsen in. My goal is under 400 eventually, really only around 250 for now. I also don't have any plans to drag race or launch with it, not really my thing.

[TitaniumTT]

I've been pushing 400 for quite some time now with the same Torsen with repeated HARD launchs.

That being said, I did just cryo treat a torsen just yesterday because I suspect in the coming year to be breaking a lot more drivetrain parts

[My5ABaby]

I've been pushing 400 for quite some time now with the same Torsen with repeated HARD launchs.

That being said, I did just cryo treat a torsen just yesterday because I suspect in the coming year to be breaking a lot more drivetrain parts

Good to know. Which half-shafts are you using? They had the vin split with early and late S4s.

[My5ABaby]

Also, has anyone used an RX-8 diff in the S4 TII diff?