FC-LSD thread
 

So I figured I would start this thread for everyone who has questions about LSD's in their FC.
My first question is :

Does my S5 90 Vert have an LSD?:scratch:

Pulled from the FAQ. Doesn't say anything about a vert though

Unless it was installed aftermarket, it does not have an LSD.

We have a sticky already stating everything that our Fc's came with. check it out

What type of LSD can I put in my car?

What's the average price range for one?

Well, you have a couple options in terms of traction control. roughly in order of price.

1.weld your diff
2.buy/install a Ebay Rx7 non-turbo Lsd ~$400 (no experience with them, just know that they exist)
3. buy a 2nd gen N/A LSD. Only the 4.3 ratio will work from the GTUs, you must also use the Stub Shafts from the donor car

4.buy a turbo diff, stub shafts, and Mazdatrix adapter drive shaft.
5.same as above but, re-drill and machine pinion flange for non-turbo driveshaft bolt pattern, and use Turbo halfshafts.
6.replace entire drivetrain with turbo components, From flywheel back.
7.buy a rebuildable Kazz or similar unit, and install into your differential

Prices vary by the deals you're capable of working out.
I don't have a lot of experience with most of these.. just know that you can do them

Couple points to add to those above:
S5 that had LSDs had viscous, the sheering action of which will have long since left the building, leaving it effectively an open diff, so if looking for a NA LSD, look S4

S4 clutch-type LSDs may need a rebuild to restore them - just to be aware of.

94-2005 Miata's with torsen LSD's can be swapped into the RX7 pumpkin, you just also have swap the ring gear from your old lsd, the Miata one won't work.

This is false. The clutch type LSD also came in S4 GXLs. Also, you can use your open-diff stub shafts with these LSDs; all you need is the LSD itself.

This might be more lore than truth. Having seen the inside of a couple of S4 LSDs, all the plates have been well within spec. Though, it seems the initial torque rating for these diffs is rather low. Like 35-40 ftlbs. So even when within spec, it still doesn't feel like a high initial torque motorsport diff like a KAAZ. Luckily, some slight shimming is all that is needed to bring the initial torque up to something like 100ftlbs.

HotRodMex, I don't have total a posteriori knowledge with this particular swap. So I checked Mazdatrix's differential page, http://www.mazdatrix.com/g5.htm
as well as their catalouge, and they claim different part numbers (and incompatibility) between open and S5 N/A VLSD's stub shafts

They also claim compatibility issues with some of the other differentials they offer and the S5 N/A VLSD stub shafts. Leading me to believe that they are two different parts.

I do apologize for the half-information though, the GXL slipped my mind and I know those are direct drop ins, without having to change shafts.

Hope this helps.
-M

So it looks like my cheapest option would be to either

A. Weld my diff
or
B. Find a GXL LSD

I think I understand what an LSD does...it makes it so both rear wheels will spin at the same time so all the power doesn't get sent to the outer wheel...right?

For the un-lsd educated. What does the initial torque rating do?

would an s4 diff fit into an s5?

Yes

Yeah, I didnt really consider the VLSD as a viable swap or as an issue. (Does anyone really? ;) ). But If you look at my post, I only reference S4 clutch type LSDs and open-diff stubshafts. It is probably good you mentioned, in case someone was cursed with an S5 N/A VLSD.

here's a quick link that does a decent job of explaining.

http://www.ppi-ats.com/LSD/LSD_basics.html

further googling of "lsd initial torque" or "lsd pre-load" will probably find you copious reading.

does my FC have an LSD??
answer: do a burnout :)

I know that this doesn't apply to the OPs car, bit incase anyone else wants to know, the turbo half shafts will indeed fit in the 4 lug hubs.

Also do you think somebody makes a Mini-spool that will fit? It is a better option then welding the diff since it is reversible.

I am the original owner of a '90 GXL with 5-speed. It came with an open differential and 4.1 final drive ratio. About 15 years ago, I picked-up a new clutch type LSD unit for an '88 GTU. I put LSD with 4.3 ring & pinion set into my '90 GXL. Stock stub shafts were compatible with the LSD. So far, I've got about 150k miles on my LSD and haven't had any problems.

ATS Carbon 1.5 way preloaded LSD is what I put in mine.