Hi everyone

I have a 1991 S5 Turbo II. Since it is a european model, it did not come with a factory LSD. So I am now looking into getting a aftermarked one.

Have you guys any suggestions on what I could get?

I've been looking at the TOMEI ADVANCE 1.5 WAY LSD mainly because it's price is not that high compared to a KAAZ LSD for example. I also think I will buy a 1.5 way and not a 2 way since I am more looking into road racing rather than drifting.

Another question is: What kind of speciality tools, new bearings, washers, seals etc. do I need to put the diff back together, since this is not clear to me by looking at the service manual.

Thanks for your help!

 

Anyone?

 

Since it is a european model, it did not come with a factory LSD.

Is this true? I thought I had a decent general knowledge of the fc and what they came with but I have never heard this before.

 

The LSD was surely not standard, on the european turbo models. I know another S5 Turbo II owner and his car also has no LSD.

It is possible that it was an option but I can't say for sure...

 

I was just asking because I was under the impression that all Turbo fc came with lsd.

What I have recently done because my NA is a non lsd car, I found a 86 gxl and am going to swap the lsd into my car, so maybe need to go that route, I am in the US so Im going off of us spec. As far as experience with kaaz and other options, I researched and could not find much except that by the time I was finished with buying a kaaz and having it installed I would be around $1500 and I was not willing to spend that much.

I would just try to find a donor car.

 

Europeon options got REALLY strange when it came to these cars

Are you 100% its not LSD? Being that ALL 87-91 rx7s that were practically anything but the base models came with LSD, it doesn't seem to make sense that they would change that logic for europe as it has almost nothing to do with emissions

 

Thanks for your help!

Well to be honest I haven't opened it yet so I can't tell for sure.

But It really feels like an open diff. If you go wide open throttle in a corner and there is nothing but one tire fire. There is also no "linkage" if you only turn one wheel when the car is on a lift.

So ether the LSD is terribly worn or it has none...

 

You don't need to open it to find out if its a LSD, jack up the rear and look at the rear end, if its a LSD it will have a tag on the fill plug stating it is

Or, if the fluid has been changed and no additive has been added, the tag could be missing, with the rear end up and trans in neutral, spins the tires by hand, they should both rotate the same direction, if its open they will spin opposite

 

Alright! I will definitely check this...

 

Allright! I jacked up the back of the car and turned one wheel, the other wheel turned in the same direction. The resistance to hold the other wheel in place however was very minimal. Other than that, I could not find the tag so it must be missing...

Does this mean it is an LSD? It's an S5 so it would be a viscous type if I'm right, so there is no friction modifier needed?

A few weeks I changed the trans and diff oil, I used 75W90 GL5 for both applications.

 

IIRC yes its a LSD, now that you mention its a s5, that changes alot, as those are not very desirable, and i don't believe you can put in the modifier, i could be wrong though

If you can find a s4 it would be better because its a clutch style and is at least rebuildable

 

At least now you know you have a lsd. the viscous style does not need an additive.

 

I would say you get what you pay for with aftermarket LSD's. I've installed and used most popular brands (Kaaz, Tomei, Cusco, and wavetrac) and the cheaper they are typically translates into very clunky abrupt locking. The best we've ever tested would be the OS Giken Superlock LSD's and it's important to also use the OS Giken 250R Oil. They are absolutely butter smooth when street or track drivin, but will lock up 100% when you need it to. Although they are one of the most expensive brands, the quality is unmatched. I run one in my FD and have numerous other friends with various cars who all love them.

Make sure you buy from an Authorized dealer many are not!

 

having an S5 you'll also need S4 T2 stub shafts to install a clutch type LSD.

if you're planning on road racing/street driving and don't have a ton of power (<400) I'd go with an FD torsen LSD. You'll have much better turn in than any 1.5way clutch type.

I switched from a t2 OS Giken 1.5 way to a torsen T2R in a ford 8.8 IRS diff and have no regrets at all.


As far as bearings go, you really only need the two diff side bearings if you're not changing your final drive.

 

Okay, thanks for all your answers and suggestions!

My S5 viscous diff is definetly no good, since it really felt like an open diff to me.

Concidering these factors I think the FD torsen diff would be the best choice for my application..

I looked at a few actions on ebay, but I am a little bit worried about the condition of these used parts...

Are the FD RX7 and the RX8 diff the same and do I still need the S4 stub shafts for the conversion?

 

torsens don't really wear out usually, so they should be fine as long as they don't have any damage on the teeth of the gears (which are visible)

no, the FD and RX8 diffs aren't the same, the RX8 has a weird preloaded fake clutch type according to this thread:
Rx8 LSD - Page 2 - RX8Club.com

and yes, you need the s4 stub shafts in order to put anything into an S5 diff except the stock viscous unit. the stock viscous s5 shafts are different lengths.

 

Ah Alright! Tanks for the great infos!

 

Hello Everyone,

What stub shafts do I need to use for my S5 viscous to FD torsen conversion?

https://www.mazdatrix.com/G8DiffMnt.HTM

Thank you

 

I installed the Torsen form the FD in the FC.

Turns out my S5 did have an open diff and no Viscous for some reason! Because of the fact that it already had S4 type stub shafts installed, I find it very likely that someone messed with this thing allready at some point.

I think for a street car the torsen is a very good choice. Turn in does not suffer but you will get decent lookup out of the corner. You can actually feel the DTSS working while accelerating out of the corner...