GTUs Viscous LSD shim mod?
 

Well I'm running a GTUs 4.33 LSD and lately it hasn't been locking up consistantly. While looking for a way to replace the fluid or sealed cartridge (I did not find anything regarding this... seems when their gone, their garbage) I found the mod shown here:

http://d1nz.org.nz/forum/viewtopic.php?t=9610

I am wondering if there is a similar preload shim in the GTUs LSD that I can add to achive better locking characteristics? If not I will end up going kaaz but 10 dollars for a shim and some oil sure seems like a better alternative lol. That leaves about $1,000.00 extra for tires and gas... that goes a long ways!

If I do end up going Kaaz, would it be benificial to use a TII case, or will the GTUs case accept the Kaaz internals and be the same quality. I'm looking at the DBZ-1810-WPC for the GTUs diff and wondering if it will fit.

i dont know, but i did look in the parts fische. they list shims in different thicknesses for the open diff. mazda only sold the viscous lsd as a unit, so they dont even show the guts.

option 2 is to find an 84-88 na lsd, its clutch type, and rebuildable

or the 94-05 miata torsen

both are drop in replacements for the VLSD

This VLSD replaced the clutch style that came with my 87 gtx. I replaced it mostly for the gear ratio (4.3 vs. 3.9 for the auto that was in the car). I think I still have the auto LSD, but it didnt lock up too well either.

That miata torsen option sounds promising. So the torsen unit will just bolt right into the GTUs case? Or is the entire diff a bolt in affair? There are a TON of those in the wreckers around here, so should be easy to source.

Still hoping that I can find a way to shim the VLSD, I actually liked the performance for street driving / autox. I only get one day on the local racecourse per year (its a bike / cart course), so the slight gain of a quality kaaz diff there would be pretty minimal. I liked the quiet operation of the VLSD, and the 4.3 gearing is PERFECT for my driving. I have heard good things about the torsen characterists though... never driven one before. Are they fairly quiet as well? Can they handle ~230hp at the wheels? I dont drag the car, so i'm not launching on slicks or anything.

all of the 84+ 7" ring gear diffs interchange, so you keep the 4.30's no matter what...

the torsens are silent, 230hp shouldnt be a problem, miata guys run that kinda power a lot.

i dunno if the shim thing would work or not, i think you'll have to pull it apart to see

The fundamental problem of a VLSD is that the fluid breaks down over time. Even if you could shim it, it won't compensate for the 20+ year old fluid.

Your cheapest, best bet it to take your old clutch type diff and rebuild it. Those you can shim for increased preload.

You can't shim a viscous LSD.


-Ted

i guess you could swap to a miata"s torsen LSD but i'm not sure does the GTUs use a turbo 2 rear end with 4.33 gears or an/a rear end eith 4.33 gears+LSD?

All turbo FC's use the same dimension rear end.
All non-turbo FC's use the same dimension rear end.

The GTUs uses a special 4.3 rear ratio in a non-turbo FC rear.
These parts cannot be used in a turbo FC rear.


-Ted

thats what i figured then he can use a Miata torsen LSD.

The shims are used to adjust pinion depth and have nothing to do with the VLSD.

Hot_Dog
90 RX7 GXL

If you decide to swap in a clutch or Torsen limited slip unit into your housing you will need the equal length stub axles.

I don't mean to thread dig, but I have had the same question lately. And thought posting here would be better than starting a new thread.

Why is it that the mazda VLSD cant be shimmed? I know that 240sx owners can shim the r200/j30 VLSD, using an extra thrust washer in the diff.

Is this not possible for the FC unit?

Here is a link to the r200/j30 shimming, http://zilvia.net/f/s-chassis/200226...-j30-vlsd.html

I don't believe you can take the mazda one apart like the nissan.

Like I said, even if you could shim it, that doesn't solve the fundamental problem with an old VLSD.

*BING BING BING!* You are very correct with this statement.

When swapping in Miata Torsen units, its a lot easier to source the Miata Stub Shafts with the torsen! Just something to keep in mind so you don't have to make a second trip back to the junk yard to pick up the shafts you left on the ground. *innocent look*

Also, you can't shim the viscous LSD.