G50 LSD install.

Madsimilius · Madsimilius's Garage

I have a few questions regarding installing a LSD in my g50/00 transmission before i order one.
Is it possible to install a LSD without taking my transmission apart?
I've read somewhere that i have to adjust the pinion depth.
I always thought i only had to shims the ring sideways, since ring should be in the same place back and forwards and i'm using the same ring?
At first i was hoping i could just move the shims and bearings straight over from my old diff and the measurements on the new LSD would be the same.

Driven97 · 07-21-2016, 04:37 PM

If your trans currently works, you *shouldn't* have to touch pinion depth.

I cannot recommend it officially, but I installed my diff by precision measuring original one and shimming the new one back to the exact same position. Watch out for changes to bearing heights with the new ones. I used gear paint as a sanity check after install.

Don't do as I do.

Madsimilius · Madsimilius's Garage

Ok that's good to hear! I'll do as you did then

What do you mean by bearing height? Should they be the same? And also if they are ok, can't i just move them over? or are they impossible to get of without damaging them?

john walker's workshop · 07-21-2016, 05:28 PM

If it's ZF posi, i've found they're pretty much a straight swap. Other brands are not. never hurts to compare the diffs on a precision measuring table, then adjust sideways if needed. Whatever is removed from one side is added to the other.

Madsimilius · Madsimilius's Garage

As long as i don't have to adjust the pinion depth, i'm happy

Is the ZF two plate 40/40 diff worth bying? cus i might be able to get one pretty cheap.
Other then that i think i'll end up with a Gripper , Guards or maby a 4 disc ZF.

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by Madsimilius

As long as i don't have to adjust the pinion depth, i'm happy

Is the ZF two plate 40/40 diff worth bying? cus i might be able to get one pretty cheap.
Other then that i think i'll end up with a Gripper , Guards or maby a 4 disc ZF.

2 friction plates per side - yes, 1 friction pate per side for a total of 2 -no

Here is a pic of a decent lsd, note 2 internal spline friction disks per side + 2 external spline drive disks per side

the 40/40 and 80/80 are the same, the difference is in pre load and how the disks are stacked, a 40/40 has the friction disks next to each other an 80/80 has them alternating as in the pic

even better are the asymmetric such as the factory Motorsport lsds and the Guards

most of us seem to be like a 40/60+/- best but for more aggressive track use 20/80. The first # is on accel the second on decel

Madsimilius · Madsimilius's Garage

My car is for street use and maby a couple of track days a year.
So i think 40/40 if i go for a zf diff and 40/60 if i go for a Guards og Gripper.

So the 2 disc ZF is useless? what's so bad with it compared to the 4 disc.
Is it expensive and hard to convert the 2 disc into a 4 disc ?

Matt Monson · 07-22-2016, 08:56 AM

Quote:

Originally Posted by Bill Verburg

2 friction plates per side - yes, 1 friction pate per side for a total of 2 -no

Here is a pic of a decent lsd, note 2 internal spline friction disks per side + 2 external spline drive disks per side

the 40/40 and 80/80 are the same, the difference is in pre load and how the disks are stacked, a 40/40 has the friction disks next to each other an 80/80 has them alternating as in the pic

even better are the asymmetric such as the factory Motorsport lsds and the Guards

most of us seem to be like a 40/60+/- best but for more aggressive track use 20/80. The first # is on accel the second on decel

Hello Bill,

I think you mean 50/80. The 20/100 was the worthless set up used on some 964 and 993 models. There's never been a 20/80 that I know of. Most 993s were either 25/65 or 20/100. Our offering for aggressive track drivers or long fast tracks like Road American and VIR is 50/80.

Also, for reference of those looking at this, the LSD Bill show is made by GKN. They became the OEM for Porsche starting midway through 993 production. You can't put a GKN into an early car with a speedo tone ring and still keep your speedo working.

Our LSD is dimensionally based on the GKN design AND keeps the holes for mounting the tone ring.

Regards,

Matt Monson
Guard Transmission LLC

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by Matt Monson

Hello Bill,

I think you mean 50/80. The 20/100 was the worthless set up used on some 964 and 993 models. There's never been a 20/80 that I know of. Most 993s were either 25/65 or 20/100. Our offering for aggressive track drivers or long fast tracks like Road American and VIR is 50/80.
......
Matt Monson
Guard Transmission LLC

Quite right, I wasn't fully awake yet, the 20/100 in the 964t and 964RS was useless, and I did mean your 50/80

the normal street 993s had either Zf 25/65('95) or GKN 25/65('96up) or GKN 22/40(I think mostly tt's)

the 993RS had GKN 40/65

never did find who made the Cup and RSR versions but I suspect GKN

howard freeman · howard freeman's Garage

Quote:

Originally Posted by Bill Verburg

2 friction plates per side - yes, 1 friction pate per side for a total of 2 -no

Here is a pic of a decent lsd, note 2 internal spline friction disks per side + 2 external spline drive disks per side

the 40/40 and 80/80 are the same, the difference is in pre load and how the disks are stacked, a 40/40 has the friction disks next to each other an 80/80 has them alternating as in the pic

even better are the asymmetric such as the factory Motorsport lsds and the Guards

most of us seem to be like a 40/60+/- best but for more aggressive track use 20/80. The first # is on accel the second on decel

Looks just like a GT3 LSD I just went thru using Matt's Steels,Disc & spring cups. What a world of difference that made.