MD355

I did a search and got a little confused.

My car is a 1995 Euro (Gearbox G50/21) 993 C2 with open Differential (option 219)
I want to install the factory LSD (I want to keep my car 100% original Porsche parts)
Is this the correct part number : 950.332.083.01

I know that the 993 with option 220 also came with ABD (Active Brake Differential) which basically applied brakes to one of the rear wheels, but I think that the LSD can be installed without ABD, correct ?

Where can I find new / rebuilt factory 993 C2 LSD (is it the same for G50/20 and G50/21 gearboxes ?)

Thanks !

goofballdeluxe

I can't help with your problem, but only 7 posts in 12 years had got to be a new record.

Good luck finding the LSD

DiegoR

Mu euro 95' C2 came with LSD option and also ABD. Stock LSD sucks, doesn't lock up much and doesn't last much either. Although, I think there were some lock up % options to order.

Steve Weiner-Rennsport Systems

Factory street LSD's are no great shake due to their questionable effectiveness and short lifespan. In normal operation, the plates are worn out by 25K miles. Given the cost of acquisition, installation labor and short life, I talk all of my clients out of this idea.

If you want to keep it all factory parts, I'd suggest installing the Motorsport LSD which has FAR better lockup/unlock percentages and lasts FAR longer. Not cheap, but you get what you pay for.

Bill Verburg

A '95 993 G50 would have used a ZF 25/65 lsd. The plates are notorious for not lasting long, fortunately GT gears has replacements that are much more enduring and effective

In '96 Porsche switched to GKN 25/65

the G64s all used gKN 25/40

RS used GKN 40/65

M220 was a 3 part option
1) 25/65 lsd
2) ABD
3) 4 channel ABS

MD355

Thanks for your replies !!

1) Is the ZF 25/65 LSD the same for 1995 Euro (G50/21) & US (G50/20) 993 C2 ?
2) Is there a different ZF 25/65 LSD for C2 & C4/S ?
3) Part number please ? (for ZF 25/65 LSD for G50/21)

Many thanks !

GTgears

Just one correction, we do not service ZF oem lsds any longer. Porsche Classic recently released parts to service them. Same original part numbers using 917 and 928 prefixes. We will continue to care for all gkn diffs.

While we were never an oem lsd supplier we were an oem supplier of gears to Motorsports in the late 90s. Also lsd supplier to Ruf until 2009, and currently oem for Singer. Sold lsd for replacement in a genuine 73 RS today. I have my lsds in 904s, 908s, 935s and all manner of RS, RSR and Cups of all generation. I don't think anyone would ever dink you for using my part.

nine9six

Bill Verburg

1 yes
2 yes, as I said G64(AWD) use GKN 25/40, G50(RWD) use GKN 25/65 from '96 on
3 ZF 25/65 for G50/20 & 21 950.332.053.05, but if buying a new one I'd but one of Matts(GT) 40/60

MD355

a) I found this 950.332.083.01 part... Is it the same as ZF 25/65 for G50/20 & 21 950.332.053.05 ???

b) How difficult is it to install the LSD ? (describe procedure if you want)

c) My gearbox is in good condition (syncros etc etc)... Is there something that I should change regardless, since I will be taking off the gearbox ??

Thanks !!

trophy

From a "Which one should I use" perspective, you have all the right people responding for you.

Installing an LSD is a pretty big job, and one that is done with the transmission on a bench. You require some special tools to do the job correctly along with a whole bunch of shims (and a set of machined bearings to make shim adjustment easier).

If you have access to the tools then the job really is just an iterative process. First you need determine the thickness of shims required (these go behind the bearings on the LSD) I like to do this before I install the ring gear as you have to put the diff in and out of the case, and it gets heavy and reduces the chance of damaging anything. Once the total thickness is determined you then need to set the R&P Backlash this is also an iterative process,

Install shims and bearings,
Install Diff (with Ring gear, including fully tightening down the side cover etc)
Measure backlash
If outside spec
Remove diff
Remove bearings
readjust shims
REPEAT till in spec

With out the correct tools it is difficult however it can be done. An important tool during this is the tool that locks the shafts of the transmission so there is no play internally for the tranny (will give false readings) The setup of this tool requires the nose of the transmission to be removed.

This is a big job and with the right tools and patience can be done. It is one of those jobs that the dealers charge an huge amount for because its a full engine and transmission R&R and then the install of the diff itself. I think when I did it myself it took about 4+ hours to get the diff perfect... and that was just the diff with the transmission on a bench.

Tools and pics



These 2 shafts need to be locked using special tool.... No pic of tool



Tools in place to measure backlash.

Bill Verburg

No idea what 950.332.083.01 is, I have no listing for it.

You wouldn't normally have to get into the gearing section of the box to replace an lsd, I'd leave that job to a qualified repair shop.

If getting into the trans gearing sections there are many upgrades, mostly intended for track use, they are great for that but are also expensive.

Again, Guard GT lsd 40/60( or in that neighborhood), is a world better than any of the street lsds and even better than the Porsche Motorsports lsds which themselves are a step up from the street lsds.

MD355

Thank you all for your replies !!

I did some research on the PET Porsche Parts Catalog and found that :

950.332.053.05 is the ZF 25/65 % LSD for models -95 G50.20/21

950.332.083.02 is the GKN 25/65 & LSD for models 96- G50.20/21

but I am confused about the part that I found that is for sale :

950.332.083.01 ??? What could this be ??

Weird...

With regards to installation, I have two mechanics : one suggested to swap the whole transmission since the differential is inside and the other mechanic is willing to install the LSD on my own transmission...

I will go with the second choice, both for cost reasons and because my transmission swifts just fine !!!

I will keep you posted..

Somebody offered me a Porsche LSD with numbers : 4061 406 902
and also 4061006312 269523 S40

but my guess is that it is from older 915 Porsche gearbox...

ToSi

950.332.083.01 was superseded to 950.332.083.03. It's a 22/40 out of a G64 (C4), should result in a more neutral car on decel vs one of the 2wd diffs.

JM993

Bill, are the GKN 25/65 LSDs more robust than the older ZF LSDs?