Premier Motorsp

LSD info in general:

If you don't change the diff case then you do not have to reshim the diff for backlash. In no case do you have to redo the pinion depth for a diff swap. This makes just changing the plates attractive from a cost of labor point of view.

All the factory street car LSDs are basically crap, with the 993 ones being the worst. Ok for street use, but they wear very quickly when pushed hard. The 993 RS LSD would be the exception to this. That one ought to work pretty well as long as it is not worn out. The 20/100% 964 RS/Turbo LSD is not too good. The 20% is very optimistic as the drive side 'locks' with preload only. This is pretty much wishful thinking. The 100% on the coast side has some drawbacks as well.

I am not sure of the possibility of putting a good plate set in the street LSDs. I am not sure if there is enough room. In any case, all these pre 2002 diff cases are prone to breaking in half when used hard. That is probably not a real concern for street and DE use.

Using a torque wrench to evaulate the effectiveness of an LSD is misleading. That is measuring preload-induced clutch friction only, and that is only a small part of what makes these things work.

There are several options for replacement diffs:

Guard trans: This would be strongest and most versatile. They are also the most expensive option.

04- 996 Cup: This is a good diff and slightly less expensive than a Guard. It will probably be quite noisy on the street.

04- GT2/GT3: This one has a good strong case but weak clutches and weak preload. Much better than a 993 LSD, but I have doubts of it holding up well in the long run. This probably wouldn't be a bad choice for a moderate DE car that didn't want any diff noise. The GT3 guys do seem to notice noise under some conditions. This diff CAN be upgraded to -02 Cup spec by changing the clutches, although the cost of that clutch pack plus the diff would be more than the Guard diff. This diff is very reasonably priced.

Guard Torsen/Quaife: Decent lockup for moderate track use, and noiseless on the street. You lose the lockup on coast though, and I think that is a bad compromise.

Chris Cervelli
Premier Motorsports

chris walrod

Chris C is right on, no setup work needed if reinstalling the same diff. This is provided the same bearings and races are used. Pinion depth, backlash and diff carrier bearing preloads will not need to be reset. Of course, installing a new diff requires backlash and bearing preload setting.

While on the subject, is the 993 LSD made by GKN or ZF? Is the clutchpack preload set by the stack height vs. the carrier depth, or is there a bellville washer to do this?

Obviously Porsche started their cost saving crusade with the LSD in the 993 series cars. Curious if all 993's had the two plate (per side) clutch pack, or was this phased-in during the 1995 model year much like slide-on second gear ratios?

Bill Verburg

ZF thru '95, GKN after, but i'll bet there's some overlap somewhere around the model year transition.

JasonAndreas

If at all possible can you get a quote for a replacement clutch pack too?


Can you give me a rough idea how many hours it would take? I've read through several manuals and didn't see anything that would take anywhere near 8 hours.

So for a mostly (98%) street-driven 911 you'd recommend the 40/65% LSD from the G50.31/32/33? I don't need the ruggedness of the PMNA discs but at the same time I'd like it to last a little while. My labor costs are $0 so if the 993RS LSD will last 30-40k miles and fit in my 964RS LSD than its not really cost effective for me to spend 4x that for a Guard unit.

A replacement plate package is only ~$5-600USD (part #950-332-983-31).

Monique

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Quote:
Originally Posted by Monique
Asked a specialist for a quote on the Porsche Motorsport unit... problem is that Motorsport are closed till next week.

If at all possible can you get a quote for a replacement clutch pack too?

Was quoted the following out of the UK.

These kits include clutch, pressure plate, release bearing and guide tube.
Complete pack for 993 RS M002 (street version) = £500.62 ($862.45)

Complete for 993 RS M003 (club sport) = £668.07 ($1150.42)


Quote:
Originally Posted by Premier Motorsp
This makes just changing the plates attractive from a cost of labor point of view.

Can you give me a rough idea how many hours it would take? I've read through several manuals and didn't see anything that would take anywhere near 8 hours.

Frankly, I do not know...


Quote:
Originally Posted by Premier Motorsp
The 993 RS LSD would be the exception to this. That one ought to work pretty well as long as it is not worn out.

Not too sure about this one. My LSD is shot at 25kmiles.

So for a mostly (98%) street-driven 911 you'd recommend the 40/65% LSD from the G50.31/32/33? I don't need the ruggedness of the PMNA discs but at the same time I'd like it to last a little while. My labor costs are $0 so if the 993RS LSD will last 30-40k miles and fit in my 964RS LSD than its not really cost effective for me to spend 4x that for a Guard unit.


Quote:
Originally Posted by Premier Motorsp
I am not sure of the possibility of putting a good plate set in the street LSDs. I am not sure if there is enough room.

From talking with Porsche, the cage is identical. Should be feasible if I were gifted like Jason


A replacement plate package is only ~$5-600USD (part #950-332-983-31).

Not on this side of the big waters

My opinion is that the Guard unit will give me piece of mind and will require less fidgeting to install... however, I hope to get a Motorsport quote early next week.

Then again, the requirements vary amongst owners. I will want a 40/65% split whereas for track applications a 80/80% would be more appropriate.

Monique

Was in contact with Paul Guard. Attached are some exerpts from his emails.

Quote: "What I am getting to is this: There is no "room" for group buy discounts on our high quality Chromoly Limited-slip differentials. The ONLY possiblity is selling at the 2005 price instead of the slightly higher 2006 prices. (Our 2006 price is $200 higher than 2005.) We would have to know the desired locking percentages (40/60 , 50/80 , 80/80), whether all are '87 and later. And we are NOT promising to sell at last years prices. We would need to see an order of four or more to consider this" Unquote.

Then in a secondary email...

Quote "The 2005 price was $2,150. The 2006 price is $2,350. If 10 or more were purchased, the price would be $2,050. As you can see, there just isn't much room to move.

For comparison, I imagine Porsche Motorsports standard 40/60 LSD is around $1,600, but I am not certain. We have more and more German companies (like RUF) purchasing our Chromoly LSD as they learn about it." Unquote.

Bottom line:

1. if 4 or more then we get the LSD with your choice of locking percentages as shown above for the 2005 price of $2150

2. If 10 or more, then we get a further $100 off.

3. For the UK based peeps: I propose the UK destined units be shipped to my business address. Then distribute from here. Will be cheaper me thinks.

4. Who is in for sure?

Add your names here:

Monique. 40/60 lock
Terry Adams 40/60

Terry Adams

Terry Adams 40/60 lock.

Monique

There it is Terry. BTW read your potential reply to the rude doc... you are a mean ****

Add your names here:

Monique. 40/60 lock
Terry Adams 40/60

NoSubEDU

I'm in, but unsure of what bias I want. This is a DE/Track car with limited street driving. Suggestions?

For now, I'll put the 40/60.

Monique. 40/60 lock
Terry Adams 40/60
NoSubEDU 40/60

Monique

Paul Guard will give you advice IMO. Call him at the numbers listed http://guardtransmission.com/

mleds

I want one.... Chris W., which bias should I take???

chris walrod

40/60, more than likely. I'll give this some thought..

Bill Verburg

The 993 Cup and 993RS used 40:65

when I bought mine I looked for and bought a 40:60

Mine is the old design w/ non interchangeable ramps, it needed to be machined down to use other than stock cwp. Don't know if the newer changeable ramps versions would need the same machining or not

The newer versions have swapable ramps so the lockup factors can be changed. Not cheap, but it can be done.

viperbob

Michael, yes go with the 40:60.

the_buch

VBob and others ... is the 40/60 the way to go for an everyday street machine that just has a worn out LSD ... are there any complexities with a four-wheel-drive car (C4S in my case)??

Thanks,