LSD make/type

From the attached photo can someone confirm the make and tye of LSD which I have. I guess it is ZF but can't go and have another look because I reassembled it without having a close look for the make.
Thanks
 

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Lynn Larsen

Lynn Larsen
Lee,

I checked your website but didn't see any indication or confirmation that you are using a Porsche transaxle.

But, since you are building a DRB, can we assume that this has been reassembled into a Porsche transaxle of some type? If so, there is a VERY good chance that it is indeed a ZF.


Regards,
Lynn
 
Lynn
Yes sorry forgot to mention that bit. It is a G50/52 but it has had some work done do it. But I don't know what has been done to it. It is the later type which has the LSD as standard, but I jsut want to check that this is indeed the standard LSD or something else in its place.
 

Lynn Larsen

Lynn Larsen
There are only three that I know that it can be: ZF, Quaife or Guard Transmission. Porsche did put a torque biasing diff in cars for a VERY short period of time. I think I posted this at one time and may have said what years this was done in.

I can't remember exatly where I found the information, but it may have been on Guard Transmission's website. You might want to check it out. (I am looking for the link and will post it when I find it.) You might also want to check out RennList and ask them about this LSD. There are very helpful Porsche experts there.

Lynn
 

Lynn Larsen

Lynn Larsen
Just dawned on me, did it have clutches?? If it did then I am about 99% sure it is a ZF. Others are torque sensing and use gears not clutches. Guard does make both types so there is an outside chance it could be one of these.

BTW, you may know this already, but I didn't, apparently all G50/52s had ZF LSDs in them. Here are some general words o wisdom from RennList as taken from the Ultima site:

Porsche also offered several other ring and pinions for racing including 7:37 and 7:33 ratios. These are not always available due to limited manufacturing qualities. The G50-series used a final drive ratio of 9:31 and the Turbo versions, G50/52 used larger, stronger ring and pinion gears.

If you do decide to change the ring and pinion in your gearbox, make sure that you get the appropriate one for either the mechanical or electronic speedometer.

Porsche has offered the ZF clutch-pack type limited slip differential in almost all 911’s and 930’s since 1966. These units are quite strong and can be set for locking factors of 40% to 80%. The clutches need replacement under racing conditions to maintain proper lockup but these are quite trouble free. An 80% locking factor is difficult to drive on the street, especially in wet conditions, but for open track racing these are quite popular. Street or Autocross usage requires the LSD to be set at 40%; simple to do with the proper parts.

There are now other LSD options for G50 transmissions called Torque-Sensing differentials. These are gear-type units as opposed to the ZF clutch-type ones, and do not require any parts to maintain optimum performance. This unique, patented design allows full differentiation between the wheels as well as providing power to both sides and they produce less understeer than the Factory LSDs. Guard Transmission makes an excellent one as well as the unit from Quaife.

For Autocross and normal street driving, the Torque-Sensing units are more benign in their operation but they do not improve the handing like the Factory clutch-pack units do. The ZF or Guard Transmission LSD's really stabilize the car under braking and help reduce trailing throttle oversteer.

Still looking for Guard's website.

Lynn
 

Lynn Larsen

Lynn Larsen
I finally talked with the guys that I sent the photo to, but they don't recognize it. The guy I talked to says it doesn't look like any of the Porsche supplied LSDs nor Guard's diffs of either style. His only conjecture was that it might be something that Powerhaus came up with at some point in time.

Sorry,
Lynn

Speaking of Powerhaus, did you contact them to see if they knew what it was??
 
Thanks very much for that Lynn.
I'll take it out again at some point and take some better photos. Then I'll forward them to Powerhaus.

Thanks again.
 
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