What types of LSDs has Porsche used for what years, and how do they hold up?
 

I understand that some of the Porsche LSDs are clutch type that "wear out" over time?

What is required to maintain them, and how fast do they wear out?

Are all Porsche 911 LSDs "clutch" type or have they used other kinds as well?

If one wanted to add an LSD to a 911, what are the various ways to go and pros and cons?

I have a factory LSD in my '89 Carrera, and it has over 124,000 miles on it. Just today I tried "tested" :) it and it is working fine!

Re: What types of LSDs has Porsche used for what years, and how do they hold up?
 

Lol, anyone that claims any mechanical device won't wear or break. is a lying sack of $%$^$. I know a guy who broke a quaiffe after less than one season, and put the stock lsd back in.


As far how long it takes for a stock lsd to wear out, my (stock clutch type lsd) has 160k on it and is working fine on my 300hp+ turbo, and 90k+ on my M491 Carrera. No maintainace is required other than the occasional fluid change in the tranny.

Re: Re: What types of LSDs has Porsche used for what years, and how do they hold up?
 

I agree that the factory unit seems to hold up well, a big part of this is because it is only 40% ltd. slip. The more "lock-up" a diff has, the more strain I would think. Open diffs seem to last forever on most vehicles.

I would say that regular oil/lube changes are a little more important on LSD cars, especially if you track it. Tyson of TRE was recently telling me that he thinks LSD oil should be changed after any track event, due to clutch pack material winding up in the oil from hard G-force cornering, etc.... :cool:

MMM:

Porsche has used ZF (clutch-pack) LSD's since the sixties. All but the 993 ones are VERY durable and last a very long time.

There are many LSD options, based on needs and budget. For fast road & track usage, the clutch-pack LSD is the best, by far. For street and autocross, the torque-sensing types minimize understeer.

You can use:

1) Factory ZF LSD (adjustable from 40% to 80% lockup)

2) Guard Transmission 4340 chrome-moly cased ZF-type LSD. These are far stronger than the factory ones.

3) Guard Transmission Torque-sensing LSD's. These have no friction plates to wear out and are largely transparent in operation. These are less expensive than ZF-types. Not recommend for track use. Stronger than the Quaife ones, IMHO.

4) Quaife Torque-sensing LSD's. These are very reasonably priced LSD's that are fine for street usage. No plates to wear but again, not recommended for track usage.

Hope this helps,

Wow, that's great. Thanks. How much? How bad is the install?

Labor rates vary all over the US but we get 12 hours of time (with the gearbox out) to install the LSD and set the backlash & pinion depth. This is NOT a DIY'er project.

LSD prices range from $ 1500 - $ 2150 depending on which one.

You may call or e-mail me directly for further info.

So is that 12 hours labor total or does that not include pulling everything out of the car and putting it back in?

Basically, not cheap, eh?

I have an 89 coupe with a factory limited slip and 30k track miles on it. The slip is working fine and I just rebuilt my transmission. The news of premature wear is new to me and this is the first I have heard of it.

That 12 hours is the labor if you bring the tranny in the door,....if we pull the engine/tranny here to do the job, that takes more time.

Nossir, its not cheap but nothing worthwhile ever is. :)

I love my torsen LSD in my Miata for autox and on the street. (I've only had my open-diff 911 for 6 days, so no autox time yet!) Why is a torsen-type LSD "not recommended for track usage?"

It opens up on deccel, so rear starts "jazzing". It's good on FWD cars but not terribly effective on rear-heavy 911's IMHO.

Yes, Audi uses Torsens as center differentials in it's quattro AWD cars (well actually only in such cars with longitudinal engines as opposed to transverse which use the Haldex AWD system).

If I recall correctly you can get torsens with different bias ratios, and yes I believe they do open up as the power to the input shaft drops off.

Porsche on the otherhand uses a VC (viscous coupling) to run power to the fronts on it's AWD 993s, 996s, and presumably 997s. The AWD 964s used a different system of electrically actuated clutches if I recall correctly.

ZF clutch type lsds help stabilize the car undere heavy braking, torens don't. even better is the the split bias ZF clutch type which can have 20/80, 40/60 or whatever differing l;ockup factors on acceleration or deceleration. The bigger the decel lockup the better the track type braking will be

Finally now available for the '75-'86 915 and 930, BTW.

Man, I wish these were avialable when I did my 3.6 Varioram -- but I did go with the 80% ZF (rebuilt) and absolutely LOVE it in all situations -