Quaiffe of ZF LSD

MuffinMan · 11-18-2003, 06:35 PM

One of the many projects I'm planning for my 911 this year is to add a limited slip differential to my 915. I know the factory uses ZF limited slip in their street cars and cup cars, but the Quaiffe (torque sensing) is also a very popular choice. I do realize that the ZF LSD needs to be rebuilt once in while. I've heard the ZF is a bit more transparent in action than torque sensing differentials, but I have not been able to properly compare the two in real world situations (track and/or autocross).

Has anyone had both of the differentials in their car(s), and what are your thoughts and preferences?

TIA

dd74 · 11-18-2003, 07:25 PM

I've heard ZF is the way to go, per Steve Weiner at Rennsport. I'd trust his opinion over many others.

petevb · 11-18-2003, 07:42 PM

I just broke the quiffe in my car, and I'm replacing it with a true LSD. The quaiffe generally considered good for the autocross and the street as long as you are not too rough on it. For more power (I have 255 hp and I'm not too kind) and track use the true LSD is more often suggested, partly because it is stronger and partly because it works under braking as well as accel. It is also rebuildable, where my quaiffe was a write-off.

Geary · 11-18-2003, 08:32 PM

Quote:

Originally posted by MuffinMan
I've heard the ZF is a bit more transparent in action than torque sensing differentials ...

Actually the other way around. The LSD is quite apparent most of the time, while the TBD is not noticed except in certain situations.

Pete -- Let us know how that "Limited lifetime warranty" turns out.

Eric Coffey · 11-19-2003, 12:01 AM

Quote:

Originally posted by petevb
I just broke the quiffe in my car, and I'm replacing it with a true LSD. The quaiffe generally considered good for the autocross and the street as long as you are not too rough on it. For more power (I have 255 hp and I'm not too kind) and track use the true LSD is more often suggested, partly because it is stronger and partly because it works under braking as well as accel. It is also rebuildable, where my quaiffe was a write-off.

Pete pretty much summed it up. You might get a little low-speed understeer with an LSD, but it makes up for it on corner exit and braking (much better trail-braking stability/predictability). There are a couple great threads on the subject in the archives as well, just do a search.

Jack Olsen · 11-19-2003, 12:09 AM

But the shorter answer is ZF for the track, Quaiff for autocross.

Eric Coffey · 11-19-2003, 12:39 AM

Quote:

Originally posted by JackOlsen
But the shorter answer is ZF for the track, Quaiff for autocross.

Oh yeah, well here's the shortEST anwer:

LSD=track, TBD=AX

Embs · Embs's Garage

Quote:

Originally posted by petevb
It is also rebuildable, where my quaiffe was a write-off.

NOT if you were the original buyer, Quaife has a lifetime warranty. I have never heard of one breaking, even with way more than 255 HP. IMHO for street driving they can't be beat.

MuffinMan · 11-19-2003, 04:29 AM

Thank you for the replies, they have confirmed my suspicions. Thoughts on 45/65 vs. 50/80 LSDs?

Geary · 11-19-2003, 07:35 AM

Quote:

Originally posted by Embs
NOT if you were the original buyer, Quaife has a lifetime warranty. I have never heard of one breaking, even with way more than 255 HP. IMHO for street driving they can't be beat.

I have heard that the "LIMITED lifetime warranty" still costs around $700 for a rebuild for the original purchaser, so long as the registration card was sent in. Full replacement price in any other instance. More than a few of these have fried. I'd like to hear how Pete does on his warranty.

Ralph@Quaife · 11-19-2003, 09:44 AM

Well, since there is some misinformation being bandied about, I guess I will chime in as well.

Quaife ATB differentials do come with a ltd lifetime warranty, even when used for competition. In my 10+ years here, I know of 3 differentials (1 Porsche) that were denied warranty. The Porsche? We had no choice to void, the customer rebuilt (or had it rebuilt) his transaxle and somehow forgot to put in the tranny lubricant. Needless to say, he didn't get very far on a dry transaxle and the diff wasn't the only thing that welded itself together!!! Also, the warranty is transferable to subsequent owners provided we can follow a paper trail. To read the warranty, please view our website at www.quaifeamerica.com and click on differentials.

As far as warranty issues go, yes they do break from time to time. We sell thousands of differentials for all makes and models every year, and the number that are returned for repair or replacement I can count on 2 hands. No part is completely infallible, but I can also tell you that you will most likely break the friction plates on a ltd slip before you will break a Quaife unit, all things being equal. YOU BREAK THE QUAIFE DIFF, WE REPAIR OR REPLACE IT, END OF STORY!!! It is unfortunate that there are so many people out there with the "I heard this or my friend knows of someone who said that". We do not charge to repair a unit. If someone is being charged for $700, it may be either for ancillary labor costs to remove or reinstall the transaxle or he is being ripped off. In fact, if a customer has his transaxle out for a gear or ring & pinion change and he is not sure about the Quaife unit, he can send it to us and we inspect and disassemble/reassemble the unit for FREE! We provide this service for race customers on a far more regular basis than having to repair or replace damaged units.

As far as the gentlemen who is having a problem with his Quaife unit now, I have not been contacted regarding the repair or replacement of any Porsche unit for quite some time. If he chooses to go to a conventional ltd slip, that is his decision but wouldn't you think that someone would at least contact us about this broken unit??? If nothing else, he can sell his used unit for a significant amount of money and put it towards his ltd slip.

We have sold hundreds and hundreds of Porsche diffs since 1987 and there are pros and cons when using in a 911. Yes, the Quaife diff does "freewheel" like an open diff under deceleration and thus is not ideally suited for race conditions in a rear engine, rear drive 911. We are attempting to correct this issue with a new preloaded torque-biasing unit where the preload can be adjusted so high that it literally locks the diff. This diff is being tested right now by a few ALMS teams using the GT3RS as the Porsche Motorsport transaxle uses the same G50 diff that has been used since the '87 Carrera. We and the teams testing expect that it will pick up a few tenths over the current ltd slip set-up.

Quaife diffs are much more popular in FWD cars, especially ones that have uprated power. They literally are a must in these cars as otherwise the torque-steer makes them undrivable. It is not uncommon to see a 400-600 horsepower turbo Honda or GTI these days and I can tell you that they break the friction discs of a ltd slip pretty regularly. A large percentage of our business is from customer's who don't want the hassle of broken friction discs or having to rebuild their ltd slip on a periodic basis due to wear. Also, there is not one company that warrants their ltd slip against breakage. For a street 911 or a mild track car that is not prepared to eke out every last tenth of a second, there is no better differential available than a Quaife. You install it and than forget about it.

If this gentlemen with the problem would be so kind to contact me at 949.240.4000 ext. 25, I would be happy to try and resolve as quickly as possible.

Thanks for your consideration of this lengthy post.

Ralph Hollack
Quaife America

Embs · Embs's Garage

Very informative and to the point. Thanks Ralph.

dd74 · 11-19-2003, 10:45 AM

Quote:

Originally posted by Ralph@Quaife
Yes, the Quaife diff does "freewheel" like an open diff under deceleration and thus is not ideally suited for race conditions in a rear engine, rear drive 911. We are attempting to correct this issue with a new preloaded torque-biasing unit where the preload can be adjusted so high that it literally locks the diff.

Any idea when this will become available, and its cost?

Thanks.

Eric Coffey · 12:04 PM

Quote:

Originally posted by Ralph@Quaife

...For a street 911 or a mild track car that is not prepared to eke out every last tenth of a second, there is no better differential available than a Quaife. You install it and than forget about it.

Ralph Hollack
Quaife America

You wouldn't be biased though would you? Can you show me any data that proves that statement? The fact is that Paul Guard's (GT) TBD unit is far superior in every respect. All you have to do is look at the internals of both units. And as for your ALMS testing, I wish you good luck, as all the top teams that have been using (and winning with) GT's ZF LSD's might not want to give them up that easily.

Bill Verburg · Bill Verburg's Garage

Quote:

Thoughts on 45/65 vs. 50/80 LSDs?

Not sure what you mean by this, but my 2&#162,

For track use a ZF because it will also help in braking. An even better choice is a split diff 25/65(all n/a 993) or 45/65(Porche Motorsports std). Which has different lockup factors on acceleration/deceleration. Going all the way to 20/100 in the extreme case.

Unfortunately I know of no one offering the splits in a 915. Though there are some working on it though.

Embs · Embs's Garage

Quote:

Originally posted by Eric Coffey
You wouldn't be biased though would you? Can you show me any data that proves that statement? The fact is that Paul Guard's (GT) TBD unit is far superior in every respect. All you have to do is look at the internals of both units. And as for your ALMS testing, I wish you good luck, as all the top teams that have been using (and winning with) GT's ZF LSD's might not want to give them up that easily.

Jeez ease up dude, this isn't Kibort (eram) selling his fockin "fan in a tube". Can you show us any data that Paul Guard's (GT) TBD unit is far superior in every respect?

So, "All you have to do is look at the internals of both units" I see, a visual inspection of the internals tells me what to expect with this unit? Whatever man. I'm not plugging for Quaife but if your going to tout one product over another, SHOW US THE DATA.

MuffinMan · 11-19-2003, 02:41 PM

Quote:

Originally posted by Bill Verburg
Not sure what you mean by this, but my 2&#162,

For track use a ZF because it will also help in braking. An even better choice is a split diff 25/65(all n/a 993) or 45/65(Porche Motorsports std). Which has different lockup factors on acceleration/deceleration. Going all the way to 20/100 in the extreme case.

Unfortunately I know of no one offering the splits in a 915. Though there are some working on it though.

I didn't realize that the "split" LSDs were electronically controlled. Therefore, I envisioned adding one to my lowly 915. I'm admittedly a little let down, but I will get over it...in time.

Bill Verburg · Bill Verburg's Garage

Quote:

I didn't realize that the "split" LSDs were electronically controlled

The are not electroniclly controlled. They have asymmetric ramps.

beepbeep · 11-19-2003, 03:34 PM

Does anybody know what kind of LSD was factory-fitted in 930 -88? We just purchased one of those and would like to know what we got... is it 40%? Are there any split LSD's available for 930's?

Thanx!

Bill Verburg · Bill Verburg's Garage

The C2 turbos and Euro 964RS were the first to use the split lockups 20/100 originally. 993 street used 25/65 and RSR & Cups used 45/65. Almost any other ratio was available by special order. I believe that the G50s can be easily retrofitted, but really have no expertise in that area.