LM964

Just been talking to the guys at Quaife querying their LSD part numbers for the 968. Two different part numbers exist (QDF2Q and QDF10Q respectively) - one for the 911(G50) / 996 / 930 / 964 / 968 /993 and then the other for the 968CS. I have an S/CS. Asked about the differences and while the guy wasn't 100% certain of the reason he suggested it to down to the bolt patterns being different. New to me is that the CS had a different open-diff (non-M220 option) installation than the standard 968. Thought all the 968 variants had the same 6-speed Audi tranny box(?)

Anyone come across this and knows if the Quaife differences are indeed down to bolt/flange pattern? Thinking of fitting a Quaife myself some point next year.

Side note: I noticed from a rennlist thread 15 years back a mention that a member had thought the '94/'95 968's came with LSD's as standard. Not the case. Only thing I recall being that the LSD was indeed standard but for the last year of the 944T's only.

jeff968

I'll tell you what I know LSD-wise:
220 LSD was indeed an option in all cases on North American 968s.
Of the 1,811 6spd coupes 584 were equipped with 220 LSD (32%).
Of the 1,447 6spd cabs 300 were equipped with 220 LSD (20%).
The retail cost of 220 LSD was $895 in 1992 and $913 for 93-95
220 LSD was not part of the M030 sport suspension package. Therefore, 22 of the 98 6spd M030 coupes did NOT have LSD.
For 1992 the LSD unit in the 968 was produced by ZF.
For 93-95 the LSD unit was a Torsen unit.

Learn more here: 968register
Jeff

LM964

Thanks Jeff. Aye, I've had info from all the 968-only owner and specialist sites. Just trying to establish why the differences between the non-CS and CS transmissions that necessitated two different Quaife torsen casing designs (especially as it's the same Audi box). Guess I need to take a look for myself as and when I get round to doing mine.

Yogii

Weren't the spindles different on M020 equipped cars? It was more that just adjustable Konis and thicker sway bars.

-Yogii
AKA 968 Virgin

chudson

Yes. Additional M030 changes were front spindles and hubs, front brake calipers, pads and disc, different rear disc, different pad compound (coefficient of friction) on the rear, stiffer front spring rate and helper springs added to rear. I believe that's all...

LM964 - perhaps Quaife is referring to the percentage of lockup on the diff? IIRC, the standard Porsche diff has a 40% ratio and the 968 Turbo RS was 60%.

Cliff

jeff968

Check our site:M030 968s

Yogii

I totally forgot about the brake upgrade.

-Yogii
AKA 968 virgin

KevinGross

You can download dimensional drawings for both differentials from Quaife's web site. The differences between the two are minor, except for the thickness of the ring (crown) gear mounting flange. However, even that difference is small enough that it wouldn't make a difference: the 0.6 mm difference would just require a slightly different allocation of S1 and S2 shimming in setting up the differential.

Unfortunately the documentation does not describe anything other than dimensions. It may be that the effective "locking" is tuned differently, which would be done through use of different worm gears. Maybe. Who knows. I would hope Quaife does.

For clarity, note that Quaife's differential are Torsen / Gleason designs, that is, they use worm gears to control locking. The term "LSD" is typically reserved for Salisbury clutch type differentials as used in every other Porsche model that I am aware of. There are pros and cons to Salisbury versus Torsen designs. Good luck with the project!

LM964

Thanks Cliff, That could be why then - if a CS with all the M030 components then mounting bolt patterns could be different. Regardless though, the only proof will be me taking a look for myself and comparing to the engineering designs drawings - unless someone already has been through the same investigation and chips in later. I think I might have buried in the pc somewhere all the specific specifications and part numbers that made up all the M030 components - that's my Sunday looking for these then.

Yes, both Quaife 968 options are ATB and of 40% locking

Cheers Kevin. I have Quaife's engineering drawings for these and will use them against what's actually in my 968 now (mating and alignment).

Indeed, Quaife's are the Torsen type and extremely effective. Plate 'LSDs' vs Torsen arguably a bit subjective for normal spirited and occasional track driving. Used to use Quafie back ends in the historic rally cars I used to co-drive and experienced no issues on mixed surfaces (plus they are guaranteed for life). Plate (Salisbury) type used and preferred by friends in 4x4 UK championships where they have the ability to make locking adjustments stage by stage if they need. Flip side though being that they are servicing/rebuilding them at least once a year.

There is a Porsche transaxle endurance racing prep specialist here in the UK who have already given me right oil and spark plug advice so I guess they should know more about the nuances between the two Quaife types. I'll give them a call Monday.

Thanks all for chipping in...

will968

The mounting bolt pattern should be identical to a G50 gearbox - I put a G50 LSD in mine.

Curious, what spark plugs did your shop recommend?

LM964

Thanks Will. The G50 LSD a plate type?

This from the EMC race prep tech manager - NGK BP6ES (7811) 0.1mm / 0.029" gap - Torque setting 25-30 Nm Think this is actually a fairly common plug anyway.