sig_a

^^^
"Adding preload raises brake away torque at all times" Perfect. Thanks.

amso3

Wow, great "skooling" Matt

Bailey-86-MA

now I know a little more about how they work. what about thoughts on the diff options out there. I have heard of Quaife, OS Giken, Wavetrac.

sig_a

Kaaz USA has a well laid out web page.

The japanese LSD manufacturing division is part of KAAZ Japan, a japanese manufacturer of agricultural equipment, golf clubs, motorsport equipment. Founded in 1922.

http://www.kaaz.co.jp/kaaz_DM/LZ600/index.html

http://www.kaazusa.com/tech_intro.html

ZSA Motorsport

here are two videos from tests we did, same day at Monticello last saturday. The cup car is a 2007 Rolex edition car, running michelins with about 3 sessions on them. car is handling like a dream, very neutral. id love to say a tad of oversteer but frankly, after some various changes earlier in the day, it was finally just about perfect. we were trying some different gears in different areas, i bang into the rev limiter on a few occassions trying first coming out of the slow right hand hairpin.
we were testing various PMNA autoblip percentages, settled on aobut 42 on the dash in warmup page sitting on pitlane, results in about 35, 37 depending on how hard i drive the shifter forward.

the camaro we ran a few hours earlier. it too was running really fast, and is just a fun fun car to drive. it doesnt rotate as easily but you can step on the throttle a bit earlier and its far easier to control it when it starts moving around on you a bit. we were trying a lower gear on occassion, particularly the left hander at the top of the uphill straight past the paddock as a little crack of the throttle would get the thing to turn.
where the car suffers is turns 2,3,4 short sectiosn, a left right left, right. not ideal for the car from a handling perspective but with a 6.2l motor with a square power curve, she was jumping from turn to turn.

its that left right left right section where i m wonderng if lock under decel might be causing the push .

these are both crazy fast times for that short course, mainly due to perfect weather and well, we had the entire section of track to ourselves, thanks Monticello!

<iframe src="http://player.vimeo.com/video/32857541?title=0&amp;byline=0&amp;portrait=0&amp;color=969696" width="940" height="635" frameborder="0" webkitAllowFullScreen mozallowfullscreen allowFullScreen></iframe>

cup car:
<iframe src="http://player.vimeo.com/video/32869805?title=0&amp;byline=0&amp;portrait=0&amp;color=969696" width="940" height="529" frameborder="0" webkitAllowFullScreen mozallowfullscreen allowFullScreen></iframe>

camaro:

911SLOW

The housing of the limited-slip differential (1) is driven by the crown wheel of the drive assembly. The pressure pieces (3) and (7) interlock with the housing (1), but can move axially and are shifted to the left and right-hand disc sets by the differential pins (2) when loads are applied. The expansion force generated (Pax) depends on the applied torque, the overrun angles (α) and the pressure pieces (3) and (7).
The higher the expansion forces Pax acting in both directions on the friction discs are, the higher the locking force of the multiple-disc limited-slip differential will be.
The limited-slip differential is preloaded by the diaphragm springs (6) in both disc sets so that it is ready for operation without torque having to be applied. The static friction moment produced by preloading the disc sets is increased considerably under driving conditions by the expansion force which also acts on the disc sets.



In a 40/60 LSD (like the one used in the 996GT3), in the acceleration phase a locking value of 40% can be achieved (expansion force Pax + preloading by diaphragm springs). The angles in the deceleration phase have been configured to give a locking value of 60%.

sig_a

---------------------------------

Let me see if I have this straight.

Limited to 60 percent maximum axle lock on power/acceleration because of the ramp/overrun angles.

Limited to 40 percent maximum axle lock on coast/deceleration because of the ramp/overrun angles.

Didn't you mean to type "deceleration phase"?

Also, I thought "overrun" only refers to coasting, or sometimes called trailing throttle?

911SLOW

Thanks it was a typo, I 've edited my post. (and added a better diagram for the Porsche 996 GT2/3 LSD)

porscheracing

[quote=Bill Verburg;9040252]this is a zero lockup stack on one side!
or to be more exact, on that 90degree side only the preload will be active.
if this is an oe 993 stack, 993 oe lsd units should be replaced or at least the ramps should be machined to something usefull!

the cayman oe ramps are a joke as well...

Bill Verburg

[quote=porscheracing;9246821]My apologies, I pulled the pic from the wrong file that is a 20/100 from a 964t

here's a Cayman


a stock 993


a GT 50/80


an older ZF 40/40

GTgears

I should change up my photobucket links just to mess with people. Nah...

sig_a

[quote=porscheracing;9246821]---------------------

Note how the pinion cross shaft end is machined flat at the right angle cuts in both pressure rings. Design is also known as a "1 way" clutch type LSD.....I think.

GTgears

The Japanese manufacturers use a different language than is traditionally used in Porsche circles. They call LSDs 1 way, 1.5 way and 2 way and almost never talk about actual locking factors. IMO, it's a very blunt system of nonemclature...

sig_a

---------------

A "1.5 Way" configuration allows driver to obtain up to 100% acceleration locking, and up to 50% deceleration locking. The "1.5 Way" term does not always describe the actual percent of lock; only that there's a difference between the percent of lock on acceleration and deceleration. Actual acceleration and deceleration locking percentage depends on various cam configurations, meaning variations in the angles cut into the inside of the two pressure rings. Always asymmetrical cut ramps in 1.5 way.

A "2 Way" configuration is simple; it allows driver to obtain up to 100% acceleration locking and up to 100% deceleration locking. Drifters need this because it provides a way to put their car in a prolonged neutral steer attitude. Always symmetrical cut ramps in 2 way.

I think this is the way it is.