blacksparrow

Dealer checked the LSD in the 62k car I am looking at and the breakaway torque was at 50lbs, Within spec of 30-57lbs as stated by Steve Wiener in a previous thread here.

Does anyone know what end of the scale this is on? Assuming as it gets closer to the 57lbs it is closer to out of spec or maybe this makes no difference... not sure how it works.

Any thoughts?

Paul902

As the diff wears out, the torque would reduce.

mr_bock

My diff was 'so' wore out that the shop thought it was not a LSD. When it was opened up, the insides were coated with black. The disks were so used up, some were smooth, no groves in the carbon disk material.

Bottom line, break away torque will get reduced as it wears out.

The shop (JB Racing in Tavaris, FL) worked with Guard Transmissions to get their internal parts that will work with the OEM carrier. Now I have the benefits of a Guard Trans and the cost savings of the OEM housing.

Win/win. Ican't wait to see how this feels on the street!!!!!

blacksparrow

Thanks, exactly what I wanted to know... I had the porsche dealer do breakaway as the car has more miles than most say that differential will be working. They say it works and that it is at 50ft lbs. Hopefully that will last a while and then...

this would be the next step... it sounds amazing, let us all know you like it!

blacksparrow

Also here are a few pix of the LSD after they did the breakaway test, they opened it up for me... looks like there are still some grooves left!

TheOtherEric

Can you explain what was involved in the breakaway test? I.e. how done, tools involved, etc.

blacksparrow

I found this cited as the only real way to difinitivly test the LSD here on the forum... it was in one of Steve Wierner's threads.

They way i understand it is you test at the CV joint, not the axle. It is done with a special tool and a torque wrench.

The values he noted for 993 LSD were between, 30-57ft lbs torque is within spec... I just learned here, thanks to these gents, that it diminished with wear... so as the number gets smaller, the more wear.

I am no expert, just learning all this, so I hope I have not miss-spoken!

Bill Verburg

This is a great pic of what makes the lsd work


on the left 2 plain(external drive) and 2 friction disc(internal drive) stack
on the right asymmetric 25/65 ramps used in the street lsds

breakaway torque was usually low on these compared to older 911 setups, rather they relied on the asymmetric clamps to dynamically clamp the disc stack tighter for less slip.

25/65 means more clamping force on trailing throttle to help stabilize braking

mr_bock

Great pix!!!
On my friction discs, two sides were practically totally smooth. Yours look very good.