Adding LSD?

SouthCoastPhil · 07-11-2009, 02:18 PM

In my search for another 911, I have found some 3.2L Carreras w/G50s but w/o LSD. What's involved in adding LSD to a G50? Assuming that its feasible, which LSD do you recommend? Any ideas, and info on costs for parts and labor will be greatly appreciated.

TIA for your help,

Phil

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by SouthCoastPhil

In my search for another 911, I have found some 3.2L Carreras w/G50s but w/o LSD. What's involved in adding LSD to a G50? Assuming that its feasible, which LSD do you recommend? Any ideas, and info on costs for parts and labor will be greatly appreciated.

TIA for your help,

Phil

It can be done w/ the engine/trans still in the car, the side cover comes off, the diff is R&Red, pinion depth reset, button it up.

It's not going to be cheap. I'd want a GT 40/60 asymmetric lsd.

Rana1 · 07-12-2009, 12:54 PM

I've heard this one is a good one.

SouthCoastPhil · 07-12-2009, 01:21 PM

Thanks guys.

Bill: Any ballpark numbers for "not going to be cheap"?

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by SouthCoastPhil

Thanks guys.

Bill: Any ballpark numbers for "not going to be cheap"?

Depends on shop rates, but WAG ~$3.5 - $4k

TimT · 07-12-2009, 03:03 PM

Quote:

but WAG ~$3.5 - $4k

Sounds right.... A Guard or Quaife diff is almost $2k Then add maybe two days labor.. You can do it while the engine tranny are in the car... it takes so little time to drop an engine, its easier to do it with the tranny on the ground...

KTL · 07-13-2009, 05:59 AM

If it's done in the car, only bearing preload can be set/adjusted. Pinion depth requires trans. removal and teardown!

It can be done a little cheaper if all you're after is a LSD for street use. A used factory Porsche diff from 87-98 can be put in. On the street, LSD honestly doesn't provide a whole lot of improvement- at the track it's a marked improvements/difference. You can get a used factory diff. for under $1K and have it reconditioned with new friction plates by shops with experience in doing this. All depends on what your intended use is.

SouthCoastPhil · 07-13-2009, 06:44 PM

thanks all!

I am thinking LSD for DE use. (esp. coming out of turn 3 at NHMS)

Don't (yet) see a need for it on the street.

911st · 07-13-2009, 08:16 PM

Why do you think you need a LSD for DE's?

I think they help more going into corners, not comming out.

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by 911st

Why do you think you need a LSD for DE's?

I think they help more going into corners, not comming out.

They serve different functions going in, mid and coming out, that's why the asymmetrics are so nice

spuggy · 07-15-2009, 11:20 PM

Quote:

Originally Posted by KTL

On the street, you really can't tell the difference with a late factory LSD most of the time

Fixed it for ya.

The more power you have, the more you'll appreciate a 40/65 LSD with a high (>70 ft/lb) torque setting in just about every driving situation except parking.

I put one in almost as an afterthought, partly because it enables the 915 to tolerate higher torque loads. It should have been at the top of the list - it transformed the way the car drives.

dvkk · 07-19-2009, 12:10 PM

Quote:

Originally Posted by Bill Verburg

It can be done w/ the engine/trans still in the car, the side cover comes off, the diff is R&Red, pinion depth reset, button it up.

This is wrong.
The pinion depth is the distance from the pinion to the differential's centerline axis of rotation. The position of the diff's axis of rotation is determined only by the trans case and side cover. Swapping out the diff does not change where the diff rotates, it rotates exactly where the original one did.

However, swapping an LSD into a gearbox that came stock with an open diff requires setting the diff bearing's preload, and the backlash between the ring gear and the pinion gear.

spuggy · 07-19-2009, 01:10 PM

Quote:

Originally Posted by dvkk

However, swapping an LSD into a gearbox that came stock with an open diff requires setting the diff bearing's preload, and the backlash between the ring gear and the pinion gear.

My tranny guy told me the same thing as dvkk and KTL are saying above.

He said that he won't take the measurements with the tranny in the car, because it's too difficult to get the accuracy required, he wants it on the bench.

He did say that once he's recorded the measurements he needs, he can measure the replacement diff, calculate the shims needed and that the actual swap can be done with the transmission fitted to the car just fine.