New 996 Owner. 1st Porsche.
#226
LSD Comparison
Here is a side by side of the new OS Giken vs the Stock differential. It's really surprising how different they are. (Of course)
In order to install, we realized we needed to use shorter axle stubs as the stock stubs are too long and shaped much differently. They wouldn't sit flush and could only be turned a few threads in the new differential.
The stocks use a ~80mm M10 which is far too long for the new hubs. The new ones use only a 40mm M10x1.50 Allen head with a spline washer. Upon a test fit it actually seems to be a much firmer connection. I don't believe this main bolt sees much tension but the idea if it did of the torque going over only 40mm on the new setup versus 80mm on the stock seems like an improvement.
Anyway, here's some photos:
New Short Hub versus Old - note the shorter height and difference in the mounting bolt holes. The new setup requires a 40mm Allen head while the stock unit has a small center cylinder in the differential that fits into the old stub hub on the right.
New Short Hub vs Old - Note the difference in the center mounting bolt holes.
OS Giken versus Stock Open Differential. Its shocking how easily the stock differential turns by hand. Very little force.
OS Giken top view - notice the clutch plates inside.
Stock Open Diff Top View
The Housing
The Transmission - were also installing a 2nd Gear Detent from GBox to prevent the common 2nd grind and pop outs. With the cup cables this should be a big improvement. You can also see what the function first transmission mounts look like on the right side of the photo. They're really well constructed.
In order to install, we realized we needed to use shorter axle stubs as the stock stubs are too long and shaped much differently. They wouldn't sit flush and could only be turned a few threads in the new differential.
The stocks use a ~80mm M10 which is far too long for the new hubs. The new ones use only a 40mm M10x1.50 Allen head with a spline washer. Upon a test fit it actually seems to be a much firmer connection. I don't believe this main bolt sees much tension but the idea if it did of the torque going over only 40mm on the new setup versus 80mm on the stock seems like an improvement.
Anyway, here's some photos:
New Short Hub versus Old - note the shorter height and difference in the mounting bolt holes. The new setup requires a 40mm Allen head while the stock unit has a small center cylinder in the differential that fits into the old stub hub on the right.
New Short Hub vs Old - Note the difference in the center mounting bolt holes.
OS Giken versus Stock Open Differential. Its shocking how easily the stock differential turns by hand. Very little force.
OS Giken top view - notice the clutch plates inside.
Stock Open Diff Top View
The Housing
The Transmission - were also installing a 2nd Gear Detent from GBox to prevent the common 2nd grind and pop outs. With the cup cables this should be a big improvement. You can also see what the function first transmission mounts look like on the right side of the photo. They're really well constructed.
#227
Rennlist Member
Mind if I ask who you went through for the LSD and how much? (I think that question could be taken wrong.). Also, how hard was it to source the shorter axle stub? I wonder if the same would be required on a C2.
#228
The shorter axle hubs are constructed by GBox out of Colorado. These guys are awesome as well and have been super helpful. They make a lot of race or cup spec parts you simply won't find anywhere else such as the 2nd Gear Detent, complete LSD and Trans Rebuilds, gearing and LSDs, Custom GT3 shift linkages and more. Super knowledgeable staff. Next time I'm out that way I'm definitely stopping by.
#229
Rennlist Member
Cool. Thanks!
#230
Rennlist Member
Is that a GT's Kombucha on your bench? My beverage of choice while working on my car as well.
#231
Looks like the guys found another little issue. When installing the differential, due to its larger size there is a piece of cast that's in the way. Nothing a little grinding can't fix.
You can see the piece in question here.
The arrow is pointing to the piece of cast that needed to be grind down for the new LSD to fit.
You can see the piece in question here.
The arrow is pointing to the piece of cast that needed to be grind down for the new LSD to fit.
#233
Rennlist Member
Found out I have to modify my axle flange if I go with the Giken as it is for an X50. Wavetrak has one that will bolt right on but it's TB. Decisions decisions. California Motorsports is awesome to work with.
#234
Car is done!
Picking it up in the morning from Chris's German Auto in Redmond, WA...guys did a ton of work!
More to come
Picking it up in the morning from Chris's German Auto in Redmond, WA...guys did a ton of work!
More to come
Last edited by vandersmith; 05-27-2016 at 02:23 AM.
#235
Rennlist Member
#236
Rennlist Member
Sorry if I missed a post along the way but you kept the FWD in car while installing the LSD? Is that right? If so, how will the LSD behave with viscous coupling in place or vice versa?
#237
The car is corner balanced so I didn't want to have to add that on top of taking out the entire front drive.
The coupling and everything is fine shouldn't change much. The big difference will be with the PSM. I already run with it turned off and may need to disable it as the LSD will keep things in check in both decel and accel where with PSM on it may interfere and counter the LSDs actions.
#238
Rennlist Member
Interesting. I'm eager to hear your impressions once you've tracked the car. Agree 100% on PSM, the first thing I do when leaving the pit is turn it off. PSM does spooky things on the track in my opinion. Side note: how's your steering temp holding up since you still have the FWD?
#239
Rennlist Member
I'm interested in how big of a difference you feel in rear end stability while trail breaking. Still trying to decide between clutch and TB and from what I can tell, this is the major difference.
#240
Interesting. I'm eager to hear your impressions once you've tracked the car. Agree 100% on PSM, the first thing I do when leaving the pit is turn it off. PSM does spooky things on the track in my opinion. Side note: how's your steering temp holding up since you still have the FWD?
As for the steering temp, I have it logged and will take a look. Haven't noticed any issues over the first 7 or so track days this year. Has this come up for you?
The AWD system seems to do a decent job but I agree, it should be night and day.