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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.
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.
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.
If you simply search for OS Giken G50 LSD, there are a ton of vendors. I was able to get mine straight from OS Giken and if I had to do it again I would recommend going through California Motorsport. Prices don't fluctuate much so it's better to work with a vendor that will stand by you and the product. They answered a ton of my questions and were extremely helpful in helping me decide which LSD to use.
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.
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.
This LSD better be worth it for all that trouble. I expect no less than 2s off your lap times to be worthwhile.
3s with the LWFW.
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.
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?
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?
Keeping it AWD to compare lap times with before first. Then may decide to try RWD.
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.
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?
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.
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?
The unfortunate part is you can never fully get PSM disengaged unless you disable it underneath the center console or through the fusebox. I can't recall which does what but I'll need to research it more before my next event.
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?
Originally Posted by Slakker
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.
The AWD system seems to do a decent job but I agree, it should be night and day.
05-25-2016, 02:43 AM
LSD Comparison
