[vasillalov]

It's been slightly over 700 miles since I've had O.S. Giken TCD LSD installed along with solid diff bushings and M3 sub-frame bushings. VAC Motorsports built the diff for me.

During this period, I've had the chance to test things out during several track days and AutoX events. Here are my impressions:

1. The rear end of the car no longer feels wavy and disconnected. I get almost direct feedback from the rear wheels through the chassis, through the seat and into my spine. It's uncanny at first, but now after I've re-learned the car, I can say that this upgrade should have been the very first thing I did on my car.

2. The traction is crazy. I am now considering going with slightly narrower tires in the rear because there is so much more grip compared to the front.

3. Accelerating from stand still is now completely predictable. The rear is not longer waving back and forth unpredictably. The car goes in a straight line.

4. On the track and AutoX events, I no longer have to wait for the car to get completely out of the corner and settle down before I give it full power. The O.S. Giken does tremendous job keeping me stable mid corner, whether its under power or not! This is where the O.S. Giken shines compared to the rest of the diffs. You get lock during acceleration AND deceleration. This becomes really useful when trail braking into a corner.

Another difference is that if I change my mind mid corner and I let off the gas, I no longer get this unsettling of the rear end. Instead, I feel the diff unlocking and re-locking again in a split second as I lift off the throttle. It's kind of difficult to explain, but it works wonders for increasing the driver confidence in the car mid corner.

5. NVH. There is a faint whine during acceleration and deceleration. It is more prominent when the diff oil is cold. O.S. Giken make their own gear oil and on the bottle it is stated that optimal performance is achieved at 100C. The diff definitely quiets down once the diff fluid is warmer. The whine is a result of the solid diff bushings.

Today, I've spent a good portion of the day draining the fluid, lowering the diff housing and removing the diff cover. I wanted to inspect the condition of the oil and the ring gear after 700 miles of break in.

Here are some pics:





Notice how the fluid looks like graphite. This is after 700 miles of break in. The new fluid is clear with a faint yellowish tint. The viscosity is unchanged compared to new fluid, so this tells me that the diff fluid is managing the heat quite well even during track days.

This should also serve as a reminder to change your diff fluid!

[quattr0]

Thank you for the detailed review. Wonder how much power do u have in regards to "Accelerating....the car goes straight line".

[tullnd]

Nice review. I've also got the TCD model. I do NOT have the M3 subframe or the solid diff bushings and I do not experience any audible whine(as you stated, this seems to be amplified via the bushings you have...which makes sense). This diff is really amazing in its performance. By far the best modification I've performed on my car.

I think you've tracked yours a bit more than mine, so glad to hear it still meets your expectations after a more thorough beating.

[ar design II]

Nice write up!

[cleex024]

Originally Posted by tullnd

Nice review. I've also got the TCD model. I do NOT have the M3 subframe or the solid diff bushings and I do not experience any audible whine(as you stated, this seems to be amplified via the bushings you have...which makes sense). This diff is really amazing in its performance. By far the best modification I've performed on my car.

I think you've tracked yours a bit more than mine, so glad to hear it still meets your expectations after a more thorough beating.

instead of getting the tcd model should have just gone super lock and vac diff cover unless you got both anyway. i have the super lock and no noise until i put in my solid diff bushings.

either way the os giken way was a pretty hefty upgrade both in performance and dollar amount. but i do love it. and for all of those that have lsd and dont really track i dont see how you can say this is the best mod you have ever gotten for the car. when i used to drop my clutch without the lsd both my tires spun.

and unless you are driving super aggressive like you are on the track i dont see how you can take advantage or even feel the lsd. i went drifting in my car and i do a lot of drifting uturns and the lsd allows for it but other than that i barely feel my lsd.

for all of you that dont really track i would probably get more tuning items first and unless you put down more than 400whp i doubt you are going to spin out in 2nd or 3rd...and for those of you that are spinning out then its more of a problem with your suspension bits and tires.

either way OP glad you like your lsd and its an awesome lsd especially if you are going to drift =)

[ilikebmxbikes]

Nice write up. I have had a lot of the same impressions after my wavetrac and quaife installs.

[tullnd]

Originally Posted by cleex024

instead of getting the tcd model should have just gone super lock and vac diff cover unless you got both anyway. i have the super lock and no noise until i put in my solid diff bushings.

either way the os giken way was a pretty hefty upgrade both in performance and dollar amount. but i do love it. and for all of those that have lsd and dont really track i dont see how you can say this is the best mod you have ever gotten for the car. when i used to drop my clutch without the lsd both my tires spun.

and unless you are driving super aggressive like you are on the track i dont see how you can take advantage or even feel the lsd. i went drifting in my car and i do a lot of drifting uturns and the lsd allows for it but other than that i barely feel my lsd.

for all of you that dont really track i would probably get more tuning items first and unless you put down more than 400whp i doubt you are going to spin out in 2nd or 3rd...and for those of you that are spinning out then its more of a problem with your suspension bits and tires.

either way OP glad you like your lsd and its an awesome lsd especially if you are going to drift =)

Hi...I can absolutely feel my LSD on daily driving. Not even aggressive daily driving. The area I live in is very hilly, lots of frequent elevation changes and very curvy roads, and I live very central, near the downtown of my city. I can easily notice the diff engagement affecting the traction as I pull away from a light on a sharp 90+ degree turn uphill. I can notice it on curves downhill, as I brake. It's not overwhelming, but it's easy to notice. I guess if I lived in a flat area with all open flat land, maybe you'd only notice it under hard acceleration or decel on tight turns, but it's very easy to feel even when just cruising through sweeping turns.

I don't drift my car at all...as a matter of fact I'd say this diff helps me maintain traction more so than actually break free, although I honestly don't try and throw the rear end out more then the occasional launch.

I do have an auto, not a manual, so I haven't had a lot of issues with losing traction from clutch dumps. I was full bolt on before my diff install so I felt the power issues without the diff, and I'm not sure this all that dramatically changed my launching. Perhaps at the drag strip, but I've never made an attempt without the factory run flats, so I can't speak to that.

I will say that many people don't necessarily need the OS Giken diff, over some of the cheaper options. I just have driven a few cars with real LSD's before I got the 335i, so the idea of having one that doesn't work on accel and decel was just something I couldn't entertain spending money on. And yes...I know that the others do, to some degree, provide some of that effect, but it's not the same, hence why they're priced cheaper(still quality options, just for different targets is all).

[vasillalov]

Originally Posted by tullnd

I will say that many people don't necessarily need the OS Giken diff, over some of the cheaper options. I just have driven a few cars with real LSD's before I got the 335i, so the idea of having one that doesn't work on accel and decel was just something I couldn't entertain spending money on. And yes...I know that the others do, to some degree, provide some of that effect, but it's not the same, hence why they're priced cheaper(still quality options, just for different targets is all).

True!

My plan is to turn this car into a dedicated track monster in the next 2 years. Next year, I'll probably rip out the interior completely and build a full roll cage in it. I don't use a car to get to work and I am planning on getting a used econobox like a Yaris or something for grocery getting. The BMW will be garage queen/ track monster so I thought: if I am doing the diff, I am doing it all the way.

[SneakyDeeky]

Nice write-up and thanks for the review.

Did you end up changing the gearing from 3.08 for the 6MT to the 3.46 for better acceleration? I ask b/c I'm very close to pulling the trigger on this and having VAC build me a 3.46 Quaife LSD for my 6MT. I plan on tracking occasionally (2-3 x year), but mostly canyon carving and daily driving. Since my daily commute is only 10 minutes, I'm not too concerned about changing the gearing, but would like your opinion on the matter.