[Liquidpaper]

Ladies and Gents:

I've been wanting (needing) to get an LSD for my 2er for a while -- port installed MP LSD was not available when I bought my car.

I was going to buy the MP LSD, but then I got into looking for possible alternatives -- Wavetrac, Quaife, etc. But then I got a recommendation to look into a custom diff from diffsonline and Dan Fitzgerald. He has a very good reputation for a quality product (even if it is a bit pricy), and my mechanic uses his differentials in spec E46 (new class this year).

So, I bit the bullet and ordered a 3 clutch, 45/45 ramp, 40% lockup diff today. Should be ready in a week to be shipped.

I don't think anyone here has gone off the reservation and tried a non-MP diff, so I will be happy to share my observations/impressions once I have it installed and have some time with it.

Super excited.

Leave any questions in the comments, and I will respond as best I can.

[hyperzulu]

Some peeps have already gone the non-MP route. Quaife had their solution available before BMW. What other mods are on the car already and is it going to see a lot of track time?

[Liquidpaper]

Originally Posted by hyperzulu

Some peeps have already gone the non-MP route. Quaife had their solution available before BMW. What other mods are on the car already and is it going to see a lot of track time?

Yes. It gets a lot of track time. I have 11 days in it so far, got the car in August.

Car has the following (non-cosmetic) mods:

Ground Control Camber Plates (getting a re-alignment next week)
H&R Sport Springs
Challenge F22 Stainless Lines
ATE 200 Fluid
Porterfield R4-S Pads
APEX 18x8.5 ET 38 in Hyper Black x4; Direzza II 255/35/18 x 4
P3 Vent Gauge
Deist Custom 6 Point Snap-In Harness

Okay, you're right, Quaife had one before BMW, but I haven't seen anyone talk about them much. Guess I got overexcited.

[Iceman51sn]

Very interested to see how this performs!! You are just a step ahead of me on mods as I'm pretty much aiming for the same things you are. lol I'm guessing this won't be on your car for the Willow Springs track day coming up?

[Liquidpaper]

Originally Posted by Iceman51sn

Very interested to see how this performs!! You are just a step ahead of me on mods as I'm pretty much aiming for the same things you are. lol I'm guessing this won't be on your car for the Willow Springs track day coming up?

Haha. No, no. Probably not.

Also, I just talked to them and because the LSD is custom, they can change the rear end ratio. I think I'm going to move to a 3.46 rear rather than the 3.08 rear for better high gear pull. As is, I rarely move out of 3rd on most tracks right now, and when I do, 4th is a little sluggish. At 3.46, I would actually be using all of my gears (except 6th -- highway only).

[Iceman51sn]

Originally Posted by Liquidpaper

Haha. No, no. Probably not.

Also, I just talked to them and because the LSD is custom, they can change the rear end ratio. I think I'm going to move to a 3.46 rear rather than the 3.08 rear for better high gear pull. As is, I rarely move out of 3rd on most tracks right now, and when I do, 4th is a little sluggish. At 3.46, I would actually be using all of my gears (except 6th -- highway only).

Interesting! Sounds expensive but as you said you are tracking the car a lot so I'm sure it'll be worth every penny!

[Liquidpaper]

Diff is finished - on its way to me. Final specs are as follows:

3 (Drexler) disc 35/60 ramped limited slip carrier with REM polished 3.46 gears; set to 100 ft/lb of preload (will settle in at around 80 ft/lb of preload after break in).

Super excited. I'll write a first impressions review, a track weekend review, and a post-break-in review.

[darkfaker]

can you explain the LSD setting? benefits on different stage % of lockup?

[Liquidpaper]

Originally Posted by darkfaker

can you explain the LSD setting? benefits on different stage % of lockup?

From what I understand, lockup % is kind of an "average" of how you look at how a differential behaves. It's more precise (generally better) to look at the preload values and ramp angles to determine differential behavior (for clutch type diffs).

For mine, the ramps are 35 on accel, and 60 on decel. You're going to want to watch a few youtube videos on differentials to know what those mean. I suggest engineeringexplained.

Anyway, basically the diff is going to lockup harder on acceleration than deceleration (a 1.5 way diff), which is generally desirable, but in any event youre going to need to apply at least the preload torque (even when the car is going in a straight line) to un-lock the wheels (to make it "slip"). My knowledge of the equations on how hard you can push the diff before it locks completely is quite fuzzy (and I have looked for some equations, trust me), but this is basically how it works (for a clutch type diff).

They way we (the fabricator and I) came to these numbers is that he had built a few differentials for the M235i, and found that this chassis like this configuration best (in his experience). I'm not one to argue, so I went with his findings. Different situations would call for different setups, but for an "all-around" differential, this seemed to fit the bill for me.

[darkfaker]

thank you for detailed explain .does less percentage mean more SlIP? and i just checked diffsonline, they have gear ratio to choose, so gear ratio relate to what? how to calculate what setup i want? thanks