Differential - Lap Time Difference?

[joeo]

Has anyone who has upgraded to an LSD experienced a significant drop in road course lap times?
If so - please share! Thank you!

-Joe

[chris_flies]

My times improved slightly, but I'm sure most of that was down to my improved confidence in the car. You'll probably reap more rewards since you have more power to put down.

It's wonderful, the difference it makes in how the car feels. It feels properly sporty and old-school.

Being back on an open diff (my LSD had a rapid unscheduled disassembly, my fault), I really miss the proper LSD.

[tsk94]

While my comparison is not directly relevant to your car I will provide my insight on my experience with my E92 M3 race car. The M3 stock comes with a clutch style, speed sensing, LSD from the factory. The unit is decent for what it is, albeit it locks up and unlocks slowly and the amount of lock is quite low. The diff was upgraded to a 2-way 8-clutch Drexler LSD (equal lock up on accel and decel). The difference is absolutely huge; predictability under power, confidence to put the power down, stability under braking are all massively improved compared to the stock unit (which was already a LSD, not an open diff). Lap time difference was estimated to be about ~3/4-1 second a lap from the diff alone around a 90 second track.

I know a lot of people preach the importance of a LSD, especially in the 1 series chassis as they come with an open diff. But not many people really emphasize the importance of a quality diff. Do not cheap out and get the cheapest LSD possible. If you have the means invest in the best diff you can. Clutch styles, for track use, will ALWAYS provide better performance. I'd recommend getting a unit that also locks up under decel for added stability under braking, and more confident trail braking characteristics.

[Ginger_Extract]

Get a clutch-type diff and send it. If I could do it again, I would have skipped the MFactory helical diff and gone for a clutch type, far superior for the torque-heavy power delivery of this platform. Helical doesn't lock hard enough, fast enough and drives like an open diff car. Works fine on an FRS with 200 horsepower, not so much with 400+ on a big heavy pig like a BMW.

[joeo]

Thanks all - sorry for the delay in responding. Price wise, M-Factory LSD is cheapest; bimmer world sells the wavetrac and clutch style (2 and 3) through diffsonline. Wavetrac is still a good bit less expensive than the clutch style and is basically maint free. While there is a lot of info on the Wavetrac, it's tough to say how well it will do on track.

[chris_flies]

Originally Posted by joeo

Thanks all - sorry for the delay in responding. Price wise, M-Factory LSD is cheapest; bimmer world sells the wavetrac and clutch style (2 and 3) through diffsonline. Wavetrac is still a good bit less expensive than the clutch style and is basically maint free. While there is a lot of info on the Wavetrac, it's tough to say how well it will do on track.

I was torn between the Wavetrac and DiffsOnline's own clutch-type, and I ended up going with the clutch-type diff again. I had an MFactory 1.5-way that I installed in a pumpkin myself, but the pumpkin was destroyed and I thought having a professionally-built diff would be a good idea after blowing up my second diff in two weeks...

Wavetrac has an unlimited mile lifetime warranty, regardless of usage, which is amazing, and it is maintenance-free (other than regular 50k-mile oil changes), so it's a great option for street-driven cars that need to remain refined. The design of their diff with the clutch puck means that it's mostly immune to the issues other helical differentials have when you lift a drive wheel off the ground.

What drew me to the clutch-type diff was the consistent and predictable performance I loved, and a very mechanical, old-school feel to it. It was such a joy to drive and always brought a smile to my face.

[cwlo]

Chris, how does the Mfactory 1.5-way compare to the diffsonline 1.5 way? I am considering an Mfactory or Cusco clutch type. Would also add OS Giken, but they seem to have some issues with their BMW unit.