Clutch

[eunosracr]

I have seen tons of talk about additional power but I have yet to hear anyone mention anything about the clutch. Will this be this car's weak spot? Who will be upgrading their clutch and flywheel? A lightweight flywheel would sure make those revs climb faster and build boost quicker. Any thoughts?

[mateo]

Originally Posted by eunosracr

I have seen tons of talk about additional power but I have yet to hear anyone mention anything about the clutch. Will this be this car's weak spot? Who will be upgrading their clutch and flywheel? A lightweight flywheel would sure make those revs climb faster and build boost quicker. Any thoughts?

Yes, I have a few... The stock OEM Flywheel will be just fine. Adding a lighter FW can sometimes hurt a turbo application, more than you might know. I'd say when the time comes for replacement, running a better clutch would be ideal, but the stock clutch should be fine for some time. Its all going to depend on ones driving style. If you beat on the car at launch, and on hard speed shifts, then it will die fast regardless.

-Mateo

[kurichan]

Problem is, a light clutch has less rotational momentum meaning the engine might dip out of the turbo sweet spot quicker meaning more spin up to get back in the sweet spot and potentially slower times...

I wouldn't mess with the clutch on this car without real evidence that it would produce the result you want - it could really backfire!

[atr_hugo]

I'll echo kurichan's comments on the clutch with the caveat that 100% of torque is availalble at 1300 RPM (that's 'diesel like' and a testament to the efficacy of the direct injection).

I also suspect the the factory diff is going to be the weak link in this process - reading the press release they talk about how they are making do with a super duper ball bearing double helical diff and less fluid. We don't even know if the diff has drain and fill plugs.

[eunosracr]

All good info. So i guess we will have to keep the full boost 4000 RPM clutch drops to a minimum huh.

[atr_hugo]

Originally Posted by eunosracr

All good info. So i guess we will have to keep the full boost 4000 RPM clutch drops to a minimum huh.

Depends on what kinda results you're looking for - I suspect the 'scattered parts' result may be possible with a 4K clutch drop. :biggrin:

But speaking of launching the car, some of the 335i owners can probably tell us what an appropriate launch RPM is.

[mateo]

If you can only do 4k launches on these then thats weak. I bet it w/handle around 5k w/no problem. Regardless, the first thing I'm buying is a Quaife.

:roundel:

[AR230WAKEBOARDER]

With all the TQ why would you drop the clutch at such a high rpm? My 335i with procede lights the tires up if power braked to 2500rpms.

[ichiban]

also, i've been hearing somethings about the tranny not being able to take more than 350whp. If that's the case, beefing up the clutch will only light the fuse for tranny failure, since the power has to go somewhere, i'd rather replace the clutch than tranny.

[BMWeber]

Originally Posted by atr_hugo

I'll echo kurichan's comments on the clutch with the caveat that 100% of torque is availalble at 1300 RPM (that's 'diesel like' and a testament to the efficacy of the direct injection).

I also suspect the the factory diff is going to be the weak link in this process - reading the press release they talk about how they are making do with a super duper ball bearing double helical diff and less fluid. We don't even know if the diff has drain and fill plugs.

I was also a little concerned about the diff from what the press release said. sounds like it will be great for fuel economy but performance wise it sounds a bit fragile

[335i=:)]

Originally Posted by ar230wakeboarder

With all the TQ why would you drop the clutch at such a high rpm? My 335i with procede lights the tires up if power braked to 2500rpms.

+1

When brake torquing, I only brake torque at 1900 because brake torquing to 2500 = spin and slower 60' times. In the MT, they are feathering the clutch at about 2300 rpm. There was a thread where a guy coming form an evo drop his clutch at 6k and the trasmission had to be replaced, he coudn't even drive it away.

Even stock the n54 develops 250wtq @2500 rpm.

[ichiban]

if 100% of the torque is at the wheels really early in the rpm range, why would it matter how high your rpm launch is? this is probably a noob question but just curious.

[335i=:)]

I don't know.......I'm sure when you feather the clutch the rpm's drop a little ....

[321]

Originally Posted by ichiban

also, i've been hearing somethings about the tranny not being able to take more than 350whp. If that's the case, beefing up the clutch will only light the fuse for tranny failure, since the power has to go somewhere, i'd rather replace the clutch than tranny.

Its not hp that breaks trannys its torque. Manual trannys will take a lot more tq than you think. Think about it... they are helical gears that can withstand tons of force. There really isn't much to a MT. You do need to worry about the syncros and unless you are a douche w/stick and time your shifts properly, i wouldn't worry about it till you get to about 550+ ft/lbs tq. If anyone breaks a gear with the MT I will be seriously impressed and ask them to refer me to their clutch manufacturer.

if 100% of the torque is at the wheels really early in the rpm range, why would it matter how high your rpm launch is?

Because you want the most tq and hp, (traction willing)at the wheels, coming off the line. We all know tq is what wins races but a good ratio (hp:tq) is needed to launch effectively.

[mateo]

Originally Posted by ar230wakeboarder

With all the TQ why would you drop the clutch at such a high rpm? My 335i with procede lights the tires up if power braked to 2500rpms.

Well I guess you wouldn't. I like the fact you can launch that low. Very nice!

-Mateo

[kerpal]

Wel, the lighter the flywheel, and with greater pressure conjured by the pressure plate and release bearing, it will definitley give the car extra boost...

[321]

Originally Posted by kerpal

Wel, the lighter the flywheel, and with greater pressure conjured by the pressure plate and release bearing, it will definitley give the car extra boost...

I don't think so. The lighter FW will reduce drivetrain losses and the motor will rev faster but it won't give you more boost. Likewise the FW will not increase the pressure plates clamping force.

[ichiban]

I'm pretty sure launching at 400+ wtq will break the N54 tranny. And I have read 335is that got blown gear on other forums. and my question about the low end torque maybe a lil ambiguous. I'm asking if you can get all the Torque at 2000 rpm ... so what's the difference from launching at low rpm compared to high if you get all the torque to the wheels at low already. In other words, how does launching at low rpms protect your tranny?

[321]

Originally Posted by ichiban

I'm pretty sure launching at 400+ wtq will break the N54 tranny.

Have you done it?

And I have read 335is that got blown gear on other forums.

Link?

and my question about the low end torque maybe a lil ambiguous. I'm asking if you can get all the Torque at 2000 rpm ... so what's the difference from launching at low rpm compared to high if you get all the torque to the wheels at low already. In other words, how does launching at low rpms protect your tranny?

The higher the rpm's climb, the more inertia/energy the motor will hold.

[frimmelnojerz]

bump. im curious about this.

[WhiteOne]

The motor makes more power at 4000rpm's than it does at 2500rpm's. If you can get traction, it should leave harder.