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      06-26-2019, 08:24 AM   #1
kern417
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6MT Clutch Strength

Goals for my build are to have maximum efficiency out of my car. I don't need to have the fastest car in town, but I don't want to feel like I'm leaving a lot of power on the table. But one of the big things I don't want to do is move to a heavy aftermarket clutch. Some people discussed that the 550i clutch might be a possible OEM+ upgrade, but that'd be as far as I go.

So just curious, has anyone experienced clutch slip after turning up the power?What tune are you running, and how much power/torque are you putting down? Anyone on upgraded turbos with stock clutch? And can anyone verify the 550i clutch bolts up? Maybe we have to reuse our flywheel or maybe we only need the 550i pressure plate....idk.

For reference, I'm currently on BM3 Stage 1 93 oct with no issues, looking forward to bumping up to e30 or e85 within the next year. I'm hoping that with the style of tuning that PTF used in V2.0, I can continue to turn it up more with less risk of clutch slip since torque onset is smooth and progressive.
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      06-27-2019, 07:30 AM   #2
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Subscribed. Good to know you are not slipping with stage 1. As a 6mt owner, I was surprised to see that the MPPSK upgrade was downgraded for 6mt cars vs ZF8 cars. Could not find a rationale published, but deduced it was concerns over transmission or clutch longevity. That said, was talking with active autowerke this week and they said the 6mt could take more power than the zf8??
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      06-27-2019, 09:50 AM   #3
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So, I don't have any slipping, but I do have juddery engagement occasionally in first. It's weird and intermittent. The dealership couldn't duplicate it, so nothing has been done about it. Based on research, I suspect it is either a failing clutch (as in, the springs involved in the dual-mass system are failing), or it's the 'automatic adjustment' not adjusting smoothly, so it gets slightly 'out of adjustment' and judders for a day or two, and then the adjuster gets un-stuck and it's adjusted properly again and it acts normal again for a couple weeks.

I'm at 54k miles, MPPSK since day 1, and most of the time I don't even drive it hard. I've been to the drag strip once (3-4 runs?), done maybe 2-dozen other launches, and mostly it's my commuter car... without a ton of stop-and-go traffic, mostly flowing highway traffic.

If I go with a tune, I'll update this thread with my experience. The most aggressive I would go is stage 2 though, I won't be doing upgraded turbos or anything like that.
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      06-27-2019, 12:16 PM   #4
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Quote:
Originally Posted by GA/\/\/\/\A_CT View Post
Subscribed. Good to know you are not slipping with stage 1. As a 6mt owner, I was surprised to see that the MPPSK upgrade was downgraded for 6mt cars vs ZF8 cars. Could not find a rationale published, but deduced it was concerns over transmission or clutch longevity. That said, was talking with active autowerke this week and they said the 6mt could take more power than the zf8??
Maybe the transmission and drive train but I'm not sure about the clutch. They just increased the ZF8 clamping limit to like 550ftlbs or something with the trans tunes.

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Originally Posted by Araemo View Post
So, I don't have any slipping, but I do have juddery engagement occasionally in first. It's weird and intermittent. The dealership couldn't duplicate it, so nothing has been done about it. Based on research, I suspect it is either a failing clutch (as in, the springs involved in the dual-mass system are failing), or it's the 'automatic adjustment' not adjusting smoothly, so it gets slightly 'out of adjustment' and judders for a day or two, and then the adjuster gets un-stuck and it's adjusted properly again and it acts normal again for a couple weeks.

I'm at 54k miles, MPPSK since day 1, and most of the time I don't even drive it hard. I've been to the drag strip once (3-4 runs?), done maybe 2-dozen other launches, and mostly it's my commuter car... without a ton of stop-and-go traffic, mostly flowing highway traffic.

If I go with a tune, I'll update this thread with my experience. The most aggressive I would go is stage 2 though, I won't be doing upgraded turbos or anything like that.
Cool thanks for the feedback. For reference I only have 9k miles, but I beat on it pretty much every day. My work commute has several opportunities to do WOT 2nd-3rd-4th runs and quick 0-60 springs from stop lights. I don't do high rpm dumps though, just get it going smoothly in 1st then floor it.

I also have 2.5į of camber in the rear, so i'm *hoping* my tires will break free before my clutch is overloaded. I chirp tires during shifts sometimes but honestly have no problems hooking low gears with 275 summer tires, even with traction in dynamic mode it barely spins if at all.
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As long as 3-pedals are an option, I will exercise my right to suffer the handicap and indignity of slower shifts and reaction times.
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      06-27-2019, 06:07 PM   #5
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I saw that there may be 2 types of manual transmissions, by ZF and Gretag. How can you tell? or is it by model year?
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      06-27-2019, 06:24 PM   #6
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My 6MT definitely slips with full bolt-on's and MHD Stage 2+ E30 mix.
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      06-27-2019, 11:07 PM   #7
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Originally Posted by SEA6MT View Post
I saw that there may be 2 types of manual transmissions, by ZF and Gretag. How can you tell? or is it by model year?
ZF: GS6-45BZ

It's the same one used since 2007 E9x.
6-cylinders get the ZF, 4 cylinders get the Getrag.
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      06-28-2019, 06:07 AM   #8
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Quote:
Originally Posted by GatorF30 View Post
My 6MT definitely slips with full bolt-on's and MHD Stage 2+ E30 mix.
I saw something like that in another post. I think they were BMW Stage 2 + Meth + JB4 so it got me thinking we might be pretty close to the limit. That makes me think I'd prefer to stay stage 1 E85 instead of stage 2 when upgraded fueling is supported.

How are you managing it? Are you planning on upgrading or is the slip intermittent?
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As long as 3-pedals are an option, I will exercise my right to suffer the handicap and indignity of slower shifts and reaction times.
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      07-07-2019, 11:55 PM   #9
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I am running MHD stage 2 91 octane. While the clutch doesn't slip with WOT, it is defiantly not strong enough to launch the car aggressively with an xDrive. In my experience you can't rev it much past 2500rpm when launching and need to just slightly slip the clutch. Too much RPM or too much slippage and the clutch won't grab. I did not try to launch when stock but I suspect result would be the same.
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      07-09-2019, 07:15 AM   #10
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Quote:
Originally Posted by F3085258 View Post
I am running MHD stage 2 91 octane. While the clutch doesn't slip with WOT, it is defiantly not strong enough to launch the car aggressively with an xDrive. In my experience you can't rev it much past 2500rpm when launching and need to just slightly slip the clutch. Too much RPM or too much slippage and the clutch won't grab. I did not try to launch when stock but I suspect result would be the same.
While stock (w/ mppsk) you can definitely launch hard with xdrive. I wouldn't call it a clutch dump, but I do rev well above 3k (I really don't know what RPM I launch from, 3500? 4k?) and launch somewhat aggressively.

I've only done that on plain pavement, never on a prepped drag strip though - last time I was at the strip the car was too new and I was pussy-footing it.
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      10-02-2019, 02:56 PM   #11
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I upgraded to Stage 1 E30 a few weeks ago and so far so good. My buddy on Stage 2 E30 + meth did just upgrade his clutch though due to it slipping.

Any other feedback?
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      10-04-2019, 06:31 AM   #12
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      10-04-2019, 02:56 PM   #13
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don't worry about it until your clutch is slipping ;-D
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      10-04-2019, 04:09 PM   #14
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The clutch is only interested in torque (hp is calculated based on torque and rpm) so with a big turbo you normally donít add a lot to the torque max but to the torque/HP high in the rpm.
The best indication would be a tuned Diesel engine (torque monster). Maybe look into what European tuners do with a 335d (or whatever the top model is called) and then use this as your limit. A good tuner will be able to keep you under the limit but still give you max hp. As the max torque is around 2-4 and the it drops off.
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      10-05-2019, 05:16 AM   #15
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Quote:
Originally Posted by marcthedark View Post
The clutch is only interested in torque (hp is calculated based on torque and rpm) so with a big turbo you normally donít add a lot to the torque max but to the torque/HP high in the rpm.
The best indication would be a tuned Diesel engine (torque monster). Maybe look into what European tuners do with a 335d (or whatever the top model is called) and then use this as your limit. A good tuner will be able to keep you under the limit but still give you max hp. As the max torque is around 2-4 and the it drops off.
i'm looking specifically for B58 clutch limits. i just saw another thread where someone else is replacing the clutch running stage 2 e30. so i think that's the limit.
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      10-06-2019, 04:37 PM   #16
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Quote:
Originally Posted by kern417 View Post
i'm looking specifically for B58 clutch limits. i just saw another thread where someone else is replacing the clutch running stage 2 e30. so i think that's the limit.
The challenge about discussing a 'limit' is that there's a very important part of clutch capability that is not controlled for: The driver.

How you engage the clutch, how you apply throttle at the same time, how long you let it cool down between hard launches, do you 'bounce' on it while stopped on a hill... all those and more impact the ultimate reliability and performance of the clutch.

The owner of a local shop only ever buys manuals if he can help it, puts crazy high torque mods on his car, and generally doesn't have problems with clutch slippage, because of the way he drives. Other people with the same cars complain about clutch slippage at stage 1 or 2. As with everything, if you're going to modify your car, be willing to pay for stuff that breaks because of it. If with the way you drive the clutch starts slipping, either take off the power mod, or upgrade the clutch.
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      10-07-2019, 07:22 AM   #17
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Quote:
Originally Posted by Araemo View Post
The challenge about discussing a 'limit' is that there's a very important part of clutch capability that is not controlled for: The driver.

How you engage the clutch, how you apply throttle at the same time, how long you let it cool down between hard launches, do you 'bounce' on it while stopped on a hill... all those and more impact the ultimate reliability and performance of the clutch.

The owner of a local shop only ever buys manuals if he can help it, puts crazy high torque mods on his car, and generally doesn't have problems with clutch slippage, because of the way he drives. Other people with the same cars complain about clutch slippage at stage 1 or 2. As with everything, if you're going to modify your car, be willing to pay for stuff that breaks because of it. If with the way you drive the clutch starts slipping, either take off the power mod, or upgrade the clutch.
there's a difference between wearing down your clutch and hitting the limits of torque though. Both people that i know swapped their clutches posted pictures of the discs. They looked just fine. But the pressure plate/material combo couldn't hold the torque and slipped in higher gears with more than half throttle.

If your clutch is just fried, then yeah. That's a different story.
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      10-07-2019, 11:56 AM   #18
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According to Real OEM, every BMW since the E90 has had the same clutch. The recommended upgrade is from an e90 335is/F10 550i. It's only about $330 on FCP Euro (Free lifetime replacement) so that's probably the route I'll go before getting tuned for more power.

Part #21207603248
https://www.fcpeuro.com/products/bmw...uk-21207603248
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      10-09-2019, 07:23 AM   #19
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Quote:
Originally Posted by kern417 View Post
there's a difference between wearing down your clutch and hitting the limits of torque though. Both people that i know swapped their clutches posted pictures of the discs. They looked just fine. But the pressure plate/material combo couldn't hold the torque and slipped in higher gears with more than half throttle.

If your clutch is just fried, then yeah. That's a different story.
Yeah, I just know tons of people complain about their clutch without inspecting it, and it turns out it's glazed when they do take it out.
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      10-09-2019, 09:24 PM   #20
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BM3 OTS E30 Stage 2 was the limit for mine.
I thought it had only slipped a few times but when the box came off the flywheel looked like this.
Car has been tracked 9 times in 2 years, and a few burnouts but mostly just daily driving.





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      10-09-2019, 10:13 PM   #21
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Quote:
Originally Posted by Nugget View Post
BM3 OTS E30 Stage 2 was the limit for mine.
I thought it had only slipped a few times but when the box came off the flywheel looked like this.
Car has been tracked 9 times in 2 years, and a few burnouts but mostly just daily driving.
Looks like we'll need a full stage 2 clutch upgrade including flywheel. I was really hoping I wouldn't have to go single mass because of chatter.
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      10-10-2019, 04:18 AM   #22
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Quote:
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Looks like we'll need a full stage 2 clutch upgrade including flywheel. I was really hoping I wouldn't have to go single mass because of chatter.
unless you plan on going much further, i still feel like the 335is/550i clutch is a viable upgrade for the majority. Tracking 9 times in 2 years is a lot more aggressive driving than most of us do. He needs a clutch that can handle the added heat.
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