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Discussion Starter #1
hey guys


i was wondering about the spec clutch for my SMG. They say its gona hold way more tourqe. is it better? there are 2 or 3 options. troyjeup said there was one good of them and some people buy a wrong one or something. he hasnt replied my wich one is supposedly good


https://www.turnermotorsport.com/p-340443-e60-m5-smg-e63-m6-spec-twin-disk-performance-clutch-kit/?pdk=Ag

Carbon/Organic Fiber Clutch (Street) (#SB60SST) ($1619.10) 1
Carbon-Graphite Clutch (Street-Track) (#SB60ST) ($1810.10)


SPEC Clutches & Flywheels: Auto Parts, Domestic, Import, Truck, Racing, Drifting :: Results By Car

SS-Trim P-Trim ST-Trim E-Trim None
Product Number: SB60SST SB60PT SB60ST
Torque Capacity: 710 910 1125
Usage: S,DR,D,RR,R S,D,DR,R,RR S,D,DR,RR,R
Pricing: $1799.00 $1899.00 $1999.00

anyone have had one of those? good or bad? great?


thanks

i have a E64 m6 08
 

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OEM is good enough. There plenty of people with Hp mods and stock clutch. Search on this board and you will see plenty of threads.
Spec clutch set up is a bit harsh on the shifts and I don't know of anyone yet that has given feed back on life span.


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Discussion Starter #3
yeah well the oem is crap right? i had my car for 2 days and i gave out. and i didnt launch once from zero. my friends m5 e60 has under 60k miles and hes on his third oem clutch. wondering if its gona be better for flooring the car and hard shifts?
 

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There is not one single running example anywhere of a SPEC SMG clutch working properly in an SMG3. There are lots of theories, ideas, and supposition, yet not a single running example.

There are parameters in the DME for moment of inertia on each gear of the SMG. Altering the mass of the flywheel and clutch change moment of inertia. Until someone figures out those parameters and tests them for the SPEC setup, I doubt its going to improve. Don't get me wrong, I'm an authorized reseller for SPEC, their 6MT clutch is great.

If the stock clutch on your car gave out, it could have been due to poor adaptations, galled guide bushing/throwout bearing, or a lot of other stuff. There are cars here with almost 800HP at the wheel on the stock clutch.
 

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There is not one single running example anywhere of a SPEC SMG clutch working properly in an SMG3. There are lots of theories, ideas, and supposition, yet not a single running example.

There are parameters in the DME for moment of inertia on each gear of the SMG. Altering the mass of the flywheel and clutch change moment of inertia. Until someone figures out those parameters and tests them for the SPEC setup, I doubt its going to improve. Don't get me wrong, I'm an authorized reseller for SPEC, their 6MT clutch is great.

If the stock clutch on your car gave out, it could have been due to poor adaptations, galled guide bushing/throwout bearing, or a lot of other stuff. There are cars here with almost 800HP at the wheel on the stock clutch.


I️ have to disagree here.... I️ have a FBO smg M5 with Spec Carbon Metallic clutch and it HELLLLLL OF A DIFFERENCE than OeM. Oem clutches are just blah, and the life expectancies on them are SHORT LIVE unfortunately. Even with proper maintenance, adaptations etc, they will give out and cost you a arm and a leg.

I️ agree that guide/throw out bearing goes, as I️ had that happen to me on my oem clutch, which fried the stock clutch. Reason why I️ upgraded to SPEC.

I️ personally love my SPEC, and again I’m smg III


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I️ have to disagree here.... I️ have a FBO smg M5 with Spec Carbon Metallic clutch and it HELLLLLL OF A DIFFERENCE than OeM. Oem clutches are just blah, and the life expectancies on them are SHORT LIVE unfortunately. Even with proper maintenance, adaptations etc, they will give out and cost you a arm and a leg.

I️ agree that guide/throw out bearing goes, as I️ had that happen to me on my oem clutch, which fried the stock clutch. Reason why I️ upgraded to SPEC.

I️ personally love my SPEC, and again I’m smg III


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And you have no problems shifting at WOT?
 

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Discussion Starter #7
There is not one single running example anywhere of a SPEC SMG clutch working properly in an SMG3. There are lots of theories, ideas, and supposition, yet not a single running example.

There are parameters in the DME for moment of inertia on each gear of the SMG. Altering the mass of the flywheel and clutch change moment of inertia. Until someone figures out those parameters and tests them for the SPEC setup, I doubt its going to improve. Don't get me wrong, I'm an authorized reseller for SPEC, their 6MT clutch is great.

If the stock clutch on your car gave out, it could have been due to poor adaptations, galled guide bushing/throwout bearing, or a lot of other stuff. There are cars here with almost 800HP at the wheel on the stock clutch.


I️ have to disagree here.... I️ have a FBO smg M5 with Spec Carbon Metallic clutch and it HELLLLLL OF A DIFFERENCE than OeM. Oem clutches are just blah, and the life expectancies on them are SHORT LIVE unfortunately. Even with proper maintenance, adaptations etc, they will give out and cost you a arm and a leg.

I️ agree that guide/throw out bearing goes, as I️ had that happen to me on my oem clutch, which fried the stock clutch. Reason why I️ upgraded to SPEC.

I️ personally love my SPEC, and again I?m smg III


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so you have the ???


Carbon/Organic Fiber Clutch (Street) (#SB60SST) ($1619.10) 1
Carbon-Graphite Clutch (Street-Track) (#SB60ST) ($1810.10)

??? ddo i need the oem slave to change with them. my friend said he needed that when he did his. and something more ? or just kit ?
 

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I️ have to disagree here.... I️ have a FBO smg M5 with Spec Carbon Metallic clutch and it HELLLLLL OF A DIFFERENCE than OeM. Oem clutches are just blah, and the life expectancies on them are SHORT LIVE unfortunately. Even with proper maintenance, adaptations etc, they will give out and cost you a arm and a leg.

I️ agree that guide/throw out bearing goes, as I️ had that happen to me on my oem clutch, which fried the stock clutch. Reason why I️ upgraded to SPEC.

I️ personally love my SPEC, and again I’m smg III


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You would be the first person on the forum with a positive review on it. I'm wondering if they've changed something. Most everyone else has reported it being harsh and "grabby" from stop.

I have to disagree on the OEM though, my first clutch lasted until 95k, I'd say that's pretty reasonable. They key is adaptation being correct and staying in front of SMG problems so it manages the clutch properly.
 

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so you have the ???


Carbon/Organic Fiber Clutch (Street) (#SB60SST) ($1619.10)1
Carbon-Graphite Clutch (Street-Track) (#SB60ST) ($1810.10)

??? ddo i need the oem slave to change with them. my friend said he needed that when he did his. and something more ? or just kit ?


I️ have the carbon-graphite clutch (1800) one. I️ have the oem slave cylinder on mine and works fine. They give you a new throw out bearing with it. It’s literally plug and play install for the most part.


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You would be the first person on the forum with a positive review on it. I'm wondering if they've changed something. Most everyone else has reported it being harsh and "grabby" from stop.



I have to disagree on the OEM though, my first clutch lasted until 95k, I'd say that's pretty reasonable. They key is adaptation being correct and staying in front of SMG problems so it manages the clutch properly.


Good point Jim. Maybe they did change something, the clutch certainly grabs great on a go and every shift but haven’t noticed it being an issue from stop honestly.


95k on stock clutch WOW, that’s really great. Would you say you were moderate driving on it or aggressive most of the time? I️ could see it lastly that long if one isn’t constantly beating the crap on it.

Mine lasted 77k before it’s first change. Agree on maintenance


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Discussion Starter #11
You would be the first person on the forum with a positive review on it. I'm wondering if they've changed something. Most everyone else has reported it being harsh and "grabby" from stop.



I have to disagree on the OEM though, my first clutch lasted until 95k, I'd say that's pretty reasonable. They key is adaptation being correct and staying in front of SMG problems so it manages the clutch properly.


Good point Jim. Maybe they did change something, the clutch certainly grabs great on a go and every shift but haven?t noticed it being an issue from stop honestly.


95k on stock clutch WOW, that?s really great. Would you say you were moderate driving on it or aggressive most of the time? I️ could see it lastly that long if one isn?t constantly beating the crap on it.

Mine lasted 77k before it?s first change. Agree on maintenance


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what kind of meintance do u mean ?
 

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what kind of meintance do u mean ?


I️Ve done smg fluid changes, REGULARLY not required but I️ did them to keep fluids fresh for the SMG UNIT than clutch per say. Also when I️ did the CHS fluid change I️ redid the adaptations as well, that’s really all you can do. I️ also have my smg unit wrapped in heat wrap to protect the heat that comes from headers etc as that fluids BOILS up an if you never change fluids it’s more goldfish in color when in actuality it should be green and sticky.


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And you have no problems shifting at WOT?


No not at all! It’s pulls hard for me a grabs nicely! I️ personally feel it like actually shifting faster when shifting honestly vs OEM, but again just POV.

My car also has the EURO flash not sure if that makes any difference honestly or not.


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You would be the first person on the forum with a positive review on it. I'm wondering if they've changed something. Most everyone else has reported it being harsh and "grabby" from stop.



I have to disagree on the OEM though, my first clutch lasted until 95k, I'd say that's pretty reasonable. They key is adaptation being correct and staying in front of SMG problems so it manages the clutch properly.


Jim one of your customers a good friend of mine out of De “Joe” bought a tune from you and he runs the SPEC smg clutch as well but the tad cheaper version and loves it. I️ drove in his car and his grabs nicely as well. We installed it at our shop


That’s the version he has.
Carbon/Organic Fiber Clutch (Street) (#SB60SST) ($1619.10)1




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...that fluids BOILS up an if you never change fluids...

I've seen this statement before and with zero evidence to back it up at all. The fluid degrades due to shear and changes color due to wear particles, exactly the same as the PS fluid because....it's the same fluid as the PS. PS fluid doesn't boil, it has it's own cooler. No data anywhere that the SMG fluid temps ever get over 130F, just assumptions. I'm not going to say the insulation won't help anything, but the notion that the fluid degradation is due to heat has no merit at all IMO and no evidence to back the claim. Further, degradation of the fluid, even if a fact, would have little effect on the mechanical components in the SMG hydraulic system with the exception of a loss of viscosity causing inceased leak-by on the .0001" spool-to-cartridge clearance as well as past the cartridge sealing o-rings that due to age, exposure, and material choice, have taken a "compression set" (see the Parker O-ring handbook for reference.) If insulation on anything would help, it would be the wiring harnesses, especially at the top of the SMG on the shift position sensor which uses significantly under-spec insulation.

Having rebuilt about 30 of these hydro units now from the ground up, the most common failures:

- The pump motor is the most common. This is a function of service life and MTBF of a sealed, brushed DC motor where the carbon dust is held inside and specific manufacturing peculiarity which prevents the brush springs from maintaining appropriate contact pressure against the commutator. Lower spring pressure results in increased armature path resistance therefore lower current flow to the armature, therefore less magnetic field strength, and lower armature torque as a result. These have become silly expensive from BMW and we have now started to refurbish these units in-house. The goal is to offer a refurb motor for less than half what BMW does while matching their warranty (2 years) and providing a more complete set of parts than the OEM does (critical o-rings not provided for the swap).

- Shift position sensor strips: The wiring insulation on these units is very poor. BMW is certainly capable of spec'ing the appropriate insulation since we don't see O2 sensors (literally inches from the header). These units sit on top of the SMG and could easily have been made to last longer. This was really more of a failing on Getrag's part as the transmission designer and FTE's fault (manufactures the sensor) for choosing low grade wiring. When we refurbish these, we use Tefzel MILSPEC wiring which is rated well above the temps seen there.

- O-rings: Most degradation in the operation of the units is due to the aging of the o-rings. These should be very malleable and form fit there environment. O-rings actually need to be soft enough to be pushed out of their position and forced into a gap to seal it. That's how they are designed. When an o-ring takes a "compression set" it actually hardens due to loss of porosity. When you take the o-rings off of an old VANOS solenoid or SMG solenoid, you often notice they break before they stretch much. Flouroelastomers (Viton) hold up better than Buna-N, but
Buna-N has always been the default choice in the automotive world due to "cost".

- Very occasionally, we see an actual pump inside the hydraulic block that is bad. Most often this not from a naturally occurring failure, but a lack of following BMW's procedure for replacing the motor and the wrong two bolts were loosened. When this happens, the dry seal established at initial assembly is broken and often overtorqued to compensate for the leakage afterwards. This results in crushing the gear rotors between the drive bushing plates followed by metal on metal wear due to insufficient oil clearance (sound familiar?).


Sorry, this wasn't intended as a rant on your post, but there's a lot of misinformation out there on why these fail and how to prevent it. A lot of claims are made without data to back it up and at some point that leads to a false sense of security and potentially very poor financial decisions.

Do I think it's beneficial to change out the hydraulic fluid? Absolutely. Do I think heat insulation will help anything? Yes, if applied in the correct place, and the reservoir and block aren't going to change anything.
 

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I've seen this statement before and with zero evidence to back it up at all. The fluid degrades due to shear and changes color due to wear particles, exactly the same as the PS fluid because....it's the same fluid as the PS. PS fluid doesn't boil, it has it's own cooler. No data anywhere that the SMG fluid temps ever get over 130F, just assumptions. I'm not going to say the insulation won't help anything, but the notion that the fluid degradation is due to heat has no merit at all IMO and no evidence to back the claim. Further, degradation of the fluid, even if a fact, would have little effect on the mechanical components in the SMG hydraulic system with the exception of a loss of viscosity causing inceased leak-by on the .0001" spool-to-cartridge clearance as well as past the cartridge sealing o-rings that due to age, exposure, and material choice, have taken a "compression set" (see the Parker O-ring handbook for reference.) If insulation on anything would help, it would be the wiring harnesses, especially at the top of the SMG on the shift position sensor which uses significantly under-spec insulation.



Having rebuilt about 30 of these hydro units now from the ground up, the most common failures:



- The pump motor is the most common. This is a function of service life and MTBF of a sealed, brushed DC motor where the carbon dust is held inside and specific manufacturing peculiarity which prevents the brush springs from maintaining appropriate contact pressure against the commutator. Lower spring pressure results in increased armature path resistance therefore lower current flow to the armature, therefore less magnetic field strength, and lower armature torque as a result. These have become silly expensive from BMW and we have now started to refurbish these units in-house. The goal is to offer a refurb motor for less than half what BMW does while matching their warranty (2 years) and providing a more complete set of parts than the OEM does (critical o-rings not provided for the swap).



- Shift position sensor strips: The wiring insulation on these units is very poor. BMW is certainly capable of spec'ing the appropriate insulation since we don't see O2 sensors (literally inches from the header). These units sit on top of the SMG and could easily have been made to last longer. This was really more of a failing on Getrag's part as the transmission designer and FTE's fault (manufactures the sensor) for choosing low grade wiring. When we refurbish these, we use Tefzel MILSPEC wiring which is rated well above the temps seen there.



- O-rings: Most degradation in the operation of the units is due to the aging of the o-rings. These should be very malleable and form fit there environment. O-rings actually need to be soft enough to be pushed out of their position and forced into a gap to seal it. That's how they are designed. When an o-ring takes a "compression set" it actually hardens due to loss of porosity. When you take the o-rings off of an old VANOS solenoid or SMG solenoid, you often notice they break before they stretch much. Flouroelastomers (Viton) hold up better than Buna-N, but

Buna-N has always been the default choice in the automotive world due to "cost".



- Very occasionally, we see an actual pump inside the hydraulic block that is bad. Most often this not from a naturally occurring failure, but a lack of following BMW's procedure for replacing the motor and the wrong two bolts were loosened. When this happens, the dry seal established at initial assembly is broken and often overtorqued to compensate for the leakage afterwards. This results in crushing the gear rotors between the drive bushing plates followed by metal on metal wear due to insufficient oil clearance (sound familiar?).





Sorry, this wasn't intended as a rant on your post, but there's a lot of misinformation out there on why these fail and how to prevent it. A lot of claims are made without data to back it up and at some point that leads to a false sense of security and potentially very poor financial decisions.



Do I think it's beneficial to change out the hydraulic fluid? Absolutely. Do I think heat insulation will help anything? Yes, if applied in the correct place, and the reservoir and block aren't going to change anything.


Great great breakdown Jim. No Rant on the post here sir, all here to help and support each other and love of S85. Thanks for clearing up the “misconceptions” as I️ agree there are a lot out there.

I️ simply was stating some of the things I’ve done and maybe it’s mind over matter lol but def seemed to help my smg life. As you reiterated 1.changing the fluids which I️ do, and 2. Heat wrap the wires above smg unit as well as I️ did the unit itself too just for peace of mind.

Appreciate you chiming in good to have your knowledge and experience on here sir.


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The pump motor is the most common. This is a function of service life and MTBF of a sealed, brushed DC motor where the carbon dust is held inside and specific manufacturing peculiarity which prevents the brush springs from maintaining appropriate contact pressure against the commutator.
Are there any options for a brushless motor? Great breakdown!
 

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No not at all! It’s pulls hard for me a grabs nicely! I️ personally feel it like actually shifting faster when shifting honestly vs OEM, but again just POV.

My car also has the EURO flash not sure if that makes any difference honestly or not.


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Great. Thanks. :cheers:

Which version do you have? Is the install straightforward?
 

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Great great breakdown Jim. No Rant on the post here sir, all here to help and support each other and love of S85. Thanks for clearing up the “misconceptions” as I️ agree there are a lot out there.

I️ simply was stating some of the things I’ve done and maybe it’s mind over matter lol but def seemed to help my smg life. As you reiterated 1.changing the fluids which I️ do, and 2. Heat wrap the wires above smg unit as well as I️ did the unit itself too just for peace of mind.

Appreciate you chiming in good to have your knowledge and experience on here sir.


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I have done the same, heat wrapped the wires. I also change the SMG fluid and transmission fluid every year because my car spends a lot of time on the track.
 
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