Why not buy a Centerforce dual friction clutch?

[bryanklay]

i finally have the jeep back up and running. the two issues that i had was not with the clutch system or putting the jeep back together, it was with the slave cylinder and setting up the shift cables. the slave cylinder would not bleed properly so i had to remove the slave cylinder and do the alternate bleed procedure that is in the tech manual. this did finally work and the system finally gravity bled. on the issue of the shift cables, the tech manual explains that you have to check the cable adjustments for the shifter if you disconnected the cables or the cable bracket that is attached to the trans. i can now wait very patiently for the clutch from centerforce.

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[seven30]

Definitely looks like you got a bad one - out of spec. Good luck with the new clutch setup.

I really appreciate the time you took to document this and confirming the dual mass clutch basket design. This, in my opinion, the the root of the clutch issues. The dual mass destroys offline grunt but is required for the stop/start system to reduce starter wear and tear. The same dual plate clutch in a non-dual mass system would almost certainly perform very well.

Like you I have owned manuals since I started driving on the ranch as a kid in 65. This is the first dual-mass clutch Ive used and is pretty bad. I have an ultra light floater and flywheel in my track car that is easier to use.

 

[JT1]

I really appreciate the time you took to document this and confirming the dual mass clutch basket design. This, in my opinion, the the root of the clutch issues. The dual mass destroys offline grunt but is required for the stop/start system to reduce starter wear and tear. The same dual plate clutch in a non-dual mass system would almost certainly perform very well.

Like you I have owned manuals since I started driving on the ranch as a kid in 65. This is the first dual-mass clutch Ive used and is pretty bad. I have an ultra light floater and flywheel in my track car that is easier to use.

Can you elaborate? The dual mass flywheel is somehow integral to the auto start/stop?
If thats the case, can a fixed single mass flywheel eliminate the ess and fix the way these things behave during clutch engagement?

 

[Gatorized]

I really appreciate the time you took to document this and confirming the dual mass clutch basket design. This, in my opinion, the the root of the clutch issues. The dual mass destroys offline grunt but is required for the stop/start system to reduce starter wear and tear. The same dual plate clutch in a non-dual mass system would almost certainly perform very well.

Like you I have owned manuals since I started driving on the ranch as a kid in 65. This is the first dual-mass clutch Ive used and is pretty bad. I have an ultra light floater and flywheel in my track car that is easier to use.

How does the clutch impact start/stop? Clutch pedal has to. be depressed to activate start. If it is disengaged is there any impact?

 

[NachoRuby]

I really appreciate the time you took to document this and confirming the dual mass clutch basket design. This, in my opinion, the the root of the clutch issues. The dual mass destroys offline grunt but is required for the stop/start system to reduce starter wear and tear. The same dual plate clutch in a non-dual mass system would almost certainly perform very well.

Like you I have owned manuals since I started driving on the ranch as a kid in 65. This is the first dual-mass clutch Ive used and is pretty bad. I have an ultra light floater and flywheel in my track car that is easier to use.

I don't think dual mass flywheels are for auto start/stop. VWs have had them for years. A lot of people don't like them on VWs either. But manual VWs don't have Auto start stop. The reason given in the VW world is for decreased nvh, which is immediately evident if you switch from dual mass to single mass on a gti/golf r/ Jetta GLi. Also, it's done to decrease wear on the crank and transmission (in theory). It's for vibrations and noise control. I don't know what cars come with dual mass flywheels, but I know many of them do not have auto start stop.

I know it's wikipedia, but check out this article. Also seems to point to the reason as being decreased vibration.

https://en.m.wikipedia.org/wiki/Dual-mass_flywheel
And also this one

https://www.pistonheads.com/news/ph-explains/what-is-a-dual-mass-flywheel-ph-explains/39036

 

[seven30]

I don't think dual mass flywheels are for auto start/stop. VWs have had them for years. A lot of people don't like them on VWs either. But manual VWs don't have Auto start stop. The reason given in the VW world is for decreased nvh, which is immediately evident if you switch from dual mass to single mass on a gti/golf r/ Jetta GLi. Also, it's done to decrease wear on the crank and transmission (in theory). It's for vibrations and noise control. I don't know what cars come with dual mass flywheels, but I know many of them do not have auto start stop.

I know it's wikipedia, but check out this article. Also seems to point to the reason as being decreased vibration.

https://en.m.wikipedia.org/wiki/Dual-mass_flywheel
And also this one

https://www.pistonheads.com/news/ph-explains/what-is-a-dual-mass-flywheel-ph-explains/39036

True but is there a stop/start car the does not have a dual-mass clutch?

I guessing that the first dual mass were probably tuned for NVH but the mass split and dynamics for stop/start systems are likely to be tuned for that purpose.

The same way our dual mass makes it easy to stall also makes it easy to start. When the starter first kicks in the extra inertia of a conventional flywheel adds wear and tear to the starter brushes and gears. No big deal unless your stop/start-ing at nearly every light.

I am thinking the JT would be a lot easier to drive with a welded up dual-mass system.

 

[NachoRuby]

True but is there a stop/start car the does not have a dual-mass clutch?

I guessing that the first dual mass were probably tuned for NVH but the mass split and dynamics for stop/start systems are likely to be tuned for that purpose.

The same way our dual mass makes it easy to stall also makes it easy to start. When the starter first kicks in the extra inertia of a conventional flywheel adds wear and tear to the starter brushes and gears. No big deal unless your stop/start-ing at nearly every light.

I am thinking the JT would be a lot easier to drive with a welded up dual-mass system.

That might have to do with gearing. I don't have a stall problem with the 4.1 gearing. I think they undergeared the models with 3.73 FD (just a hypothesis). Especially if you go to larger tires.

The 4.1 ratio drives itself without throttle input even. It's literally hard to stall. Dual mass makes it pretty numb (in my experience with VW and Jeep), but it doesn't make it harder to prevent a stall or to take off. Now, that soft pedal feel does have me looking at the aftermarket, but more for durability than drivability. I'll wait for mine to go before upgrading, though. I'm in no rush.

It does seem like every one with stalling issues is on 3.73 gearing, and those with 4.1 are not having that issue. We only complain about the soft feel, but not drivability. So I think I think the 3.73s are just undergeared.

I also think reverse is a little tall, requiring more speed than I want to keep the RPMs up. That's gotta be even worse on 3.73s. But with Rubi/Mojave gearing, it's perfectly drivable. I test drove and almost purchased a Willys Sport (3.73), but not long enough to know if stalling would be an issue.

 

[Bbannongmu]

That might have to do with gearing. I don't have a stall problem with the 4.1 gearing. I think they undergeared the models with 3.73 FD (just a hypothesis). Especially if you go to larger tires.

The 4.1 ratio drives itself without throttle input even. It's literally hard to stall. Dual mass makes it pretty numb (in my experience with VW and Jeep), but it doesn't make it harder to prevent a stall or to take off. Now, that soft pedal feel does have me looking at the aftermarket, but more for durability than drivability. I'll wait for mine to go before upgrading, though. I'm in no rush.

It does seem like every one with stalling issues is on 3.73 gearing, and those with 4.1 are not having that issue. We only complain about the soft feel, but not drivability. So I think I think the 3.73s are just undergeared.

I also think reverse is a little tall, requiring more speed than I want to keep the RPMs up. That's gotta be even worse on 3.73s. But with Rubi/Mojave gearing, it's perfectly drivable. I test drove and almost purchased a Willys Sport (3.73), but not long enough to know if stalling would be an issue.

The Centerforce heavier flywheel and grippier clutch and much more positive engagement really turn this into a much tougher, better vehicle to drive. Towing is greatly improved too.

 

[seven30]

That might have to do with gearing. I don't have a stall problem with the 4.1 gearing. I think they undergeared the models with 3.73 FD (just a hypothesis). Especially if you go to larger tires.

The 4.1 ratio drives itself without throttle input even. It's literally hard to stall. Dual mass makes it pretty numb (in my experience with VW and Jeep), but it doesn't make it harder to prevent a stall or to take off. Now, that soft pedal feel does have me looking at the aftermarket, but more for durability than drivability. I'll wait for mine to go before upgrading, though. I'm in no rush.

It does seem like every one with stalling issues is on 3.73 gearing, and those with 4.1 are not having that issue. We only complain about the soft feel, but not drivability. So I think I think the 3.73s are just undergeared.

I also think reverse is a little tall, requiring more speed than I want to keep the RPMs up. That's gotta be even worse on 3.73s. But with Rubi/Mojave gearing, it's perfectly drivable. I test drove and almost purchased a Willys Sport (3.73), but not long enough to know if stalling would be an issue.

I have the 4.1 gearing and it does drive its self with clutch out. Like many others on this thread have found initial start off is problematic hence the desire to switch to centerforce. But I like the dual disc system. Its just the dual mass that is problematic.

 

[NachoRuby]

I have the 4.1 gearing and it does drive its self with clutch out. Like many others on this thread have found initial start off is problematic hence the desire to switch to centerforce. But I like the dual disc system. Its just the dual mass that is problematic.

I'm probably already used to dual mass. Seems to be the norm now. So maybe that's it then. My VW had it, and I think my compass did too. My only problem is the soft clutch. I'd welcome the heft/grip of the centerforce. I have no stalling issue whatsoever. I don't know then. Just a guess. You might also want to try a pedal commander. Maybe it's the delayed electronic throttle response? Throttle lag is real on this platform.

I don't think I had a stalling issue with dual mass on the VW. But I hated the compass. I hated everything about it. But that second article I linked is from the UK, where most cars are still stick. It says 50% of all new cars have a dual mass flywheel, so it seems to be taking over the manual options that are left. It's harder to "launch" the dmf, but I don't launch the jeep anyway. Just taking off in traffic, it's fine.

When mine goes, I'll go centerforce or south bend. I don't expect the stock clutch to last forever. But while it lasts, I have no drivability issues with it. No stalling. Just seems weak.

 

[bryanklay]

in doing my research, i went to the tech manual and found this:

"The dual mass flywheel is used on all engines. The flywheel incorporates the ring gear around the outer circumference to mesh with the starter to permit engine cranking. The primary flywheel side is bolted to the crankshaft. the secondary flywheel side serves as the driving member to the clutch disks. Internal springs between the flywheels are used to dampen energy. The dual mass flywheel is serviced as an assembly only and should never be taken apart."

"The flywheel is bolted firmly to the crankshaft which transmits part of the engine torque to the clutch disks. The rest of the torque passes into the cover through the bolts holding the clutch to the flywheel. From there, the straps transfer it to the clutch pressure plates. The diaphragm spring clamps the pressure plates against the clutch disks to achieve positive lockup with the flywheel. The clutch disks transmits the entire engine torque to the transmission via splined connection to the transmission input shaft. When the driver depresses the clutch pedal, the release bearing actuate the diaphragm spring pivots on this fulcrum ring, so that the outside diameter moves away from the pressure plate. this causes the preloaded drive straps to pull the pressure plates away from the clutch disks, interrupting torque transmission. When the driver releases the pedal, the outer portion of the diaphragm springs act on both of the pressure plates which clamp both disks with the dual mass flywheel."

Operation
"The flywheel serves to dampen the engine firing pulses. The heavy weight of the flywheel relative to the rotating mass of the engine components serves to stabilize the flow of power to the remainder of the drivetrain. The crankshaft has the tendency to attempt to speed up and slowdown in response to the cylinder firing pulses. The flywheel dampens these impulses by absorbing energy when the crankshaft speeds and releases the energy back into the system when the crankshaft slows down."

The Clutch
"The clutch assembly controls the transfer of torque from the engine flywheel to the manual transmission input shaft. the clutch assembly consists of the two disks, two plate, and cover. The clutch disk consists of multiple friction material surfaces positioned on a metal frame and a free floating center hub. The clutch disks may have damping characteristics. The clutch cover assembly consists of 2 cast pressure plates and a heat treated steel spring contained under a stamped steel cover. It is bolted to the flywheel and exerts load against the clutch friction disks."

I hope this helps. it did for me. and yes i am greatly and patently waiting for the centerforce clutch.

 

[bryanklay]

I don't think dual mass flywheels are for auto start/stop. VWs have had them for years. A lot of people don't like them on VWs either. But manual VWs don't have Auto start stop. The reason given in the VW world is for decreased nvh, which is immediately evident if you switch from dual mass to single mass on a gti/golf r/ Jetta GLi. Also, it's done to decrease wear on the crank and transmission (in theory). It's for vibrations and noise control. I don't know what cars come with dual mass flywheels, but I know many of them do not have auto start stop.

I know it's wikipedia, but check out this article. Also seems to point to the reason as being decreased vibration.

https://en.m.wikipedia.org/wiki/Dual-mass_flywheel
And also this one

https://www.pistonheads.com/news/ph-explains/what-is-a-dual-mass-flywheel-ph-explains/39036

these two articles are a very good read and hey help explain the propose of the dual mass flywheel which follows what the tech manual states.

 

[bryanklay]

Definitely looks like you got a bad one - out of spec. Good luck with the new clutch setup.

i think you might be right and i have been wondering how the centerforce clutch will handle this transmission because i am thinking this might be one of those transmissions that have the issue of the wobble with the input shaft.

I really appreciate the time you took to document this and confirming the dual mass clutch basket design. This, in my opinion, the the root of the clutch issues. The dual mass destroys offline grunt but is required for the stop/start system to reduce starter wear and tear. The same dual plate clutch in a non-dual mass system would almost certainly perform very well.

Like you I have owned manuals since I started driving on the ranch as a kid in 65. This is the first dual-mass clutch Ive used and is pretty bad. I have an ultra light floater and flywheel in my track car that is easier to use.

based on all of the research that i have done and all of the the work and changes that i did, i do not believe the dual mass flywheel has anything to do with the Stop/start system. the Stop/start system is all about the starter and the batteries. just so you know, i have been known to be wrong.

 

[seven30]

i think you might be right and i have been wondering how the centerforce clutch will handle this transmission because i am thinking this might be one of those transmissions that have the issue of the wobble with the input shaft.

based on all of the research that i have done and all of the the work and changes that i did, i do not believe the dual mass flywheel has anything to do with the Stop/start system. the Stop/start system is all about the starter and the batteries. just so you know, i have been known to be wrong.

Dual-mass is a design but the details vary. For example, if you took a heavy centerforce flywheel and added the secondary flywheel it would still have the advantage of the centerforce inertia. The mass of the primary and secondary flywheels and the coupling between them are engineering design points for some objective. I asked myself why would the primary flywheel be low inertia and it seems one good reason is to assist stop/start. But the inertia to carry over between cylinder firings at low rpm is just marginal with the stock design.
A dual-mass for a buzzy four makes sense but it kind of superfluous with a V6.

To add to this further, I find I need the minimim rpm to prevent stalling higher than the conventional design in my old Comanche truck. There is only one good reason for that: Flywheel intertia.

"The primary flywheel side is bolted to the crankshaft. the secondary flywheel side serves as the driving member to the clutch disks. Internal springs between the flywheels are used to dampen energy. The dual mass flywheel is serviced as an assembly only and should never be taken apart."

 

[NachoRuby]

Dual-mass is a design but the details vary. For example, if you took a heavy centerforce flywheel and added the secondary flywheel it would still have the advantage of the centerforce inertia. The mass of the primary and secondary flywheels and the coupling between them are engineering design points for some objective. I asked myself why would the primary flywheel be low inertia and it seems one good reason is to assist stop/start. But the inertia to carry over between cylinder firings at low rpm is just marginal with the stock design.
A dual-mass for a buzzy four makes sense but it kind of superfluous with a V6.

To add to this further, I find I need the minimim rpm to prevent stalling higher than the conventional design in my old Comanche truck. There is only one good reason for that: Flywheel intertia.

"The primary flywheel side is bolted to the crankshaft. the secondary flywheel side serves as the driving member to the clutch disks. Internal springs between the flywheels are used to dampen energy. The dual mass flywheel is serviced as an assembly only and should never be taken apart."

Camaros and CTSs (with the v6) have dual mass flywheels, circa 2013. No start stop there. So did the last generation of v6 mustangs, with no start stop.

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