Centerforce Clutch Installed on JL Rubicon

[fspalt]

Sounds like the new CF kits with Hydraulics are shipping soon. Anyone have one on order? Also another thought on the hydraulic issue. If the fluid is boiling has anyone tried a higher temp fluid? Not sure what the JL calls for but a DOT5 or perhaps a racing fluid with a higher boiling point may help. I had a 2002 Camaro and in that the pedal would go soft after running it hard. That helped with the issue.

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[DanW]

Sounds like the new CF kits with Hydraulics are shipping soon. Anyone have one on order? Also another thought on the hydraulic issue. If the fluid is boiling has anyone tried a higher temp fluid? Not sure what the JL calls for but a DOT5 or perhaps a racing fluid with a higher boiling point may help. I had a 2002 Camaro and in that the pedal would go soft after running it hard. That helped with the issue.

I've never heard of a JL having an issue with the fluid getting hot.

 

[fspalt]

I've never heard of a JL having an issue with the fluid getting hot.

Yes but standing next to the Jeep on a summer day it feels like you are next to a flamethrower. Maybe its the way the airflow is routed compared to my JK but this thing just feels hotter. As the brake fluid ages it absorbs more water and will boil at a lower temperature. Could that be causing partial engagement of the clutch / slipping?

 

[beaups]

Yes but standing next to the Jeep on a summer day it feels like you are next to a flamethrower. Maybe its the way the airflow is routed compared to my JK but this thing just feels hotter. As the brake fluid ages it absorbs more water and will boil at a lower temperature. Could that be causing partial engagement of the clutch / slipping?

The hydraulic system is used to disengage the clutch, not engage it. Boiling/air/etc in the hydraulic system would create troubles disengaging it, not troubles keeping it engaged - i.e. won't contribute to slipping.

 

[Gregj]

Does the clutch hydraulic system have a residual pressure valve? I think that would be the only thing that *could* contribute to the slipping if the fluid in the line was too hot.
Gregj

Eta: maybe a blockage in the line/master cylinder?

 

[fspalt]

The hydraulic system is used to disengage the clutch, not engage it. Boiling/air/etc in the hydraulic system would create troubles disengaging it, not troubles keeping it engaged - i.e. won't contribute to slipping.

If hot fluid would cause troubles disengaging the clutch couldn't that mean that the clutch is still partially engaged with each shift. Would not fully disengaging the clutch during ever shift cause premature wear / hot spots? It would be like only pushing the part of the way down during shifts.

 

[Toycrusher]

If hot fluid would cause troubles disengaging the clutch couldn't that mean that the clutch is still partially engaged with each shift. Would not fully disengaging the clutch during ever shift cause premature wear / hot spots? It would be like only pushing the part of the way down during shifts.

Yes, but only during the time your foot in on the clutch, which isn't long. Even if you rode the clutch while at a light, your motor is at idle and not developing much heat. Which is why Jeeps initial recall of the reservoir hose was total baloney

 

[beaups]

If hot fluid would cause troubles disengaging the clutch couldn't that mean that the clutch is still partially engaged with each shift. Would not fully disengaging the clutch during ever shift cause premature wear / hot spots? It would be like only pushing the part of the way down during shifts.

Yes that is possible and some speculate that was FCA's theory with the first recall. In reality there should be other obvious symptoms if that is happening. Stalling while stopped and in-gear with the clutch depressed, tough to engage/grinding when shifting gears, etc.

 

[n8billings]

I’ve found this to be helpful. I’ve got a 2023 JLUR 6sp on order and while I hope it’s all sorted out, I’m bracing myself for the inevitable CF or SB upgrade.

 

[BuyHold]

The hydraulic system is used to disengage the clutch, not engage it. Boiling/air/etc in the hydraulic system would create troubles disengaging it, not troubles keeping it engaged - i.e. won't contribute to slipping.

I think that the theory is that when the fluid in the hydraulic system gets exceptionally hot, it expands and then partially disengages the clutch thus allowing the flywheel to slip in way that causes excessive heat in the whole clutch assembly which then ultimately fails in a grenade-like fashion. At least that seems to be the hypothesis that folks seem to be latching onto now as I am understanding it.

 

[DanW]

Yes but standing next to the Jeep on a summer day it feels like you are next to a flamethrower. Maybe its the way the airflow is routed compared to my JK but this thing just feels hotter. As the brake fluid ages it absorbs more water and will boil at a lower temperature. Could that be causing partial engagement of the clutch / slipping?

I'm still on the original fluid with mine and we have very humid summers. No slipping. I don't think these things are old enough to really test that out. Mine is 1st year early production. My guess is no.

 

[LLRubylady]

I think that the theory is that when the fluid in the hydraulic system gets exceptionally hot, it expands and then partially disengages the clutch thus allowing the flywheel to slip in way that causes excessive heat in the whole clutch assembly which then ultimately fails in a grenade-like fashion. At least that seems to be the hypothesis that folks seem to be latching onto now as I am understanding it.

So this would happen even if a centerforce clutch were to be installed? It still uses the hydraulics?

 

[Toycrusher]

I think that the theory is that when the fluid in the hydraulic system gets exceptionally hot, it expands and then partially disengages the clutch thus allowing the flywheel to slip in way that causes excessive heat in the whole clutch assembly which then ultimately fails in a grenade-like fashion. At least that seems to be the hypothesis that folks seem to be latching onto now as I am understanding it.

It's a good theory, but in reality, brake fluid boils when hot rather than expands, resulting in aeration which reduces it's ability to exert force

 

[DanW]

It'll be interesting if any failures occur with the Centerforce. The problem is that there will be such a low percentage of them among the fleet that even if the problem is unrelated to the clutch itself, you might not see a failure just because there are so few and most installers of the Centerforce actually know how to properly bleed the slave cylinder, which is believed to be the root of the issue, anyway.

 

[Toycrusher]

It'll be interesting if any failures occur with the Centerforce. The problem is that there will be such a low percentage of them among the fleet that even if the problem is unrelated to the clutch itself, you might not see a failure just because there are so few and most installers of the Centerforce actually know how to properly bleed the slave cylinder, which is believed to be the root of the issue, anyway.

Just for the record, with the CF, the dual mass flywheel and twin-disc clutch are replaced with a traditional flywheel and single clutch, thereby completely eliminating any chance of such a failure. It's possible to make such a bold statement as having a pressure plate scatter is pretty much an unheard of failure among any clutch, especially a traditional single disc unit. Maybe somewhere in the world at some time it's happened, but neither I nor anyone I know has never heard of it occurring. At worst, when a clutch fails, you get a smoking molten goo and no transfer of power

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