Clutch Recall (FCA W12 | 20V-124) on 2018-2020 JL Manuals [overheating clutch pressure plate]

DanW

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...just an observation here: The heat generated by the friction material does not have an easy conduction path to the bell housing since they are not directly connected. So any temperature increase due to the hot pressure plate would either be by convected air inside the bell or by radiation, certainly not as efficient as direct conduction.
It doesn't need much of one with aluminum, just milimeters away from the pressure plate. I it overheated in a significant way, it would have gotten that bell housing hotter than 105 degrees. Mine has never given a symptom of excessive heat. It had another opportunity today and it showed nothing of concern.

Mine passed the clutch wear test at 35k. It now has 41k. It has towed, done long days of off-roading, and been driven hard many, many times. I'm convinced mine has no issue. The external temp is just another piece of evidence. Not conclusive in and of itself, but I think it is a pretty good sign that it didn't show a higher temp than 105, immediately after being punished like it was.





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DanW

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The question I've always had, even back during the initial recall, is whether these fire events were during long drives on highways, where clutch disengagements are few, or during stop-and-go inner city traffic, where normal operation of the vehicle requires frequent clutch operation.
Good question. But if the pressure plate was weakened in stop and go driving, it might not come apart until it gets high centrifugal force from spinning at highway speeds. So the investigation would have to look beyond just the conditions where it actually came apart.
 

sf5211

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Good question. But if the pressure plate was weakened in stop and go driving, it might not come apart until it gets high centrifugal force from spinning at highway speeds. So the investigation would have to look beyond just the conditions where it actually came apart.
I actually remember the poster who’s Jeep burned up said he was in 3rd gear and climbing a slight hill.
 

Jebiruph

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I actually remember the poster who’s Jeep burned up said he was in 3rd gear and climbing a slight hill.
That's interesting. Prior to my clutch replacement, on several occasions I would smell something burning while getting on the freeway, accelerating uphill in 3rd gear. It did not smell like a burning clutch, more like burning paper. It took about 3 or 4 times before I noticed a pattern. I did not detect any slipping and I'm still not convinced it was the clutch. Here's what my clutch and pressure plate looked like when they where replaced.
jl clutch pressure plate old.jpg

jl clutch old.jpg
 

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That's interesting. Prior to my clutch replacement, on several occasions I would smell something burning while getting on the freeway, accelerating uphill in 3rd gear. It did not smell like a burning clutch, more like burning paper. It took about 3 or 4 times before I noticed a pattern. I did not detect any slipping and I'm still not convinced it was the clutch. Here's what my clutch and pressure plate looked like when they where replaced.
jl clutch pressure plate old.jpg

jl clutch old.jpg
how many miles?

as designed? lol
 

DanW

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I actually remember the poster who’s Jeep burned up said he was in 3rd gear and climbing a slight hill.
High rpm?
 

Jebiruph

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High rpm?
Not sure, might have been around 4.5k, whatever rpm is at 55mph in 3rd gear for a sport on stock tires. Since I was accelerating from a stop, rpm's in 2nd gear would have an impact too, but I don't usually get it over 4.5 -5K.
 

beaups

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Not sure, might have been around 4.5k, whatever rpm is at 55mph in 3rd gear for a sport on stock tires. Since I was accelerating from a stop, rpm's in 2nd gear would have an impact too, but I don't usually get it over 4.5 -5K.
55 in 3rd on sport in 3rd = ~3100rpm
 

Jebiruph

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55 in 3rd on sport in 3rd = ~3100rpm
I probably hit around 4.5k in 2nd, I typically don't rev higher than that. I haven't really put any miles on it in the 8 months since repair due to working from home, so it hasn't been driven in that situation since then.
 

DanW

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I probably hit around 4.5k in 2nd, I typically don't rev higher than that. I haven't really put any miles on it in the 8 months since repair due to working from home, so it hasn't been driven in that situation since then.
There's still a great deal of centrifugal force even at 3100 rpm.
 

Torero

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That's interesting. Prior to my clutch replacement, on several occasions I would smell something burning while getting on the freeway, accelerating uphill in 3rd gear. It did not smell like a burning clutch, more like burning paper. It took about 3 or 4 times before I noticed a pattern. I did not detect any slipping and I'm still not convinced it was the clutch. Here's what my clutch and pressure plate looked like when they where replaced.
jl clutch pressure plate old.jpg

jl clutch old.jpg
Wow, I have replaced many clutches but never a Jeep one. That is a weird disc. First it doesn’t have shock absorbing springs that I can see, and what the heck is that sprocket and what does it do? Would someone mind to explain? I have attached a picture of a typical disc for comparison.
8D769AFB-9968-45EF-85FC-C2E9475751E8.jpeg
 

Toycrusher

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Good question. But if the pressure plate was weakened in stop and go driving, it might not come apart until it gets high centrifugal force from spinning at highway speeds. So the investigation would have to look beyond just the conditions where it actually came apart.
Technically it spins at engine rpm. Force is the same revved up in neutral as it would be at 100 mph in 3rd or 4th
 

Toycrusher

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Wow, I have replaced many clutches but never a Jeep one. That is a weird disc. First it doesn’t have shock absorbing springs that I can see, and what the heck is that sprocket and what does it do? Would someone mind to explain? I have attached a picture of a typical disc for comparison.
8D769AFB-9968-45EF-85FC-C2E9475751E8.jpeg
It's a twin disc clutch. As you release the pedal it grips a clutch inside the pressure plate. That clutch is splined to the disc we can see which then applies pressure between the outer part of the pressure plate and the actual Flywheel.

Theoretically the pressure is applied evenly and you have a smoother application of torque between the two sets of discs and plates.

In reality you have double the slippage and heat and lots of opportunity for inconsistent engagement. A disaster with the lightweight dual mass Flywheel. My first disc would engage enough to stall my motor if I didn't apply enough throttle, but yet it wouldn't pass enough torque to move my Jeep. It would slip the 2nd disc with a lot of rpm before it would abruptly engage.
 

sf5211

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High rpm?
No Dan, he claimed he was driving normally.
What I find interesting is I just searched the forum and can’t find that thread. Hmm,
I remember it was Ocean Blue but I wish I could remember the person.
I also tried to go back on my history and the only thing I found was the first clutch recall thread which was after that guys fire.
 

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