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

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So the idea here, per JeepCares’ post, is that no matter what currently unidentified design flaw is causing the transmission to explode, the PCM flash should force the engine into limp mode before permanent damage is sustained by any transmission components because the PCM can detect that clutch slippage is occurring for some reason and put a stop to it. So let’s say it does that. What then?
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TheKeither

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This is all very interesting and troubling at the same time. Since 2001, I have driven two manual transmission vehicles. The first being a 2001 Honda Accord 2dr that I drove to 289,000 miles. On the original clutch. The second is a 2010 Mazda 3 5dr that I am still driving, currently at 193,800 miles and counting. Again, on the original clutch. Neither of these vehicles are something I wanted, but family and money considerations caused me to compromise on them.

Now, I placed an order for a 2021 Jeep Wrangler Unlimited Willy's Sport on January 29th. And of course with a manual. This is a bucket list item for me, as I have wanted one since I saw my very first CJ7 @ about 1986 (I was 13).

How, exactly, worried should I be about this?:(
 

kevinfloats

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Hi everyone, there has been a lot of questions and different threads so I am going to post this and you may see the same info posted on other threads:

Towing capacity or performance will not be affected by this flash update.

There is no difference in the 3.6L engine's power output under "normal circumstances" with the Y01 flash. The torque reduction only happens if the engine controller calculates the clutch pressure plate temperature is above a certain temperature threshold.

The PCM monitors the engine RPM and the wheel speed sensors to determine if clutch slippage is occurring, how often, and at what intensity. Based on that information, the PCM calculates the clutch pressure plate temperature. The temperature threshold that reduces the engine torque is lower than the temperature needed to do permanent pressure plate damage. The vehicle cannot reach or exceed the temperature threshold under normal operating conditions, including towing and off-roading, and only occurs if the driver repeatedly slips the clutch, performs multiple, consecutive 2nd or 3rd gear launches, or if air is present in the hydraulic clutch system.

Kaitlin
Jeep Cares
@JeepCares Thank you for the information. Do you have any information about timelines for Jeeps that are on order with manual transmission? Will they be held until March 19 to deploy the flash update?
 

Kreepin1

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This is all very interesting and troubling at the same time. Since 2001, I have driven two manual transmission vehicles. The first being a 2001 Honda Accord 2dr that I drove to 289,000 miles. On the original clutch. The second is a 2010 Mazda 3 5dr that I am still driving, currently at 193,800 miles and counting. Again, on the original clutch. Neither of these vehicles are something I wanted, but family and money considerations caused me to compromise on them.

Now, I placed an order for a 2021 Jeep Wrangler Unlimited Willy's Sport on January 29th. And of course with a manual. This is a bucket list item for me, as I have wanted one since I saw my very first CJ7 @ about 1986 (I was 13).

How, exactly, worried should I be about this?:(
I'm a mechanical engineer with 30 years experience in software development. I'm also a gearhead and recently installed a similar dual-disk clutch in my 1982 CJ-7 (a McLeod RST). Like you I've got a Wrangler on order and am very concerned about this issue and the way it would be addressed by FCA. I considered cancelling my order and started looking at other vehicles (including the Ford Bronco).

At the heart of the matter is a thin metal plate sandwiched between two friction disks. It is heated from both sides when the clutch slips and doesn't have much exposed surface area to dissipate this heat, so it must be conducted through the friction disks. There is nothing inherently wrong with this design. It used used on many high power sports cars and is a good way to increase torque capacity while reducing clutch pedal effort. However, there have been several cases where the plate gets so hot it flies apart and can start a vehicle fire.

I don't know the driving habits of these owners. But I do know how I will use my Jeep. Mostly I am easy on the clutch. I don't sit at a light in first gear with ESS disabled waiting for the light to change. I don't coast in gear with the clutch depressed. But I will install larger tires. I will crawl through rock gardens, frequently backing up and trying a new line. I will drop the clutch in 2nd or 3rd at 2,500 rpm to blast up sand dunes or muddy hills. And dammit, the clutch better be up to this kind of abuse.

Kaitlin's post has eliminated my concerns. The technical approach of monitoring relative rotational speeds and calculating disk temperature is valid. The software fix acts as a safety net and doesn't reduce torque unless the temperature becomes elevated. You clearly know how to drive a vehicle with a clutch. We will be fine.
 

TheKeither

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I'm a mechanical engineer with 30 years experience in software development. I'm also a gearhead and recently installed a similar dual-disk clutch in my 1982 CJ-7 (a McLeod RST). Like you I've got a Wrangler on order and am very concerned about this issue and the way it would be addressed by FCA. I considered cancelling my order and started looking at other vehicles (including the Ford Bronco).

At the heart of the matter is a thin metal plate sandwiched between two friction disks. It is heated from both sides when the clutch slips and doesn't have much exposed surface area to dissipate this heat, so it must be conducted through the friction disks. There is nothing inherently wrong with this design. It used used on many high power sports cars and is a good way to increase torque capacity while reducing clutch pedal effort. However, there have been several cases where the plate gets so hot it flies apart and can start a vehicle fire.

I don't know the driving habits of these owners. But I do know how I will use my Jeep. Mostly I am easy on the clutch. I don't sit at a light in first gear with ESS disabled waiting for the light to change. I don't coast in gear with the clutch depressed. But I will install larger tires. I will crawl through rock gardens, frequently backing up and trying a new line. I will drop the clutch in 2nd or 3rd at 2,500 rpm to blast up sand dunes or muddy hills. And dammit, the clutch better be up to this kind of abuse.

Kaitlin's post has eliminated my concerns. The technical approach of monitoring relative rotational speeds and calculating disk temperature is valid. The software fix acts as a safety net and doesn't reduce torque unless the temperature becomes elevated. You clearly know how to drive a vehicle with a clutch. We will be fine.
Thanks for taking the time to respond, and respond in an awesome and technical way at that!

I, too, felt a bit better about the situation after reading Kaitlin's post, but I was hoping someone with more knowledge than I would re-enforce that feeling.

Funny, I know how to drive them, but never took the time to learn how they work!
 

EMS

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So the idea here, per JeepCares’ post, is that no matter what currently unidentified design flaw is causing the transmission to explode, the PCM flash should force the engine into limp mode before permanent damage is sustained by any transmission components because the PCM can detect that clutch slippage is occurring for some reason and put a stop to it. So let’s say it does that. What then?
Yup. That's really the only open question. My guess is there will be a blame game when you take it to the dealer to get a new clutch, so essentially you are gambling with the manual transmission. At least with the new FW, you are no longer gambling with your life.
 

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Will this formula of engine RPM and wheel speed for calculating clutch temp dictate what tire size (35,37,or 40)we might run ? Or also if you run different gears (4.88,5.13 or taller)? All of these or any combination change RPM and wheel speed.
Also what exactly is done to reduce engine torque ? Is it a simple mater of cutting fuel and slowing RPM to a minimum ? Will it go back to normal after a certain amount of time or an acknowledgement of some type ? If it is a false alarm or bad readings and you are 100 miles from the closest town, with 40 miles of it being not good dirt roads, this might be a problem.
 

Kreepin1

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Will this formula of engine RPM and wheel speed for calculating clutch temp dictate what tire size (35,37,or 40)we might run ? Or also if you run different gears (4.88,5.13 or taller)? All of these or any combination change RPM and wheel speed.
Also what exactly is done to reduce engine torque ? Is it a simple mater of cutting fuel and slowing RPM to a minimum ? Will it go back to normal after a certain amount of time or an acknowledgement of some type ? If it is a false alarm or bad readings and you are 100 miles from the closest town, with 40 miles of it being not good dirt roads, this might be a problem.
I can give you my opinion, but don't claim to have any insider information.

Tire size and gearing will not impact the calculation. They are going to be looking for non-linear behavior, engine speed going up without a corresponding change in wheel speeds. This is similar to what they are already doing for traction control, with the addition of engine rpm.

Engine torque will most likely be controlled by cutting fuel and timing until no slippage is detected.

No clue on what will cause a reset and return to normal, good question. Regardless, I would rather have to limp home on 40 miles of dirt road than walk 40 miles of dirt road after complete failure.
 

OldGuyNewJeep

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JeepCares

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Here is another interesting question, and maybe the answer will tell us if FCA acknowledges the defect: When the condition is sensed by the PCM, will it throw a "service engine soon" warning to the driver?
It is my understanding a warning message will populate. I don't have details on what it will say or anything.

Kaitlin
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JeepCares

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@JeepCares Thank you for the information. Do you have any information about timelines for Jeeps that are on order with manual transmission? Will they be held until March 19 to deploy the flash update?
I just know they will be delayed until the flash is available, which is anticipated to be in March.

Kaitlin
Jeep Cares
 

DanW

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So the idea here, per JeepCares’ post, is that no matter what currently unidentified design flaw is causing the transmission to explode, the PCM flash should force the engine into limp mode before permanent damage is sustained by any transmission components because the PCM can detect that clutch slippage is occurring for some reason and put a stop to it. So let’s say it does that. What then?
Then you go to the dealer and they should begin the process to diagnose what caused it. If it continues to happen infrequently, then they'll probably be contacted by an engineer or higher level tech rep to give them a procedure to check the hydraulic system for air. After that, they'll likely order and install a new transmission. Your old one would then be shipped to Detroit or wherever their forensic engineering team is located so they can dissect it and analyze it.

If it happens frequently, then by that point, they'll address whatever they have determined is the specific problem. If it does not require a new transmission, then they'll likely test/inspect the clutch and pressure plate for damage and wear and replace them if necessary.

Either way, that scenario hopefully greatly reduces the odds of you ever experiencing an uncontained failure, as the jet engine community puts it, and the resulting potential hazards that could cause, such as a crash or a fire and injury or death.

But I could be wrong.
 

DanW

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Hi everyone, there has been a lot of questions and different threads so I am going to post this and you may see the same info posted on other threads:

Towing capacity or performance will not be affected by this flash update.

There is no difference in the 3.6L engine's power output under "normal circumstances" with the Y01 flash. The torque reduction only happens if the engine controller calculates the clutch pressure plate temperature is above a certain temperature threshold.

The PCM monitors the engine RPM and the wheel speed sensors to determine if clutch slippage is occurring, how often, and at what intensity. Based on that information, the PCM calculates the clutch pressure plate temperature. The temperature threshold that reduces the engine torque is lower than the temperature needed to do permanent pressure plate damage. The vehicle cannot reach or exceed the temperature threshold under normal operating conditions, including towing and off-roading, and only occurs if the driver repeatedly slips the clutch, performs multiple, consecutive 2nd or 3rd gear launches, or if air is present in the hydraulic clutch system.

Kaitlin
Jeep Cares
Thank you, @JeepCares !!!

To all others.....Well, sometimes even a blind squirrel finds a nut. I'll take my moment in the sun for that one lucky time I was right. Thank you, thank you very much!


JUST KIDDING!!!!!!

And may the fleas of a thousand camels infest the armpits of the NHTSA bureacrat who confused everyone by leaving out important details. And congrats to the other one who essentially got it right.
 
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