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desmo2

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I chose a manual transmission.

My '97 TJ was a manual (as were a few of my other previous cars). I enjoy the driver involvement with a manual. It may make technical off-roading a bit more difficult, but I don't think I am going to get into anything too hairy in my off-road endeavors, anyway.
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mgroeger

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No way recall Y07 changed any of that. My 2018 with Y07 (and many others who have newer models and got Y01) is exactly as it was before.

The software initates limp mode when temperature is calculated to be above the threshold. It does not reduce power under any other circumstance.

Edit: For anyone concerned by zgn’s comment, please read his posting history. He only got recall #1 done and the dealership (allegedly) damaged his drivetrain: https://www.jlwranglerforums.com/forum/threads/clutch-pressure-plate-recall.52018/post-1554414

Y01/Y02 (aka recall #2) will not affect the way your Jeep drives (unless the clutch slips and generates enough heat to trigger limp mode). I don’t love this “fix” and would greatly prefer new hardware, but I’ll take it over the (very slim) chance that my pressure plate comes apart.
The thing that concerns me about this recall is that it messes with the power when it "calculates" the clutch plate is too hot. I would really like to know how they calculate that since there is no sensor in the manual transmission to determine temp. The reason I am concerned is because I wheel out here in the desert heat and it's not uncommon for my water temp to hit mid 220s and the oil temp to go into low 230s. It doesn't stay there for long and I've never had any temp related issues... i.e. the Jeep is performing as it should.
What I fear is I'm either ripping a dune or climbing a 10 foot wall and the new software decides "Danger Danger!!!" and throttles me back.
 

OldGuyNewJeep

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The thing that concerns me about this recall is that it messes with the power when it "calculates" the clutch plate is too hot. I would really like to know how they calculate that since there is no sensor in the manual transmission to determine temp. The reason I am concerned is because I wheel out here in the desert heat and it's not uncommon for my water temp to hit mid 220s and the oil temp to go into low 230s. It doesn't stay there for long and I've never had any temp related issues... i.e. the Jeep is performing as it should.
What I fear is I'm either ripping a dune or climbing a 10 foot wall and the new software decides "Danger Danger!!!" and throttles me back.
In the recall thread some eginerds detail their hypotheses on how the calculation is done. Regardless of whether or not they are correct, the result of crossing that threshold is limp mode and not just reduced power. If it kicks in on a trail, you’re gonna be stuck until things cool off (hopefully - who knows if there is some reset procedure? I’d think a Tazer or JSCAN programmer could clear CELs and reset, but just a guess). 🤷‍♂️

Personally, I’d rather be inconvenienced and frustrated than have a full blown mechanical failure, so I didn’t hesitate to get the recall done. My teenager drives my Jeep, and no way I want to risk his safety.
 
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eck

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The thing that concerns me about this recall is that it messes with the power when it "calculates" the clutch plate is too hot. I would really like to know how they calculate that since there is no sensor in the manual transmission to determine temp. The reason I am concerned is because I wheel out here in the desert heat and it's not uncommon for my water temp to hit mid 220s and the oil temp to go into low 230s. It doesn't stay there for long and I've never had any temp related issues... i.e. the Jeep is performing as it should.
What I fear is I'm either ripping a dune or climbing a 10 foot wall and the new software decides "Danger Danger!!!" and throttles me back.
How I understand it works (and I have no dog in this fight so I'm not following so close, but as a software guy it interests me...):

It's using the engine RPM combined with the Trans/ABS outputs to estimate clutch temperature.

Easy enough in software to map between these and detect when the clutch is slipping. If you know RPM X in gear Y with final drive Z then you know at 0% clutch slip that you'll get some expected output at the wheels. If you were expecting to get 50 mph but instead you're getting 45 mph, then you've got 10% "slip". Then they likely have a table that maps slip% against speed/RPM. So 10% slip at 50mph is going to generate more friction than 10% slip at 5mph. Then you just do some real world tests to force it to slip a certain amount and see the rate of temperature change.

Over time it just watches for slip and starts accumulating "heat points". If it thinks you're slipping like crazy and about to blow the clutch apart, it goes into limp mode.
 

Toycrusher

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How I understand it works (and I have no dog in this fight so I'm not following so close, but as a software guy it interests me...):

It's using the engine RPM combined with the Trans/ABS outputs to estimate clutch temperature.

Easy enough in software to map between these and detect when the clutch is slipping. If you know RPM X in gear Y with final drive Z then you know at 0% clutch slip that you'll get some expected output at the wheels. If you were expecting to get 50 mph but instead you're getting 45 mph, then you've got 10% "slip". Then they likely have a table that maps slip% against speed/RPM. So 10% slip at 50mph is going to generate more friction than 10% slip at 5mph. Then you just do some real world tests to force it to slip a certain amount and see the rate of temperature change.

Over time it just watches for slip and starts accumulating "heat points". If it thinks you're slipping like crazy and about to blow the clutch apart, it goes into limp mode.
I think your spot on with your logic. I think the slip calculator is a great idea. My beef is... we've been building clutches for over a century. Clutches have been wearing out resulting in uncontrolled slippage for over a century. Why does this clutch become a sudden grenade upon failure while all other clutches to date have ended their lives as a smokey gooey mess and/or fire if someone is really really determined to take it that far.
 

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DanW

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I think your spot on with your logic. I think the slip calculator is a great idea. My beef is... we've been building clutches for over a century. Clutches have been wearing out resulting in uncontrolled slippage for over a century. Why does this clutch become a sudden grenade upon failure while all other clutches to date have ended their lives as a smokey gooey mess and/or fire if someone is really really determined to take it that far.
First of VERY few are confirmed to have had catasrophic failure with one causing a fire that caused the Jeep to be destroyed by fire. They aren't grenading all over the place. I'm not going to go over the specific problem again because it has been laid out several times. If I'm wrong, Stellantis is welcome to correct me. They haven't and won't. My source knows the engineers personally who are on the team that identified the problem and developed the fixes in both recalls. The last recall wasn't because the first failed, but rather the second phase of the overall solution. The second phase is an insurance policy designed to stop the root problem from ever progressing to a catastrophic failure. That's what they told him.

It was not a weak clutch or weak pressure plate. Rather, a condition caused by other factors that had this effect on the clutch and pressure plate. Factors that were human error on the assembly line, and I believe sometimes in dealer service departments that didn't bleed them and set them up correctly when fixing them.

I've driven clutches for 35 years and have run this one harder than any of them with no issue. And I tow with it, too. If it was a bad design, I'd have found it by now. Mine happened to be set up perfectly, and it has passed the clutch wear test more than once. When it is set up properly and has no defects, it works fine and will last a long time.

This part is unrelated to the original problem, but is a truth that nobody likes to admit. Manual transmissions in general are abused more than automatics, by a long shot. Why? Because some people don't know how to properly drive them. Automatics drive themselves. Manuals require a driver to have a skill that has to be learned. Clutches are not nearly as forgiving of abuse as automatic transmissions, these days. (It didn't always used to be that way.)

I am pretty certain of three things.

1. Many of the clutches that were worn out early had the problem. Nearly all of those never approached the temperatures that cause damage to the pressure plate. Driving technique had nothing to do with these.

2. Some of the clutches that have worn out early are caused by improper technique by the drivers.

3. Those who wore them out with improper technique will NEVER admit and most probably don't know it and honestly believe they did nothing incorrectly.
 

DanW

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In the recall thread some eginerds detail their hypotheses on how the calculation is done. Regardless of whether or not they are correct, the result of crossing that threshold is limp mode and not just reduced power. If it kicks in on a trail, you’re gonna be stuck until things cool off (hopefully - who knows if there is some reset procedure? I’d think a Tazer or JSCAN programmer could clear CELs and reset, but just a guess). 🤷‍♂️

Personally, I’d rather be inconvenienced and frustrated than have a full blown mechanical failure, so I didn’t hesitate to get the recall done. My teenager drives my Jeep, and no way I want to risk his safety.
The reset procedure is simply to let it cool. But if it happens once, even if it returns to normal, I'd strongly advise to get it to a dealer to be looked at ASAP.

That said, the temperature threshold is low enough that someone badly slipping it enough can trigger it. That doesn't necessarily mean it has the root problem that caused the recall. But I'd get it checked, anyway, unless I knew I was slipping it excessively. (Most who properly drive them would know). My understanding is that the temperature threshold is far below the temp that would damage the pressure plate.

Not sure why anyone would slip it that much off-road unless they didn't know what they were doing. Especially if in low range.
 

nomographer

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Even on rough rocks I had it mostly in 4L fourth and things were fine, maybe a little luggy. Downshifting into 3rd was not easy; no metal clunking just the obvious mismatches in speed. That was a slow shift though, so other than the engine braking it was probably harder on the driveshaft than the clutch.

I figure an automatic would fair worse because it would constantly be shifting where the manual is just running 400--3000 rpm. (Considering that I was fighting the automatic on a mixed city/highway test drive) I'd probably overheat an automatic and end up with some active feedback loop that pitched it off the side of the mountain.

But I probably don't know how to drive so... :lipssealed:
 

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And one more thing. The way the temp is caculated without a temperature sensor is easy. Data from wheel speed sensors and engine rpm are compared. ANY clutch slip is easily detected and the amount is precisely measured. The amount of slip and the amount of time it is occurring is calculated and the temperature is predicted. The temperature rise in that equation is linear, so it is easy to achieve accuracy. And it was tested over and over and over to fine tune it to be consistently accurate. Turns out it is spot on. That's easy, too. The test mules had temp sensors all around.

And before anyone wets themselves over this depending on an algorythim, please realize that there are thousands, and maybe even tens of thousands of algorythims determining a whole smattering of performance perameters in the engine alone, every second the vehicle is driven. Every modern car/truck relies on the PCM to make these decisions. We don't even think about them. No need to.
 
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DanW

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Even on rough rocks I had it mostly in 4L fourth and things were fine, maybe a little luggy. Downshifting into 3rd was not easy; no metal clunking just the obvious mismatches in speed. That was a slow shift though, so other than the engine braking it was probably harder on the driveshaft than the clutch.

I figure an automatic would fair worse because it would constantly be shifting where the manual is just running 400--3000 rpm. (Considering that I was fighting the automatic on a mixed city/highway test drive) I'd probably overheat an automatic and end up with some active feedback loop that pitched it off the side of the mountain.

But I probably don't know how to drive so... :lipssealed:
It is normal in low range to struggle with matching engine/transmission speed, so it is normal for shifting to be much rougher than in high range. Every manual 4wd I've ever driven is that way.

The autos are easier, but they annoy the hell out of me the way they stop/go in 1st gear low range. It's just wierd to me. Probably because I've rarely driven them.
 

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And one more thing. The way the temp is caculated without a temperature sensor is easy. Data from wheel speed sensors and engine rpm are compared. ANY clutch slip is easily detected and the amount is precisely measured. The amount of slip and the amount of time it is occurring is calculated and the temperature is predicted. The temperature rise in that equation is linear, so it is easy to achieve accuracy. And it was tested over and over and over to fine tune it to be consistently accurate. Turns out it is spot on. That's easy, too. The test mules had temp sensors all around.
Based on your earlier comments, I suspect these are details you've gotten second hand (as opposed to third hand / hearsay). Any reason they're using wheel speed sensors instead of the transfer case input shaft speed sensor? It just seems like wheels could be spinning. (But I seem to recall when I checked wiring diagrams ~four months ago there was a transmission output sensor.)
 

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First of VERY few are confirmed to have had catasrophic failure with one causing a fire that caused the Jeep to be destroyed by fire. They aren't grenading all over the place. I'm not going to go over the specific problem again because it has been laid out several times. If I'm wrong, Stellantis is welcome to correct me. They haven't and won't. My source knows the engineers personally who are on the team that identified the problem and developed the fixes in both recalls. The last recall wasn't because the first failed, but rather the second phase of the overall solution. The second phase is an insurance policy designed to stop the root problem from ever progressing to a catastrophic failure. That's what they told him.

It was not a weak clutch or weak pressure plate. Rather, a condition caused by other factors that had this effect on the clutch and pressure plate. Factors that were human error on the assembly line, and I believe sometimes in dealer service departments that didn't bleed them and set them up correctly when fixing them.

I've driven clutches for 35 years and have run this one harder than any of them with no issue. And I tow with it, too. If it was a bad design, I'd have found it by now. Mine happened to be set up perfectly, and it has passed the clutch wear test more than once. When it is set up properly and has no defects, it works fine and will last a long time.

This part is unrelated to the original problem, but is a truth that nobody likes to admit. Manual transmissions in general are abused more than automatics, by a long shot. Why? Because some people don't know how to properly drive them. Automatics drive themselves. Manuals require a driver to have a skill that has to be learned. Clutches are not nearly as forgiving of abuse as automatic transmissions, these days. (It didn't always used to be that way.)

I am pretty certain of three things.

1. Many of the clutches that were worn out early had the problem. Nearly all of those never approached the temperatures that cause damage to the pressure plate. Driving technique had nothing to do with these.

2. Some of the clutches that have worn out early are caused by improper technique by the drivers.

3. Those who wore them out with improper technique will NEVER admit and most probably don't know it and honestly believe they did nothing incorrectly.
Mine was a "Bad" clutch, did not engage properly at all, yet it took a ton of abuse and was not slipping at all when I replaced it. I agree fully with your 1.2.3.

Still, why did any of them ever come apart? I believe official tally is under 10 catastrophic failures out of 35,000. But still, why?
 

Ken Ztopolovky

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Mine was a "Bad" clutch, did not engage properly at all, yet it took a ton of abuse and was not slipping at all when I replaced it. I agree fully with your 1.2.3.

Still, why did any of them ever come apart? I believe official tally is under 10 catastrophic failures out of 35,000. But still, why?
I hope you are right but I did meet a man whose JL clutch failed at 20K .
 

DanW

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Based on your earlier comments, I suspect these are details you've gotten second hand (as opposed to third hand / hearsay). Any reason they're using wheel speed sensors instead of the transfer case input shaft speed sensor? It just seems like wheels could be spinning. (But I seem to recall when I checked wiring diagrams ~four months ago there was a transmission output sensor.)
Really technically third hand (Or is that 2nd hand? LOL!). A powertrain engineer who knows members of the team with whom he spoke. I believe it is accurate info. But even experts can get details wrong when passing info from one to another.

Even if the wheels are spinning, they will be locked in with engine speed. They differentiate when the clutch is slipping. I wouldn't be surprised if the T-case input sensor is used, too. Either way, they can tell when there is slip and exactly how much is occuring.

What I'd really like to see is to also program in a warning message when the clutch is worn, before it gets to the point where it goes into limp home. I know many of us can feel it, but not everybody knows what that feels like. (My sister used to wear clutches out in 25k miles. I drove some of those and have a pretty good feel for it! LOL!)
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