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JT/JL Clutch and Flywheel explained by ACT

ericnewcom

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JP6-HDSS ordered! With the 5.13s, this ought to be a new truck.

Sounds like it'll be a nice setup. I plan to do 5.13s too when my stock 33s need replacing and I step up in tire size.
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Zachattack50

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ACT what's the weight difference from my CF to your pro mass?
 

Zachattack50

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I was just curious. Like I've already stated it was a time crunch thing for me. Well worth it whichever way you go. Just be thankfull you didn't need to get the master cylinder out, that sucked.
 

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ProMass is 40.8 @ 11" diameter
CF is 43.8 @ 10.4" diameter

Google calculator says Pro Mass has more inertia given the wider diameter.
Google calculator doesn't take into account where the mass is. The 11" vs 10.4" is clutch disc size. You would need to compare the two assemblies including the pressure plate and disc for each to get an accurate value. Without testing on our inertia tester, I would just say they are comparable, and I huge increase over standard JL/JT parts.
 

loganjeeps

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Clutch Assist Spring Testing

From a recent clutch installation on a Gladiator with 62K we were able to get more testing done and gain more data points to consider. First, we focused a lot on the pedal assembly and testing the assist spring.

Installation is super easy. If you don’t like it, take a couple minutes, and change it back. You may want to change it a couple times just to be sure you are not imagining anything in your analysis.

I am not saying that this will solve the OE clutch issues of the JL/JT, but maybe this will improve the driving experience with the stock clutch.
Been running the lighter spring for about a week now. I only had 2500 miles on my JT when I did the swap so my factory spring was still really fresh. So far I, prefer it over the factory spring. The most notable positive is at the very top and very bottom of the pedal stroke there is no longer the drastic "slapping" action that is more obvious in Dirk's video of the pedal assembly off the vehicle. This makes for a much more consistent pedal feel and I can detect the clutch engagement point a bit better. Only downside from my perspective is the spring is lighter and makes the overall feel of the clucth slightly lighter as well. But we all know the only solution for that problem. I like perfer my clutches feel like I'm pushing on a diving board. Overall very nice easy install and budget option to improve driveability.

Added a pic below of the spring from a different angle. I found it easier to pull up on the bottom white part of the srping collar to get it off than pulling down on the black top collar. Arrow is pointing up toward dashboard

Jeep Gladiator JT/JL Clutch and Flywheel explained by ACT 1686108354954
 

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If you’re one of the many thousands of manual JL/JT’s and your experiencing issues with the factory clutch, and/or you're looking for peace of mind over the factory clutch, this new clutch from ACT with their Pro-Mass flywheel is incredible!! I love it!! Here’s my 5000 mile evaluation. https://youtu.be/Kg8Ie6fJSFQ

IMG_5972.jpeg
 

udrugby09

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Hey ACTman (and other contributors/guinea pigs ;)),
Appreciate all the info! One thing I am still curious about is why, if anyone knows, CF did decide to change to change out the hydraulics with their kit, and (directed more toward you) why ACT deemed it unnecessary.

I've read through the few main threads regarding the recalls and your clutch kit, but that's one thing I haven't seen be discussed. Admittedly, I haven't watched any videos yet, so my apologies if it's covered there and I missed it!
 
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ACTman

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Hey ACTman (and other contributors/guinea pigs ;)),
Appreciate all the info! One thing I am still curious about is why, if anyone knows, CF did decide to change to change out the hydraulics with their kit, and (directed more toward you) why ACT deemed it unnecessary.

I've read through the few main threads regarding the recalls and your clutch kit, but that's one thing I haven't seen be discussed. Admittedly, I haven't watched any videos yet, so my apologies if it's covered there and I missed it!
The difference between the JL hydraulics and JK hydraulics (what CF adapted for the JL) is the cylinder piston size. The JK hydraulics move the clutch arm further than the JL but otherwise of the same construction. By adapting the JK hydraulics CF now has enough travel to operate their clutch.
As indicated in my videos, ACT was able to make our 11" clutch more efficient so it didn't require additional travel, so there is no need to change the operating system.
 

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udrugby09

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Appreciate the quick reply! Should have just done my homework and watched your videos at home tonight lol.

I was just about to start ordering parts for a lift & tire upgrade on my Overland before deciding I should look into the clutch recall first... esp. adding more rolling resistance with hay season just about in full swing where I'd be further pushing tow cap! 😅

Not having to swap those parts out AND having an installation video is huge; I'm no experienced mechanic, but I'll DIY things I can do in a weekend. Being on crutches now I may be outsourcing that work, but I'll save on both parts & labor with your kit either way!

Also nice not to worry about Stellantis potentially gimping performance to maintain EPA numbers if/when a real fix and parts become available. Something tells me the Sep 2023 estimate is a little optimistic... and I've got way too much towing and traveling to do while I wait. From the sounds of it (besides obv. safety concerns) it solves the only complaints I've had about driving it, so I'm really excited.

Thanks again!
 

hawkijon

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Appreciate the quick reply! Should have just done my homework and watched your videos at home tonight lol.

I was just about to start ordering parts for a lift & tire upgrade on my Overland before deciding I should look into the clutch recall first... esp. adding more rolling resistance with hay season just about in full swing where I'd be further pushing tow cap! 😅

Not having to swap those parts out AND having an installation video is huge; I'm no experienced mechanic, but I'll DIY things I can do in a weekend. Being on crutches now I may be outsourcing that work, but I'll save on both parts & labor with your kit either way!

Also nice not to worry about Stellantis potentially gimping performance to maintain EPA numbers if/when a real fix and parts become available. Something tells me the Sep 2023 estimate is a little optimistic... and I've got way too much towing and traveling to do while I wait. From the sounds of it (besides obv. safety concerns) it solves the only complaints I've had about driving it, so I'm really excited.

Thanks again!
@udrugby09 i have a little over 6K on the ACT clutch and Pro-Mass fly wheel, and i can say it's without a doubt one of the best improvments over stock that i have done to the JT (thats my youtube video review above). ACTs increased clamp load for torque capacity and heat capacity will be a great match for towing and traveling, especially with the added flywheel inertia. As mentioned in the review with normal hand tools the swap is pretty straight forward and is flagged for 5.5-6 hour install by shop. Ideally you'll want the ability to support the trans and tcase as a whole to save alot of time. Check out ACT's youtube playlist tab and they have a category called "ACT Clutch Installs" that has a step by step how to with torque specs. Let us know how it works out for you. I absolutely love my ACT upgrade, not only is is peace of mind over the stock unit, but it's also comforting knowing it all engineered to work with the OEM equipment rather than requireing additional aftermarket components. For reference, mine is the JP6-HDSS-HD-O/Perf Street Sprung (479 ft/lb w/ Pro-Mass)
 

seven30

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In an ACT videos I noticed two different flywheels available. Has anyone tested the lighter one yet?
My stock clutch at 58K is fine but the dual mass flywheel has got to go.
One of the ACT videos clamps the flywheel/clutch in a lathe and demonstrates it rather well.
For a truck, the dual-mass gives you the worst of both worlds. A low mass off idle flywheel and heavy flywheel at rpm.

Another point ACT mentioned was the dual-mass allows solid center discs they reducing the disc assembly rotational inertia(syncro life). Any info on the ACT disk inertia vs stock?
 
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ACTman

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In an ACT videos I noticed two different flywheels available. Has anyone tested the lighter one yet?
My stock clutch at 58K is fine but the dual mass flywheel has got to go.
One of the ACT videos clamps the flywheel/clutch in a lathe and demonstrates it rather well.
For a truck, the dual-mass gives you the worst of both worlds. A low mass off idle flywheel and heavy flywheel at rpm.

Another point ACT mentioned was the dual-mass allows solid center discs they reducing the disc assembly rotational inertia(syncro life). Any info on the ACT disk inertia vs stock?
I think you misunderstand. The total inertia of the flywheel and clutch is what prevents stalling, which is reduced on the JL/JT compared to the JK (and ACT of course). The engine characteristics don't change if it is single mass or dual mass. What changes is downstream of the engine, with the clutch and transmission.

To answer your question about inertia. From our testing of the discs we found the spring center ACT disc has about twice the inertia over the OEM solid center twin discs, which is going to be similar to any current single disc alternative. Increased inertia will potentially slow shifting as the synchros have to speed up or slow down the disc to match the next gear. As long as you aren't trying to shift it like a race car, you wouldn't know the difference and the synchros will last a long time.

If we were to offer a solid center disc, inertia would be lower, but there would be no torsional damping at all and you will hear a lot more gear noise from the transmission.

It's a matter of design benefits and tradeoffs.
 

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Hey ACTman (and other contributors/guinea pigs ;)),
Appreciate all the info! One thing I am still curious about is why, if anyone knows, CF did decide to change to change out the hydraulics with their kit, and (directed more toward you) why ACT deemed it unnecessary.

I've read through the few main threads regarding the recalls and your clutch kit, but that's one thing I haven't seen be discussed. Admittedly, I haven't watched any videos yet, so my apologies if it's covered there and I missed it!
I installed the ACT clutch with the Promass flywheel today, and when I drove it away, the slave cylinder blew. I hope a new one last a while.
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