JT/JL Clutch and Flywheel explained by ACT

[hjdca]

Ordered mine today. Awaiting confirmation email with tracking info. I'm looking forward to experiencing the difference.

Which one did you order to get the Pro-mass Flywheel ? Was it SKU JP6-HDG6 for $987.70

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[ACTman]

I would recommend the JP6-HDSS. It is best suited for over 90% of Jeep JL/JT applications.

The JP6-HDG6 meant for racing and holds over 600ftlbs. It will engage very quickly and aggressively.

 

[ericnewcom]

Which one did you order to get the Pro-mass Flywheel ? Was it SKU JP6-HDG6 for $987.70

I ordered the JP6-HDSS I'm happy overall excluding the throwout bearing my shop had to replace with the factory one due to them reporting the supplied one having a rotational noise and chatter. One other thing I've noted since install is with the promass the rev hang is pretty bad. It may get better after the engine has more miles but I don't spin her up past 5 or 5200 due to having to wait mid shift for the rpms to drop enough to have a smooth transition.

I get in my 75 f250 and drive it and just think how the hell is the manual in this truck light years ahead of a modern vehicle.

The promass really does help down low though it will idle in 1st and reverse up my driveway now and didn't have a chance of doing that before. My wife being a novice manual driver can now drive it. 3mph at idle is still to fast in my opinion but that is a gear issue and nothing to do with the clutch.

 

[ACTman]

I ordered the JP6-HDSS I'm happy overall excluding the throwout bearing my shop had to replace with the factory one due to them reporting the supplied one having a rotational noise and chatter. One other thing I've noted since install is with the promass the rev hang is pretty bad. It may get better after the engine has more miles but I don't spin her up past 5 or 5200 due to having to wait mid shift for the rpms to drop enough to have a smooth transition.

I get in my 75 f250 and drive it and just think how the hell is the manual in this truck light years ahead of a modern vehicle.

The promass really does help down low though it will idle in 1st and reverse up my driveway now and didn't have a chance of doing that before. My wife being a novice manual driver can now drive it. 3mph at idle is still to fast in my opinion but that is a gear issue and nothing to do with the clutch.

Thanks for the comments. I hate the rev-hang on the newer Jeeps especially during that first 90 second warm up. In our testing I didn't notice a big increase in how long the rev hang lasts, but I sure noticed the added force from the inertia.

 

[Zachattack50]

I ordered the JP6-HDSS I'm happy overall excluding the throwout bearing my shop had to replace with the factory one due to them reporting the supplied one having a rotational noise and chatter. One other thing I've noted since install is with the promass the rev hang is pretty bad. It may get better after the engine has more miles but I don't spin her up past 5 or 5200 due to having to wait mid shift for the rpms to drop enough to have a smooth transition.

I get in my 75 f250 and drive it and just think how the hell is the manual in this truck light years ahead of a modern vehicle.

The promass really does help down low though it will idle in 1st and reverse up my driveway now and didn't have a chance of doing that before. My wife being a novice manual driver can now drive it. 3mph at idle is still to fast in my opinion but that is a gear issue and nothing to do with the clutch.

I dont think I have ever had the need to rev it past 4500, I take it your not geared at all. That would also help your idle speed. The only time we are in first is off road, or when I'm hooked to my sxs trailor, normal driving even with the stock clutch we start in 2nd with the 5.13's

 

[ericnewcom]

I dont think I have ever had the need to rev it past 4500, I take it your not geared at all. That would also help your idle speed. The only time we are in first is off road, or when I'm hooked to my sxs trailor, normal driving even with the stock clutch we start in 2nd with the 5.13's

Yeah I plan to gear to 5.13s and as far as the rpms go I have never had an engine I don't fully utilize. The redline is over 6k and I run it out as I have every vehicle I've owned. I don't run 2nd up every time its just during spirited driving.

 

[Zachattack50]

Yeah I plan to gear to 5.13s and as far as the rpms go I have never had an engine I don't fully utilize. The redline is over 6k and I run it out as I have every vehicle I've owned. I don't run 2nd up every time its just during spirited driving.

Send er bud 5 13's made world's of difference, even with the stock clutch. I guess I'm just not impressed by ripping all 310hp to the moon, lol. I've been paying attention more to my rpms, scince the clutch install. Even getting after it, I'm only at 4-4200 maybe the centerforce is different, but it really doesn't give you any more by taking farther up in the revs, IMHO.

 

[ericnewcom]

Thanks for the comments. I hate the rev-hang on the newer Jeeps especially during that first 90 second warm up. In our testing I didn't notice a big increase in how long the rev hang lasts, but I sure noticed the added force from the inertia.

Yeah the what I call high idle during first crank is nuts. The rev hang I'm talking about is when your really on it driving "spiritedly" an run 2nd up to around 6k when you hit the clutch to shift to 3rd it rev hangs in the high rpm you either have to pause when out of 2nd into the 3rd transition, don't rev as high, or send it and hit 3rd with the higher than needed rpms and feel it resist the transition.

 

[Zachattack50]

Your syncros hate you, lol.

 

[ericnewcom]

Your syncros hate you, lol.

I don't choose the send it option. Been driving manuals my entire life and never had to replace a syncro. I've put over 200k miles on stock clutches too.

 

[Zachattack50]

Max tq is around 4800rpm for the 3.6, in a truck, especially a cable shifted, slow reacting trans, I just don't see the benefit. Its not any quicker. Now I kinda want to plug my draggy in and see, for science

 

[AustinL911]

Yeah the what I call high idle during first crank is nuts. The rev hang I'm talking about is when your really on it driving "spiritedly" an run 2nd up to around 6k when you hit the clutch to shift to 3rd it rev hangs in the high rpm you either have to pause when out of 2nd into the 3rd transition, don't rev as high, or send it and hit 3rd with the higher than needed rpms and feel it resist the transition.

They program in rev-hang for emissions BS. Freakin' Greenies ruin everything.

 

[AustinL911]

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

 

[ericnewcom]

Max tq is around 4800rpm for the 3.6, in a truck, especially a cable shifted, slow reacting trans, I just don't see the benefit. Its not any quicker. Now I kinda want to plug my draggy in and see, for science

https://www.jlwranglerforums.com/forum/threads/2018-wrangler-3-6-pentastar-dyno.3225/

The dyno graphs I've seen shows the torque pretty flat throughout but it keeps making HP all the way to redline. I'm not saying I run it out every time in 2nd its occasionally on a nice back road you pull on to run it out and keep her exercised. I typically shift at lower rpms too but if there was no reason to go above 4800 then 5k would be the redline not 6200?

I have a road on the way home from the farm that I sometimes run it out. I can tell you that there is a sign I let out at and if I turn into that road and shift 2nd to 3rd at 4800 I won't have the same mph as I do if I run it up to the higher 5s.

Regardless it's not a sports car and I'm not trying to prove how fast I can make it go. I'm was just relaying that with the pro mass and this engine it has rev hang in the upper rpms. With the stock clutch this wasn't the case. Someone else may find this information useful when trying to decide on street mass vs pro. At the end of the day I'd choose pro mass again for its low rpm benefits.

In my perfect world my gladiator would have the same setup as my 75 (390 fe, 4 speed, divorced transfercase) with stock 4.10 gears it'll idle up almost twice the incline the gladiator will and it's on 35s vs the gladiator currently on 33s.

 

[Zachattack50]

The stock clutch deffintly has a lighter feel with rpms, an object in motion tends to stay in motion, ill be curious to see if the rpm hang is actually able to be tuned out, your spinning a lot more mass, so by design it's going to carry longer. As far as the old Ford, no replacement for displacement.

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