Manual Transmission - Issues shifting into 1st & Reverse (Compilation thread)

[roaniecowpony]

Can we use the Center Force upgraded hydraulic master and slave cylinder with the stock set up? I'm leaning more towards the hydraulics as my issues seem to have started after some spirited driving through the twisty mountains. Something is not holding up!

I think the link I provided to the thread indicates that the OP did use the CF "upgraded" master, slave and line, yet still got the creaking and poor pedal.

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[SadRobot]

Maybe everyone has seen this old 2023 thread already, but I thought I'd post a link to it anyway. Looks like there was no resolution to their problem of squeaking and difficulty shifting.
Manual transmission Center Force II getting stuck in 1st and reverse. **UPDATE** attached video of sound | Page 3 | Jeep Wrangler Forums (JL / JLU) -- Rubicon, 4xe, 392, Sahara, Sport - JLwranglerforums.com

After having worked on @SadRobot 's clutch hydraulic system for a few times, I suspect the creaking is from an internal problem with the piston-cylinder friction/stiction, possibly from a small side load caused by the geometry of the pedal or clutch fork, in combination with the materials used in the piston and cylinder not being tolerant of the extra force from the ACT clutch. This creaking could be allowing air past the seals. I can't tell if it's the master or the slave. It's all just speculation on my part.

Whoa that sounds even worse than mine did. I think my whole life has just become a game of "Name That Sound". Yesterday there was a weird knocking sound coming from somewhere in my house. It happened about every 20 seconds. I walked around trying to find the source but every time I moved it went away. Maybe ghost of my Jeep is haunting me?

 

[SadRobot]

I woke up today to a text from my mom with this picture and the message "Good sign for your jeep dealers"

 

[ski-line900]

I'm not hopeful for a universal resolution for everyone having issues with ACT, seems too common and widespread. Especially the change in feel after driving a while.

 

[linux_guy]

This would be my advice to anyone on the fence about messing with it. If you don’t have kids or pets I’d say let the Jeep burn to the ground before doing the recall or aftermarket route.

I'll grab fire extinguisher and purple cushion before filming my Wrangler self-immolate. For extra effect, I'll do at dealership.

 

[ski-line900]

I have a theory about the issue getting worse when warm. Maybe the input shaft of the trans expands a bit from heat, and then the clutch disc doesn't slide and release easily enough. If I blip the throttle after depressing the clutch, during any gear shift, it's smoother going into gear.

I heard CF and McLeod designed their clutch disc splines to make it easier for the disc to release. I think this was like V1 vs V2/3 for CF. There is misalignment for some between the trans and engine.

I used ACTs grease on the splines, I've also heard graphite lube as an alternative.

Maybe there is such little tolerance for the ACT to release that any air or grabbiness to the clutch disc and splines causes the disc to not release fully from either the pressure plate or flywheel.

Could explain why some folks don't see the issue till after some miles, the grease dries up or becomes contaminated.

 

[roaniecowpony]

When you go to the dealer to pick up you Jeep, get any parts they changed...cylinders is what I want to look at. They have to give them to you by law.

 

[Terrymo]

I woke up today to a text from my mom with this picture and the message "Good sign for your jeep dealers"

You both have a good sense of humor

 

[SadRobot]

You both have a good sense of humor

One day when I write my autobiography make sure to read the Jeep chapters. You'll laugh until you cry.

 

[Steve104]

I have a theory about the issue getting worse when warm. Maybe the input shaft of the trans expands a bit from heat, and then the clutch disc doesn't slide and release easily enough. If I blip the throttle after depressing the clutch, during any gear shift, it's smoother going into gear.

I heard CF and McLeod designed their clutch disc splines to make it easier for the disc to release. I think this was like V1 vs V2/3 for CF. There is misalignment for some between the trans and engine.

I used ACTs grease on the splines, I've also heard graphite lube as an alternative.

Maybe there is such little tolerance for the ACT to release that any air or grabbiness to the clutch disc and splines causes the disc to not release fully from either the pressure plate or flywheel.

Could explain why some folks don't see the issue till after some miles, the grease dries up or becomes contaminated.

Would you then expect the jeep to move with the clutch pedal depressed, transmission in gear, and revving the engine?

 

[ski-line900]

Would you then expect the jeep to move with the clutch pedal depressed, transmission in gear, and revving the engine?

I think if that's the case then the clutch is really dragging. I've tried this up to like 4500rpm and have no movement.

With respect to my situation, I think it's minimal hangup, but enough to affect the feel of gear shifts, but not to the point I can't get into first or reverse easily.

 

[m3reno]

Can the oil in the transmission be the problem? I know it uses ATF+4, maybe use something better?

 

[ski-line900]

I tried redline c+ATF, which still has the Mopar certification, no difference.

 

[Duece McCracken]

Would you then expect the jeep to move with the clutch pedal depressed, transmission in gear, and revving the engine?

That occurs with complete hydraulic failure, or not enough to engage the pressure plate at all.

I've only seen, and am currently experiencing, lockout of a few gears when stationary shifting, or difficulty shifting into 5th on the highway sometimes. It's very intermittent, which makes it tough to properly diagnose.

If I started moving with the clutch depressed consistently, it'd be hydraulics for sure. A proper "smoking gun". Which is easier to accept and just fix.

So a few of us in here are trying to really figure out what is happening, and a proper solution.

What makes this a bit odd, is theres several different combinations of aftermarket clutch components.

The CF clutches are smaller diameter JK sized clutches iirc. Which means they have less friction area and a higher pressure plate clamp load to handle JL power. Which taxes their external modified JK hydraulics. This lead to their internal hydraulic throwout bearing assembly.

The ACT clutch is about an inch bigger in diameter and designed around the JL Hydraulics. Going single disc increases the pressure plate loading over the soft OEM twin disc, which taxes the OEM JL hydraulics.

Im hoping to run the CF external JK hydraulics, on the larger ACT clutch. Which should require less force to actuate the larger ACT pressure plate than the CF pp.

My fingers are crossed that this will be a sweet spot in operation. Slightly stronger hydraulics with a PP that requires less force than the CF.

Unless the ACT clamps more than the smaller CF, then I have less hope, lmao

 

[Duece McCracken]

I tried redline c+ATF, which still has the Mopar certification, no difference.

Im running redline as well, I dont think this is a factor though. The only common link it seems, is having a clutch replaced. Whether its ACT, CF, or the recall clutch. Appears to randomly affect across all of them.

Which is the focus is on hydraulics, clutch fork operation, and OEM parts tolerances.

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