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

[Reflektr]

I am really in over my head on this topic, which is why I was inquiring if anybody had looked into it lol. My guess is that EVERYTHING would need to be swapped to ensure that the transmission operated smoothly. Master cylinder, slave cylinder, clutch components, etc.

But the 3160 has been used in other applications, so I think the approach would be to use components that are known to work and just figure out how to integrate it into the JL platform. I can't imagine it is any more difficult than a full engine swap, although that is one option I would consider if I ever start having clutch issues: 5.7l swap w/ auto transmission. Of course, my preference would be just to swap in a manual transmission that works haha!.

I hear that. Some days I just want to call up AMW and tell them to give it everything but the kitchen sink, but that would take all the fun out of building it myself, which is kind of why I bought it in the first place. And I don’t want my face to wind up on a milk carton. The wife’s already a little salty about the Jeep being a manual. I originally wanted this High-Tide JT in anvil that a local dealer had, but she said she could never drive something so insanely hideous. So now we have a 4-door in ‘41 with a funky shifter

I will say though, those bobbed AMW JT’s give me the straight-up cold sweats.

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[GabeBoyTheGreat]

I hear that. Some days I just want to call up AMW and tell them to give it everything but the kitchen sink, but that would take all the fun out of building it myself, which is kind of why I bought it in the first place. And I don’t want my face to wind up on a milk carton. The wife’s already a little salty about the Jeep being a manual. I originally wanted this High-Tide JT in anvil that a local dealer had, but she said she could never drive something so insanely hideous. So now we have a 4-door in ‘41 with a funky shifter

I will say though, those bobbed AMW JT’s give me the straight-up cold sweats.

 

[SadRobot]

The design of the slave cylinder is poor when it comes to bleeding. The supply line and the bleed port share the same fluid path, air cannot get out of the slave if fluid is flowing through the supply line. Thus a pressure bleeder will do nothing. Here is an illustration of what I am talking about:

The orange line depicts the fluid flow from the master cylinder under normal operation. The green line is the fluid flow when bleeding as described in the FSM. The blue line shows the fluid path when pressure bleeding.

Another thing working against us is the rod end of the slave cylinder is higher than the bleed port when the Jeep is sitting level. Air rises, therefore it will move away from the bleed port.

I had success by jacking the rear of the Jeep up enough so that the bleed port end of the slave cylinder was higher than the rod end. Fully depress the clutch pedal and block it with a 2X4. Then climb under and crack the bleed port open. Close the port, remove the 2X4 and lift the clutch pedal off of the floor (it will not return on its own). This method imitates the procedure described in the FSM without having to pull the slave cylinder from the transmission.

Yeah just bad design overall. I did every kind of bleeding. Jacked up the rear of the Jeep, removed the cylinder to get the bleed port higher, compressed the cylinder while bleeding to force bubbles out. I've done vacuum and pressure bleeding from the reservoir. Really just tried it all.

To me the only thing that worked was just bleeding it forever. Once you think you are done and all the bubbles are gone keep going for another 30 minutes. Then maybe you'll have bled the system.

 

[GabeBoyTheGreat]

I think the quality of the cylinders are just crap. Air has to be sneaking in through the seals somewhere. Maybe not enough to let fluid out but even the tiniest bit of bubbles just screws up the entire system. It's not forgiving at all. No one has figured out yet why the transmission locks up. Previous Wrangler generations don't do that. If you push the stick a little harder it will eventually go into gear on a JK. With the JL no amount of force will get it to go into gear when the disc is dragging - it just locks you out of gear.

It may be worth bleeding it from the slave cylinder instead of pulling a vacuum. Eventually I'll pick up one of these one way brake bleeder hoses when I inevitably get lockout issues again.

In 2019, the clutch on my 2018 failed completely. Not sure exactly what happened, but I had to get it replaced under warranty.

After the clutch replacement, my clutch pedal was extremely light and had almost no return force. It barely had enough force to overcome the clutch assist spring. However, the clutch seemed to be completely disengaging/engaging when it was supposed to.

After driving around like that for several months, I brought it to a different dealer to diagnose the lack of return force. They ended up bleeding the system, which improved the return force.

I drove like that until 2025 when I bought my now 2025 JLU and noticed just how much more return force the 2025 pedal had compared to the 2018. That prompted me to bleed the clutch on the 2018 again, which once again improved the return force but still was never as stiff as the 2025.

My point to all of this is that there was clearly air in the system for years and over 30k miles, yet never once did I notice any issue with the clutch disengagement/engagement. The only effect I noticed was a change in the pedal return force.

Seems like if air in the hydraulics is what is causing the clutches to not fully disengage then I should have experienced this, right? Perhaps the root cause has nothing to do with air in the hydraulics, but rather the air is amplifying the effect of some other root cause? I honestly have no idea; just spitballing here.

 

[gek]

In 2019, the clutch on my 2018 failed completely. Not sure exactly what happened, but I had to get it replaced under warranty.

After the clutch replacement, my clutch pedal was extremely light and had almost no return force. It barely had enough force to overcome the clutch assist spring. However, the clutch seemed to be completely disengaging/engaging when it was supposed to.

After driving around like that for several months, I brought it to a different dealer to diagnose the lack of return force. They ended up bleeding the system, which improved the return force.

I drove like that until 2025 when I bought my now 2025 JLU and noticed just how much more return force the 2025 pedal had compared to the 2018. That prompted me to bleed the clutch on the 2018 again, which once again improved the return force but still was never as stiff as the 2025.

My point to all of this is that there was clearly air in the system for years and over 30k miles, yet never once did I notice any issue with the clutch disengagement/engagement. The only effect I noticed was a change in the pedal return force.

Seems like if air in the hydraulics is what is causing the clutches to not fully disengage then I should have experienced this, right? Perhaps the root cause has nothing to do with air in the hydraulics, but rather the air is amplifying the effect of some other root cause? I honestly have no idea; just spitballing here.

That is half the problem, similar symptoms for everyone, but different things seem to intermittently work. This stopped it for a while for this person, but not this one, this worked for them but not that person. This worked until it didn't. There doesn't seem to be an rhyme or reason to it which is why no one can seem to pinpoint what the actual issue is.

 

[yokramer]

That is half the problem, similar symptoms for everyone, but different things seem to intermittently work. This stopped it for a while for this person, but not this one, this worked for them but not that person. This worked until it didn't. There doesn't seem to be an rhyme or reason to it which is why no one can seem to pinpoint what the actual issue is.

 

[SadRobot]

That is half the problem, similar symptoms for everyone, but different things seem to intermittently work. This stopped it for a while for this person, but not this one, this worked for them but not that person. This worked until it didn't. There doesn't seem to be an rhyme or reason to it which is why no one can seem to pinpoint what the actual issue is.

I even tried slaughtering a goat and offering it up as a sacrifice to the clutch but it did not work and all I ended up with was a mess on the floor of my garage.

 

[yokramer]

I even tried slaughtering a goat and offering it up as a sacrifice to the clutch but it did not work and all I ended up with was a mess on the floor of my garage.

But hopefully got some good birria tacos out of it

 

[Reflektr]

That is half the problem, similar symptoms for everyone, but different things seem to intermittently work. This stopped it for a while for this person, but not this one, this worked for them but not that person. This worked until it didn't. There doesn't seem to be an rhyme or reason to it which is why no one can seem to pinpoint what the actual issue is.

Hey I just had another thought on this over the weekend. Since this problem eventually happens to nearly every manual, new clutch or not - Is there some far-out possibility that it could be related to firewall-flex around the master cylinder?

I noticed this when my dad pushed on the clutch pedal with his hand while I was looking for leaks under the hood. Kind of a Monza Spyder type situation where the clutch eventually stops working because the firewall gives away?

 

[eastern]

Sometimes i read what people experience, and cant help but to ask what exactly they mean by that?
In years of reading about death wobble, i think only 1 poster properly identified a death wobble experience. Same goes for vibrations, people be discussing about harmonic driveshaft vibrations, and someone later derails threat with his out of round tires wobble - not the same vibrations bud, not the same!

With that said, the bubbles, can we describe them?
You guys and gals aware that bubbles will form when pump is used to create positive or negative pressure, even if there is no air in the system? Unless one puts effort to vacuum seal the connection between hydraulic hose and clear drain tube, the air will seep through and form bubbles? How clear tube connects to the line also matters, fluid can be airless in the line, but once it cross the connector, it will bubble up.

 

[GabeBoyTheGreat]

I know this is not a perfect solution, but I highly recommend that anyone who is displeased with the OEM clutch look into getting a engine tune for the 3.6l. There is a forum member offering tunes under this thread: https://www.jlwranglerforums.com/fo...g-all-18-26-jl-3-6-non-etorque-models.164496/

There are several improvements that this tune offers. I encourage you to read the tread, but the one improvement that I feel pertains to this thread is improved resistance to stalling. I am not sure exactly why the tune helps, but my 2025 JLU is less prone to stalling after getting the tune done. Others have made similar comments (see the linked thread). The engine definitely runs better in the low-end RPM range, and my guess is this helps prevent the engine from stalling when the load suddenly changes (i.e. letting the clutch out).

I won't say it is a night/day difference. The OEM clutch is still a weak point, but the tune makes it just a little more forgiving. You will still stall if you let the clutch out too quickly with 0 throttle input, but slow, controlled clutch engagement seems to work a little better than before, maybe 20-30% (it is really difficult to gauge/measure).

Of course, I usually am always giving it a little bit of throttle when engaging the clutch, and when I am giving it throttle, it really seems difficult to stall unless I am actually trying to make it stall, whereas before it felt like a total crapshoot. That is why on the stock tune, I had a tendency to overrev the engine a little to prevent from stalling; it doesn't feel like I have to do that anymore.

Also, overall engine response in the low-end RPM range is improved, so starting off in 1st gear is so much smoother and less jerky. I also haven't noticed that low-speed bucking phenomenon with the new tune that occurs sometimes with the old tune.

All in, you are looking at just around $1,300 for the tune itself and everything that is required to get the tune uploaded. I can honestly say, even if the OEM clutch wasn't trash, the tune is absolutely 100% worth the money. The improvement in stall resistance is just a bonus. It sounds like these aftermarket clutches will cost at least twice that much and is kind of a crapshoot whether or not you will have problems down the road. Personally, I don't see any downsides with the tune, only improvements across the board.

 

[eastern]

I know this is not a perfect solution, but I highly recommend that anyone who is displeased with the OEM clutch look into getting a engine tune for the 3.6l. There is a forum member offering tunes ...

BLA BLA BLA BLA NONSENSE

.... It sounds like these aftermarket clutches will cost at least twice that much and is kind of a crapshoot whether or not you will have problems down the road. Personally, I don't see any downsides with the tune, only improvements across the board.

Did you even bother to understand what this thread is about?

 

[WJ43]

I have an ACT clutch, sob story is posted somewhere in the last 67 pages. I was recently getting a soft pedal and the groaning noise again.

I saw a instagram post about using a massage gun on brake lines to help pull out any residual air - I figured what the hell, I would give it a try on the clutch lines.

Lo and behold I got a bunch of bubbles coming out in the reservoir (my wife was watching the reservoir while I was under the jeep) and the reservoir level dropped about 1/8 to 1/4 of an inch. After the massage, the pedal feel improved dramatically and the groaning noise is gone. I am going to do it again once I have the fluid warm to see if it gets any better but I am super happy now.

I used a pointed attachment on a sharper image hot and cold massage gun and I put it on level 6 because I felt the lower settings put too much impact and not enough vibration. I started at the slave and worked my way up the line. There are places where you can't get the gun on the line, so I skipped those and just hit the lines I could reach. I didn't put it directly on the master, as I didn't want to screw it up and go through the nightmare of having to change it, but i did hit the short line between the master and the reservoir. When I was doing that there were a fair number of bubbles.

The pointed attachment is beat to hell, but if that is the cost of getting the jeep to run right I will take it. I wrapped the gun in cellophane to try and save it from getting to dirty, but it ended up with some scuffs anyways.

 

[eastern]

I have an ACT clutch, sob story is posted somewhere in the last 67 pages. I was recently getting a soft pedal and the groaning noise again.

I saw a instagram post about using a massage gun on brake lines to help pull out any residual air - I figured what the hell, I would give it a try on the clutch lines.

Lo and behold I got a bunch of bubbles coming out in the reservoir (my wife was watching the reservoir while I was under the jeep) and the reservoir level dropped about 1/8 to 1/4 of an inch. After the massage, the pedal feel improved dramatically and the groaning noise is gone. I am going to do it again once I have the fluid warm to see if it gets any better but I am super happy now.

I used a pointed attachment on a sharper image hot and cold massage gun and I put it on level 6 because I felt the lower settings put too much impact and not enough vibration. I started at the slave and worked my way up the line. There are places where you can't get the gun on the line, so I skipped those and just hit the lines I could reach. I didn't put it directly on the master, as I didn't want to screw it up and go through the nightmare of having to change it, but i did hit the short line between the master and the reservoir. When I was doing that there were a fair number of bubbles.

The pointed attachment is beat to hell, but if that is the cost of getting the jeep to run right I will take it. I wrapped the gun in cellophane to try and save it from getting to dirty, but it ended up with some scuffs anyways.

I just want to make sure that i understood this correctly

Also, I'm glad that you and your wife are good now and back to normal, I am all for healthy stress relievers, what ever keeps the marriages happily going.

But you actually .. You know, the process... You applied it on the Jeep, right? You two didnt just get underneath, hit your heads really hard and completely forgot about the Jeep...?

 

[WJ43]

I just want to make sure that i understood this correctly

you pretty much nailed it.... although the noise was groaning, not moaning and that was pre-vibration

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