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

[58Willys]

Throwing in my own anecdotes in case it helps with identifying the issue(s).

I had the ACT pro mass installed June 2023, about 13k miles ago.

Started experiencing first and second gear lockout approximately 2 months ago. Behavior is similar to the 1st gear lockout when going too fast.

I noticed that once the lockout starts happening, it will lock me out if I spend ANY time in neutral with foot off the clutch.

If I come to a stop and keep the clutch depressed the entire time, I have no issues entering first gear. (This is one of my methods to bypass the issue)

However, as soon as I release the clutch and depress it again, I am locked out.

When I am locked out, I also have difficulty trying 3rd gear. I am able to shift into 4, and that seems to release 1 and 2. (This is my other method of bypassing the issue)

It seems that sometimes it locks me IN gear, where it becomes challenging to shift to neutral. Releasing the clutch a bit seems to alleviate this when it happens.

When locked IN GEAR, I have also noticed my Jeep moving forward even with the clutch fully depressed. I also notice a groaning sound when this happens at a stop, as if it is trying to move forward but can’t because my foot is on the brake.

Everything you’ve said here points to the clutch not fully disengaging.

This could be weak or malfunctioning hydraulics , or a mis-aligned disk or other mis-alignment such as main shaft alignment, or excessive crank/flywheel lateral runout.

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[AVGeek99]

True but what a bizarre diagnosis. Was the dealer just getting a huge battery kickback or something? I just don't understand the logic unless they just figure it's a cheap way to get a customer to go away? Feels like weaponized incompetence to me.

My response was half sarcasm. Bizarre diagnosis for sure.

 

[OldGuyNewJeep]

It seems that sometimes it locks me IN gear, where it becomes challenging to shift to neutral. Releasing the clutch a bit seems to alleviate this when it happens.

Oh, wow. Somehow for this whole thread I’ve been reading “lock out” as “locked in” in my brain!

What my wife and I have experienced a few times (only last summer) was lock IN, not OUT!

So I have never experienced lock OUT with my ACT pro mass. What happened to us a few times is reversing from a parking space and then can’t get out of reverse. Once it was the other way around- pulling out of a space and couldn’t get out of first.

When it happened to me I double and triple clutched my way out along with copious yanking and swearing. My wife said she just turned the Jeep off and back on (which would results in a double clutch, I guess).

So I guess I’m a rarity inasmuch as I’ve had the pro mass installed since 6/23 and haven’t had lock OUT, groan, creak, or vibration. (I do have a thread I started somewhere about a click I was getting every time I pushed in the pedal. I solved that by lubricating the plastic slider thing inside the spring.)

 

[SadRobot]

My response was half sarcasm. Bizarre diagnosis for sure.

ha well with the follow up post about the heating blanket it now it makes a bit more sense why they replaced the batteries. I feel like the lead of that whole story got buried a bit.

 

[SadRobot]

Oh, wow. Somehow for this whole thread I’ve been reading “lock out” as “locked in” in my brain!

What my wife and I have experienced a few times (only last summer) was lock IN, not OUT!

If it makes you feel any better I've had both happen. Got both locked out and stuck in gear.

 

[58Willys]

OK, there is a 1st and 2nd gear lockout mode (doesn't allow shifting into 1st or 2nd at too high a speed/rpm). Looking at the wiring harness diagram there is a skip shift module with connection to 1st and 2nd gear lockout. I imagine this is a PCM controlled function. There is no reverse gear lockout, except for the ring on the shift lever, which appears to be just a mechanical lockout on the linkage, nothing in the tranny itself.

Several people are reporting getting locked out as well as locked in a gear, as well as vehicle creep when in gear with clutch disengaged; this tells me clutch is not fully disengaging. (If you're locked in a gear because the clutch is not fully disengaging, try giving it a little throttle blip, release throttle and pull out of gear at the same time).

I suppose someone could test the lock out system by disconnecting it (it's pin 4 & 5 on Connector XYA303A). From reading everyone's posts, i doubt this is the issue, but possible).

IMO, the clutch is not fully disengaging, with vehicle creep it's really the only sensible explanation. Since some have reported decent shifting after bleeding, then it deteriorates; points to a weak hydraulic system. Someone would have to drill a hole in the bell housing, tap it for a pipe plug, and insert a feel gauge between flywheel and friction disk @ 8 different places around the flywheel to measure clearance. Old school clearance were .040" to .060"; not sure what JL specs are supposed to be. Not sure if there a place to drill and tap on these bell housings either.

Hopefully one of these aftermarket suppliers will tackle this and come up with a good hydraulic system for this.

 

[Duece McCracken]

OK, there is a 1st and 2nd gear lockout mode (doesn't allow shifting into 1st or 2nd at too high a speed/rpm). Looking at the wiring harness diagram there is a skip shift module with connection to 1st and 2nd gear lockout. I imagine this is a PCM controlled function. There is no reverse gear lockout, except for the ring on the shift lever, which appears to be just a mechanical lockout on the linkage, nothing in the tranny itself.

Several people are reporting getting locked out as well as locked in a gear, as well as vehicle creep when in gear with clutch disengaged; this tells me clutch is not fully disengaging. (If you're locked in a gear because the clutch is not fully disengaging, try giving it a little throttle blip, release throttle and pull out of gear at the same time).

I suppose someone could test the lock out system by disconnecting it (it's pin 4 & 5 on Connector XYA303A). From reading everyone's posts, i doubt this is the issue, but

Ugh, wtf is with this nanny BS. It's a manual trans. Im ok with gear position sensors, but anything else is ridiculous for a Jeep. Where did you pull the pinouts from?

I swapped and rebleed all my hydraulics, shifting has never been better. Still randomly get the lock in, lock out, and wonky 5th shift. Also experience some vehicle motion when attempting to get past "the block".

Really leaning towards the friction disc hanging up on the input shaft. Explains all the symptoms, and its intermittent occurance in my case.

Was entertaining pulling the slave and blasting some brake clean on the input shaft.

My borescope pics show a fair amount of dust, seems the aftermarket produces more, especially for the mileage. Which accumlated on the input shaft could prevent disengagement.

Makes sense that I had 15k trouble free miles, now I get random lockout, that my be enhanced by heat it seems.

 

[Jmos4]

Hi,

Didn't realize the JL's has a skip shift, my 2020 Challenger has that, they make a resistor to eliminate that from turning on wonder if one from a Challenger would work?

Regards,
Jim

 

[Duece McCracken]

Hi,

Didn't realize the JL's has a skip shift, my 2020 Challenger has that, they make a resistor to eliminate that from turning on wonder if one from a Challenger would work?

Regards,
Jim

Its not a skip shift*in what I've read about the challenger* sense, its a downshift lockout apparently.

Which doesnt explain any of our Reverse issues, and its a Downshift only lockout. Shouldnt affect getting into 1st from a stop.

 

[ski-line900]

a feel gauge between flywheel and friction disk @ 8 different places around the flywheel to measure clearance. Old school clearance were .040" to .060"; not sure what JL specs are supposed to be.

There is no clearance, the throw out bearing is always touching the pressure plate.

 

[Kfoo]

Throwing in some more anecdotes from today.

In addition to the ACT clutch, I also have a 4.56 regear and 35s, both of which are configured through a tazer mini. I mention this because the tazer lets me disable auto start stop and it remembers the setting.

With all this chatter about batteries and electronic stops, I discovered that re enabling auto start stop actually fixes the worst of the issues for me!

When I come to a stop, it stops the engine, then depressing the clutch starts the engine and lets me easily shift into first, much like when I had the clutch depressed the entire time. My guess is that the lock out is electronically linked to the auto start stop mechanism and disabling it doesn’t disable this lockout entirely. If I restart then leave it in neutral, it is sometimes difficult to shift into first, but not impossible like it has been.

Ultimately, there are probably multiple issues, some of which are tied to the heavier clutch mechanically, but at least this brings some credence to replacing the batteries as a way to fix this since a bad aux battery disables the auto start stop

 

[ski-line900]

Throwing in some more anecdotes from today.

In addition to the ACT clutch, I also have a 4.56 regear and 35s, both of which are configured through a tazer mini. I mention this because the tazer lets me disable auto start stop and it remembers the setting.

With all this chatter about batteries and electronic stops, I discovered that re enabling auto start stop actually fixes the worst of the issues for me!

When I come to a stop, it stops the engine, then depressing the clutch starts the engine and lets me easily shift into first, much like when I had the clutch depressed the entire time. My guess is that the lock out is electronically linked to the auto start stop mechanism and disabling it doesn’t disable this lockout entirely. If I restart then leave it in neutral, it is sometimes difficult to shift into first, but not impossible like it has been.

Ultimately, there are probably multiple issues, some of which are tied to the heavier clutch mechanically, but at least this brings some credence to replacing the batteries as a way to fix this since a bad aux battery disables the auto start stop

Likely not electronic but instead when you push the clutch to restart it revs the engine a bit and helps to release the disc from dragging.

 

[Duece McCracken]

Likely not electronic but instead when you push the clutch to restart it revs the engine a bit and helps to release the disc from dragging.

My thoughts exactly.

When I get lockout, I can shut off the engine, shift smoothly into that gear and start it back up, lol

Additionally, i'm one of the people that clutches in at stops, and gets it into first before I completely stop. I rev match downshift to decell in gear.

So my clutch is depressed a whole lot, and never got any creep from it, even if I just sit clutched in and no brajes at a light. Which reinforces that this issue is most likely NOT hydraulic.

I try to be as scientific as possible with any kind of troubleshooting. So I've fiddled and notated mentally with all sorts of variables, lol

 

[Kfoo]

🥲 here I was hoping it’d be a silly fix! Thanks for the enlightenment!

 

[Duece McCracken]

🥲 here I was hoping it’d be a silly fix! Thanks for the enlightenment!

I really wish it was.

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