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-   -   Manual Transmission Crunch (http://www.wranglerforum.com/f274/manual-transmission-crunch-212146.html)

clayps 01-15-2013 01:50 PM

Manual Transmission Crunch
 
I've done a bit of research on the forums and have found some people having trouble getting their manual into 2nd gear smoothly. I too seem to be having this issue, as the shifter makes a 'crunch' or 'click' noise when going from 1st to 2nd..sometimes from 2nd to 3rd. Was just wondering if this is the typical problem that most people are having with the second gear. Tends to be worse when cold, but still happens when engine and transmission are fully warmed up. The sound seems to be coming more from the actual shifter and not the transmission.

mathew85 01-15-2013 01:52 PM

I've faced this and thought it was just me. Glad to know it's not just me :)
And like you say, worse in cold starts.

Siren Assassin 01-15-2013 01:53 PM

My 2012 shifts like any other truck style manual tranny. It's no where near smooth like my lil bros wrx though.

I'd say if you're worried, use the warranty for them to take a looksie. Lol

clayps 01-15-2013 01:57 PM

I'll also mention that it only does it when actually engaging the gear when moving, and not when shifting gears when parked and ignition off (I tried this to see if I could hear it better with the engine off)

mathew85 01-15-2013 02:06 PM

Quote:

Originally Posted by clayps (Post 3232148)
I'll also mention that it only does it when actually engaging the gear when moving, and not when shifting gears when parked and ignition off (I tried this to see if I could hear it better with the engine off)

Same with me again.

Blastek 01-15-2013 03:08 PM

try shifting between 2500-3000 from 1-2. Or pause at the 2nd gear gate for half a second before sending it home. The 1-2 synchro is not adequate IMHO. Sometimes i get full grinds.

kik 01-15-2013 03:53 PM

It shouldn't make a crunch sound, but with these manual 6 spd.'s you will here/feel a distinct two clicks when you shift. That's normal.

maleman876 01-15-2013 04:14 PM

Mine did this, I rev a little higher in 1st before shifting. It just took some getting used to and now it's a non isue.

mathew85 01-15-2013 04:15 PM

Quote:

Originally Posted by Blastek (Post 3232419)
try shifting between 2500-3000 from 1-2. Or pause at the 2nd gear gate for half a second before sending it home. The 1-2 synchro is not adequate IMHO. Sometimes i get full grinds.

I second your synchro theory. you can feel it through your hand..

SilverSport 01-15-2013 09:58 PM

When the transmission is cold, double clutching when going from 1st to 2nd eliminated this issue for me.


USantigoon posted this in a similar thread back in 2010:

First and second gear are triple cone synchronizers..
With very cold oil the viscosity will delay the synchronizer in doing its job and the triple cone will make it even worse because of the additional friction in the synchro lining..

A hard or shift block into first is because there are NO moving parts in the transmission.(the thick oil keep the input shaft from spinning at all)

Therefore I always double clutch before shifting into first..(Don't force it) If first is still hard to get into.. make a shift into the other gears first.. Double clutch one more time and you should be able to go into first....

Once you get moving the shift to second is easier as you have movement in the output shaft, but in very cold conditions you have to double clutch as well.. This will align the synchro rings much better allowing the coupler dog teeth to engage..After 1/4 mile all will go much smoother..

Letting your Jeep warm up (in neutral with clutch released) will help as this will warm up the oil the quickest....Then perform a few shift cycles with the clutch depressed..

In summary the hard 1/2 shift in cold condition is somewhat inherent to triple cone designs..

onetraveller 01-15-2013 10:33 PM

It's all about technique. You don't need to double clutch on the up shift but it can help on down shifts, just don't rush the shift (it's not a sport car). The JK's manual transmission is much closer in feel to a big truck transmission than it is to modern japanese or european import cars.

Think of the shift as a two part motion. The first part is moving it out of the current gear. You need to let off the gas just before doing this to take the load off the gear splines. The second part is applying a little pressure towards the gear you want to move it into. As the RPMs drop, the gear splines will line up and you'll feel it slide into gear.

I spent many years driving old commercial trucks that didn't have synchronizers. You should be able to feel it when it is ready to go into gear. With a little practice, you can drive without the clutch at all (except for starting), simply by letting off the gas to unload the gear splines, and letting it slide out of and into gear with minimal pressure on the shifter.

Mike

mathew85 01-15-2013 10:36 PM

Quote:

Originally Posted by SilverSport (Post 3234389)
When the transmission is cold, double clutching when going from 1st to 2nd eliminated this issue for me.


USantigoon posted this in a similar thread back in 2010:

First and second gear are triple cone synchronizers..
With very cold oil the viscosity will delay the synchronizer in doing its job and the triple cone will make it even worse because of the additional friction in the synchro lining..

A hard or shift block into first is because there are NO moving parts in the transmission.(the thick oil keep the input shaft from spinning at all)

Therefore I always double clutch before shifting into first..(Don't force it) If first is still hard to get into.. make a shift into the other gears first.. Double clutch one more time and you should be able to go into first....

Once you get moving the shift to second is easier as you have movement in the output shaft, but in very cold conditions you have to double clutch as well.. This will align the synchro rings much better allowing the coupler dog teeth to engage..After 1/4 mile all will go much smoother..

Letting your Jeep warm up (in neutral with clutch released) will help as this will warm up the oil the quickest....Then perform a few shift cycles with the clutch depressed..

In summary the hard 1/2 shift in cold condition is somewhat inherent to triple cone designs..

Thanks for the post. Makes a lot of sense. Just one clarification though - so only the first and second are tripple cone synchros, the others are what then?

SilverSport 01-15-2013 11:12 PM

3rd and 4th look like triple cones also while 5the and 6th appear to be double cone.

JKUCRUSHMIKE 01-16-2013 04:06 AM

My 12 does the same thing and I'm not happy about it.

Moha 01-16-2013 04:58 AM

Mine does it and compared to my previous Shelby GT500, it is still very smooth.

The colder it gets the crunchier it feels.

steve66 01-16-2013 05:15 AM

Mine does the same thing, 1 of several reasons why im getting rid of it

Maritimer 01-16-2013 06:21 AM

My 2010 JKU Sport does the same and I was wondering what was going on. Cold weather definately plays a factor in this.

We recently experienced a warm spell and the old girl was back to her normal self!

Binx 01-16-2013 08:53 AM

Its the synchro and the cold, after driving for 10 min give or take it goes away. Most manual vehicles do this, its just a lot more noticeable in a JK.

maleman876 01-16-2013 10:04 AM

I kinda like the big clunky shifting feel

Siren Assassin 01-16-2013 11:02 AM

Quote:

Originally Posted by maleman876 (Post 3235895)
I kinda like the big clunky shifting feel

This.
Gives it that beefy offroad feel in my eyes and I love it.

Jackster3 01-16-2013 11:12 AM

Idk about you guys but i dont want anything crunching.

My 13 does this too. More noticeable in the cold. Ill be taking it in to my dealer and have it looked at once its out of storage.

onetraveller 01-16-2013 12:01 PM

Jackster, you can take it to your dealer if you want, but there's probably nothing wrong with it. It's just the nature of the beast.

Mike

Jackster3 01-16-2013 12:11 PM

Quote:

Originally Posted by onetraveller (Post 3236248)
Jackster, you can take it to your dealer if you want, but there's probably nothing wrong with it. It's just the nature of the beast.

Mike

oh yeah i know mike. Im just not a fan of crunching gears happening on my 4k mile vehicle. Im just taking it in so its on there records incase something in the future happens.

Matty87 01-16-2013 12:44 PM

Mine does that, just figured I was doing something wrong

BrianN 01-16-2013 02:27 PM

Quote:

Originally Posted by SilverSport (Post 3234680)
3rd and 4th look like triple cones also while 5the and 6th appear to be double cone.

Actually, I think 3rd and 4th are double cone while 5th and 6th are single cone.

clayps 01-16-2013 08:02 PM

Did a lot of driving around today. I found that if you really ease it into 2nd and slightly pause it doesn't crunch so bad. Just need to be really patient with it.

SilverSport 01-16-2013 08:10 PM

What seems odd to me is the six speed in my '11 never acted up in cold weather.

On a side note, called the shop foreman at the dealer and told him what was going on.
Also said my '11 didn't so this. So dropped it off on the way home so he can drive it tomorrow morning. Supposed to drop into the low 20s or teens tonight. He also lined up a new Jeep to drive and compare. He confirmed the synchros can be slow to mesh when the weather is cold, but the "crunchiness" I mentioned got his curiosity.

mathew85 01-16-2013 08:21 PM

Quote:

Originally Posted by SilverSport (Post 3238119)
What seems odd to me is the six speed in my '11 never acted up in cold weather.

On a side note, called the shop foreman at the dealer and told him what was going on.
Also said my '11 didn't so this. So dropped it off on the way home so he can drive it tomorrow morning. Supposed to drop into the low 20s or teens tonight. He also lined up a new Jeep to drive and compare. He confirmed the synchros can be slow to mesh when the weather is cold, but the "crunchiness" I mentioned got his curiosity.

:popcorn:

Jackster3 01-16-2013 08:27 PM

Quote:

Originally Posted by SilverSport (Post 3238119)
What seems odd to me is the six speed in my '11 never acted up in cold weather.

On a side note, called the shop foreman at the dealer and told him what was going on.
Also said my '11 didn't so this. So dropped it off on the way home so he can drive it tomorrow morning. Supposed to drop into the low 20s or teens tonight. He also lined up a new Jeep to drive and compare. He confirmed the synchros can be slow to mesh when the weather is cold, but the "crunchiness" I mentioned got his curiosity.

keep us informed. very curious to the problem. ill be taking mine in as well.

Splittrain 01-16-2013 08:45 PM

Quote:

Originally Posted by onetraveller

Think of the shift as a two part motion. The first part is moving it out of the current gear. You need to let off the gas just before doing this to take the load off the gear splines. The second part is applying a little pressure towards the gear you want to move it into. As the RPMs drop, the gear splines will line up and you'll feel it slide into gear.

Mike

THIS.

I picked up my first wrangler the other day. Learned the basics of stick shift from a friend and have been driving around a parking lot after work every day since because I'm waiting on the title to transfer from the previous owner's bank. I drove a motorcycle all through college and thought the shift was the same concept. On cycles, you just hold the clutch and jam the lever into the next gear (downshifting requires something different). So when I started shifting from 1st to 2nd on the JK, I noticed it was notchy and not smooth. I searched around and what you are supposed to do is shift out of first and put a tiny bit of pressure into second while your foot is off the gas and it should slide right in!

Happy shiftin'


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