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Discussion Starter #1
Hi,

Like some JK my 2013 manual transmission was grinding when shifting from first to second gear when it was cold.
No problem in summer but when it was -10 celcius or below the gear were grinding when shifting.

Downshift had no problem at all, only shifting.

Normal jeep thing, I don't think its normal.

So first I change the transmission oil, with Redline MTL no real change (maybe worst but hard to say it also become colder outside) then I tried penzoil syncromesh and I saw a difference it was better but not by much.

So different oil and different temperature made difference.
enough to see a relation between oil visco and grinding of the gear.

the syncro are not doing there job.
I have 2 idea why,

1 is that the surface of the (brake) of the syncro is not fully touching the other surface to brake it before shifting. not enough friction.

2 the syncro cant stop the shaft because of the friction between shaft and gear (not enough clearance, cold reduce clearance)

So here is the solution I tried and it work for me, the grinding stopped in one day.
Maybe the cause is not the good one but the solution did work for me.

First
I am not responsible if you broke something, there is a small possibility that you can broke your transmission ( very small, I don't see why it would on a new car but an old maybe...)

Second,
IT IS 200% SURE THAT YOU WILL DESTROY YOUR ENGINE HEAD IF YOU DROP THE CLUTCH WHILE DOING THIS,
I REPEAT DON'T DROP THE CLUTCH !!

third
this trick is for a NEW wrangler with a manual 6 speed transmission having problem shifting from 1st to 2nd and having no problem at all downshifting from 3rd to 2nd


Now for the trick.

Go to the highway, drive at 100KPH like normal.
start at 100 then if everything work try higher, I only needed to go to 120KPH, more feel dangerous by the sound of the transmisison

then press the clutch
KEEP THE CLUTCH PRESS all the way down until the end of the procedure

try to put it in second gear WITHOUT DROPPING THE CLUTCH
(If there is any grind at this moment this trick is not for you.)

you will feel the syncro working its way, it will be a little bit hard to enter the gear but it will.

now you will hear you transmission spinning really fast, (at 120 I hear a vibration)
then when the car slow down to 80 KPH I just put it in 6 gear drop the cluch (you only drop at this moment when back in the 6th gear) and repeat the procedure.

I did that a couple of time (5 time fist day, then I saw it was better and I tried it again 5time when it was cold)

the problem was gone.

This either resurface the syncro brake to match the other part or make the clearance of the shaft bigger by wearing it.

I know you do put small wear on transmission and there is big chance the problem will solve itself with time but I prefer wear instead of grinding my way to the second gear every time its cold and really doing some damage, and here in quebec... cold IS an issue.

I hope this help. It was really a nightmare for me. Painful to hear each time.
Now its gone the jeep is trouble free.
Lets do some winter trail ;)
 

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Trying to force a manual transmission into gear at too fast of a speed, regardless of whether you disengage the clutch or not, will ruin your transmission. There's a reason it resists going into gear at that speed.
 

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When I had my 08 JK 6 speed it did it as well. Very common on Jeeps according to Service manager with 25+ years experience at local Jeep Dealer.
 

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My 07 also has a little problem on the 1-2 shift.....I changed to Amsoil Synchromesh fluid.
This helped a lot...I clutch and pull the lever out of 1st gear into the neutral gate and Clutch again and pull it into 2nd, The Ol Double Clutch ....Seems to go a lot better..even in the cold, but around here we'll be lucky to see ZERO....

"BH"
 

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Mine does the same when cold (-15C and below), but after 3 or 4 miles it gets near its operating temperature and just do fine.

The trick not to grind when very cold is just to take your time to shift, not my first vehicle that does that, it's normal, the thing is frozen.

Not only that, even the overhead lights, pressing the switches, located on either side of the lens, like I did this morning at -26C, just ended up having the switches stocked, and no light, after a few minutes they released and they were on, pressed them again, they were again stocked, lights still on, and after a few minutes they released and the lights went off.
 

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Discussion Starter #8
Thank for all you input



the syncro is resisting because its not finished doing is job, the more difference in speed the longer it take.
In my GTI I can even downshift in first gear, you hear the syncro starting to spin really high, yes it make the syncro work harder but that was the idea, to resurface the syncro or the shaft.
I think a little bit of wear on the syncro slipping surface and shaft is better then grinding the teeth. It will last longer. (that's only my opinion base on the fact I saw)

And you can actually go to 100kph in second gear (cut off) so I think its not that bad. doing it a couple of time, it a speed the transmission is able to achieve "normally" I know its not a race car but it still something "jeep" let you normal do. The cutoff is there to prevent damage. Going higher is risky but not certain death. ( my transmission is not ruin, its going great)

I will try Amsoil Synchromesh fluid, I heard a lot of good thing on it and its gonna be better than the normal penzoil oil, and double clutching was helping when it was grinding, although even now after 3 day of -23 celcius here (I hate my location for that, wind make it fell like -40) and no grinding. I do feel that its frozen and having a hard time but no grinding noise.

About the automatic...
I preferred manual transmission, I feel more in control of the truck. I was hating this one but now its ok, its not a GTI transmission (indestructible). It still feel cheap but its doing the job. And I would need to restart from scratch all my mod on a new one so...

And I really don't like hearing that its normal.
common problem dealer don't care... ok but normal,
I was prepare for a lots of "its a jeep thing" but not a new car grinding. Its not normal.
I had a lots of garbage car without grinding gear when cold, and in my GTI "beater" car (a old 2003 1.8t) I could, at cold start, exit the parking lot on first gear cut off then ram the second gear without grinding ( loved the blow-off sound and the car was heating faster ;) surprisingly that car is still alive... this one was not a mexican built lol) and this car is more design for a warm day at Nürburgring then a cold night at quebec.

thank again for you opinion. I just put it here to help so I hope it will.
 

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Hello folks -

I bought my '12 JK brand new with a 6spd manual. No problems shifting into 6th, ever. Suddenly this week at 27k miles I cannot get it into 6th without grinding. Even easing it in makes noise and feels horrible on the stick - but it does eventually go in.

I have made no changes to the vehicle - it is completely stock. Have others experienced this sudden problem?

Thanks!
 

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Fair enough xzy. I have been driving this thing daily for two years - road trips half way across the country, city commute, etc. Suddenly, something has changed. Same old guy, same old habits, same Jeep - then on Wed, this problem started.
 

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Hello folks -

I bought my '12 JK brand new with a 6spd manual. No problems shifting into 6th, ever. Suddenly this week at 27k miles I cannot get it into 6th without grinding. Even easing it in makes noise and feels horrible on the stick - but it does eventually go in.

I have made no changes to the vehicle - it is completely stock. Have others experienced this sudden problem?

Thanks!
Take it to the dealer asap. That's not normal and will be covered under the powertrain warranty. It sounds like a syncho failure.
 

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Fair enough xzy. I have been driving this thing daily for two years - road trips half way across the country, city commute, etc. Suddenly, something has changed. Same old guy, same old habits, same Jeep - then on Wed, this problem started.
I'm sorry I didn't make myself more clear. The suggestion was for the OP.

Blastek is right. You're under warranty. Have a dealer look at it.
 

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Discussion Starter #14
Pretty old post but to update, I'm at 100 000KM and the transmission is working great, even in cold weather now, no more 2nd gear grind at all.
The syncro where really just to tight on there shaft when it was cold. (here in quebec it can be -30 easy, and from what I heard with other cold weather jeeper, its almost a common problem, American transmission with machining spec not made for extreme cold) A little wear on the 2nd gear syncro and now it do its job perfectly.

I will update a 200 000km loll
 
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