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2015 GT transmission issue

20K views 29 replies 12 participants last post by  Mathieu9836 
#1 ·
I bought a 2015 3 GT with a 6 spees manual transmission. I has been hard to ahift between gears since its new. Went to the dealer with it and you know what they always say, then found nothing wrong. Seem to be worst when its cold, any one have ever tried different oil in these type of trans? Or any advice? Sorry for bad english, im french canadian.
 
#2 ·
I also have a 2015 S GT with the 6speed MT. I haven't had any problems shifting, but it did take a little while to learn how to be smooth with this transmission. I've driven manuals for over a decade now, and this transmission definitely feels different. It's not a bad different, but it is different. :)

Not sure what you mean as far as being hard to shift between gears. The shifter has been smooth as butter for me. It was the clutch/gas transition that took me a little while to adjust to.
 
#3 ·
Defenetly feela different then my Spec-V and my civic SI, cant shift first to second in a hurry, 2nd wont get in at all. Sometime it feels like collar between 2 gears wont slide in easely. once the transmission get hot, usually shift like butter. Im going the change oil in it for something better like Redline ligjt shock proof or even synchromesh and see if the issue goes away.
 
#4 ·
I believe it has something to do with pushing the clutch all the way in, as I was having trouble going into third gear, but found I wasn't pushing the clutch all the way, so it made shifting a bit harder. I would suggest, trying to see if that may be the problem, instead of going through the trouble of changing your transmission oil. If you do go that route, make sure it doesn't void your warranty.
I've been driving manuals for as long as I can't remember, thought I was an expert and everything. Then along came this third gear shift, and it turned out, I had lazy-clutch foot.:wink2:
 
#8 ·
I have found a lot of people who have driven manuals their whole life are incapable of recognizing that they suck at shifting when they switch cars.... and then always blame the bad shifting on the car, or just seem to ignore the fact that their passengers are getting severe whiplash at every shift. The issue is that you're so used to driving one particular transmission that may have been super forgiving, or maybe was just vastly different, and then you switch to another transmission you're forced to shift correctly and if you don't, the results are very bad.

My current GF suffers from this same issue in her honda fit. I'm not about to tell her that her shifting isn't good. Interestingly though, I let her drive my speed, and her shifting was nearly perfect.... turns out she grew up driving a car with a super heavy clutch like the speed, and the honda's clutch is feather light and has zero driver feedback.
 
#9 ·
:werd:That's a good point. I've owned and driven 4 other manual transmission vehicles from econo boxes to sports cars to 4x4 trucks along with a few rentals and there are very real differences between them. So if one is used to driving just one other M/T then switching to something different can have some challenges. Just need to change your driving (or at least shifting) habits and all will be good :grin2:
 
#12 ·
Well that is short shifting it a little bit, but I'm almost positive your issue is that you're dumping the clutch too fast, or unintentionally dwelling at the friction point of your old car's clutch, which is not the correct spot for the new car and therefore isn't working.

As dumb as it sounds, take some time to slow down and re-learn how to drive manual. From a stop, slowly let the clutch out and find exactly where the clutch starts to catch. This is where you should be dwelling for a second or two when letting out the clutch when shifting at low RPMs. It may take a few weeks worth of practice to break the old habits. Sidenote related to shifting at higher RPM - if you're shifting at high RPMs while on the gas, you can dump the clutch all you want and it should still be smooth so that is probably why you found that it is better that way.
 
#13 ·
I've been having the same issues with my 2015 M3 GS. Shifter is notchy which "might" be acceptable, but the real problem is that sometimes I feel like the clutch is not disengaging completely. I'm pushing it all the way. It also starts catching really low, maybe 1" from the floor. I'm suspecting air in the hydraulic line or faulty master/slave cylinder. On two occassions the car nudged a bit forward as I was trying to engage 1st gear the first time after getting into car. First time it happened I thought I was crazy and immagining it, but the second time it happened yesterday and I don't have any doubts anymore there is something going on. It felt like I was pushing synchro against the loaded shaft.

I will ask the dealer to test drive other unit. The car I drove as a tester before buying didn't have such issues. If it had, I wouldn't buy this thing.
 
#14 ·
OK, it's not the clutch. I've tried thre reverse test after spinning up the input shaft. I've also tried to engage and disengage the same gear while holding the clutch. And engaging the reverse while revving up with the clutch in. It is fine.

The issue is in the tranny. So, what I figured is that it takes really long time for the synchros to slow down the shaft. I did the following: Rev up to 3-4k RPM in neutral to spin up the input shaft -> clutch in -> engage any gear. There is significant resistance for a long time. I'd say for a 1-2 seconds before it slips into gear.

Is it normal that it takes the synchros this long to completely stop the shaft? I've read on couple of places that this tranny oil that Mazda puts in is too thin and that some other's (as Redline) are much better. Could this be the case here?
 
#15 · (Edited)
If you go with another oil make sure it is GL-4 only.

If it says GL-4 and GL-5 then stay away. Your tranny is only GL-4.

Anything GL-5 is not backwards compatible.

Use this

AMSOIL Manual Transmission & Transaxle Gear Lube 75W-90

or this

http://www.amazon.com/Genuine-Ford-XT-M5-QS-Synthetic-Transmission/dp/B000NUES82

I used amsoil when I had my 08 speed

I think the 10+ speeds have pretty much the same tranny as the 2015. At least they use the same oil 75w-80 GL-4.

Redline is known to be good as well.

Lots of info on it out there. Ford stuff seems to be at the top of the list. I used amsoil it worked well for me.
 
#16 ·
Slightly load the gear shift a half second prior to the shift, and release accelerator at the same time...NOT BEFORE YOU SHIFT. back on the gas as the clutch is engaging. Practice this. You'll be smooth as butter. Good clutch work takes practice no matter how experienced you thought you were. My new 2015 3 is the nicest steering/driving vehicle I have ever had (for the price). I'am 69 and I have driven many good manual shift cars and I love this car. Maybe a bit more than my 04 Mazdaspeed MX5.
 
#17 ·
Ive been having this issue for several months now, and for your info, ive driven many different manual boxes without issue but this one, and i'm also a diesel mechanic, so i'm used to drive 18 speed trans without problems. like Khyansaid, it feels like the synchros do not slow the gear fast enought. The only way i manage to make it shift smoothly between all the gears is to use double clutch. My girlfriends 03 civic shift better then my new GT.
 
#19 · (Edited)
I usually shifted in the 3-4k range. It is a weird tranny to get used to. I had a manual on the 08 speed. also drove my buddies 10 speed that uses the same oil they use now. So I am curious on the differences. But when I drove his speed It felt very similar to mine. I found this bad boy likes the higher revs. I did enjoy driving the manual once I got it down.
I also switched to amsoil. Shifting was better after. My buddy went with the ford stuff and he felt improvement in shifting. something to consider.
I had this one time in the first couple of weeks driving the car were I shifted from 3rd to 2nd coming to a stop light. I did not go to 2nd right away but when I did I felt like putting a metal rod against something spinning and sounded terrible. It was like the synchros were off when going to that gear. Had me worried. Never happened again. I dont downshift much just once in a while. First time ever had that happen to me in a manual. But the tranny was solid and ran great until I traded. The change of oil helped a good bit with shifting. Just make sure you get a GL-4 lube only if you do.

Also I always push the pedal all the way to ground when shifting. Never rest your foot on the clutch pedal either while cruising. It will wear it down. More for the folks who are newer to a manual.
 
#20 ·
Slightly off topic from the OP but I have found that sometimes when starting out, the "hill assist" in the MT can sometimes make shifting from neutral into 1st gear a challenge, almost to the point of preventing you from getting into gear. If you just let the car roll a little, it will snap right into place though.

Another practice that I did (more of a habit) is when slowing down, I run down through the gears without letting the clutch out. Not saying this does anything but idk for sure. Basically clutch goes in, then I shift down, 6,5,4,3 neutral usually. Just a thought, again though, no logic or reasoning behind it.

I have 13k miles on mine, not a single complaint with the shifting. I too push my clutch to the floor when shift and really dont push my car past 4k RPM's too often....gotta keep that MPG high!
 
#21 ·
Hmmm, just test drove a 2016 Mazda3 s Grand Touring with a 6-Speed manual, and neither my wife or I had any issues shifting smoothly regardless of how high or low the RPMs were. That said, the car did feel very similar to the 2012 GTI we're trading in on a new Mazda3, so maybe we were just used to shifting how the Mazda likes to be shifted.
 
#27 ·
On my 06 Miata I switched to a Ford transmission fluid that's made in Germany (important - get the German stuff not the regular) and it made a big difference in smoothness of the shifting (Miata's are pretty good stock, but this was noticeable improvement). It was expensive but really worth it I felt. You might look into it and also search around on the Miata.net site for some discussion on it.


I got old and now have an auto in my 2015 GT Mazda3 so not up to date on this issue anymore.
 
#30 ·
Its been a while now and i though i should get you in touch with what i have found to be the issue. After replacing the trans oil with synchromesh, it was shifter a bit better. Since the rear motor mount was way to soft to me, i decided to replace it with the corksport rear montor mount and i was very pleased with the result, trottle response is a bit better but the shifting is waaayyyy better, no more issues with that transmission. After 2-3 months, the urethane in the motor mount teared appart around the sleave, and i noticed slowly an increased in shifting harshness if i can say, so after the motor mount was replaced under waranty, it came back to normal. I also have to say that this car have a slow trottle response and i tended to shift with the foot on the trottle, which was about 10% of the issue imo.
 
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