2004 to 2020 Mazda 3 Forum and Mazdaspeed 3 Forums banner
1 - 20 of 21 Posts

·
Registered
2018 Mazda3 6MT
Joined
·
79 Posts
Discussion Starter · #1 ·
Hi all,

So, I have a 2018 6MT GT. I noticed recently that I will hear a grinding sound going into 2nd gear on occasion. I tried to see if it only happened when the fluid was cold or only in a certain RPM range, but cannot seem to find a pattern. I have a road tests scheduled with the dealer this Monday, but I really cannot afford for them to take it apart, inspect the gears, and possible have to replace the 2nd gear or anything else out of warranty. I'm worried that the previous owner drove this car improperly causing excessive wear, which to my understanding would void the warranty claim anyways. I will probably request a fluid flush but am unsure if this is necessary, I guess I should pay the money to have them check it at the least.

The car currently has 34k on the odometer. Sometimes, the shift is smooth. Like I mentioned, I cannot seem to find a pattern but I do feel like I've been able to mitigate it based on how I grab the shifter (maybe it responds better with a more gentle shift?).

Is there any other information I should provide here? I'm pretty nervous because this sounds a really expensive fix.

Thank you all.

Sent from my SM-F711U using Tapatalk
 

·
Registered
Joined
·
2,431 Posts
First thing is always the gear oil. Since it was previously owned, did the last guy put the wrong oil in it?

Clutch or clutch hydraulics are a possibility, but since you're saying only 2nd gear it's probably not. Still, bleed the clutch cylinder to be sure there's no air in it.

There's also a TSB with a procedure to realign the shift cables. Many members here have had very good results.

After that, yes a failed trans is still on the table. Likely would be a synchro gear. However, if it's occasional and money is an issue, I'd say keep going until it gets bad. It's very unlikely that it would fail suddenly.

Another possibility is a bearing failing. Excessive bearing play could cause this. Listen for an unusual high pitched whine. That would need to be addressed asap. You should hear the noise in all gears if that is the case.

I've always had a very mild whine from mine in 3rd gear, but it's never gotten worse. I believe it to be gear lash slightly out of spec. 225k kms now so pretty safe to say that it doesn't matter.
 

·
Registered
Joined
·
1,241 Posts
First thing is always the gear oil. Since it was previously owned, did the last guy put the wrong oil in it?

Clutch or clutch hydraulics are a possibility, but since you're saying only 2nd gear it's probably not. Still, bleed the clutch cylinder to be sure there's no air in it.

There's also a TSB with a procedure to realign the shift cables. Many members here have had very good results.

After that, yes a failed trans is still on the table. Likely would be a synchro gear. However, if it's occasional and money is an issue, I'd say keep going until it gets bad. It's very unlikely that it would fail suddenly.

Another possibility is a bearing failing. Excessive bearing play could cause this. Listen for an unusual high pitched whine. That would need to be addressed asap. You should hear the noise in all gears if that is the case.

I've always had a very mild whine from mine in 3rd gear, but it's never gotten worse. I believe it to be gear lash slightly out of spec. 225k kms now so pretty safe to say that it doesn't matter.
I agree with all... except the order. Test for air in clutch hydraulics is super easy to do with a measuring tape... Clutch that doesn't fully release manifests most (as gravelly downshifts) into 1st and 2nd gears... except that by far the most-often downshifted-into gear (when the car is moving) for most drivers is 2nd gear.
 

·
Registered
2018 Mazda3 6MT
Joined
·
79 Posts
Discussion Starter · #4 ·
First thing is always the gear oil. Since it was previously owned, did the last guy put the wrong oil in it?

Clutch or clutch hydraulics are a possibility, but since you're saying only 2nd gear it's probably not. Still, bleed the clutch cylinder to be sure there's no air in it.

There's also a TSB with a procedure to realign the shift cables. Many members here have had very good results.

After that, yes a failed trans is still on the table. Likely would be a synchro gear. However, if it's occasional and money is an issue, I'd say keep going until it gets bad. It's very unlikely that it would fail suddenly.

Another possibility is a bearing failing. Excessive bearing play could cause this. Listen for an unusual high pitched whine. That would need to be addressed asap. You should hear the noise in all gears if that is the case.

I've always had a very mild whine from mine in 3rd gear, but it's never gotten worse. I believe it to be gear lash slightly out of spec. 225k kms now so pretty safe to say that it doesn't matter.
Thanks so much for this. I'm gonna use this so ask the techs to flush the oil and check it and bleed the clutch cylinder.

Sent from my SM-F711U using Tapatalk
 

·
Registered
2018 Mazda3 6MT
Joined
·
79 Posts
Discussion Starter · #5 ·
I agree with all... except the order. Test for air in clutch hydraulics is super easy to do with a measuring tape... Clutch that doesn't fully release manifests most (as gravelly downshifts) into 1st and 2nd gears... except that by far the most-often downshifted-into gear (when the car is moving) for most drivers is 2nd gear.
I rarely ever downshift into 2nd. Lowest I downshift into usually is 3rd.

Sent from my SM-F711U using Tapatalk
 

·
Registered
Joined
·
2,431 Posts
I agree with all... except the order. Test for air in clutch hydraulics is super easy to do with a measuring tape... Clutch that doesn't fully release manifests most (as gravelly downshifts) into 1st and 2nd gears... except that by far the most-often downshifted-into gear (when the car is moving) for most drivers is 2nd gear.
Well I can't argue with this one :) in hindsight I'd put that shifter cable alignment as second.

For the OP, the TSB doesn't apply to your model year but the procedure should be performed none the less. We've seen several instances here like yours.

Here's the link Extremely Notchy Gearbox Fix (2->3 and 4->5)
 

·
Registered
2018 Mazda 3 GT
Joined
·
3,627 Posts
1-2 shift is the toughest in these cars.. big change in gearing between the two. Are you fully depressing the clutch pedal before shifting and then releasing it to the bite point and holding before releasing the remainder at a steady pace? You should also do this shift pretty quickly after getting going in first. 7-10 mph

3rd requires a much shorter pause at engagement and 4th to 6th require almost none.
CK
 

·
Registered
2018 Mazda3 6MT
Joined
·
79 Posts
Discussion Starter · #8 ·
1-2 shift is the toughest in these cars.. big change in gearing between the two. Are you fully depressing the clutch pedal before shifting and then releasing it to the bite point and holding before releasing the remainder at a steady pace? You should also do this shift pretty quickly after getting going in first. 7-10 mph

3rd requires a much shorter pause at engagement and 4th to 6th require almost none.
CK
I am pretty inconsistent with when I decide to shift. When I want to get up to speed, I get the car to about 15 mph or close to 3k rpm. In calm settings, I do 7 - 10 mph.
 

·
Registered
2018 Mazda3 6MT
Joined
·
79 Posts
Discussion Starter · #9 ·
Just to update everybody, I was planning on taking a dealership tech. on a road test last Monday, but had to stay late for work so I couldn't. However, I started changing the way I shift; I began pulling the shifter just how I would going from 3rd to 4th (no downward pressure or pulling toward myself). I now have a very smooth shift, almost as if the problem just completely went away. It's very odd. How was me applying pressure to the shifter causing this?
 

·
Registered
Joined
·
1,241 Posts
Well, it 'kinda sounds like the shifter neutralization adjustment (to the extent that perhaps it is not neutralized) may allow this behaviour of the shifter. I do know that for me, a light, two-fingered touch (not a grabbing- and holding of the gear-change knob) is the right touch for me. You've 'gotta "will" it into gear, not "cane" it into gear (or variants thereof).
 

·
Registered
Joined
·
1,241 Posts
1-2 shift is the toughest in these cars.. big change in gearing between the two. Are you fully depressing the clutch pedal before shifting and then releasing it to the bite point and holding before releasing the remainder at a steady pace? You should also do this shift pretty quickly after getting going in first. 7-10 mph

3rd requires a much shorter pause at engagement and 4th to 6th require almost none.
CK
Agree...first-to-second is the hardest. Your comments re achieving the full throw of the clutch pedal is a segue-in to the whole matter of an air-free clutch hydraulics system, indeed allowing full clutch disengagement (and then some).
 

·
Registered
2012 Mazda 3 GX MT5 non sky
Joined
·
1,412 Posts
I agree with all the Mazda Einstein's above.

Fluid - just replace with Mazda OEM or equivalent grade performance gear oil -use the best you shouldn't need to replace for a long while.
Synchro's do wear out and degrade over time as do the bearings - but at 34K its like new still.
Grinding a gear - most likely from clutching incorrectly / timing . You are shifting before completely
depressing the clutch and gear is not synched to receive it. Happens to me all the time when at the track when aggressive driving and shift gears fast. Foot faster than hand or vice versa.

Shift linkage is also a possibility. This usually happens over time alot of milage that repetitive motion loosens or wears something out. That happening to me know at 270k KMS

When the synchros are completely worn it will block you shifting into that gear all the time
 

·
Registered
Joined
·
1,241 Posts
Yes... and the third gen Mazda6 too.

You should approach removal of the centre console pieces with some delicacy. Plastic trim removal tools and access to the factory service manual to learn the shape and location of the attachment dogs. Also, remove any cup holder rubber liners and look for screws.
 

·
Registered
2018 Mazda3 6MT
Joined
·
79 Posts
Discussion Starter · #17 · (Edited)
Yes... and the third gen Mazda6 too.

You should approach removal of the centre console pieces with some delicacy. Plastic trim removal tools and access to the factory service manual to learn the shape and location of the attachment dogs. Also, remove any cup holder rubber liners and look for screws.
I removed most my center console with screwdriver when I was changing out my shiftknob but definitely wasn't delicate. What are the names of some of the tools you recommend? Do you recommend the tools in this google search? Essentially, could this whole service you posted above be relatively easy DIY? It seems like it.
 

·
Registered
Joined
·
2,431 Posts
I removed most my center console with screwdriver when I was changing out my shiftknob but definitely wasn't delicate. What are the names of some of the tools you recommend? Do you recommend the tools in this google search? Essentially, could this whole service you posted above be relatively easy DIY? It seems like it.
I have a very similar Amazon set and it's served me well for years. Highly recommend. Do note that when you see reviews with people complaining about the tools being too soft, they're supposed to be softer than your trim so you don't damage it. They're idiots.
 

·
Registered
Joined
·
1,241 Posts
I removed most my center console with screwdriver when I was changing out my shiftknob but definitely wasn't delicate. What are the names of some of the tools you recommend? Do you recommend the tools in this google search? Essentially, could this whole service you posted above be relatively easy DIY? It seems like it.
Yes, DIY if you use care with the console pieces.
 
1 - 20 of 21 Posts
Top