Ascension

Firstly, I did search for those two keywords, and no threads on the topic came up. Secondly, I'm asking in regards to a bone stock vehicle.

I mainly want to know how the 6MT transmission holds up after a prolonged period of time. We can use 100k, 150k, and 200k as intervals. I have to assume that with normal, civilized driving, the transmission won't have any issues whatsoever. However, what about spirited, and harsh driving? I'm not referring to launching as harsh, since that's just pure abuse. I'm referring to harder, forceful shifts. This isn't necessarily alluding to banging gears, as in a race either, per se.

Let me try asking a different way! At what point does the clutch begin to slip? At what point do the syncros begin to grind? How sturdy is the transmission, and how much punishment can it endure before something begins to give out?

Obviously, I'm aware the the main concern is always user error, and this becomes subjective. If you have a 6MT, please tell me about your driving style, and how your transmission has endured your style of driving. Thank you in advance!

FlyingDagger

I can't speak to longevity, but the delay on the clutch pedal was the source of most of the issues I ran into. I replaced the master with a Luk LMC410. The pedal was totally transformed. I would say that it is less easy to stall now which could be controversial. I didn't find it particularly easy to stall in the first place once I got even remotely used to it. The engagement is high and the pedal does not have an even feedback all the way through. If you are going for a fast technical shift then the delay will cause you to grind. Ive also found that overly casual shifts can fall short too. When you do get it near a stall the issue is that its hard to correct the situation. The delay makes it so that you under or over correct and you might stall. With the delay gone you might find yourself in the near stall situation very slightly more often but you can immediately and intuitively correct the situation. I've only ever really stalled when the delay/engagement point caused me to double pump on the correction, but that doesn't happen anymore. The feedback pressure from the pedal is much stiffer in general but also consistent the whole way.

Its a very worthwhile upgrade in of itself, but I also feel like I am putting less strain on the clutch now since I'm not searching for the engagement point like before or accidently missing a shift due to the delay being weird.

The other common issue is resolved by swapping out the transmission fluid. 1st to 2nd and 2nd to 3rd can have some issues with the OEM fluid. I am in a colder climate so I went with the ACDelco. If I was in a warmer climate I would have done Amsoil. I might go Amsoil anyway, I'm probably going to dump the ACDelco way early to compare.

I can definitely see there being issues on a car that was shifted sporty without those issues being addressed. But again, its mostly going to come down to the driver and how their performance with it was. I've only heard of the transmission itself getting issues in very rare cases and I feel like they were from drag racing the car....

WDPanda

Is that LMC410?
Rockauto coming up with LMC433 for me.
The delay is not as bad as the 3g but it's annoying. I would love to do this mod if its a significant difference.
The 4g seems to suffer more in the 2nd gear notchiness than the 3rd gear like 3g

FlyingDagger

I wrote down 410 on my notes from the box after install. Looked up the order, it says 410 too. The 433 might work also?

Yeah, I would agree with the 2nd gear being the notchy one as well. Never drove a 3g, but do feel like most of the comments about 3rd were probably about them now that you mention it.

Definitely significant. I would still prefer if the engagement was a little bit lower but it really is night and day difference in both pedal feel and the ability to use the clutch effectively.

BROlando

These transmissions don't seem to like banging the gears. There's a sizeable gear delta between each shift.

So...don't bang gears and it should last virtually forever. 200-300K miles before needing serious work.

Clutches are wear items that will wear differently for each person. It would be like asking how long the tyres and brakes last on someone else's car. I wouldn't be surprised with well over 100K miles before needing a clutch, if the car is driven well.

WDPanda

GM Synchromesh Friction Modified transmission fluid helps get rid of notchiness in the 4G also. My 3G was buttery smooth 5 years after having started with a notchy 3rd gear.
4G is smooth now having started with a notchy 2nd gear.

JM2010 SH-AWD

My '10 has only about 66K miles on it, but no issues whatsoever (knocks on head). The engagement point is a little tricky to master at first, but you'll quickly learn it. The clutch does not like to be slipped -- if you slip it excessively, it'll let you know at first from the smell. Do it long enough and it'll let you know when it fails.

I like the MT a lot. It has good feel and is very precise. First gear is pretty low, 2-5 are pretty close, and 6th is an overdrive gear -- pretty big jump from 5th.

I'd expect the transmission to last under normal "enthusiast" (not abusive) use the same as all my other Honda/Acura MTs -- trouble free for well over 100K miles. (We've owned 7 Honda/Acura MT-equipped cars on which we put, collectively, over 500K miles and have never replaced a clutch or had a transmission issue of any kind).

Riboflavin

GM Synchromesh FM 10-4014 was a night and day difference from OEM Honda MTF. Significantly better 1-2 and 2-3 shift. OEM fluid left those shifts relatively vague and squishy feeling (causing me to grind 2nd gear under heavy load multiple times), but GM Synchromesh made them much cleaner and more precise feeling.

I have 167,000 miles on my 2010 (167k on the trans, 72k on the motor after a warranty shortblock replacement), and the trans is holding up fine. Original clutch didn't go until 150k miles, and I taught myself how to drive manual on this AFTER I bought it at 56k lol. Original clutch master cylinder blew at 136k.

I'd consider my driving style to be pretty spirited, since I like hearing my XLR8 exhaust... I don't granny shift, but I also don't regularly WOT bang gears (only on occasion on highway on-ramps), and everything seems to be going alright.

Ascension

I'm glad to hear about your positive experience, and I value your input. Thank you for sharing!

I'm glad to hear about your positive experience, and I value your input. Thank you for sharing as well!

Nev05

I have a 2012 in manual that I bought at 150k KM. I am the second owner so I'm not sure if the clutch was replaced before but I had to replace the clutch at 180k KM. I read about all the greatness of the GM synchromesh so I decided to give it a try. I never had any issues shifting before but I wanted to see if it betters the experience in any way and it did not. I do drive "spirited" quite often and I did not feel any difference in shifting feel with the GM synchromesh vs. the Honda/Acura MT fluid. Also, up here in Canada, a bottle of the GM synchromesh goes for around $25 a bottle while the Honda/Acura fluid goes for $12.

Ascension

Now that I actually own my very own 6MT, and having driven nearly 2,000 miles this month, I'd like to add some input regarding durability. So, my car has 219k miles on it now. The transmission was swapped out in 2018, at 160k miles with a used unit, that was serviced with new parts at that time. The previous owner didn't have much information in addition to this, and I don't know what the cause would've been for replacing without speculating. While I'm not certain what a brand new clutch feels like, all I can say is that this one feels superb. All gears are buttery smooth, regardless whether it's during a cold start, or at fully operational temperature. So, ~59k miles on the current transmission, and it feels superb. I haven't smelled what a burnt clutch smells like in over a decade, and I haven't smelled any scents that were off-putting from my driving thus far. I have to assume that I'm adept enough at driving a manual, especially after 13 years. I'll replace all of the drivetrain fluids after Winter, in Spring, with OEM products.

In one of my other threads, I've mentioned that I began practicing heel toe downshifting in the 6MT SH-AWD. Other than some rough shifts initially, I've been progressing rather well. I'm hoping the initial rough patches will not speed up the wear and tear on the clutch.