M2B4 gearbox downshift issue 4th gen

[vanzep]

I was out today in the BB1 on a B road and found i could not downshift from 4th to 3rd - it just would not go. No issues going up the gears or going down except 4th to 3rd. Was ok when i came back into town and was doing lower speed 20-30mph - 4th to 3rd was a bit notchy at first but then seemed okish.

Anyone had this issue on the M2B4 manual gearbox?

I will have a look over things tomorrow but any input welcome

p.s clutch changed around 2016 with oem honda atr clutch and gearbox oil changed a couple of times most recently again with genuine honda MTF.
so well maintained and about 50k-60k miles on clutch.
there seems to be a bit of vibration from gearbox mount side so will have a look at that.

[vanzep]

had a quick look today and found clutch master cylinder was down on fluid - nothing in there except for some crud.
cleaned it up and topped off the clutch fluid and it feels better will have to keep any eye on the fluid level for the next while

[Drax]

sounds like you've nipped the issue in the bud! i've heard once before of the shifter cables loose on the engine bay side, that would have been another thing to check but i wouldnt bother at this point lol

[Scott560]

had a quick look today and found clutch master cylinder was down on fluid - nothing in there except for some crud.
cleaned it up and topped off the clutch fluid and it feels better will have to keep any eye on the fluid level for the next while

My experience is that once it's leaking somewhere, you are not far off a complete failure which might leave you stranded. It also seems to always coincide with cold weather I seem to recall. Worth keeping some fluid and an 8mm (I think) in the car with some pipe...

I have had fluid leak at both ends (Should see a doctor lol). If time permits, get on your back, head under the steering wheel - you may start to see fluid leaking into the foot well from the master cylinder. Its a little bit of a ball ache to replace but not such a bad job so as to put it off.

It's a little harder to check the slave as its supposed to be sealed and its not leaking into a clean area. Luckily the slave cylinder is easier and cheaper to replace.

Last time 1 gave me any trouble I just replaced both. Also, it seems that fluid in this system gets darker than the brake fluid at the callipers - perhaps a sign that the seal material leaches out and darkens the fluid as it wears (unlike brake seals which must be higher quality/high regulation).

I also seem to recall that the 4th gen and 5th gen slaves are different (as I got sent a 4th gen in a 5th gen box annoyingly).

[vanzep]

thanks Scott560 - yeah im keeping some clutch fluid in the boot just in case. will give it a visual check for leaks - it can only be mc or slave and slave looked dry - i have a couple of spare clutch mc and some used oem clutch lines and stuff so should be ok if i need to replace anything.

[wurlycorner]

Just as a related comment since you mentioned crud in the master reservoir - its amazing how dirty the clutch fluid gets. You can do a full flush through the system and within weeks you can already see it starting to cloud up etc.
Pretty sure it can only be the inside of the clutch hoses breaking down that causes that, microscopic rubber particles.

[Vtecmec]

My clutch fluid goes really dark really quickly.

I thought breaking seals too, so replaced everything, both cylinders, the lines, the reservoir and the hose, all with high quality stuff, only for it to turn dark again a few weeks later.

[wurlycorner]

That's so weird then?
The brake system doesn't suffer from it.
Only differences are the volume of fluid that gets moved on each application (clutch is more) and the volume of fluid in the reservoir/size of reservoir (clutch is much less)?

[Vtecmec]

Weird indeed, I suppose the fluid is also open to the atmosphere too via the cutch reservoir, which its not in the brake system.

[Drax]

if time permits, get on your back, head under the steering wheel - you may start to see fluid leaking into the foot well from the master cylinder. Its a little bit of a ball ache to replace but not such a bad job so as to put it off.

this is a good point, i saw this when my reservoir was leaking and needed changing on the 5g i think