M2B4 5th gear issue - 1st world problem

Free Ranj Egg · Post by **Free Ranj Egg** » Wed Nov 30, 2016 8:40 pm

Fellow luders.

So today my M2B4 gearbox went into my car and I was excited to pick it up and drive it home. So after work I call the mechanic who happens to be my uncle and I'm told there is no 5th gear.

Needless to say I wasn't a happy bunny. So I pick the car up and decide to run a few tests myself. This is where I'm hoping you guys can really help me.

When the car is off the gears engage fine, 1-4 feel like they are going into the forks and you get the usual reverse crunch. 5th felt quite flimsy but I was told that the car wouldn't even go into 5th over the phone. Reverse was fine as well.

I fired the car up and sat there for about a minute to admire the sound of the skunk 2 exhaust. Then I was like... er get back to reality mate.

So I let the car idle for a few minutes and went through the gears with the clutch down and all the gears seems to engage fine. A new clutch has been fitted so it felt a little weird. There was a slight crunch in 5th but when I went through the gears the second time, there was no crunch.

I took the car for a drive and 1-4 engage fine. Reverse is also fine so ive ruled the syncro mesh out.

Now when the car goes into 5th sometimes it engages without crunching, it seems to engage fine when the clutch is down. However as soon as the clutch is lifted its popping out of 5th and crunching.

The car had an ATR clutch and Honda MTF3 oil from ebay,

I don't really want to take the gearbox out, and put the old M2P4 back in as I feel that is just a waste of money.

Has anyone got any ideas as to what the problem is or what remedies I can try?

I was tempted to change the gearbox oil for another one to see if that cures the problem. The LSD from what I can tell seems to engage fine.

Any advice or guidance is appreciated.

@cutz - if you quote me happy like the Churchill dog I may come and see you before xmas.

Cheers in advance gents.

Ranj

damon · Post by **damon** » Wed Nov 30, 2016 9:12 pm

@Drax is a con man, I'll drive to his a bum drokk him till he pays you back.

Free Ranj Egg · Post by **Free Ranj Egg** » Wed Nov 30, 2016 9:17 pm

Drax feels bad mate.... I'm hoping I can find a solution to the issue. jobby happens

preludemanh22 · Post by **preludemanh22** » Wed Nov 30, 2016 9:29 pm

rebuild

Free Ranj Egg · Post by **Free Ranj Egg** » Wed Nov 30, 2016 9:31 pm

Please don't say that Preludemanh22. On another note I wrote faces happen... no idea how it turned in jobbly lol. That has made my jobby day turn good lol

preludemanh22 · Post by **preludemanh22** » Wed Nov 30, 2016 9:35 pm

ive got a perfect working low milage box here

Cutz · Post by **Cutz** » Wed Nov 30, 2016 9:51 pm

Hi Ranj,

The 5th gear selector is the common fault on these gearboxes so don't be surprised if its at fault.

However, if you bought the boxed from a trusted individual then it could more likely be down to the installation....I would be interested to see the condition of the shifter cables, bushings and their correct routing. If they are not in the correct position, a slightly worn box can appear far worse.

MTF 3 is perfect for the gearbox, nothing more is required.

Also, if you're running any kind of a short shifter, that will exacerbate the problem.

Hope that helps a little.

Matt

Post by **vanzep** » Wed Nov 30, 2016 10:05 pm

the selector fork does seem to be the bit that gets snagged up when taking the box in and out at least thats my experience when doing the job off axle stands. If doing it this way then it really needs two people to remove/fit it

mind u im no mechanic

if it helps any ive got a known/good m2b4 box here but the casing is broken at the vss so i was keeping it as spares for either of my boxes but if you find you need to replace some parts then let me know

Cutz · Post by **Cutz** » Wed Nov 30, 2016 10:14 pm

I can't say I've ever heard of issues with 5th gear crunch that came down the physical removal & installation... Apart from maybe dropping it on the mechanism itself but that's just clumsy!

The selector I'm referring to is on the gear shaft itself...high rpm shifting between 4th and 5th just seems to wear them out.

Best option is a Synchrotech full carbon rebuild kit along with a new selector. Then she's good to go for years.

Post by **RattyMcClelland** » Wed Nov 30, 2016 10:45 pm

The selector folks can fatigue over time. This then makes 5th gear more difficult to select and causes the usual problem.

I think paw did a few super folk mods to strengthen them.

Ranj did you drive the car and get the engine and gearbox nice and warm?

I'd first look into how the cables are positioned.