M2P4 gearbox sticks in 5th gear..

[tobyslude]

Hi,

So I've recently finished my M2J4 to M2P4 gearbox swap on my 99' BB9, been out tonight and once you put it in 5th cruising along it doesn't wanna come out. Unless you put the clutch in, rev match and let the clutch out, then put the clutch in again and then it comes out. Or, as I learned tonight, if you come to a stop in 5th I have to stall it on purpose, turn the car back on, clutch in then it comes out. Is someone able to clarify whether this is the classic 5th gear/reverse synchro failure and if I'll inevitably lose 5th/reverse altogether (which was the reason I did the swap in the first place) or something else? Gear linkages ontop of the box look fine, and I filled the box up with 2l of Honda MTF when swapping it.

Any info is appreciated, really hope this isn't a gearbox fault again..

[Scott560]

sounds knackered if you ask me did the box come from a car that was running or was it an unknown been kicking around in someones garage for a few years? My ATR box was supposedly good but been in someones garage for a few years, turns out 5th gear syncros were knackered (had it checked before it was fitted).

[Vtecmec]

How does it act when the car is off? How well does reverse gear engage?

[tobyslude]

How does it act when the car is off? How well does reverse gear engage?

With the engine off, clutch in 5th feels pretty fine going in and out. Reverse sometimes requires double clutching for it to go in otherwise you can feel it go halfway in if you know what I mean.

[Vtecmec]

That does not sound good.

I think the only thing you can try is different box oil. Redline MTF can make a difference with syncro issues.

It worked for the gearbox in my e90 BMW, it used to crunch terribly 2-3 at pace, I swapped the oil 30k ago and it's been fine since.

[Vtecmec]

I guess there now called lubricants rather than fluids.

https://www.opieoils.co.uk/p-1019-red-l ... 0-gl4.aspx

I'm sure you can get it cheaper elsewhere, but this stuff is excellent.

[tobyslude]

I guess there now called lubricants rather than fluids.

https://www.opieoils.co.uk/p-1019-red-l ... 0-gl4.aspx

I'm sure you can get it cheaper elsewhere, but this stuff is excellent.

That's a shout to be fair. I have an IS200 too and lots of people on the forums have trouble with a couple rough gear changes and swear by Redline gearbox oils. Thanks mate might give that a go come payday!

[wurlycorner]

Just a thought, but considering this is the second box in the same car with the same problem... Have you got the right gear shifter in the car?
It's not been swapped for something from a different Honda/after-market (that has a slightly different length throw on it) has it???

Is the clutch fully bled?
Has the clutch been messed around with (after market cylinders or clutch lines)?
Are the clutch cylinders leaking?

[Vtecmec]

The selector mechanism is a good shout, worth looking at the bushes / interfaces under the centre console to see that it moves across to the right side properly.

[tobyslude]

Just a thought, but considering this is the second box in the same car with the same problem... Have you got the right gear shifter in the car?
It's not been swapped for something from a different Honda/after-market (that has a slightly different length throw on it) has it???

Is the clutch fully bled?
Has the clutch been messed around with (after market cylinders or clutch lines)?
Are the clutch cylinders leaking?

Hi mate thanks for the advice, I haven't checked the shifter so I'll have a look at that this evening. Shift cables on top of the gearbox looked standard and fine but I'll take off the gear surround and take a look under there.

I've just bled the clutch, the fluid was pretty dirty, took it around the block and no change. Everything clutch related looked standard under the bonnet.

The selector mechanism is a good shout, worth looking at the bushes / interfaces under the centre console to see that it moves across to the right side properly.

Indeed mate good shout, I shall have a look this evening.

Thanks guys will let you know