5th gear grinding w/ new trans swap

[Losiracer2]

I JUST bought a new M2B4 LSD trans from an importer back in mid March, had it installed and now, less than 2500 miles later, 5th gear grinds going in at anything above 3500 RPMs. I used Honda MTF, as I sure wasn't going to make the mistake of using Redline MTL which is 70w90 wt. that made my mainshaft bearing make all sorts of noise.

Is my only option to replace the entire 5th gear syncros? Should I upgrade this time to those Carbon Syncros? I need something more durable. This is really frustrating.

[ThrakBarts]

I had the same problem when I bought a m2a4 from a local, but I changed the way I shifted and added some 10w30 to the honda mtf and it went away for the most part.
I also recently bought a low mileage u2q7 accord type r tranny, shipped it from england, installed it and circuit tracked it once before the 4th gear synchro started failing.
Every tranny I have owned has some sort of grind, and I feel like H trannys just don't take much before they start grinding a gear. Sucks doesn't it.
I now know why so many serious h builds use b series trannys.

This summer I will be freshening up the u2q7 with new bearings and carbon lined synchros from synchrotech, so we will see how long those last.

I suggest you add or change fluid, change your shifting, and just tough out the 5th gear grind. That is not a gear that you need to shift quickly during daily driving or almost any racing, so just be content to shift below 3500rpm. If you choose to replace the synchros, replace the bearings as well, and if you remove the transmission and take it to a shop for a reduced service charge. I don't trust any of my local transmission shops, so I am going to do it myself.

[Granite CB7]

The 5th gear grind is very common w/ M2B4's, there's more info over on honda tech about it. During the winter, it's very fussy when cold, but all in all, w/ honda mtf, it's been getting better and better. Once the trans. is warmed up, it's all good.

[Losiracer2]

I had the same problem when I bought a m2a4 from a local, but I changed the way I shifted and added some 10w30 to the honda mtf and it went away for the most part.
I also recently bought a low mileage u2q7 accord type r tranny, shipped it from england, installed it and circuit tracked it once before the 4th gear synchro started failing.
Every tranny I have owned has some sort of grind, and I feel like H trannys just don't take much before they start grinding a gear. Sucks doesn't it.
I now know why so many serious h builds use b series trannys.

This summer I will be freshening up the u2q7 with new bearings and carbon lined synchros from synchrotech, so we will see how long those last.

I suggest you add or change fluid, change your shifting, and just tough out the 5th gear grind. That is not a gear that you need to shift quickly during daily driving or almost any racing, so just be content to shift below 3500rpm. If you choose to replace the synchros, replace the bearings as well, and if you remove the transmission and take it to a shop for a reduced service charge. I don't trust any of my local transmission shops, so I am going to do it myself.

yeah I just got back from the Honda dealer w/ 2 qts of MTF. I'm hoping maybe this was sitting at the importer for a long time w/ now fluid and maybe the current MTF thats in there is just dirty or something. But either way, I'm draining and filling it today and see if that helps.

So, what mixture did you do? 1 qt 10w30 and 1 qt MTF?

The 5th gear grind is very common w/ M2B4's, there's more info over on honda tech about it. During the winter, it's very fussy when cold, but all in all, w/ honda mtf, it's been getting better and better. Once the trans. is warmed up, it's all good.

yeah i was reading up on that after googling M2B4 5th gear grind. Seems like its weak as hell or something. But I guess I can't exactly do the TSB for it through Honda since its a JDM tranny and didn't come w/ my car. Its just really frustrating that I spent about a grand putting this in and its not perfect.

I mean this is going to get worse and eventually break again right? I went though this same crap w/ my first M2A4 but the problem in that was the mainshaft and intermediate shaft bearing went bad and third gear was grinding, not fifth. What the hell is wrong? I thought Honda made great transmissions

[Granite CB7]

^Yeah, it's a very common problem and I don't really know what it's not all across the board, that I know of. I mean, I don't really hear about this w/ the M2F4's or S4's. It is very frustrating since JDM LSD is so sought after and very expensive compared to non LSD.

Will yours break? I hope not, but I've had plenty experience w/ trashed honda trannies and MTF helps ALOT. My stock H2U5 was run w/ 90 wt gear oil, would grind basically every upshift and downshift, MTF flushes made it function like it should 100%, much later, the trans. got pretty loud, which is understandable, the damage was done.

There's this 1 guy on HT that seems to specialize in the M2B4 and has said that a rebuild will cure the grind. He's rebuilt a bunch of them I guess

I say keep on it w/ the MTF and go easy w/ the syncro, delay shifting into 5th for afew seconds while waiting for the revs to drop, then go into 5th and revmatch. That's what I have to do usually.

[Losiracer2]

^Yeah, it's a very common problem and I don't really know what it's not all across the board, that I know of. I mean, I don't really hear about this w/ the M2F4's or S4's. It is very frustrating since JDM LSD is so sought after and very expensive compared to non LSD.

Will yours break? I hope not, but I've had plenty experience w/ trashed honda trannies and MTF helps ALOT. My stock H2U5 was run w/ 90 wt gear oil, would grind basically every upshift and downshift, MTF flushes made it function like it should 100%, much later, the trans. got pretty loud, which is understandable, the damage was done.

There's this 1 guy on HT that seems to specialize in the M2B4 and has said that a rebuild will cure the grind. He's rebuilt a bunch of them I guess

I say keep on it w/ the MTF and go easy w/ the syncro, delay shifting into 5th for afew seconds while waiting for the revs to drop, then go into 5th and revmatch. That's what I have to do usually.

yeah i'm NEVER putting Redline MTL in ever again, thats what made me remove my first tranny, it was so loud in every gear.

But you expect me to drive my LSD tranny like a granny would? That just seems stupid, I bought this trans to enjoy driving, lol, not to nurse my car along. Damn, I guess I gotta save up 500 bucks now to have my swap guy pull the trans and replace the 5th gear syncro. I'm considering those Syncrotech Carbon coated syncros....but we'll see how it goes after i put this new fluid in, if its not THAT bad, I guess I'll live w/ it. Gears 1-4 work great though

[wherm]

I have to double clutch 5th gear to keep it from grinding.

[wed3k]

yea, just rev match it....or just let it grind.

[DeathFromAbove]

i've had a grinding 5th for the last 4 years on my non-LSD. never got worse.

5th never gets used in high RPM anyway. my top speed being limited to 180, i would top out in 4th.

i always try and work it the grooves and double clutch. i've been doing it so long i can't tell you what i do exactly, it's just habit when going into 5th. sometimes it's smooth, sometimes i shove it through the little grind. i would be pissed if it was in 1-4 but it's not, so it's way down at the bottom of my priority list (in the context of a 20yr old car lol).

also because even if you replace it, there's probably a 50% chance that any used H tranny will end up doing it. so uff that. not worth the risk.

[tommi]

I have to double clutch 5th gear to keep it from grinding.

should be granny shifting like u should.

[bruno8747]

Drain the honda fluid and use the GM brand syncromesh. Get the Friction modified version. I've had no problems with that specific fluid.

PN: 12377916

[Losiracer2]

Drain the honda fluid and use the GM brand syncromesh. Get the Friction modified version. I've had no problems with that specific fluid.

PN: 12377916

is that the same weight as the Honda MTF? b/c I had issues in the past using this redline shit. So its around 10w30 wt?

[wed3k]

its good enough, thats all that matters.

[Shag Wagon]

Yea I have heard good things about synchromesh. But its $40 a bottle ftl!

[bruno8747]

is that the same weight as the Honda MTF? b/c I had issues in the past using this redline shit. So its around 10w30 wt?

Its about the same thing, Its not as heavy as the redline stuff. Its much better as far as shifting goes. I had notchy shifts with the new style MTF from honda on my 6 Speed, Then switched to the syncromesh and the shifts are muchh smoother and crisp. And I used the honda MTF for about 500 miles and it sucked.

Yea I have heard good things about synchromesh. But its $40 a bottle ftl!

It was $9 a bottle for me. I dunno what you were looking at for $40 a bottle.