When I first did my manual transmission swap in June of 2010, I had M56H internals swapped into an M56L casing (so it could work in my 94) by a reputable member on VS who has done numerous manual swaps. With the transmission apart, he said he did a careful inspection of it and everything appeared to be in good working order and they were know working transmissions.

When it was first installed for the first month I would get constant grinding from 2nd to 3rd in higher RPMs, however, in normal driving everything shifted fine. Well, after a month or so, it completely went away and I didn't have any grinding, even after repeat high RPM shifts and downshifts and beating on it. Well, a couple weeks ago, it grinded again, I didn't think anything of it, I thought maybe I was just excited because this was all during the same time that I started getting my engine and tune and boost running properly and maybe I just let off the clutch too early, however, it happened a couple more times.

Then this weekend on the way up to Midwest Madness, it grinded a few times, there were even a couple instance where it grinded into 3rd, then just to see, while cruising at about 60, I engaged the clutch and I couldn't pop it into third whatsoever, it would just grind and would not budge. This doesn't happen all the time, I had a few hard 2nd to 3rd shifts at high RPMs and it shifted fine, and then all of a sudden, it would grind.

Am I looking at some worn synchros here? I think it's odd how it would go almost a year without grinding, and then start doing it again. I'm going to drain and put in new fluid and see if that makes a difference or not.

Thoughts? :unsure:

Gabe

 

Shift forks?

 

This transmission has the strong shift forks, I've never really heard of those failing before something like the synchros would. I don't know.

 

What kind of trans fluid are you using? Could try a slightly lighter weight to make shifts easier.

Other than that, then yeah, you're looking at synchros and/or forks.

 

I'm running Pennzoil Synchromesh right now because when I first put in the transmission, I was using OEM fluid, and it was grinding and did a couple flushes with more OEM fluid, but it didn't help. Put in Synchromesh and it went away...until now.

 

weird. and what's this about having to run an L casing on a 1994? Did I miss something?

 

93-95=M56L=Speed Sensor
95-97=M56H=Speedometer signal from ABS

 

so if i want to do a manual swap for my 94 i need to use the L case at least? Good to know thanks!

 

No, you don't, it's just easier. Read the pinned thread on VS about it, you can use whatever case you want, the only difference is where the signal for the speedo comes from.

 

Who here has rebuilt an M56? I have a leads on a cheap parts transmission from a buddy.

 

the way i understand it is that they do not sell new syncros for these transmissions, they cannot be rebuilt.
hopefully maybe one day ipd will get these produced.

 

I'm well aware they don't sell new internal parts for these transmissions. Hence why I'm looking at a used one from a friend. And yes, they very well can be rebuilt, Volvo rebuilds them, I have a couple friends who have rebuilt them, you just can't buy new internal parts for them.

 

so what do you want to know exactly? Send your transmission out to be rebuilt and dont worry about it for another 15 years... If you intend to keep your car a while.