Hi guys, I've some how destroyed the first gear in my m41. I think this may be due to another long present problem, if i gave it too much gas in reverse it violently slamed out of gear, its the only other issue ive ever had. the trans was noisy for a day and then last night 1st gear would not engage. today i pulled the trans and 1st gear is missing about half of its teeth! great. should i go through the time and effort of trying to source a new gear and try to rebuild the thing or just grab a used m41 box and slap my OD on?

extra credit- my box casting is labeled M48A? anyone what that designates?

UPDATE

OK trans is now apart, i will need a new 1st gear (rearmost on the mainshaft) a new layshaft (gear below 1st is stripped of all teeth), brass/copper layshaft end bearings, and the syncro ring behind fourth.
im gonna say its time for new/used box, i doubt i can get all of this stuff for less than an m41 box itself, if all of those parts are even still avalible.

any ideas how i shredded these gears mid drive without warning or drama?

anyone have a good used gearbox for sale? no od or cover needed.

Ouch, that is nasty!. Erik will know but it might be possible to replace the broken parts with those from an M40. Those are available complete for not much money. Cause? You mentioned problems with reverse and wonder if this started out due the OD solenoid being stuck on.

hey derek, i am very curious as to the cause, i dont think the od was involved, i do have a bad lockout switch but im very mindful of disengaging when i down shift. the reverse issue has always been there, as soon as i accelerate in reverse it makes a horible slam that seems to shudder though the whole drivetrain as it pops out of gear. this is the only other issue i've had, im baffled that I couldnt hear or feel any of this destruction taking place.

Can you post some pictures of the broken gears?
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

will try to get some up soon but i think all may be lost anyway..

here is the damage;

That looks alarmingly familiar to me. That's what I found in my transmission ('65 1800s). In my case, the cause was quite simple. Noisy box before hand, frustrated trying to find an address while delivering pizza.. dump clutch in 1st at redline. Crunch.

Problem was those laygear bearings nearest 1st gear being gone (noise), so lay gear hung low at that end and gear mesh at first was minimal.

I'd get a new/used M41.

Keep your old input shaft for a clutch alignment tool, Use your old lay gear as a candle holder.

That's what I did.

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-Matt I ♥ my ♂

well Ive certainly abused it but the needle bearings were great in the layshaft, the bronze thrust washers at each end were a bit worn but ok.
the parts are available through iroll, but the cost would be way more than a used unit. I am very curious if the M40 parts will fit as im looking to buy a used gearbox ASAP and that would likely save some time and cash.

Interesting that there's a ridge on the broken lay gear teeth that didn't break... leads me to believe they were worn, possibly cracked, prior to giving up the ghost, and also leads to believe those thrust washers were largely the cause.

In my cast, the lay gear bearings were completely gone, the gear had been metal on metal with the shaft, wearing both down.

Abuse, indeed.

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-Matt I ♥ my ♂