MF40 Instant Reverse Problem

Jowo

New User
After restoring an MF40, the gears would grind when attempting to shift, indicating a warped or sticky clutch pack. I split the tractor and replaced the discs and plates in both packs. After reassembling the tractor, the transmission worked flawlessly with no grinding and smooth engagement into forward and reverse. After about 30 minutes, and numerous forward/reverse cycles (allowing engine to idle down before engagement), I lost reverse. I checked the system pressure and it was steady at 156 psi. I then checked pressure after engaging the forward clutch and it dropped momentarily and returned to 153 psi. But, when I engaged reverse, the pressure dropped and never recovered, indicating a loss of pressure integrity in the rear pack. I split the tractor again, pulled the packs and immediately found a large circumferential crack extending 2/3 around the rear clutch pack cylinder (at the base).

I have found replacement parts ($$$) and am prepared to put the transmission back together. Obviously, I don't want the new cylinder to fail the same way, and have been unable to determine the cause of failure. I found no indications of anything assembled incorrectly and it worked perfect, initially. It seems the failure would indicate excessive pressure within the cylinder, but the system pressure has always been within limits when tested.

Sorry for the long post, but if anyone has any ideas/experience that they might share, it would be appreciated. Although this is my first post, the forum has been a tremendous benefit throughout this restoration. Thanks for your help!
 
I don't know but I have an idea who may. I will send him an email and it my take a couple of days. I don't want to just post his info. Older Massey mechanics are hard getting harder to find these days.
 
If you want to send me a private message, I will give you some contact info. Also Is the failed part OEM or an aftermarket? Can you see the cross section of the crack? You may have to finish breaking the part to see this. Check for defects in manufacture (crack along a grain deviation) or signs that the crack was started prior to your repair. Use a 10X magnifying glass. It would still be detectable even in a oiled part, discoloration from particulates in oil in a prior failed area, new break would be less discolored.
 
JBKINWA, I've sent you an email. I'll look forward to hearing from you. To my knowledge, the clutch cylinder is original. I've only owned the tractor for a short period but the previous owner had never worked on the transmission and he purchased the tractor when it was nearly new.

I failed to mention on my original post that I did examine the failure surface and it all appears to be fresh with no indication of an older fracture surface. The failure appears to be a classic brittle tensile failure with a 45 degree fracture plane. There is no indications of corrosion or pitting anywhere on the cylinder.

Thanks again for all your help.
 
I sent the current contact info I have. Do you have access to the 5 volume Service manual set the dealers had or just the 2 volume set we can currently buy? Also what is your S/N. There are significant gaps in available information after 3rd quarter of 1974.
 
I received your email and appreciate the info. I have the 2 volume set of manuals. It provides reasonable detail regarding the Instant Reverse transmission. It is a relatively simple transmission once you figure out how it operates.

The S/N for my tractor is 9A 98956, which I have assumed is somewhere around a '70 or '71, although I may be wrong. I haven't spent much time researching the year.
 

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