Got a '56 F100. Want to put in a 300" six with OD. Anyone care to comment on the trans selection? I know nothing about them but found several behind 300's in a local yard. Cost? Bellhousing back? Thanks
Keep it full of fluid and it's a pretty good unit. It's a truck transmission so don't expect silky smooth speed shifts. Most of the problems with these units came from the rear plugs on the shift top. They were made of rubber and over time would harden and start seeping fluid. Tens of thousands of miles later when no one ever checked the level, the transmission would finally overheat and fry the rest of the fluid out of it. The second most common problem was from the clutch not releasing and people forcing them into reverse. After hundreds of gear clashing reverse engagements the "dog" teeth would get buggered up and not let the transmission shift into reverse or fifth. Oh, I can't ever remember one that did not have a hydraulic clutch, no place to put a regular fork, and the bell housing doesn't come off.
My OT 94 F150 went through two M5R2's by the time the truck had 215K on it. It's a weak transmission for true truck use. It might be fine for just cruising around. I've seen M5's go for cheap but I replaced mine with a ZF S5-42 for piece of mind.
First gear is almost like a granny gear,I have a 95 F150 beater with that trans and usually take off in second when not loaded.
Its a very weak trans,had one in my old 89 F150 and I went through 3 finally replaced mine with an NP435
I had one in a 95 F150 that I put 80,000 miles on...but I broke a shift fork 2 times...started running a heavier gear lube in it...put about another 50,000 miles on it with no problems.
Thanks for the input guys. Kind of leary about a junk yard unit in light of what Tranny Man and others have said. The NP435 is what I have now but that doesn't have OD. So what would a better choice trans with OD be? Guy
Putting a TKO500 or TKO600 behind a 300 is the same as for a 5.0/302. You'd get a stout transmission and better ratio selection. Second option might be to look at a Keisler. A T-45 based transmission, but still pretty strong. http://www.keislerauto.com/ford/unm...50-essentials-kit-350-lb-ft/flypage_tabs.html What kind of rear gear are you using? Is this going to be used as a working TRUCK or a cruising Truck?
i broke one in my 94 f150 200 miles after a rebuilt..... i also put a real healthy sbf in front of it though lol i made some plates for the top of the shift tower to A) keep the plugs in, B) seal it if the plugs weaped. i just take it easy on it now. 10,000 miles on it after the second rebuild with no problems tk
The M5R2 is ok if you don't have alot of power, and don't pull a trailer with it or something. If you plan on pulling a trailer a ZF S5-42 works good, or if you just want to hammer it hard (racing) a TKO 5 speed is your best bet.
BTW, the 42 in ZF S5-42 stands for the torque rating of transmission which is 420 ft-lbs. There is another version that can handle even more torque. A 2WD ZF can be had for fairly cheap if you look around. I found my 4WD version for only $400 and these are usually more expensive than the 2WD versions. What ever transmission you look for make sure that it's from a small block since the 300 uses that pattern.
Not to hyjack this thread but what type of heavier lube did you put in it as I want to do the same with the one I have in my beater truck.
Related to the comments above, I have a 1986 F150 fitted with a 5.0/302 engine and 4 speed manual granny gearbox. It is also 4X4. It has a 9" rear end. I want to upgrade to 5 speed overdrive. My application will be mostly cruising with medium load and towing time to time. I am wondering if TKO 500 or 600 would be an ideal transmission for my truck or there might be other alternatives?
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