Ford Select-O-Speed operation

NCWayne

Well-known Member
Read the post yesterday where the guy was asking about getting a Select-O-Speed transmission rebuilt. I volunteered my services if the guy was close and akined it to an automatic. Showcrop called me out on saying that, and given the way I stated it in the post I'll admit I made a mistatement. While I haven't done a rebuild on a Select-O-Speed I have worked on a couple of them and the basic design is the same as any true automatic in that they operate using hydraulically applied clutch packs along with a series of planetary gears. The difference is with the Select-O-Speed the gear change is made manually and with a true automatic it's made depending on the speed of the transmisson's internals acting on a governor, that moves a hydraulic spool to direct the oil to apply or release the proper clutch packor brakeband. Basically a fairely easy rebuild if you know the thickness of the clutches/clutch packs, torque specs for everything, etc.

That said how may of you know that at least one model of Ford with the Select-O-Speed also has a clutch, and if the clutch goes out it won't pull??? Had a customers 4200 experience that dilemma some years back. The clutch involved isn't one that can be applied or released like on a standard tractor. It's actually more or less designed like an overrunning clutch and is a single clutch disc held under pressure by a heavy wave spring. When the splined center's welds give up and it gets twisted out of the disc assembly the end result is s tractor that won't go anywhere regardless of what gear you put it in.
 
This repair scheme for worn input splines looks like it will work but for how long?

http://www.oldfordtractors.com/sosinput.htm
 
I believe all of them had the torque limiting clutch after '61 or '62. I know the '68 5000 SOS I had used that type of clutch. Not an over-running clutch, though.
 
The torque limiting clutch and/or worn input shaft splines is a common failure mode for Ford S-O-S transmissions.

Dean
 
My understanding was that all Jerk-A-Matic's had a torque limiting clutch on the flywheel. Very early models also had over running clutches on at least some clutch drums/ratios. I'm not sure on the specifics of that.
I would agree that they are essentially the same as any other planetary automatic transmission except that there is no torque converter and the valve is manually shifted...

Rod
 

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