Thiokol 1201 Automatic Transmission Conversion

Fellow Thiokol 1201 Owners,
I would like to do the C4 automatic transmission conversion I have heard so mutch about. Has anyone completed one with photos showing the configuration of the drive train and extent of custom fabrication required?

Thanks
64Thiokol1201

Have you had any luck with your C4 conversion ? I've got a C3 in my 1200 Spryte (lasted about 5 years) and I want to convert to a C4 but I'm having a devil of a time finding a bell housing for the conversion...I'm trying to marry the c4 to a Ford 200 6 that I was useing with the C3. camp10skiarea@yahoo.com

Your question confirms my concerns that they dont all just bolt together. I plan to start the process of procuring the auto trans in the near future. I have been researching the transmissions and know they the internals very by years and the 70s models I think have more heavy duty inards. However, they may not bolt to my 1964 Ford industrial in-line 6. I guess the trans would need to be procured locally to ensure the bolt pattern on the bell housing matches the block. What year and configuration is your tranny and engine? Are there any other members on this board that have done this conversion to an early model 1200/1201 Spryte with the OC-4 axle? Are yu running an OC-4 or OC-12?

We changed from the original Ford 170 to a Ford 200 out of a Falcon. This was a direct replacement for the 170 and worked fine with the Clark (OC4?) rear end that combined steering brakes and a 4 speed manual transmission. Over time the Clark became more and more troublesome and expensive and was locking up frequently. So we located a C3 that bolted directly to the Ford 200 and eliminated the clutch. We hold the OC4 rear tranny in either 3rd or 4th gear, depending on what we are doing, and do all of the up or down shifting with the C3. Worked beautifully for about 5 years (winters) and crapped out last winter. Did some research and found out that the C3 is the weakest of the series (we have a C6 in our big groomer which is great). The C4 was rated as a much tougher tranny and that the direction we decided to go. Just this past week we concluded that a bell housing does not seem to exist to match the C4 up with our Ford 200 - they do exist for some Ford 200's but not our particular one.
So the only option to use the C4 would be to go out and buy a different Ford 200. This was a problem as we would be adding a wild card of an unknown used engine plus whatever other mods may be reqd to get the engine installed. So I've decided to rebuild the C3 and to use it next winter. Then betwen now and winter 2015 I plan to look into the posiblity of modifying the existing C3 bell housing to work with the C4 or rework a C4 bell housing to work with the Falcon 200 I6. We happen to have a spare 200I6 and thats another reason I dont want to swap engines. Installing the C4 would also require modifying the drive shaft because of a length difference between the C3 and C4 housings. As a side note we still have the original pedal and hydraulic master cylinder that was used as a hydraulic clutch untit. Since the clutch was removed we now have the clutch pedal/hydraulic master cylinder powering a drive line disc brake we installed.

Would you happen to have any photos of your setup you could share. It sounds like exactly what I am trying to accomplish. I have a complete spare drive train with a hydraulic clutch set up and a drum e-brake behind the clutch and bell housing. I was planning to install the C4 auto, delete the clutch and hydraulic slave, then install the drum e-brake that is mechanically actuated somewhere along the drive line. My curent machine does not have an e-brake set up which is a mystery to me since its early life was on a ski resort here in California. I was going to leave the four speed tranny in front of the OC-4 and was figuring I could get rid of the clutch and use neutral in the auto trans to shift the manual gears. I would then have 3 speeds in the auto times four in the manual for 12 gears. Am I figuring this right or do I need a clutch somewhere? Any info you can share would be gret, thank you.

I'll take some pictures when we've got it back together- right now I've got the C3 pulled as it needs to be rebuilt or replaced. I think I'm going to get it rebuilt as I'm running into time limitations. It should be possible to relocate your drum brake. You'll need to get creative in useing some additional drive line u joints and bearings so you have a stable section for reinstalling a drum. We went to a hydraulic disc brake set up instead of the drum arrangement. If I had it to do over I'd do the drum arrangement. The hydraulic disc brake works but after about one season the rotor cracks because of heat load build ups (we use the disc for as much of the brakeing as possible because its cheaper and easier to replace the rotor than it is to replace the bands in the OC4). We are going to try (when I have time) a much larger truck rotor with greater surface area and larger pad size to see if that will help the disc heat dissapation and reduce cracking. The current rotor/caliper was cannibilized from an 86 Dodge Caravan so its, as a single rotor providing all of the brakeing, pretty undersized.

I think you'll find very few situations where you'll need the 12 gears that you have available. We have removed the shift linkage and are removing the shift cab handle (for more cab room). On occasion we'll manually reset (at the shift lever located oin the OC4) the gear into either 3rd or 4th...we're still deciding on the best setting....and do all of the shift work with rthe C3. Thats another reason we want to eventually get a C4. Putting the c3/C4 into neutral so you can manually shift the OC4 from the cab should work fine...we changed it because the shifter forks in the OC4 are badly worn and we just didnt need 12 gears. Other stuff we've done is convert from a ford charging system to a GM system as we got tired of changeing voltage regulators. One big mistake I made in the systemn was changing the shot original radiator over to a brand new 86 Dodge Caravan radiator I just happenbd to have..pretty dumb for an engineer because I neglected to check cooling system capacities....the dodge was set up with about a 10 qt systemn while the Ford is looking for 15-17 qts . Result was a necessity to really baby it to avoid overheating (we used an external tranny cooler to reduce load oin the skimpy radiator). We are putting in a bigger radiator this summer .

I finally found a C4 Automatic transmission from a guy in CA. It will take me some tome to do the swap. Probly 2-3 years with current to do list. The final configuration will be the Ford Industrial 6 (200 possible to 300 later), Ford C4 Auto behind, delete clutch and use clutch pedal and slave cylinder to activate the drum emergency brake as a primary brake with a hydraulic brake lock valve to lock the brake in the engaged emergency position. I'll then have 2 braking systems, the bands in the OC4 and now the left pedal that used to be the clutch.