Broken output shaft on open drive trans

R

revkev6

Senior Member
So, as if I didnt have enough things to distract me from current projects. I have been convinced to drive a 1936 ford modified that raced dirt ovals in upstate ny in the 60s. It has a flathead, an early ford truck trans and a big truck fabricated quick change. I took it for a race in NH last weekend and it threw a U-joint which caused a train wreck of disaster. Front and rear yokes bent, driveshaft bent and the output shaft snapped off the transmission.

I just pulled the transmission this morning and got the offending shaft out now I have to figure out what shaft I need to replace it. Mac van pelts site shows 3 different part numbers for open drive main shafts. Anyone know the differences?
 

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"revkev6" - you are my new hero. I usta do this, but I'm gettin' too old. Go get 'em when you get it fixed.
 

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That car is badass! Hemi in dirt! This is just pavement in an old dirt car. I've run both in midgets so this thing feels like I'm driving an A1 Abrams tank.
 
Do you all the pieces for the trans shaft? If so, take some measurements (length, diameter) count the teeth and then give Van Pelt call
 
Sure looks like an F-1 (48-52) trans, but yes, you'll need to pull the whole shaft out and measure. Looks like it broke right where the speedo gear snap ring groove is?
 

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From what I can tell all the truck output shafts look the same from 42-52... ish. Not sure if there are small differences that make them specific. I have this one out but haven't pulled the snap ring off to take it all apart yet. And yes it broke right st the speedo gear groove.
 
I’m at the EFV8 National Meet so I can’t send anything out yet. Get a tooth count on the low/reverse sliding gear.....it’s either 28 or 29. Count carefully. Post that here and we can ID the shaft.
 
Thanks mac, just checked and it's a 29 tooth. I had sent you an email last night as well just so we aren't duplicating your efforts. Thanks for the help
 
There are two different shafts that use the 29T low. The early one , approx 1942-45?, uses about a 1/8 inch spacer, with a stabilizing pin in the shaft behind the second gear. The later type, approx 1946-50 has more spline length and the second gear rides directly on the shaft.

BTW, there is another tailshaft that uses straight cut spline teeth. If you got that one, you may have some trouble finding another.
 
If the low-reverse gear has 29 helical teeth (and 16 helical splines inside) it’s going to match with the 42-44 version and the 46-50 version. I may have one of those in stock but can’t confirm that until I get back later on this week. If you don’t find one beforehand, call me Friday or Monday.
 
Mac VP said:
If the low-reverse gear has 29 helical teeth (and 16 helical splines inside) it’s going to match with the 42-44 version and the 46-50 version. I may have one of those in stock but can’t confirm that until I get back later on this week. If you don’t find one beforehand, call me Friday or Monday.
Click to expand...

Thanks! I know you are busy right now but I will also need both yokes and universal joints. They were all wiped out. Do you have or know a good source for them? Rear yoke is big truck.
 
Mac and all!, still looking for an output shaft. Car owner found the yokes we need. Just need to find the shaft. Mac, I called and left my number.
 

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well, it's been a month but she's back together and track tested! transmission rebuilt, new driveshaft, fixed pinion angles, new mounts for the seat and belts, moved steering box and added a big support on the framerail for the steering box because it was twisting the left front rail. Ran it two warmups, a heat and a 15 lap feature with no issues. ran 200 degrees and I think I topped out at about 4700rpm. probably could have gotten a couple hundred more out of it with some more seat time and tweaking but it's really a shakedown for me and the car. I haven't driven a race car since 2003!

here's a few warmup laps at waterford, a nice 1/3rd mile track in southern Ct.
https://youtu.be/XhEwZh3M1dg
 
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