It always amazes me how short those vintage transmissions are.
With the engine out of our project ramp truck, we figured it best to have our local transmission shop, Volusia Drive Train, go through our original New Process four-speed gearbox.
While the transmission shifted well, the shift lever seemed to vibrate more than it should when the drivetrain was under load—even for a 45-year old truck.
What they found was a little surprising. The transmission’s main shaft had been bent, presumably when the driveshaft failed. That bent rotating shaft then created the shake that we experienced while driving the truck.
A used main shaft set us back $100. Going through the rest of the gearbox cost about $300 and netted us new gaskets, a couple of bearings and a whole lot of piece of mind.
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It always amazes me how short those vintage transmissions are.
Yeah, the 3 speed in my 67 Chevy ('Ol Yeller) wasn't much bigger than the one on my Harley.
Tom Suddard wrote: It always amazes me how short those vintage transmissions are.
Vintage!? I keep thinking that it's amazing how long the new fangled ones are.
The more the speeds, the more need for room.
Tom Suddard wrote: It always amazes me how short those vintage transmissions are.
It always amazes me how heavy those vintage transmissions are. 
In my younger days I pulled the transmission out of my 1965 F-250 to replace the clutch; I had to bench press that thing to remove and replace it, laying out in the driveway under the truck. I'm not man enough anymore to do that sort of thing.
Don't forget tail housings may or may not hold gears. Look at the difference between a Jeep T-5 (from a 4wd) and a car version.
Good call on the rebuild. If that vibration got bad enough it could ruin the case. With the new mainshft, there might be some whining until the gears get to know each other a little better.
Tom Suddard wrote: It always amazes me how short those vintage transmissions are.
They saved a few inches of space (and a lot of money) by using a sliding gear 1st gear that doubles as the reverse gearset. That's why most of the really old 3 speeds and heavy duty 4 speeds never have a synchronized 1st gear.
The trans is super quiet so far, but a bit stiffer to shift, until things wear in a bit.
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