I'm sure I'm dreaming but does anyone know if you can swap a 3 speed out for a 4 speed and everything fit or is there an issue with the drive shaft length and differential gears? Although I don't want to drive it at warp factor 12, I would like to go faster than 35 on the road. Any thoughts? My 28 just came back from the paint shop and it looks great. This is too much fun. Working for a living just takes too much time if you know what I mean... It was a good day at the Closson's. Maxie.

Maxie,
I believe that they will swap without any changes, but that will not change the speed of the vehicle. Both transmissions are a 1 to 1 ratio in hi gear.

I have take crownhweel and pinion fram a -29 truck.
25 to 28 truck have 38/7 teeth and
29 have 39/8 teeth . My truck runs faster.May be 5-6 mph
http://www.chevroletnorge.com

Maxie,

I have a 28 LO truck and I found where I would like to go faster than 35 MPH (truck can do 40 mph after a few blocks or 45 mph down hill)I get a little concern about braking.

If the 4 speed transmissions are anything like the other ones used on Chevy trucks you tend to start off in 2nd gear anyway since first granny gear is so low.

Mike Quezada

Hi Maxie

Yes you can swap the 4 speed transmission straight out for the 3 speed and you will gain about 5 mph. Add a 1929 truck crown wheel and pinion to the rear end, which is also a straight bolt in bolt out swap and you get another 5+ mph. Change your rear tires to 650 x 20 or 700x 20 and you get 5 + mph, but you must reset the castor angle to allow for the oversize tires on the rear. Add a better carby will help. This should let the truck run at 45 - 50 mph without any trouble. The weight of the truck will help it corner but you may wish to add a steering damper as you increase the speed of the Truck.
If you really want to do some low flying along the freeways then install an overdrive and you will be able to run 60+ mph with no problem except stopping in a hurry. Lots of fun passing a late 30's fat fender car at freeway speeds in an old Chev 4 Truck. Some great looks on peoples faces as you roar pass them. All of the changes require no modifications and are of the era modifications that can be changed back at any time should you wish to return to a top speed of 30 mph and be a problem for modern traffic.

Dave

I think chevy b have right. The 3 and 4 speed transmission has the same ratio in hi gear, 1 to 1. The 4 speed have no overgear, and it will not add 5 mph .
http://www.chevroletnorge.com

Yes you are correct the 3 speed to 4 speed swap is the same and will not add to the speed. My mistake sorry. The rest of the swaps will work fine and add to the top speed. The 4 speed is only a lower 1st gear which means more gear changing before reaching highway speeds. Use the 4 speed for a boat anchor that is all they are good for.

Twin 4