Overdrive for a Ford FE big block???

That's the perfect idea for your bus toyman. Keep on keeping on, the hive will be here cheering you on

In reply to mazdeuce:

I haven't because of the 5" of rain we've had in the last few days. I'm 95% certain it's a Clark 5 speed. Basically a 3 speed with a granny gear. 4th is 1:1.

Military deuce and a half uses a Spicer 3053 5-speed. At some point during the life of the truck someone figured out that the main and aux shaft gears for 4th could be swapped to make that gear into an overdrive. Probably the least expensive heavy duty overdrive option.

Otherwise, I do have a contact who has a couple auxiliary transmissions from medium duty trucks that are for sale in the $700-1000 range.

If its a clark, start looking for the mythical Clark 280V0 transmission it has a .80 overdrive and should bolt right up.

In reply to eebasist:

I read about that one, but haven't seen were anyone has actually had one in the real world.

Depending on what the bellhousing pattern of that motor is, you could also start hunting for a Road Ranger 10sp with OD or similar. And those would still be usable with a diesel swap too.

When I think big truck builds, I usually end here: http://www.boyceequipment.com/#!transmissions/cay8

rslifkin wrote: Assuming the tires on the bus are 11R22.5

Bus of this age likely uses 9.00-20 tires maybe 10.00-20s but 98% sure there 9-20

44Dwarf wrote:

rslifkin wrote: Assuming the tires on the bus are 11R22.5

Bus of this age likely uses 9.00-20 tires maybe 10.00-20s but 98% sure there 9-20

Based on the original posts about the thing and the pictures, they're not the original wheels. I think Toyman said they were 22.5s at some point, but 11R22.5 was just a guess on my part, being a common bus size. They very well might be something a bit shorter though.

44Dwarf wrote:

rslifkin wrote: Assuming the tires on the bus are 11R22.5

Bus of this age likely uses 9.00-20 tires maybe 10.00-20s but 98% sure there 9-20

It has more recent wheels/tires on it than its age. They looked like 19.5's to me, but who knows for sure.

In reply to rslifkin:a 10 speed seems like overkill. The have a lot of of heavy bits to keep spinning and if I remember right they need air to change ranges.

Wall-e wrote: In reply to rslifkin:a 10 speed seems like overkill. The have a lot of of heavy bits to keep spinning and if I remember right they need air to change ranges.

Good point about the air. I forgot that bit. Although the extra gears wouldn't necessarily hurt, as it would give a wide enough gear spread to ditch the 2 speed axle with no downsides if he wanted to get a more modern rear end / brake setup under the thing.

WOW Really Paul? wrote:

44Dwarf wrote:

rslifkin wrote: Assuming the tires on the bus are 11R22.5

Bus of this age likely uses 9.00-20 tires maybe 10.00-20s but 98% sure there 9-20

It has more recent wheels/tires on it than its age. They looked like 19.5's to me, but who knows for sure.

It's running 255/75R22.5s. That gives a diameter of a little over 36".

Ok, so you definitely need a taller cruising gear. That gives ~3250 rpm at 60 mph based on 36" tires and 5.83 gears in the diff.

NickD wrote: Gear Vendors overdrive unit?

This!

rslifkin wrote: Ok, so you definitely need a taller cruising gear. That gives ~3250 rpm at 60 mph based on 36" tires and 5.83 gears in the diff.

And the basic FE's redline at 4000 I think.

gm used the NV4500 in the 15k gvwr 90's 3500HD. it should be up to the task.

Here is a gearing calculator for excel I found and tuned up a bit with the truck transmissions at the bottom.

https://www.dropbox.com/s/51wif90gi1mualn/gearing.xlsx?dl=0

It looks like it's best to download it using the '...' button in the corner.

ultraclyde wrote:

rslifkin wrote: Ok, so you definitely need a taller cruising gear. That gives ~3250 rpm at 60 mph based on 36" tires and 5.83 gears in the diff.

And the basic FE's redline at 4000 I think.

Not sure if the valves are floating or what, but the motors completely fall on their faces if you try to rev them. It's kind of hilarious.

I guess its not just the Clark 280V0 but any of the Clark series with a V0 at the end are the ones with overdrive.

NV4500 zf s5-52 and s5-47 spicer 3053 possibly

good site to look for medium duty stuff http://www.vanderhaags.com/Search-Results.php?subcategory=transmission-transmission&manufacturer=zf&inventorytype=transmission&typesetid=4000

https://www.heavytruckparts.net/search.php

skoolie forum http://www.skoolie.net/forums/f34/transmission-need-more-speed-4000.html

The trans is probably the good old bull low 4 speed box that came in every medium duty truck built by every manufacturer until about 1984, when they added an overdrive to it. Climb under, scrape 60 years worth of grease off, figure out what it is, and then search for a similarly named trans from a 3500 sized pickup truck built in about 1986. I'd bet pretty good money the bolt pattern of the trans to the bellhousing will be the same, so you will need and appropriately splined and sized clutch disc and an updated front driveshaft.

Maybe find an adapter plate and throw a 4l80 into it with a standalone controller...or leave the 6.0 that was bolted in front of the 4l80. LS swap!