Hi,
I’m facing a problem with the build of my truck.
I would need your opinions!
It’s making 4-6 months that my build is stalled because I can’t decide which way to go.

Here is what I’m facing:
1948 F-5
Frame: Done
Engine: Done (What a nice sound)
Transmission: Done (4 speed non syncro)

Here is what I want:
A nice truck that can do 60 mph, I will never be pulling any trailer or load the bed…

My problem:
Engine: 2000 rpm
Tire size: 35’’ (total)
Transmission: 1-1
Differential: 6.66!!!!!
Speed: 31 mph far from 60mph

Need to do:
Differential ratio would need to be 3.4…
Or
Transmission overdrive 0.52-1

Here is my question…
How can I convert my truck to go faster? What would you do? What have you done?

1- Use a ranger overdrive… Would bring me to a 40 mph?
2- Change the entire rear end for another drum dually unit?
3- Any other solution?

I’ve tried to locate a differential from a dodge motor home with no success here in Canada.
At the same time I was looking for widow maker replacement wheel but no luck.
I’m not sure wheel adapters will pass the inspection so I won’t have the choice to go with custom wheels anyway!

I have a 2004 differential with 3.5 ratios but with disc… And after reading much stuff I understand to never do this! Really dangerous!

Thanks for all your helps! Has usual!

 

You're limiting yourself unnecessarily to 2000 RPM. You really need to be up around 2500 (maybe more) to make enough HP for wind resistance at 60 mph (pushing a barn door thru the air) and moving that much weight. It won't hurt the engine, even for long periods.

But you need to address the widowmakers issue first, because that will determine tire size and potentially axle ratio.

 

Building on Ross' comment, moving to a set of 22.5" tubeless wheels with 9R22.5" tires yield a 38" + tire diameter. Below is a pair now on eBay in NH if you can travel south to pick them up. For the other four you might check with Chuck Mantiglia of Chuck's Trucks in CT for a set of the new reproduction 22.5s.

Then if you can get creative on shipping, perhaps shipping it to Chuck for you to pick up there, below is a Dana 70HD now on eBay. It yields a 4.56/1 ratio which will give all the road speed you'll want with the taller tires. Stu

Chucks Trucks LLC., Chuck's Trucks, Chucks Trucks

http://www.ebay.com/itm/252528460640?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIThttp://www.ebay.com/itm/172288382330?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

Has anyone tried to run a truck of F5 size and weight with that type final gearing we're discussing here? Looking at c249a's signature line, I see he lists a 1946 engine which would be a 59A block and rated at 85 HP, would it not?
I would think the type of terrain driven would be a big factor in success or failure of such gearing to HP. The crash box would make it interesting if many mountains were transversed.
I would think that Dana 70 as shown would need a rebuild from what I see on the ring gear faces.
To the OP, I wanted an F4 that I could run at highway speed and did not think it was practical to do this with a stock Ford engine of somewhere around 100 HP. I installed a later V8 with an automatic OD transmission pulling 4:10 gears in a Dana 70. I do run a mismatch front to rear wheels. I have five lug 19.5" with 225s on the front and 285/16s on the rear. Front and rears are the same OD.

 

Valid points, Ray. I know of two trucks with the D70HD. The guy I sold mine to and a Studebaker guy I met. But both of them run 19.5s at 34" diameter, same as the motor home. That early flatty would be short on torque to make the wheels and axle be roadable, I agree. Stu

 

For a truck that will be light all the time, 5.14 is the ideal ratio, with either 8.25-20's or 9R-22.5's. The truck will be happy at 65 MPH. If you were going to carry a load, 5.83 is the desired ratio. The truck will be happier at 60 MPH, but will do 65 for short periods. You need a modern engine, with big HP to pull gear ratios in the 4's.
I have NOS 5.14 ring & pinions, as well as a bunch of 5.57's that are in Nash boxes. I haven't tried the 5.57's yet, but I think I will in my 4 x 4 F-5 school bus. That way it will have enough power if it has a bunch of people in it, but should still be comfortable on the highway.
Chuck

 

Correct. Even the mighty 8BA with 100 HP (gross) needs to be spinning in the high 2000's to keep a rig this size moving at 60 mph. 2000 RPM would be appropriate for a lightweight roadster or maybe a streamlined car, not an F-5.

Yes, and not like a crashbox is fun on ANY road!

 

Wow thanks for all this info!
Ross: I'm happy to know about 2500rpm
Ray: Pretty flat terrain... I don't plan to use this truck far away from home!
Chuck: I will contact you.
Others: thanks for the info

 

Well it looks like the good knowledgeable folks at FTE 48-56 solved another problem to get an old rig back on the road. Don't you just love this site and the good guys/gals on it.
Now you mission Benj should you choose to accept it is just implement it!
Have fun and keep us in the loop.

 

The 59A engine has the same HP and torque as the early 8BA. An empty F5 with 5.83 gears and a flathead V8 will run 60 mph all day long without hurting the engine. Fuel mileage won't be great. I had no trouble running my '47 COE with an 8BA, T9 4 speed and a two speed axle with 5.83 in high, 60 mph. It would run 65. It was a 158" w.b. with an 1800lb 16' flatbed.
Mark

 

Thanks Mark
It's really good info!