4 Spd Truck Trans Differences ?

[55 Fargo]

C38spitfire6,

I also have a 251 Chrysler in my 52 1/2 ton with a 4 speed syncro.  My rear end ration is 3.0 and I still never need to use 1st gear. I have tried it a few times starting out on steep hills but by the time I can get the trans into 2nd gear the truck has just about lost all it's forward momentum. It's still a stump puller even with the 3.0 !

Hey Reg, gotta love these old trans, still stump pullers in 1st with high gears in the backend.

Hey what kind speeds you cruise at on the highways? What size tires you runnin?.......Fred

[wallytoo]

i usually use 2nd for starting, even in my 1.5-ton. 1st really is for a load, or a steep hill, or when i'm on a real woods road. of course, with the 2-speed rear, i can get moving a bit from 1st low to 1st high, and then split into 2nd low without losing momentum.

greg, i bet you're hearing a bit of fan noise in your truck as you get up to 45. i recently installed a tach in my truck, and although noisy, was only pushing about 2500 rpm around 45. clearly can go a little faster as far as rpms, but 45 is comfortable.

[55 Fargo]

i usually use 2nd for starting, even in my 1.5-ton. 1st really is for a load, or a steep hill, or when i'm on a real woods road. of course, with the 2-speed rear, i can get moving a bit from 1st low to 1st high, and then split into 2nd low without losing momentum. greg, i bet you're hearing a bit of fan noise in your truck as you get up to 45. i recently installed a tach in my truck, and although noisy, was only pushing about 2500 rpm around 45. clearly can go a little faster as far as rpms, but 45 is comfortable.

I am going to have to wire in a cheap tach, and see where I am at. My set-up is 12 volt. This old truck is chilly even with good heat from heater box, gonna have to insulate and stop drafts.....LOL

[Dodgeb4ya]

Look at the gearing ratio's of my 4 ton truck..out lined in red... I have moved Martian meteorites in 1st gear- rear axle in double reduction low from Siberia to Moscow.  Sloooooooow long trip!

[Plymouthy Adams]

that is more like a tractor than a road machine...winch on wheels

Edited February 16, 2013 by Plymouthy Adams

[tom'sB2B]

I just swapped out my rear end last fall. I have a 3:55 now, three speed fluid drive trans. I can go 55 comfortably, at 60 the engine is racing.

[55 Fargo]

I just swapped out my rear end last fall. I have a 3:55 now, three speed fluid drive trans. I can go 55 comfortably, at 60 the engine is racing.

 At 60 mph with your present set-up, with 28 inch diameter tires, you would be at 2556 rpm, 27 inch tires, 2650 rpm.

At 55 mph with 28 inch 2349 rpm , 27 tire 2429 rpm. This is why 55 mph would be comfortable, and 60 mph begins to sound busy, add fan and wind noise, and things are louder, rpm is not hugely different...

[Young Ed]

 At 60 mph with your present set-up, with 28 inch diameter tires, you would be at 2556 rpm, 27 inch tires, 2650 rpm.

At 55 mph with 28 inch 2349 rpm , 27 tire 2429 rpm. This is why 55 mph would be comfortable, and 60 mph begins to sound busy, add fan and wind noise, and things are louder, rpm is not hugely different...

 

And at those RPMs you could easily push it another 400-500rpm easy. I drove my p15 with a 3.73 rear across MN and well into WI going 65 the whole time which for my car is ~3000rpm. The temp gauge went up 5-10 degrees but otherwise it was fine.

[55 Fargo]

And at those RPMs you could easily push it another 400-500rpm easy. I drove my p15 with a 3.73 rear across MN and well into WI going 65 the whole time which for my car is ~3000rpm. The temp gauge went up 5-10 degrees but otherwise it was fine.

Hi Ed, yes with an engine and drivetrain in good condition should be no problem. You and I both know the cars may ride and handle better at faster speeds though, but that is too be expected with the truck solid front axles, and heavier suspension, no weight in the back end.

I just came back from running an errand with my truck, drove on highway at 55mph, very comfortable speed, pushed her up to 65 mph, got busy and some vibration at that speed. I need new tires, and balanced rims, and gain tie rod ends are a bit loose. Speeds between 50-65 mph were attained very easily, this truck had lots to go at 65 mph..

[Young Ed]

Good point Fred. I drive my truck 55-60 but thats about it.