1954 GMC 4WD Ideas

[octanejunkie]

sounds like you'vyou're got a good plan.
4.10s with 265/75-16 are a great combo.
Grab the p/s box from the Toyota too.

[OrrieG]

4.10 might be a little steep unless you get tall tires. My 74 axles are 3.74 with auto trans. There are rpm calculators online that let you play with the variables; tranny ratio output (1.0 in this case), rearend ratio, tire height and rpm. you can input any three to find the 4th variable. Salt flat racers also add in frontage area, drag coefficient to determine horsepower to get certain speed. Not a big deal for the trucks, but been playing with it for my Chevelle make over.

[69l46vert]

Originally Posted by OrrieG

4.10 might be a little steep unless you get tall tires. My 74 axles are 3.74 with auto trans. There are rpm calculators online that let you play with the variables; tranny ratio output (1.0 in this case), rearend ratio, tire height and rpm. you can input any three to find the 4th variable. Salt flat racers also add in frontage area, drag coefficient to determine horsepower to get certain speed. Not a big deal for the trucks, but been playing with it for my Chevelle make over.

Thanks OrrieG, I tried one of the calculators and 4.10's at 2000 rpm with 31" tires gives 45 mph so I see what you mean. Not great for highway speeds. I really don't think I want anything larger than 31's either. Rick

[OrrieG]

For a while I ran a 1 ton axle with 4.56 and sm460. Would climb a tree but 235 six maxed out at 45 mph. Good for back wood, but getting there took some time!

[octanejunkie]

Originally Posted by 69l46vert

Thanks OrrieG, I tried one of the calculators and 4.10's at 2000 rpm with 31" tires gives 45 mph so I see what you mean. Not great for highway speeds. I really don't think I want anything larger than 31's either. Rick

4.10 is the "correct ratio" for 31" tires to get the best overall performance potential out of your engine assuming you are properly cammed (not too big) and have the the right stall (about 2200-2400) to match your cam.

The following chart assumes 1:1 ratio at 65 MPH



At 65 mph you will make 2890 RPM at 1:1, and with 0.7 OD ratio that drops to 2023 RPM. This configuration of tire and gear has been pretty much standard with Toyota in the pickup and 4runner line for a long time.

If you want to drop to 3.73 gears, you will likely not get the best 4x4 experience but it will be 10% more highway friendly. 3.42 will be 20% lower than 4.10 and not optimal for a 4x4.