PretendFarmer
Well-known Member
I was at a stone boat pull yesterday. Since I have been pulling with it, I have gotten random comments from people asking which gear I was pulling in. When I say 1st gear, I get "really? That was kind of fast".
Another guy was there with a 1952 SM. He was running 16.9/38 rears and they appeared to be 2" taller than my 15.5/38's. By ear, our RPM's were about the same at full throttle. I am sure there was some amount of variance but you couldn't tell.
So he had an idea to do a 1st gear race. At full throttle, I was pulling away from his tractor. With his noticeably bigger tires, he should have been going faster than me.
By guess, I would say my tractor was .1-.2mph faster than his.
Why would this be? My theory is that someone might have swapped in W6/SW6/400/450 utility ring and pinion gearing. If that's why, how much faster would a SM go with a set of utility ring and pinion gears?
This is a good thing for transfer sled pulls, but she kind of struggles with a heavy stoneboat in 8000lbs class and runs out of power in 9500lbs class on the stoneboat, but excels on a transfer sled in those classes.
Another guy was there with a 1952 SM. He was running 16.9/38 rears and they appeared to be 2" taller than my 15.5/38's. By ear, our RPM's were about the same at full throttle. I am sure there was some amount of variance but you couldn't tell.
So he had an idea to do a 1st gear race. At full throttle, I was pulling away from his tractor. With his noticeably bigger tires, he should have been going faster than me.
By guess, I would say my tractor was .1-.2mph faster than his.
Why would this be? My theory is that someone might have swapped in W6/SW6/400/450 utility ring and pinion gearing. If that's why, how much faster would a SM go with a set of utility ring and pinion gears?
This is a good thing for transfer sled pulls, but she kind of struggles with a heavy stoneboat in 8000lbs class and runs out of power in 9500lbs class on the stoneboat, but excels on a transfer sled in those classes.
