gearing is everything

[squekster]

I read some where in a ford forum where this guy was braging about 400 pound ft of torque at the rear wheels. My scooter has more rear wheel torque than that. The mistake he made was that ,that was
the flywheel torque as measured at the rear wheels. With the proper gearing a driil motor with 2 pounds feet can be geared to produce 2000 pounds feet of torque. The only problem with that is by using
a gear reduction of that size the rpms are like 1 rpm with is not practical. If we change the gears by
changing the drive gear with the driven gear we can make 1 million rpm but the torque will only be
.002 pounds feet which is also un useable. The trick is finding a middle ground. Basicly you can push very hard but not very fast or you can push very fast but not very hard.

 

[David Pepiton]

so whats the point to this thread?

 

[squekster]

so whats the point to this thread?

The point is that some people don't know how to read dyno results, they mistake
rear wheel torque with flywheel torque measured at the rear wheels . Did you know the difference?

 

[David Pepiton]

yeah im very aware of the difference. you just seemed to be rambling.

 

[FoxMustangLvr]

:worthlesa

 

[88LX5.Oh]

Dynos pulls are done with the trans in whichever gear that is a 1:1 ratio. As in the input and output shaft are spinning the same speed. So there's no gear reduction or gear multiplication.

 

[gearheadboy]

so whats the point to this thread?

^

 

[RacEoHolic330]

Basicly you can push very hard but not very fast or you can push very fast but not very hard.

That's what she said!

 

[MikeUrban]

Neat.

 

[HuskerNation]

 

[David Pepiton]

I like PIE!

oh this guy is ranting about some sort of gear thinggy im not quite sure though

 

[Mr. Snrub]

What's all this about a scooter?

 

[Mustang5L5]

 

[squekster]

What's all this about a scooter?

My scooter is a 1200 harley sportster. and in 1st gear the rear wheel torque is 1085 ft pounds at 3500 rpm

 

[squekster]

Dynos pulls are done with the trans in whichever gear that is a 1:1 ratio. As in the input and output shaft are spinning the same speed. So there's no gear reduction or gear multiplication.

Sorry to burst your bubble, but you are forgetting the rear differential which on my car is 3.55.

 

[Mr. Snrub]

My scooter is a 1200 harley sportster. and in 1st gear the rear wheel torque is 1085 ft pounds at 3500 rpm

I don't think so. Stock is 75ft/lbs or so... how exactly did you add 1010 to that?

 

[Bullitt347]

I question the whole gear ratio having an effect on measured torque. Why? Well when I had my car on a chassis dyno I asked the dyno operator about this very thing. He said it did not matter. We made pulls in 2nd 3rd and 4th (1:1) gear and the rear wheel torque reading was within 1 to 5 lb/ft every time. A turbo engine will react differently to gear, because they seem to like higher engine loads (read higher gear/lower numerically) to make the most boost. I tried this dyno gear thing with 2 different cars, one N/A and the other with a positive displacement supercharger and each run was within the margin of error dispite the gearing. This was on a Dynojet, have not tried it on a Mustang Dyno.​

 

[pearlnotchback]

i like cheese

 

[squekster]

I don't think so. Stock is 75ft/lbs or so... how exactly did you add 1010 to that?

Thats exactly my point . Primary ratio 1.5:1 a 3.0:1 first gear an a 3.0 final drive
ratio 75 ft/lbs x1.5 . aprox 120x30 or 360ft/lb x 3.0 = aprox 1080 ft/lbs

 

[squekster]

I question the whole gear ratio having an effect on measured torque. Why? Well when I had my car on a chassis dyno I asked the dyno operator about this very thing. He said it did not matter. We made pulls in 2nd 3rd and 4th (1:1) gear and the rear wheel torque reading was within 1 to 5 lb/ft every time. A turbo engine will react differently to gear, because they seem to like higher engine loads (read higher gear/lower numerically) to make the most boost. I tried this dyno gear thing with 2 different cars, one N/A and the other with a positive displacement supercharger and each run was within the margin of error dispite the gearing. This was on a Dynojet, have not tried it on a Mustang Dyno.​

Just think , if you had a car weighing 2600 pounds and rear wheel torque of just 400 ft/lbs How fast do you think that car would be off the line? Gearing is everthing. The best bang for the buck when building a street car is the gears. When I bought my car the first thing I did was get rid of the dead rear. 2.73 to 3.55 what a difference that made alone