ok rocket scientist, need help calulating force on pinion and driveshaft??

[GSXR1216]

ok, need some math help from you rocket scientist, got a little science project that my buddy is trying to figure out. is there any way ( i'm sure there is!) to figure the force put on the pinion gear or driveshaft? lets say you you got a car that puts down 300lb/ft of torque with a 25" tall tire with a 3.73 rearend ratio, dyno number for torque was calculated running it in 1:1 ratio on the tranny on the dyno pull.


thanks!

 

[rd]

This is how this stuff is designed.

If you are putting 300 ft lbs to the flywheel, multiply that by the gear ratio. In fourth or 1:1, you will have 300 ft lbs trying to rotate the pinion gear. The force applied by the pinion teeth is the torque divided by the radius of the pinion. If you have a 3.73 or so, with a 3in dia pinion, that's 1.5 in/12 in is .125 ft. 300 ft lb /.125 ft is 2400 lbs. How to figure that out over the teeth of the gear would take some more figuring.

Now, with say, a 3:1 first gear, its 3 times that, or 7200 lbs.

I am not a rocket scientist, so feel free to add to this.

 

[GSXR1216]

i figured gear diameters would play a role in this somewhere, along with pressure angles on the gears also to get the numbers right. where would tire diameter fit in this, the "quoted" 300lb/ft number was RWHP was off the dyno, not flywheel HP.

 

[88-GT]

In the case of the torque on the dyno I think you are probably confused becuase the dyno converts it but if you were going to take that route you would have to work backwards.

Torque is simply broken down into Force * a Perpendicular Distance. From that you can go pretty much anywhere, gear ratios will just multiply the torque and there will be losses. Could be an interesting project but I dont have the time to draw it all out for it to be accurate but it shouldnt be that bad.