Look inside Ford's (and G.M.) 10 speed
linc Just some half time reading
Forum Discussion
4.5:1 first gear, and 0.65:1 double (or is it triple) overdrive!
That is a wide spread between first and top gear ratios. Great job.
So to start out at 5 MPH with a huge load on the transmission, the engine can build up speed quickly, with 4.5:1 axle ratio, and say a 4.1:1 rear axle ratio. This will allow the engine to turn 18 times for each turn of the tires! 1,800 engine RPM = 100 tire revs per minute. or 6.6 minutes to go 1 mile.
At 0.65:1 ratio, the engine running 2,000 RPM will have a output shaft speed (say the transmission transmits all the RPM, and not lose one) the output shaft will be turning around 2,700 RPM. The same 4.10:1 rear axle reduction will bring this down to around 658 tire revs per minute.
If the tire outside diameter is about 30", then it should be turning around 660 revolutions per mile. 658 tire revs per mile - about 60 MPH? With a diesel, it would be better to have the 3.73:1 rear axle, or 2,700/3.73= 720 revs per minute or about 65.5 MPH at 2,000 RPM.
If you have the gas engine then the upper speed limit would be well over 120 MPH. Diesel is limited to around 110 MPH by the engine RPM governor. If you really wanted to go for speed, then a 3.23:1 rear axle ratio will lower the engine RPM's at all road speeds.
Looks like we will all have a better truck in a couple of years!
Fred.
That is a wide spread between first and top gear ratios. Great job.
So to start out at 5 MPH with a huge load on the transmission, the engine can build up speed quickly, with 4.5:1 axle ratio, and say a 4.1:1 rear axle ratio. This will allow the engine to turn 18 times for each turn of the tires! 1,800 engine RPM = 100 tire revs per minute. or 6.6 minutes to go 1 mile.
At 0.65:1 ratio, the engine running 2,000 RPM will have a output shaft speed (say the transmission transmits all the RPM, and not lose one) the output shaft will be turning around 2,700 RPM. The same 4.10:1 rear axle reduction will bring this down to around 658 tire revs per minute.
If the tire outside diameter is about 30", then it should be turning around 660 revolutions per mile. 658 tire revs per mile - about 60 MPH? With a diesel, it would be better to have the 3.73:1 rear axle, or 2,700/3.73= 720 revs per minute or about 65.5 MPH at 2,000 RPM.
If you have the gas engine then the upper speed limit would be well over 120 MPH. Diesel is limited to around 110 MPH by the engine RPM governor. If you really wanted to go for speed, then a 3.23:1 rear axle ratio will lower the engine RPM's at all road speeds.
Looks like we will all have a better truck in a couple of years!
Fred.
