Ford Flathead transmission Gear Ratios

[Bustingear]

I know it is a Ford open drive post 1939 with the desireable large double detent shift tower but I am trying to find out the 1st, 2nd ,and 3rd gear ratios. Anyone close to these?
Number on the base rear case 78-7006
Number on Shift Tower 81A-7222B
Serial number on upper bell area 799C-I 906942

Thanks

 

[Ken/Alabama]

Depends on tooth count on the cluster gear. Third gear is 1:1 regardless.

 

[Bustingear]

i have it open, which gear and how do i go about counting? Is the cluster one of the bottom gears in the case or is it sevral i have to count?

 

[deuce lover]

Yes the bottom. The large end which is at the front of the case should be 28 or 29 tooth.

 

[tubman]

Yes the bottom. The large end which is at the front of the case should be 28 or 29 tooth.

After 85 years, there's a chance it might be 25 or 26 as well.

 

[Bustingear]

any tricks to counting that without taking it apart? Can only see the edge and too greasy to mark?

 

[Ken/Alabama]

You can count the teeth on the top gear that’s on the input. Most of the time , if it has 16 teeth the cluster will have 28 teeth. If it has 15 the cluster will have 29. Usually between the two they will add up to 44. But I have seen this not always applies.

 

[cadillac512]

The input shaft will have either 16 or 15 teeth if the cluster has 28 or 29. The pairs will add up to 44. (16+28 or 15+29) Those are common. VanPelt's website lists the ratios of the various combinations over the years.

 

[Mac VP]

Here’s the link to our gear ratio chart:

http://www.vanpeltsales.com/FH_web/flathead_trans-gearratios.htm

 

[Tim Ayers]

I use a grease paint pen to mark a tooth on the large cluster. You’ll see it as it comes around and use a thin straight screwdriver to help you count the teeth

 

[Bustingear]

According to Macs chart and the fact that it has a 15 tooth main gear there is no need to count the cluster ...It will have a 3.14 1st gear. Got it. Thanks Mac ! Going to call you for some gaskets and seals when you return from vacation.

 

[Tim Ayers]

According to Macs chart and the fact that it has a 15 tooth main gear there is no need to count the cluster ...It will have a 3.14 1st gear. Got it. Thanks Mac ! Going to call you for some gaskets and seals when you return from vacation.

Like Tubman says, after 85 years, nothing is for certain in these transmissions and take nothing for granted. I would confirm everything is right while you have it apart.