Ford Flathead transmission Gear Ratios
 

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

Re: Ford Flathead transmission Gear Ratios
 

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

Re: Ford Flathead transmission Gear Ratios
 

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?

Re: Ford Flathead transmission Gear Ratios
 

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

Re: Ford Flathead transmission Gear Ratios
 

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

Re: Ford Flathead transmission Gear Ratios
 

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

Re: Ford Flathead transmission Gear Ratios
 

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.

Re: Ford Flathead transmission Gear Ratios
 

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.

Re: Ford Flathead transmission Gear Ratios
 

Here’s the link to our gear ratio chart:

http://www.vanpeltsales.com/FH_web/f...gearratios.htm

Re: Ford Flathead transmission Gear Ratios
 

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

Re: Ford Flathead transmission Gear Ratios
 

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.

Re: Ford Flathead transmission Gear Ratios
 

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.