MTFCA Forum

Hello all !! Are the ring and pinion gears the same between the small drum and the large drum
Thanks

Sure are !

Old Rusty,

The Ford ring and pinion is interchangeable 1909-27.
Ruckstell made special rings and pinions that are not interchangeable with the Ford ones.
The differential carrier and spider gears changed through the years but are interchangeable in sets.

Mike

Thanks Mr Silbert !! Appreciate your help. Working in a 25 and the ring gear is toasty

Mike Silbert wrote: ↑

Mon Mar 09, 2026 3:48 pm

Old Rusty,

The Ford ring and pinion is interchangeable 1909-27.
Ruckstell made special rings and pinions that are not interchangeable with the Ford ones.
The differential carrier and spider gears changed through the years but are interchangeable in sets.

Mike

Well........ Not exactly.
There are ring & pinion gear sets produced with a slightly different tooth angle.
They are marked with about an 1/8" round dimple on both gears. They are not to be mixed with non dimple marked gears.
I believe there was a service bulletin warning to this effect.

I haven't come across any of the late USA Ts having the dimple marked gears but have in the Canadian Ts, Canadian service bulletin in 1923 shows them as new design drive gear and pinion.

Kerry wrote: ↑

Mon Mar 09, 2026 6:46 pm

I haven't come across any of the late USA Ts having the dimple marked gears but have in the Canadian Ts, Canadian service bulletin in 1923 shows them as new design drive gear and pinion.

I have several sets & loose individual gears I have acquired over the years.
I don't know how they made their way to the swap meets. I acquired them in the USA.
I know enough not to mix em from a service bulletin. Something to be aware of.

This is the Service Bulletin in question:


I have tried to match the ones that I have together in sets and identify them as such.

My mum taught me to avoid anything with spots on. Now you guys say it's OK in given circumstances!

Allan from down under.

Not being a Canadian car guy I have never seen spotted ring gears or heard of them.
I also have never seen or read Canadian service bulletins.
I did read the American service bulletins cover to cover as a kid 50 years ago, what was I thinking.
Maybe I live too far from the border.

There is always something new to learn about the Model T Ford.
Mike