MTFCA Forum

Hello everyone. Thanking about changing my pinion gear.I've got a 11tooth pinion and a 40 tooth ring gear can I use a 10 tooth pinion on the 40 tooth ring gear. Thanks in advance Harold

Yes.
I did quite successfully on the Town Car. It required a little more effort than an 11 tooth pinion but just a few shims.

I built a speedster with a Warford aluminum three speed and a 10 tooth pinion.
The 10 tooth was made to run against the stock ring gear.
The gout to one rear end gives you plenty of power in direct Warford or high Ruxtell.
But....if going up a slight upgrade if you run in high Ruckstell or direct Warford the motor is running very fast to tour with stock T’s.
If you run in overdrive Warford the engine will overheat from running too slow and lugging.
If you run in underdrive Warford or low Ruckstell everybody with the stock setup will overheat because their engines will be running too slow.
We found I just could not lead tours with that setup. The 3:63 overall gear ratio is by far the best in hilly country.

Unless you do a lot of driving on mountain roads, I would suggest sticking with the stock ratio.

Changing the differential gears from original has shown to be questionable after years of reading different outcomes on the forum. More than a few have noted that overall leaving the original gear ratio is the best way to go. Different opinions on this will always arise.

If you are pulling hills all the time the ten tooth is great but if you are flat lands I would run the eleven tooth.