Rear end Ratios

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Model T Ford Forum: Forum 2018: Rear end Ratios
Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Young in Mays Landing, NJ on Friday, February 09, 2018 - 12:49 pm:

I'm in the process of re-doing a Ruckstell that had 3:1 gearing in it. I wanted to go back to standard with a 40 and an 11 tooth. Here's my question/dilemma... Can I run this as a 3.54:1 ?

The 39 tooth ring gear that came out of this rear looks absolutely perfect and has "Mark USA" stamped on it. I think this rear was done in 1963 and has very little time on it. I don't have a 40 in anywhere near the condition of the 39. I have a perfect 11 that I got at Hershey a while back.

Guys have told me how they like doing 3.25:1 in the Rux. My car is a '26 Touring and we use it a lot.. I've been running a stock rear with 3.65 in this car for the past 5 years and maybe 10,000 miles. Will I be in for any unusual challenges setting up the backlash with this combo?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Longbranch,WA on Friday, February 09, 2018 - 01:13 pm:

That MARK Auto Parts 39 tooth gear is just for a 3-1 set - I don't believe you can run an 11 tooth pinion against that ring gear.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan McEachern on Friday, February 09, 2018 - 02:22 pm:

Steve is correct that ring will not mesh correctly with an 11 tooth pinion. Notice I said
"correctly".


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Young in Mays Landing, NJ on Friday, February 09, 2018 - 04:03 pm:

Good to know. Maybe someone out there wants to trade the 3:1 set for a standard set?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Friday, February 09, 2018 - 06:24 pm:

Dave, somewhat off track, but Chaffins sell a 12 tooth pinion which will work with the 39 tooth ring gear, to give you a ratio of 3.25 This sits nicely between the 3:1 and standard. My roadster loves it.

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Young in Mays Landing, NJ on Friday, February 09, 2018 - 07:55 pm:

Thanks Allan. I've decided to stick with standard 40/11. Now I just need to trade someone my 39/13 set.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Brancaccio - Calgary Alberta on Friday, February 09, 2018 - 08:56 pm:

Dan, could you give us a little education on gear meshing as you eluded to it above.

Why can we have a 10 tooth & 11 tooth pinion work with a 40 tooth ring gear?

Thanks


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Longbranch,WA on Friday, February 09, 2018 - 10:43 pm:

Ford designed and "specially" cut the 10 tooth pinion to "roll over" the teeth on the 40 tooth ring gear. There is information written up about it in the Ford Service Bulletins.


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