The Ford Barn

firerod · 03-31-2017, 10:49 AM

Anyone out there have a Ford speedometer gear chart that could help me pick the right size gear? I have 700x16 rear tires (approx. 30.4" diameter) and 3:78 ring and pinion.

alanwoodieman · 03-31-2017, 11:16 AM

19 tooth is for 3:78 with 29 1/2" tires 6:/6:50 by 16 tires. 18 tooth is for 3:54 gears, 21 is for 4:11 gears

deuce lover · 03-31-2017, 11:17 AM

Your choice is either 18 or 19 tooth.Given your tire size I would try the 18.

firerod · 04-01-2017, 11:10 AM

Thanks guys.

JSeery · 04-01-2017, 11:51 AM

Quote:

Originally Posted by firerod

Anyone out there have a Ford speedometer gear chart that could help me pick the right size gear? I have 700x16 rear tires (approx. 30.4" diameter) and 3:78 ring and pinion.

There are charts in the Green Book, pg 632-634 in my book.

JM 35 Sedan · 04-01-2017, 12:16 PM

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I don't think you're going to nail it any closer than +/- 5 mph with any of the standard Ford speedo turtle gears available. I played around with 4.11 & 3.78 gears in my 35 fordor with 750 x 16's on the rear and could never seem to get any closer than +/- 5 mph.

39portlander · 04-02-2017, 06:05 AM

I put an 18 in the 39 pickup as the rear end is now 3:54. I think I found that gear in one of the model A catalogs.

firerod · 04-03-2017, 03:00 PM

I will try an 18. Thank you all.

03-31-2017, 10:49 AM	#1
firerod Senior Member Join Date: May 2010 Location: Lakewood, CO Posts: 416	Help with speedometer gear Anyone out there have a Ford speedometer gear chart that could help me pick the right size gear? I have 700x16 rear tires (approx. 30.4" diameter) and 3:78 ring and pinion.

03-31-2017, 11:16 AM	#2
alanwoodieman Senior Member Join Date: May 2010 Location: upstate SC Posts: 3,006	Re: Help with speedometer gear 19 tooth is for 3:78 with 29 1/2" tires 6:/6:50 by 16 tires. 18 tooth is for 3:54 gears, 21 is for 4:11 gears

03-31-2017, 11:17 AM	#3
deuce lover Senior Member Join Date: May 2010 Location: Rockwall TX Posts: 6,018	Re: Help with speedometer gear Your choice is either 18 or 19 tooth.Given your tire size I would try the 18.

04-01-2017, 11:10 AM	#4
firerod Senior Member Join Date: May 2010 Location: Lakewood, CO Posts: 416	Re: Help with speedometer gear Thanks guys.

04-01-2017, 12:16 PM	#6
JM 35 Sedan Senior Member Join Date: May 2010 Location: Near Rising Sun, Maryland Posts: 10,876	Re: Help with speedometer gear Sponsored Links (Register now to hide all advertisements) I don't think you're going to nail it any closer than +/- 5 mph with any of the standard Ford speedo turtle gears available. I played around with 4.11 & 3.78 gears in my 35 fordor with 750 x 16's on the rear and could never seem to get any closer than +/- 5 mph. __________________ *John* *"Never give up on what you really want to do. The person with big dreams is more powerful than one with all the facts". Albert Einstein*

04-02-2017, 06:05 AM	#7
39portlander Senior Member Join Date: May 2010 Location: Suth'N Maine Posts: 2,026	Re: Help with speedometer gear I put an 18 in the 39 pickup as the rear end is now 3:54. I think I found that gear in one of the model A catalogs.

04-03-2017, 03:00 PM	#8
firerod Senior Member Join Date: May 2010 Location: Lakewood, CO Posts: 416	Re: Help with speedometer gear I will try an 18. Thank you all.