The Ford Barn

Matt in Alameda · 05-07-2015, 07:00 PM

In my 1935 Ford 5 Window coupe, I have a 4.11 rear end ratio. The speedometer turtle on the torque tube is stamped with the number 19...this is for a 3.78 rear end and explains why the speedometer is inaccurate.I am looking for a turtle with a 21 to go with the 4.11 rear end ratio. My question is, do I have to also change the gear that is driving the turtle that is on the drive shaft?........Thank-you,.....Matt in Alameda

DD931 · 05-07-2015, 07:04 PM

No - the same shaft gear is used by both. Only the gear in the turtle is different.

JSeery · 05-07-2015, 08:49 PM

The actual assemble part number would depend on the tire size. The Green Book list the combinations, such as:
A-17270-E 21 teeth for 4.50 x 21 tire
B-17270-B 21 teeth for 4.75 x 19 & 5.25 x 18 tire
and so on.

DD931 · 05-08-2015, 02:40 PM

I thought you were asking about the driving gear, not the speedometer drive gear. If so, per the Green Book middle of Page 632: "The B17285 Driving Gear (7 teeth) is used exclusively."

JSeery · 05-08-2015, 07:12 PM

I thought he was asking about both! LOL

Matt in Alameda · 05-09-2015, 02:12 PM

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Thank-you guys..DD931 was able to decipher my garbled post best. This site is fantastic, I would have never attempted this project if it didn't exist...... a very, very sincere thanks to all of the contributors.....Matt in Alameda

DD931 · 05-09-2015, 05:57 PM

I love a happy ending!!

Heard · 05-09-2015, 07:26 PM

Hey Matt...if you have a difficult time finding the entire turtle, you can just change the gear inside. That is what I did. PM me if you want to know the details.

Flowmeister · 05-10-2015, 02:07 AM

I have a 21 tooth turtle here.
If you want to pay the shipping, it's yours.

05-07-2015, 07:00 PM	#1
Matt in Alameda Senior Member Join Date: May 2010 Location: Alameda, California Posts: 335	changing turtle speedometer drive question In my 1935 Ford 5 Window coupe, I have a 4.11 rear end ratio. The speedometer turtle on the torque tube is stamped with the number 19...this is for a 3.78 rear end and explains why the speedometer is inaccurate.I am looking for a turtle with a 21 to go with the 4.11 rear end ratio. My question is, do I have to also change the gear that is driving the turtle that is on the drive shaft?........Thank-you,.....Matt in Alameda

05-07-2015, 07:04 PM	#2
DD931 Senior Member Join Date: May 2010 Location: PA Poconos Posts: 723	Re: changing turtle speedometer drive question No - the same shaft gear is used by both. Only the gear in the turtle is different.

05-07-2015, 08:49 PM	#3
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: changing turtle speedometer drive question The actual assemble part number would depend on the tire size. The Green Book list the combinations, such as: A-17270-E 21 teeth for 4.50 x 21 tire B-17270-B 21 teeth for 4.75 x 19 & 5.25 x 18 tire and so on.

05-08-2015, 02:40 PM	#4
DD931 Senior Member Join Date: May 2010 Location: PA Poconos Posts: 723	Re: changing turtle speedometer drive question I thought you were asking about the driving gear, not the speedometer drive gear. If so, per the Green Book middle of Page 632: "The B17285 Driving Gear (7 teeth) is used exclusively."

05-08-2015, 07:12 PM	#5
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: changing turtle speedometer drive question I thought he was asking about both! LOL

05-09-2015, 02:12 PM	#6
Matt in Alameda Senior Member Join Date: May 2010 Location: Alameda, California Posts: 335	Re: changing turtle speedometer drive question Sponsored Links (Register now to hide all advertisements) Thank-you guys..DD931 was able to decipher my garbled post best. This site is fantastic, I would have never attempted this project if it didn't exist...... a very, very sincere thanks to all of the contributors.....Matt in Alameda

05-09-2015, 05:57 PM	#7
DD931 Senior Member Join Date: May 2010 Location: PA Poconos Posts: 723	Re: changing turtle speedometer drive question I love a happy ending!!

05-09-2015, 07:26 PM	#8
Heard Senior Member Join Date: Sep 2013 Location: Florida Posts: 584	Re: changing turtle speedometer drive question Hey Matt...if you have a difficult time finding the entire turtle, you can just change the gear inside. That is what I did. PM me if you want to know the details. __________________ Do I look like I have a plan B?

05-10-2015, 02:07 AM	#9
Flowmeister Senior Member Join Date: Sep 2012 Location: Calgary Alberta Posts: 133	Re: changing turtle speedometer drive question I have a 21 tooth turtle here. If you want to pay the shipping, it's yours.