The Ford Barn

chrs1961815 · 01-14-2019, 01:09 PM

Are the speedo gear caps interchangeable on the different kinds of transmissions? My problem is that I had my speedo rebuilt but it still does not work. I am trying to narrow it down between it being not the right cable or a gear cap problem.

I pulled the gear cap and everything looks fine, the gear isn't missing any teeth. According to the judging standards, my speedo gear cap is the 10-37 one used from February 1928 to early 1929 with the 3:70:1 ratio. Will certain caps and cables not work with certain transmissions and vice versa?

chrs1961815 · 01-14-2019, 01:11 PM

I also am not sure when the trans is from. I have a 31 engine in my early 28 which may or may not help. From what I read there is really no way to tell from the outside.

Jim Brierley · 01-14-2019, 01:26 PM

Disconnect the cable at the speedo head, drive the car a few feet to check that the cable is turning. Measure (roughly) to see that the cable is interring the head as it should. If all is good, check to see that the cable ends match the opening in both the lower and upper end, most are square, some have a slot in them.

DD931 · 01-14-2019, 01:26 PM

Try moving the car with the speedometer cable unattached from the speedometer and the instrument panel out of the way so you can see the end of the cable. If the core turns the problem is not the cable or drive gear. If the cable doesn't turn, have a friend watch the top end while you detach the bottom from the "turtle" at the rear of the transmission and turn the cable core. If it doesn't turn at the top, replace the cable core. If memory serves, the gear meshes with the drive shaft, not the transmission itself. There should not be any "mix and match" problems.

DD931 · 01-14-2019, 01:28 PM

Jim - your post came up at the same time I was writing mine!! Seems we have the same approach.

chrs1961815 · 01-14-2019, 01:43 PM

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Quote:

Originally Posted by Jim Brierley

Disconnect the cable at the speedo head, drive the car a few feet to check that the cable is turning. Measure (roughly) to see that the cable is interring the head as it should. If all is good, check to see that the cable ends match the opening in both the lower and upper end, most are square, some have a slot in them.

Some additional info: I did that yesterday and the cable turned fine. Also, when I pulled the cap I discovered that the speedo end is square while the gear end is the turtle/round end.

jw hash · 01-14-2019, 02:01 PM

sounds like you have a early turtle. change it out for a later one. I had one awhile back that the cable itself was to short.

I did cut a short peace of cable and installed it in the turtle, and it worked

chrs1961815 · 01-14-2019, 02:02 PM

Quote:

Originally Posted by jw hash

sounds like you have a early turtle. change it out for a later one. I had one awhile back that the cable itself was to short.

I have heard of people shimming the cable to get extra length.

01-14-2019, 01:09 PM	#1
chrs1961815 Senior Member Join Date: Jul 2018 Location: Spring Grove, Illinois Posts: 1,371	Speedo not working Are the speedo gear caps interchangeable on the different kinds of transmissions? My problem is that I had my speedo rebuilt but it still does not work. I am trying to narrow it down between it being not the right cable or a gear cap problem. I pulled the gear cap and everything looks fine, the gear isn't missing any teeth. According to the judging standards, my speedo gear cap is the 10-37 one used from February 1928 to early 1929 with the 3:70:1 ratio. Will certain caps and cables not work with certain transmissions and vice versa?

01-14-2019, 01:11 PM	#2
chrs1961815 Senior Member Join Date: Jul 2018 Location: Spring Grove, Illinois Posts: 1,371	Re: Speedo not working I also am not sure when the trans is from. I have a 31 engine in my early 28 which may or may not help. From what I read there is really no way to tell from the outside.

01-14-2019, 01:26 PM	#3
Jim Brierley Senior Member Join Date: Jun 2010 Location: Temecula, CA Posts: 4,087	Re: Speedo not working Disconnect the cable at the speedo head, drive the car a few feet to check that the cable is turning. Measure (roughly) to see that the cable is interring the head as it should. If all is good, check to see that the cable ends match the opening in both the lower and upper end, most are square, some have a slot in them.

01-14-2019, 01:26 PM	#4
DD931 Senior Member Join Date: May 2010 Location: PA Poconos Posts: 723	Re: Speedo not working Try moving the car with the speedometer cable unattached from the speedometer and the instrument panel out of the way so you can see the end of the cable. If the core turns the problem is not the cable or drive gear. If the cable doesn't turn, have a friend watch the top end while you detach the bottom from the "turtle" at the rear of the transmission and turn the cable core. If it doesn't turn at the top, replace the cable core. If memory serves, the gear meshes with the drive shaft, not the transmission itself. There should not be any "mix and match" problems.

01-14-2019, 01:28 PM	#5
DD931 Senior Member Join Date: May 2010 Location: PA Poconos Posts: 723	Re: Speedo not working Jim - your post came up at the same time I was writing mine!! Seems we have the same approach.

01-14-2019, 02:01 PM	#7
jw hash Senior Member Join Date: May 2010 Location: Auburn Washington Posts: 2,552	Re: Speedo not working sounds like you have a early turtle. change it out for a later one. I had one awhile back that the cable itself was to short. I did cut a short peace of cable and installed it in the turtle, and it worked Last edited by jw hash; 01-14-2019 at 07:53 PM.