The Ford Barn

oldmotorsguy · 02-25-2017, 02:34 PM

I am in the process of fixing a non-operational speedometer on a 1929 Model A Sedan. Everything looks good, with the exception of the speedo cable, which had the square end of the cable pretty much worn to round.

I replaced the cable, ran up the car and put it in fourth gear while on jack stands, still no operation of the speedo/odometer. I then looked up into the driveshaft speedo gear cavity, and noticed that I could spin the speedo worm gear on the drive shaft with my fingers. It obviously is not turning with the drive shaft. Is there a pin or something that holds this gear in place that was sheared off, and if so (or if not) how do I fix this?

V8COOPMAN · 02-25-2017, 03:18 PM

Quote:

Originally Posted by oldmotorsguy

I am in the process of fixing a non-operational speedometer on a 1929 Model A Sedan. Everything looks good, with the exception of the speedo cable, which had the square end of the cable pretty much worn to round.

I replaced the cable, ran up the car and put it in fourth gear while on jack stands, still no operation of the speedo/odometer. I then looked up into the driveshaft speedo gear cavity, and noticed that I could spin the speedo worm gear on the drive shaft with my fingers. It obviously is not turning with the drive shaft. Is there a pin or something that holds this gear in place that was sheared off, and if so (or if not) how do I fix this?

As can be seen in this pic, the gear has six splines internally that fit it to turn with the driveshaft. If it turns freely of the shaft by hand, you have a slight problem. DD

oldmotorsguy · 02-25-2017, 04:56 PM

Doh! You are right. It does not spin on the shaft, but does move from center to the rear of the housing hole easily with my finger. The spin was imagined by me due to grease and no light. Sorry.

The back and forth movement is maybe 3/4", give or take a 1/16th" or so. Isn't that too much?

Mitch//pa · 02-25-2017, 04:57 PM

Thats normal lateral movement
Once the turtle is in place it will hold the drive gear centered...

Barry B./ Ma. · 02-25-2017, 05:05 PM

There is a small roller bearing in the housing, you may need a couple of thrust washers to get the gear in the right place, I had that problem with my 29 roadster and I remember pulling the rear back and placing the thrust spacer behind the gear.

Tom Wesenberg · 02-25-2017, 07:57 PM

Sponsored Links (Register now to hide all advertisements)

I haven't worked on that gear for several years, but I thought extra play was only 1/8" or so.

Mitch//pa · 02-25-2017, 08:18 PM

Actually its more in the 1/4" range

BILL WILLIAMSON · 02-25-2017, 09:49 PM

It HAD to be turning before, to grind the cable end to ROUND! PROBABLY a dear old SEIZED speedomometer ?????
Bill Square

katy · 02-26-2017, 11:53 AM

"ran up the car and put it in fourth gear while on jack stands"

What kind of 4 speed tranny?

Did you verify that the speedometer itself is operational?

Bob C · 02-26-2017, 12:54 PM

Does your turtle have a square hole for the speedometer cable or a round hole
with a slot, maybe you have the wrong cable.

Bob

B-nut · 02-26-2017, 01:58 PM

Some of the early speedometer gear turtles seem to have a deeper cable hole and require a small spacer about 1/4'' long be dropped into the hole before screwing the cable into place. Am I remembering this correctly?

mantta · 02-26-2017, 02:45 PM

My speedometer did that several years ago. What I found was a thick gasket between the speedometer drive housing and the housing it bolts to. I made a paper gasket and used silicone on it, it works fine now. The drive gear was too far away from the worm gear.

oldmotorsguy · 02-26-2017, 03:27 PM

Katy: don't know what kind of 4-speed tranny. Reverse is all right and down, then the other 4 are standard: 1st is left and up, 2nd is left and down, 3rd is slightly right and up, 4th is slightly right and down.

In any event, got it figured out, thanks to the 1931 Model A Ford that was sitting right next to this one, also with a bad speedo. Thought I would fix both simultaneously. Turns out the 29 had the skinny housing with the square end cable, and the 31 also had a skinny housing, but the drive gear shaft had the opening for the keyed end cable. Essentially, each car had wrong parts.

Ordered a fat cable housing with keyed cable end, slapped it on the speedo gear drive that used to be on the 31, fired it up and the speedo ran perfectly, along with the odometer. I have yet to complete the 1931, but I suspect it will be OK as well.

How's that for top notch wrenching? (we call it luck, where I come from).

02-25-2017, 02:34 PM	#1
oldmotorsguy Senior Member Join Date: Jun 2010 Location: Crossville, Tennessee Posts: 157	Speedo drive gear on driveshaft spins freely... I am in the process of fixing a non-operational speedometer on a 1929 Model A Sedan. Everything looks good, with the exception of the speedo cable, which had the square end of the cable pretty much worn to round. I replaced the cable, ran up the car and put it in fourth gear while on jack stands, still no operation of the speedo/odometer. I then looked up into the driveshaft speedo gear cavity, and noticed that I could spin the speedo worm gear on the drive shaft with my fingers. It obviously is not turning with the drive shaft. Is there a pin or something that holds this gear in place that was sheared off, and if so (or if not) how do I fix this?

02-25-2017, 04:56 PM	#3
oldmotorsguy Senior Member Join Date: Jun 2010 Location: Crossville, Tennessee Posts: 157	Re: Speedo drive gear on driveshaft spins freely... Doh! You are right. It does not spin on the shaft, but does move from center to the rear of the housing hole easily with my finger. The spin was imagined by me due to grease and no light. Sorry. The back and forth movement is maybe 3/4", give or take a 1/16th" or so. Isn't that too much?

02-25-2017, 04:57 PM	#4
Mitch//pa BANNED Join Date: May 2010 Location: Bucks County, PA Posts: 11,454	Re: Speedo drive gear on driveshaft spins freely... Thats normal lateral movement Once the turtle is in place it will hold the drive gear centered... Last edited by Mitch//pa; 02-25-2017 at 05:08 PM.

02-25-2017, 05:05 PM	#5
Barry B./ Ma. Senior Member Join Date: May 2010 Location: Southbridge, Ma. Posts: 1,614	Re: Speedo drive gear on driveshaft spins freely... There is a small roller bearing in the housing, you may need a couple of thrust washers to get the gear in the right place, I had that problem with my 29 roadster and I remember pulling the rear back and placing the thrust spacer behind the gear.

02-25-2017, 07:57 PM	#6
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: Speedo drive gear on driveshaft spins freely... Sponsored Links (Register now to hide all advertisements) I haven't worked on that gear for several years, but I thought extra play was only 1/8" or so. Last edited by Tom Wesenberg; 02-25-2017 at 08:25 PM.

02-25-2017, 08:18 PM	#7
Mitch//pa BANNED Join Date: May 2010 Location: Bucks County, PA Posts: 11,454	Re: Speedo drive gear on driveshaft spins freely... Actually its more in the 1/4" range

02-25-2017, 09:49 PM	#8
BILL WILLIAMSON Senior Member Join Date: Dec 2010 Location: FRESNO, CA Posts: 12,560	Re: Speedo drive gear on driveshaft spins freely... It HAD to be turning before, to grind the cable end to ROUND! PROBABLY a dear old SEIZED speedomometer ????? Bill Square __________________ "THE ASSISTANT GURU OF STUFF"

02-26-2017, 11:53 AM	#9
katy Senior Member Join Date: Jun 2015 Location: Red Deer, Alberta Posts: 5,043	Re: Speedo drive gear on driveshaft spins freely... "ran up the car and put it in fourth gear while on jack stands" What kind of 4 speed tranny? Did you verify that the speedometer itself is operational? __________________ If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn! Last edited by katy; 02-26-2017 at 11:55 AM. Reason: Addition

02-26-2017, 12:54 PM	#10
Bob C Senior Member Join Date: May 2010 Location: So Cal Posts: 8,749	Re: Speedo drive gear on driveshaft spins freely... Does your turtle have a square hole for the speedometer cable or a round hole with a slot, maybe you have the wrong cable. Bob

02-26-2017, 01:58 PM	#11
B-nut Senior Member Join Date: May 2010 Location: Vt Posts: 231	Re: Speedo drive gear on driveshaft spins freely... Some of the early speedometer gear turtles seem to have a deeper cable hole and require a small spacer about 1/4'' long be dropped into the hole before screwing the cable into place. Am I remembering this correctly?

02-26-2017, 02:45 PM	#12
mantta Senior Member Join Date: May 2010 Location: Keweenaw Bay, MI (Michigan's Upper Peninsula) Posts: 218	Re: Speedo drive gear on driveshaft spins freely... My speedometer did that several years ago. What I found was a thick gasket between the speedometer drive housing and the housing it bolts to. I made a paper gasket and used silicone on it, it works fine now. The drive gear was too far away from the worm gear.

02-26-2017, 03:27 PM	#13
oldmotorsguy Senior Member Join Date: Jun 2010 Location: Crossville, Tennessee Posts: 157	Re: Speedo drive gear on driveshaft spins freely... Katy: don't know what kind of 4-speed tranny. Reverse is all right and down, then the other 4 are standard: 1st is left and up, 2nd is left and down, 3rd is slightly right and up, 4th is slightly right and down. In any event, got it figured out, thanks to the 1931 Model A Ford that was sitting right next to this one, also with a bad speedo. Thought I would fix both simultaneously. Turns out the 29 had the skinny housing with the square end cable, and the 31 also had a skinny housing, but the drive gear shaft had the opening for the keyed end cable. Essentially, each car had wrong parts. Ordered a fat cable housing with keyed cable end, slapped it on the speedo gear drive that used to be on the 31, fired it up and the speedo ran perfectly, along with the odometer. I have yet to complete the 1931, but I suspect it will be OK as well. How's that for top notch wrenching? (we call it luck, where I come from).