The Ford Barn

Vic in E-TN · 08-23-2021, 12:23 PM

I have a 29 Pickup and the speedo has not been working for some time. I pulled the cable off the gear case on the driveshaft and found the inner cable broken. A long time ago I put a 4.11 R&P in the truck and I could not remember if I changed the drive gear in the assembly so I pulled this and discovered I had the correct 21 tooth gear. I broke the gasket when reinstalling the gear case so I looked in Snyder's catalog and they sell a set of 3 gaskets so you can set the backlash on the gear. My question is - how do you determine the backlash and what is the correct number?

Thanks,
Vic

john charlton · 08-23-2021, 01:00 PM

I fit one gasket while I tighten up the two retaining bolts I insert a small screwdriver into the female cap end . If the drive begins to lock with zero lash I put in a second gasket this normally does the trick . A little bit of lash is fine . When the drive begins to lock stop tightening the cap or damage to the housing can result , I have never had to use three gaskets . You need a medium screwdriver for the flagged female .

John in Suffolk County England .

Vic in E-TN · 08-23-2021, 08:40 PM

John:
Thanks. Your answer makes sense.
Vic

Terry, NJ · 08-24-2021, 08:42 AM

Why did it break! My 29 has abut the same problem. But I found out that the speedo is very tight, not seized, but very tight. I tried oiling it and running it in with an electric drill, (Reverse) but no luck so far. I'm thinking of having Papanick do the rebuild. ($160 +).
Terry

Vic in E-TN · 08-24-2021, 09:31 AM

Terry
I don't have the speedo out yet because I found the broken cable. It is probably a good thing to check out the speedo before I put in the new cable. My speedo has 72K miles on it and I do not want to put in a rebuilt one with zero miles on it. Last week I sent an e-mail to papanick but have not heard a response. Thanks for the advise.
Vic

john charlton · 08-24-2021, 10:25 AM

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You can spin the input shaft to and fro forever and it will never free off sufficiently . The aluminum sulphate is trapped in the shaft indents and cant escape . A rebuilder will unswage the rotating magnet from the shaft and remove it . Get it rebuilt for sure .

John in Suffolk County England .

chrs1961815 · 08-24-2021, 11:25 AM

Rebuilders don't have to turn the odometer back to zero fyi.

08-23-2021, 12:23 PM	#1
Vic in E-TN Senior Member Join Date: May 2010 Location: Maryville, TN Posts: 491	Speedo Drive Gear Question I have a 29 Pickup and the speedo has not been working for some time. I pulled the cable off the gear case on the driveshaft and found the inner cable broken. A long time ago I put a 4.11 R&P in the truck and I could not remember if I changed the drive gear in the assembly so I pulled this and discovered I had the correct 21 tooth gear. I broke the gasket when reinstalling the gear case so I looked in Snyder's catalog and they sell a set of 3 gaskets so you can set the backlash on the gear. My question is - how do you determine the backlash and what is the correct number? Thanks, Vic

08-23-2021, 01:00 PM	#2
john charlton Senior Member Join Date: May 2010 Posts: 1,304	Re: Speedo Drive Gear Question I fit one gasket while I tighten up the two retaining bolts I insert a small screwdriver into the female cap end . If the drive begins to lock with zero lash I put in a second gasket this normally does the trick . A little bit of lash is fine . When the drive begins to lock stop tightening the cap or damage to the housing can result , I have never had to use three gaskets . You need a medium screwdriver for the flagged female . John in Suffolk County England . Last edited by john charlton; 08-23-2021 at 01:12 PM.

08-23-2021, 08:40 PM	#3
Vic in E-TN Senior Member Join Date: May 2010 Location: Maryville, TN Posts: 491	Re: Speedo Drive Gear Question John: Thanks. Your answer makes sense. Vic

08-24-2021, 08:42 AM	#4
Terry, NJ Senior Member Join Date: May 2010 Location: Bucks Co, Pa Posts: 3,740	Re: Speedo Drive Gear Question Why did it break! My 29 has abut the same problem. But I found out that the speedo is very tight, not seized, but very tight. I tried oiling it and running it in with an electric drill, (Reverse) but no luck so far. I'm thinking of having Papanick do the rebuild. ($160 +). Terry

08-24-2021, 09:31 AM	#5
Vic in E-TN Senior Member Join Date: May 2010 Location: Maryville, TN Posts: 491	Re: Speedo Drive Gear Question Terry I don't have the speedo out yet because I found the broken cable. It is probably a good thing to check out the speedo before I put in the new cable. My speedo has 72K miles on it and I do not want to put in a rebuilt one with zero miles on it. Last week I sent an e-mail to papanick but have not heard a response. Thanks for the advise. Vic

08-24-2021, 10:25 AM	#6
john charlton Senior Member Join Date: May 2010 Posts: 1,304	Re: Speedo Drive Gear Question Sponsored Links (Register now to hide all advertisements) You can spin the input shaft to and fro forever and it will never free off sufficiently . The aluminum sulphate is trapped in the shaft indents and cant escape . A rebuilder will unswage the rotating magnet from the shaft and remove it . Get it rebuilt for sure . John in Suffolk County England .

08-24-2021, 11:25 AM	#7
chrs1961815 Senior Member Join Date: Jul 2018 Location: Spring Grove, Illinois Posts: 1,371	Re: Speedo Drive Gear Question Rebuilders don't have to turn the odometer back to zero fyi. __________________ "The more things change, the more they stay the same."