I'm just finishing my 1952 F1 restoration and ran into a problem with the speedometer. I put in an R10 overdrive transmission which I believe came out of a 1950 Mercury car. Two years ago when I was installing the drive train, I purchased and installed a A9A speedometer cable, a worm bearing and a 20 tooth Driven gear, part # AB-17332-A-20T. Now that I fired the truck up I find that the speedometer doesn't work. Upon closer inspection I discovered that the Driven Gear is stripped. The local Antique Ford Parts dealer has since gone out of business so they are unavailable for advice or recourse.

My question therefore is, What went wrong? Did they sell me the wrong part? Did I install it wrong? I checked the DC website and they sell a very similar looking gear which is part # B5A-17322-A. I checked the speedometer itself and it appears to turn freely.

 

Sounds like that new speedometer cable just might be sticking you stated the gear was stripped. Did you use graphite and lube the cable before you installed it. Years ago I was instructed to take the cable when using graphite install the power with the cable vertical and rotate the cable while installing the graphite power. Then install the cable. Learned that in Vo tech. AJ

 

Thanks. I think you're right. I'll check the lube. I ordered a new one from eBay. Same price as DC but shipping was less than one third the price, $14.95 compared to $48 for DC, which I thought was rediculous.

 

You can't mix and match drive/driven speedo gears, they have to be matched for pitch. You would want the stock F-1 gear set. My '52 with 3.92 rear axle has a 23 Tooth driven gear, 01Y-17271-F. That may work with the drive gear that's in your trans, but might not.

 

Ya I hear ya shipping is totally out of control. I started using mid America out of Ohio. They seem.to have the parts I.need and the shipping is very reasonable. My speedometer I don't know I bought the 55 and drove it 550 miles home from south Texas. The gauge was jumping. I've been working on the truck ever sense suppose to be a driving restoration. Right! I had Graphite lube and worked it in by dis connecting it at the tyranny and gauge. Turning the unit and applying the graphite. I.reconnevted everything. But I think I am.going to replace the instrument and complete panel. Everything new. Stewart Warner Gauges hope yours works out.AJ

 

I second what @ALBUQ F-1 says about matching the drive and driven gears. My Ford literature has 60, yes, 60 pages on matched pairs. Because of all the options/variations the typical year, make, and model doesn't cover it. These gears are specified by rear axle & ratio, tire size, and transmission combination. If you can share all this information, I can see if I can find a set of part numbers for you to seek.

 

I did mention that I have an R10 out of a Mercury car and not the original F1 tranny so it should work. The part's been ordered and hopefully it will work and give the correct speed.

 

My Ford documentation shows that the R10 is the overdrive unit on the back of the actual transmission. I'm sure the Mercury has a few transmission options, so I would need to know which actual transmission such as the BW T86 3 speed along with everything else requested. "1950 Mercury Car" is not specific enough.

Purchasing a gear and hoping it works doesn't lend to good probability of proper gear mesh, and even lesser of an accurate speedometer reading.

You can read here about assisting a fellow member with the same: https://www.ford-trucks.com/forums/1...l#post20913235

 

Actually I don't know what the tranny came out of and the guy that I bought it from thought it was from a 1950 Mercury. I understand that Ford sold these transmissions with or without an OD. I believe they both had the same dimensions and the speedometer connection was situated in the same position in the tail or OD section and the worm gears were probably identical. I'm modelling and 3D printing a copy of my broken gear and I'll see tomorrow if it fits and works. Modelling gears in Fusion 360 is fun and really easy and my printed copy probably won't stand up for long but long enough for a test run. I can model the part in about 15 minutes on my computer and the material cost is only $0.10. Printing the part takes about half an hour. When I finally get the truck on the road I can check the speedometer with my phone and print new gears with different tooth counts until I find the right one. Hope it works.

 

Can you post a picture of the trans, including the rear mount area and the bellhousing? That would help identify its origin. As noted, the OD trans is the same basic trans as the light duty 3-sp, so I would assume Ford used the same speedo gearsets, but in different ratios, that the trucks used.

What rear axle ratio do you have?

3D printing a set of gears is a good idea, but it will still need to be a matched set. I think the first step would be to remove the drive gear, so you can see the part number stamped into it. From that you can determine the pitch.

 

Since the transmission is in the truck it's pretty much impossible to take any kind of useful pictures but I'll attach some pictures from my files. Removing the drive gear is not an option either as far as I can see. I haven't even figured out how to look inside the speedo hole to look at the drive gear and it's pretty uncomfortable lying under the truck for this old guy. The ratio is 3.92. I have the original 3 speed truck tranny that came with the motor and it's very different than the transmission with the OD.

 

That does appear to be a Merc trans, the cast iron bellhousing is a solid clue. Did you measure the input shaft diameter? Cars typically used a 1- 3/16" shaft, while trucks use a 1- 3/8" shaft.

To access the drive gear, you just have to pull the rear extension housing/bearing retainer. The only trick is to remove the tailhousing without disturbing the OD section, There are manuals available on-line, if you don't already have onie. This is the Official manual: Borg-Warner Overdrive Manual / Overdrive_Page_01.jpg

 

I think I have things figured out. Today I installed my 3D printed Driven Gear and it seems to work fine so the one I have on order should be the right one. I did the calculations and the speedometer seems to be correct. With the rear wheels off the ground the speedometer reads about 19 mph at 1000 rpm in third gear. With a wheel circumference of approximately 6.8 feet and a rear end ratio of 3.92 my calculations work out to 19.72 mph.

So far I have not had the truck out on the road. I have someone coming tomorrow to do an appraisal and then I'll get insurance. I still need a vacuum advance which is on order. As soon as I have that I'll take it for a spin and see how it drives. Without the vacuum advance it will probably drive like a bucking bronco. I hope to get it registered before too long.

I also understand now what the problem was and how things happened. Two years ago when I was assembling the drive train I also installed the new speedometer cable so I wouldn't misplace the little gear and it was easy to get at. I didn't lube the cable and sort of forgot about it. When everything on the drive train was assemble, I of course ran it with the wheels off the ground to see if everything worked as it should before tackling the body. That's probably when the gear got mangled. My bad. Live and learn. Many thanks to those who gave advice.

 

Well sounds like you have it wired. STATE troopers are along the highway everywhere I asked one to check my speed on my 55 went 1 mile and ran buy him at 55 mph it register on his radar at 54mph. I plan on changing my Speedometer to a Stewart Warner mechanical. Your high tech is interesting.AJ.

 

My new gear arrived and is installed and I finally got the truck out of the garage and on the road last Saturday for a first drive. The speedometer is right on according to GPS. All is well.