Speedo Gear Question

[mrtleavitt]

So my wife and I went on a date and drove my old ford into Las Vegas (about a 50 mile drive) just for the heck of it. The speedo was reading 80 mph and we were flying by everyone so we broke out our GPS and it read 87 mph. I already got the smallest speedometer gear I could find but wanted to ask if there was a smaller one available. I have a T19 4 speed manual tranny and a 16 tooth speedo gear. I run 31" tall tires and a 3.00 rear end. Anyone know of a 15 tooth speedo gear for a manual 4 speed?

[basketcase0302]

In the NPD catalog page 133 they have a 15 tooth gear listed-not sure if it will work on the T-19 though, (maybe call em').
I'd also look at DC and BOTP also as I believe they should also have this.

[70_F100]

Which drive gear do you have (on output shaft of transmission)?

There's a 7-tooth and 8-tooth available, and possibly others (I just looked it up for my transmission, and it's from an '84 model).

Edit: Just checked a speedometer calibration site, and with your gearing and tires, it says to use an 8-tooth drive gear and 16-tooth driven gear (assuming the speedometer is calibrated for 1000 revs/mile.

With 3.00 gears. the MPC shows that it takes a C8OZ 17285-B drive gear (8-tooth, brown in color) and since you already have a 16-tooth driven gear, that should put you right where you need to be. The 7-tooth gear is C3OZ 17285-C, and it should be yellow in color.

Hint: If you pull your speedometer cable out of the transmission, you should be able to look up in the hole and see what color your drive gear is.

[mrtleavitt]

Tell me more about the output shaft gear. Can I change that fairly easily or does it require like a complete transmission disassembly?

P.S. Looks like I have a yellow gear on the output shaft.

[70_F100]

You just have to pull the rear extension housing. Four bolts is all, once you get the driveshaft and output yoke off.

Look in the lower left of this diagram for 17285: http://www.fordification.com/tech/images/T18.jpg

T18/T19 are basically the same. The picture shows 6 bolts holding the housing on, but I'm pretty sure it's only 4.

If it wasn't for the little ball that goes in the shaft to turn the gear, I'd say you MIGHT get it out without pulling the housing, but I wouldn't advise that.

[mrtleavitt]

Thanks a bunch! Very helpful info.

[mrtleavitt]

Two more questions: I noticed in the NPD catalog pg 133 there is a type 3 and a type 3a speedometer driven gear. My tranny came from a '85 F250 2wd diesel. I've been running the type 3 driven gear.

1.What is the type 3a driven gear for?

2. Can I simply switch the drive gear from the 7 tooth yellow to the 8 tooth brown? Is there a chance I can run into problems with different diameters and the new one won't fit the tranny shaft?

[70_F100]

Try your local Ford dealer first. I think I got mine from Green Sales Co, but they don't show to have any now. Should be about the same price as NPD.

The part number I came up with for a T19 is C0DZ 17271-A, which is a type 3A, but doesn't specify rotation. The type 3 is a D0AZ 17271-B. Dennis Carpenter has a crap load of both, but they think their NOS parts are made of gold!!!

The NPD catalog kind of contradicts itself, saying that trucks with 4-speed manual transmission usually use LH rotation gears, and trucks with the speedometer hole on the driver's side usually use RH rotation gears. Pretty sure all of the T18/T19/NP435 are 4-speed manuals, and all of them have the speedometer hole on the driver's side. Kinda confusing, huh?

As for the drive gears, they will swap out without any problem. Both are the same inside diameter, both listed for T19 transmission.