Transmission / Overdrive: T10 Driven Speedometer Gear

[GinettaG12P]

The speedometer in my 1959 Silver Hawk reads about 20% greater than true speed, probably because the car was originally equipped with a six and a three speed with overdrive, and now it has a T10. I have removed the speedometer driven gear housing from the side of the transmission, but I don't know how to get the gear out of the housing. I can't see how the gear is retained in the housing and photos of the correct gear on the internet don't show how the gear is retained. Could someone please tell me how to get the speedometer driven gear out of the housing (not out of the transmission, I've already done that.) Thanks.

[cosmo556]

There is a clip which retains the gear in the housing. Use a pocket screwdriver and pry it out.

[GinettaG12P]

Where, exactly is this clip? Thanks.

[cosmo556]

It is on the steel housing that the gear fits into. It is flat against the circumference and has tangs that fit into slots in the housing and gear locking it in place.

[GinettaG12P]

Thanks for the information.

[stude1964]

Just a thought about checking the part number on the drive and see if it matches what the parts book calls for your axle ratio. Who knows what was swapped in some of these cars over the years? Good luck.
Rob in PA.

[StudeRich]

You will need to know if your car still has the 4.10 or 4.56 Ratio Model 27 Rear Axle in it, or what it has been changed to for the V8 and direct 4 Speed Trans. in order to buy the right Pinion Gear.
It may now have a Model 44 and a lower numerical Ratio.

[GinettaG12P]

Here's what I know: The speedometer reads almost exactly 125% of actual speed (50mph at true 40 per GPS); there are 17 teeth on the speedometer drive gear; the T10 speedometer "bullet" is no longer available; different T10 speedometer gears are no longer available; the speedometer "bullet" from a TH350 will fit the T10; 21 tooth TH350 speedometer gears are available. So, I ordered a TH350 bullet and a 17 tooth speedometer gear. (17/21 = 0.81; 0.81 X 1.25 = 1.0125) I can live with 1-1/4% error. I'll let you know if it works.