electric speedometer

[qmdv]

I have a 3.27 rear end gear set. Just got off the phone with Bratton's and they have a 17 tooth gear but no gear cap (turtle). And not even sure it would work on a later rear end. I have just about decided to go with an electric speedometer. Do they make a sending unit that will attach to the turtle?

[rich b]

Should fit; cable has regular speedo cable threads and square drive.

[Als48]

I bought an electric speedometer for my '48, but had Muncie 4 Sp. transmission. I found an electronic pulse generator for the Muncie that attached to the original gear drive turtle. Don't remember the brand name, but one of the transmission shops should be able to provide it. It works fine, just had to calibrate it to read properly. You would still need a turtle, tho. It wouldn't matter which gear it had, you would compensate for that during the electronic calibration.

Al Hook

[TJ]

Originally Posted by rich b

Should fit; cable has regular speedo cable threads and square drive.

X-2. The electric drive will attach to the stock turtle. Also check out a unit called a "sky drive" by Classic Instruments. It's a small unit that is a GPS and easy to calibrate. No sure but I think it eliminates using the electronic cable from the trans

[drolston]

I have 3.25 rear end gears and used the 17 tooth gear from Bratton in a turtle marked with 18 for an 18 tooth gear. It has fewer teeth, but the teeth still have to be the same size to work with the gear on the drive shaft, resulting in slightly smaller diameter gear. That puts the 17 tooth gear in the 18 tooth housing a little too far away from the drive gear. That caused some skipping in the speedometer. I filed down the housing a little and installed without the gasket and the speedometer has been working steadily and accurately since then. Since the turtle is near the top of the torque tube, there has been no oil leaks from that installation without a gasket.



I might not work with a 19 tooth turtle; just too big a gap between the turtle gear and the drive gear.

[qmdv]

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Originally Posted by drolston

I have 3.25 rear end gears and used the 17 tooth gear from Bratton in a turtle marked with 18 for an 18 tooth gear. It has fewer teeth, but the teeth still have to be the same size to work with the gear on the drive shaft, resulting in slightly smaller diameter gear. That puts the 17 tooth gear in the 18 tooth housing a little too far away from the drive gear. That caused some skipping in the speedometer. I filed down the housing a little and installed without the gasket and the speedometer has been working steadily and accurately since then. Since the turtle is near the top of the torque tube, there has been no oil leaks from that installation without a gasket.



I might not work with a 19 tooth turtle; just too big a gap between the turtle gear and the drive gear.

I have thought that you could use any turtle with a 17 tooth gear if you machined it for proper clearance.

[Krylon32]

I have done several cars with an electric speedo with a GPS sender. Simple to hook up and very accurate.

[Shoebox]

Originally Posted by Krylon32

I have done several cars with an electric speedo with a GPS sender. Simple to hook up and very accurate.

X2 on GPS speedo, didn't catch if the OP was 6 or 12 volt though.

[drolston]

Originally Posted by qmdv

I have thought that you could use any turtle with a 17 tooth gear if you machined it for proper clearance.

True, if you have the ability to machine stuff, which I do not. So, hence the file and no-gasket farmer-fix.