speedometer correction
As promised, here are the pics and details on my speedometer correction:
I purchased a new speedometer from Saturn Surplus to replace the failed one. It had about 2 miles on the odometer...so it must not quite have been NEW new, but close enough
Installation was straightforward and only took a few minutes.
Since I switched to 395's, my speedometer has always read too slow (as expected). I contemplated several solutions:
1. GPS speedometer (expensive, and I do like the vintage gauges in the deuce)
2. A 5 ton speedometer 90 degree .200:1 adapter (part number 7065893, NSN 2520-00-404-3098 ). The factory deuce adapter is a .187:1 adapter, so this provides roughly a 7% increase in the speedometer reading. It gets it close, but isn't quite enough. The advantage is...it is easy. No work required, other than some online searching for the part.
3. Have the speedometer itself worked on (too much hassle for me, and likely too expensive, although I didn't get any quotes)
4. Order a custom speedometer correction gearbox (this is what I did)
Using the old speedometer's error, I calculated that I needed an 18% increase in the speedo reading. The closest one they had was a +20% adapter...so my speedometer would read 1 MPH fast at 50 MPH. Close enough for me!
The box I ordered was a universal gearbox from PATC,
http://www.transmissioncenter.net/speedometer_calibration_______va.htm
They provide custom ratio adapters, and are able to adjust the speedometer reading up to 200%. I had hoped it would be a simple bolt on, but I did need to spend about 20 minutes customizing a few parts.
The problem was that the deuce's speedo cable was slightly smaller than the drive keys that came with the gearbox. So, the speedo cable fit a little too loosely in the gearbox, and the supplied key didn't fit inside of the deuce's angle adapter. I chose to make my own new drive key on the lathe...but it would have probably been quicker and easier just to take a sander and sand down the supplied drive key. I am guessing it would have taken me about 5 minutes to do this. It only needs a few thousands taken off of it.
To compensate for the cable's loose fit, I just took a piece of nylon tubing, cut a slit in it, and then drilled it out to match the OD of the speedo cable. I actually think it would work fine without this...but I think that it may wear out more quickly.
I put it all together, and took the deuce out on the highway with the GPS. I ran it up to 60 MPH, and the speedometer was dead on. No error at all.
Some pics:
