Thanks, Paul.

It does but it's not really that bad. I haven't done a great job of showing in enough detail why there's so little to do on these units, but will post more photos with explanations when reassembling--which I hope will be this weekend.

Joel

 

Okay, here are some photos showing how straightforward and robust this mechanism is.

First, it's easy to adjust the odometer barrel to reflect whatever starting mileage you want. In my case, allowing time to get the drive method and ratio adjustment box back from the guy in Colorado, I'll probably set it at 3,000 miles, since right now I've got 2,356 on the V-Twin unit that I installed shortly after rebuilding the top end on this Pan-Shovel (thought it was more). But I temporarily set this OEM '60s Stewart Warber police special's main barrel at 2,370 to show how easy it is to do this. (see pics)

What you do is carefully hold the barrel by the steel tangs that ordinary engage the mechanism's frame--taking care not to put resistance on the dials themselves--but just hold the tangs related to the numerals you want to advance. You have to work left to right, so you grab the last two tangs and gingerly turn the hundreds dial to advance the thousands and ten-thousands, until you've got the last two numerals where you want them. This takes just a few seconds. Now grab the hundreds tang as well, and adjust that numeral, and so forth. Easy-peasy.

Note: do not turn them the wrong way, as I suspect they've got the same delicate arms advancing the gears inside each dial, as did the drive on the trip odometer--and which were broken by the PO pushing in (unnecessary on these speedos) and turning the wrong way.


Second, the next few photos show how the clock spring's outer coil arm ordinary rests against the last tang in the main odometer barrel--and note that you've got to retain it before removing the barrel or else it'll unwind, and I'd bet one would lose track of how many turns it needs to get the tension right. So, I used thin bolt safety wire to retain it--bending a 'V' into the wire before inserting it between the barrel and frame, then squeezing it down onto the frame, being careful not to damage the clock spring.

Then, you simply compress the little spring and cup retainer on the barrel's shaft, and remove the barrel.


Finally, the remaining pics in this post show the drive mechanism (though I have not dismantled the magnet cup and clock spring on the pro's advice--and it's working fine, anyway). It's a simple worm gear setup, and turning the drive shaft with your fingers, you can easily see if anything's hanging up. Everything is held together with screws, so it'd be straightforward to repair any damaged or excessively worn parts.

There are adjustment screws to get the magnet and cup aligned and the distance right, but you'd really have to wack this thing around to disturb those. The main vulnerabilities appear to be the clock spring and advance wires for the odometer barrels.

*Reassembly note: take photos before disassembly, but it'll be easy to remember that the clock spring's retaining arm rests against the main barrel's tangs. Also, the trip odometer is drive by a white plastic gear on the opposite side of the frame--visible in the first clock spring photo, and also in the final photo.


I'll now clean the barrels up with a paper towel and Simple Green to get the grime off, wipe off the frame, and reassemble the unit so the drive shaft can soak overnight before final assembly.

 

Thanks for the detailed explanation and great pictures.

Paul

 

Here is a sequence showing cleaning and reassembly. Apart from using Scotchbrite to polish the shaft after wiggling the little retainer ring off to remove the old drive gear, the only things to watch out for are:

1) carefully tuck the spring arms down to engage the first dial's gears as you gently press the drive gear down into place;
2) do not 'bottom out' and flex the spring arms, or they'll snap off (like the old gear's did, although perhaps those failed from old age). The old gear had a few thousandths of clearance up and down under the retainer ring but I decided that rather than try to reproduce that clearance, I'd just ensure the arms weren't flexed, as you can see in the photo;
3) Simple Green worked very well to de-grime the dials, as you can see in the comparison shot;
4) it's a bit of a juggling match to reinsert the main odometer barrel, given that you've got to get the clock spring's stop to lay against the last advancement tang as you tilt the barrel into place;
5) I show a screwdriver being used to compress the retainer spring--but it's far easier to just use a fingernail on either side of the retainer, I found out;
6) take extra care when snipping the bolt safety wire used to retain the clock spring after the barrel is in place.

*Note: that little U-shaped cutout in the magnet cup in the last photo showing the barrel installed is for the electro-magnetic servo that locks in the speed an offender was driving when clocked by your friendly neighborhood motorcycle cop. (last pic)

After the drive shaft soaks over night (I used air tool oil), I'll reinstall the dial (two screws), press the needle back on, and fiddle with re-crimping the bezel.

I can't remember the last time I used that silly little vise... but I'm suddenly glad I kept it!

 

Here is the final assembly, save for crimping the bezel into place. The little pod screwed into the side is the 'speed lock' servo mentioned earlier. It actually works, too, after all these years.

Only thing that was dicey was reinstalling the needle. Took several tries, as the thing's taper likes to grab and you're trying to get it realigned per the disassembly photos. My method was to gently place it and let go, then turn the drive shaft a little to let the clock spring settle into place / rinse, lather, repeat. Then, once satisfied with the alignment, press it firmly home--straight down, so as not to upset the magnet cup's alignment.

Anyway, here you go. The main barrel's numerals will even out when tension is placed on the dial during operation--or whenever I turn over 10,000 miles. No biggie; I was just a little fumble-fingered when setting the mileage. The trip odometer now resets nicely with the NOS drive gear with those delicate brass arms.

I'll post the crimping method whenever I get that figured out. I'm thinking maybe getting a piece of pipe and cutting a bevel into one end, using that to start the crimp, then flip it around and complete it...?

I've also ordered the 1.25:1 vintage Triumph (Smiths reproduction) 3/4" rear axle drive. Looks like a stock '71 Triumph speedo cable will work fine re: length, though as with the mousetrap clutch cable I recently bought modified from Barnett, you can get these in any length you like--though the Triumph vendors sell them in two or three lengths to accommodate choppers and bobbers. So, it's possible that all I may have to do is get the speedo ratio box guy in CO to install the smaller square drive for this unit and flange on the speedo end of the cable, test the readout, and then order the reducer/increaser gear box--which he'll spice into the cable wherever I want it.

 

Okay, I was going to make up an elaborate crimping die out of hardwood, but then spied this plastic container in the recycling and realized that its walls were strong enough to withstand some significant force if applied straight down @ the long axis...

Well, anyway, here you go--a simple method of simultaneously compressing the silicone O-ring and holding the assembly firmly enough to allow me to go around the bezel with a tiny hammer and drift. My only concern was that the tapping might dislodge the needle... but it didn't.

I tested the unit (again) and the needle floats smooth and steady, and the odometer advances properly.

I'll post later on whenever I get the drive setup copasetic, but at least now folks have enough info to recondition one of these babies. Total cost was $10 for a trip odometer drive gear, $11.72 for the bezel kit (including shipping), and $21.63 for the soft(er) silicone O-ring (with shipping).

Out the door? $334 for the OEM Harley police special speedo, plus above parts is $377.35. Not too bad! And I really prefer the aesthetics of the OEM '60s unit vs. the V-Twin re-pop.

 

All rightee then... I am finally getting around to finishing this project, and I noticed something when going over an earlier post.

I had written this in an earlier post: "The seller told me this was a 2:1 unit and John [professional speedo rebuilder] says no, the Police Special wasnot made until '62, and mine is a '67 or thereabouts (made in Florida and tested in July of that year - see photos). It's a 1:1."

However, I think it's possible that I misunderstood what John was telling me, re: when the 1:1 units started. I found this assertion on another forum--and wonder if anyone knows whether it's accurate:

"Most Harley transmission cable drive speedometers were 2:1 from 1947-1967. The 1968-1980 were 1:1."

If that is indeed correct, then the seller of this unit that I refurbished was right--and I would have no need to futz with the rear-axle Triumph drive and a custom cable. All I'd have to do is (if I wished) get a ratio adjuster gear box to compensate for my 25-tooth tranny sprocket. That'd be very nice...

 

Well, I got her installed to test the ratio, and sure enough the cable flange fit the threads... which I hope means the drive end is the right size (should be). However, the wind's gusting up to 60 mph today here in northern-central New Mexico. So, I think I'll wait until tomorrow.

But she looks good installed, at last (never mind the sawdust). Only final mod I had to do was drill out the mounting ears slightly to take the rubbers and pins they sell nowadays. Illumination bulb from the V-Twin repop speedo works just fine. I did not hook up the unit's 'speed lock,' as I have no handlebar switch and no intention of clocking anyone.

That said, because the servo would require current to be maintained so long as one wanted to retain the setting, a simple momentary button hooked up to another air-cooled VW headlight relay--like I use for the Hi/Low beam now on this bike--would do the trick. Specifically, you'd simply choose either the Hi or Low beam lead from the relay, connect it to one of the wires on the 'speed lock' servo, then connect the servo's other wire to ground (I'm not sure if it's polarized, but that'd be easy to determine before wiring it up). This is because the VW relay, while triggered by a momentary switch, will toggle back and forth with each click and stay there: power to either Hi or Low beam each time you depress the button. So, one click would trigger the 'speed lock,' and another would release it.

I'll report back on the ratio test for folks shopping around for this style of speedo, as it would be helpful for people to know if one can rely on the handwritten test date scribbled on the case--assuming that was a standard practice back in the day.

Note: just a reminder that the trip odometer reset **** on these true vintage Police Special Stewart Warner units works in the opposite direction of the reproduction/replica units--that is, you rotate the **** toward the rider, while sitting on the bike. Cranking on it reflexively if used to a replica unit (and perhaps later model OEM speedos...?) could break off those delicate little arms on the trip odometer's first driven gear, per earlier in this thread.

 

@NM Pan-shovel I'd like more info on that VW latching relay. Thanks

 

Hey, Joe.

Here's the description from Scamazon, where it was $29: "Relay, Headlights 12 Volt, for Beetle & Bus 67-79 Ghia 67-74, Compatible with Dune Buggy." Generally costs a bit more if you buy it from 'VW specialist' websites. This isn't the best photo, but I put the relay on its side and zip-tied it beneath the dash, so the leads aim toward the R/H side of the bike... (perhaps arbitrary but that's how I did it).

It's got a little diagram printed on the relay's case. But as discussed above, if used for the 'speed lock' servo, I'd just be omitting one of the two leads from the two respective circuits that correspond to Hi or Low beam--in this case, to power the servo. I like this because then you don't need a big dorky button that's one click on, one click off; you can use any momentary button. Well, and the juice flows through the relay rather than the switch, which is always good IMHO.

Lemme know if that helps, or if I can provide more info...