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Speedo

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Keith

Posts: 186

Joined: Sat Jun 28, 2008 10:25 pm

Post Tue Mar 31, 2009 4:30 pm

Speedo

I have what I think is a replica stewart warner speedo I want to use on my 45 project. i am having it restored. What is the standard drive ratio from the rear wheel. How many revolutions does the speedo cable make in comparison with the rear wheel, on a standard WLA setup.
Thanks in advance Keith Atkinson
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FlatHeadSix

Posts: 49

Joined: Tue Mar 03, 2009 9:45 am

Post Wed Apr 01, 2009 8:17 am

Re: Speedo

Keith
All the Harley twins thru 1967 used a 2:1 ratio Stewart Warner, the original one on your WLA should have a "509-" in the numbers stamped on the back of the can. The original had a 5/8" female thread on the speedo with a matching 5/8" male connector on the drive cable, a repop speedo usually has the opposite with the female (nut) connection on the cable. All the originals will also have the bar-and-shield logo on the speedo face.

The WLA has 20 teeth on the speedo drive gear inside the rear brake drum, the fiber gear on the stem of the speedo drive which the cable connects to has 8 teeth. If you do the math that will tell you that the actual drive ratio is 2.5:1

The speedos should indicate 60 mph when the cable is spinning at 2000 rpm. Do some more math; your rear wheel should have roughly a 25.2" diameter, at 60 mph this will turn the hub @ 800 rpm, the 2.5:1 ratio in the speedo drive will then spin the inner cable at approx 2000 rpm. If the magnets and hair spring inside the speedo are calibrated correctly and everything is oiled up and running smooth you should see 60 mph on the speed dial if you're brave enough to take your eyes off the road while trying to make the old 45 go that fast!

hope this helps

mike
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Keith

Posts: 186

Joined: Sat Jun 28, 2008 10:25 pm

Post Wed Apr 01, 2009 9:45 am

Re: Speedo

Whooaar; What a brain twister.
OK
Now lets get this straight
1 mile = 63360 inches
60 mph = 3801600 inches / hour
circum of wheel if dia 25.2 = 79.16
3801600 / 79.16 = 48024.25 revs/ hour
/ 60 = 800.4 RPM
now if the rear wheel has 20 teeth, and the speedo drive has 8, then
800.4 x 2.5 = 2000 rpm
Surely the speedo cable doesn't spin up that fast when doing 60 mph.
Shouldn't it be 320
Keith
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Keith

Posts: 186

Joined: Sat Jun 28, 2008 10:25 pm

Post Wed Apr 01, 2009 9:54 am

Re: Speedo

My replica stewart warner speedo has the same connections as the genuine stewart warner I have on my other 45.
The reason I think it is replica is it has a different face I have never seen before.
The needle starts on 16, then its increments are 16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192. It has the correct logo on the face,
Also it has a flat glass.
All other aspects of it are the same.
If I knew how to post a picture, I can show you what I am on about.
Anyway thanks for the info, I'll be able to send that to my speedo restorer.
Thanks very much.
Keith
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FlatHeadSix

Posts: 49

Joined: Tue Mar 03, 2009 9:45 am

Post Wed Apr 01, 2009 11:40 am

Re: Speedo

Keith
Sounds like your "replica" is apparantly a WLC speedo with a kilometer/hour face plate.

You did the math exactly right, the speedo cable actually does turn 2000 rpm at 60 mph, keep plenty of lubricant on it, avoid thick grease.

mike
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Pa

Site Admin

Posts: 4700

Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Wed Apr 01, 2009 12:34 pm

Re: Speedo

Keith.......email me your speedo pics. I'll put them up for you. Pa
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Keith

Posts: 186

Joined: Sat Jun 28, 2008 10:25 pm

Post Wed Apr 01, 2009 2:27 pm

Re: Speedo

My other 45 has lots of heavy grease on the speedo flexible drive cable.
Does that mean when I'm doing 60 it will let go, and whiplash my nuts off. Keith
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FlatHeadSix

Posts: 49

Joined: Tue Mar 03, 2009 9:45 am

Post Wed Apr 01, 2009 4:47 pm

Re: Speedo

Keith
It could happen.......trying to explain it to the doc in the ER would be interesting. Probably the worst thing that could happen is that the speedo will waiver on cold mornings, they will spike and drop back and repeat the cycle until the grease warms up, not good for the speedo guts.

I never had a speedo cable come loose and whiplash my nuts off but I did have an 18mm plug come out of a stripped rear cylinder head at 60 mph, came pretty close!

mike
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Keith

Posts: 186

Joined: Sat Jun 28, 2008 10:25 pm

Post Thu Apr 02, 2009 6:31 am

Re: Speedo

Pa

Speedo pictures sent last night.

Keith
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Pa

Site Admin

Posts: 4700

Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Thu Apr 02, 2009 2:31 pm

Re: Speedo

Keith......I didn't receive them. Trying resending them to [ vtwinrebuild@yahoo.com ]. Note "speedo pics ' in the subect line of your email. My spam software may have dumped them. Pa
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100incscoot

Posts: 2399

Joined: Wed Dec 31, 2003 1:01 am

Location: atascadero cal usa

Post Thu Apr 02, 2009 5:58 pm

Re: Speedo

never had a speedo cable come loose b4 either but had a chain break one time flipped up and left a foot long welt on the ol' ladies ass and leg
needless to say she doesn't care for chains much after that
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Pa

Site Admin

Posts: 4700

Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Thu Apr 02, 2009 6:13 pm

Re: Speedo

Keiths speedo.... Pa

Image

Image

Image

Image
<<

Keith

Posts: 186

Joined: Sat Jun 28, 2008 10:25 pm

Post Thu Apr 02, 2009 6:33 pm

Re: Speedo

Thanks Pa for posting the photo's.
Very sorry about the quality. Probly too much Jack's that day. Anyway, can any-one possibly tell me what this speedo might be off. I thought it was replica. It has a flat glass, and I'm led to believe a genuine stewart has a domed glass to keep the precipitation off. This unit looks the same sturdy quality as a genuine, and it definately looks closer to the original, in comparison to the aftermarket unit we fitted to my mates 45 U big twin, complete with opposite ferrules as previously mentioned. ect. As you can see from the condition of the can at the back. I can't make out the number 509 at all. (May-be I looked the same day as I took the photo's) :lol: LOL.
Also one last question (for today) How come if I have heavy grease on my cable inner. How can it be harsh on the speedo internals????
Still can't believe 2000 RPM. My 45 does 70. Hmmm Scary.
Thanks for all your valued help..Keith
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Pa

Site Admin

Posts: 4700

Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Thu Apr 02, 2009 8:18 pm

Re: Speedo

Glad to help you out Keith. IMO.... Your speedo is an original. I'm not sure what year the face plate is though. There is a comprehensive list on original HD speedos here on the forum. Try the search engine. Where is Chris when ya need em ?? :mrgreen: He usaully knows exactly where that data is hiding. :wink: Pa
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Chris Haynes

Posts: 2631

Joined: Wed Jul 05, 2000 12:01 am

Location: Los Angeles, CA

Post Thu Apr 02, 2009 9:08 pm

Re: Speedo

It appears to be a kilometer speedometer. Can't tell for sure but possibly a home made face.
Last edited by Chris Haynes on Sat Apr 04, 2009 12:07 am, edited 2 times in total.
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FlatHeadSix

Posts: 49

Joined: Tue Mar 03, 2009 9:45 am

Post Thu Apr 02, 2009 10:25 pm

Re: Speedo

Home made face :?: c'mon Chris, you know better than that!

That's a one-year-only 1947 export speedo set up for Kilometers.

Keith, None of the pictures show the side of the can which faces the rear, at the bottom of the face, there should be a "window" for the speedo light to shine through. It originally had a flimsey plastic lens rivetted to it which may be gone by now. 1947 was the first year for the 2-light dash and the only year that they put the light for the speedo in the outer dash cover instead of inside the speedo can, so there is no hole in the speedo can to stick a dash light socket in it.

The lens may have been replaced with an incorrect flat piece of glass but the rest of it is original and very rare!

mike
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100incscoot

Posts: 2399

Joined: Wed Dec 31, 2003 1:01 am

Location: atascadero cal usa

Post Thu Apr 02, 2009 11:08 pm

Re: Speedo

Mike the very first pic is of the bottom of the speedo where the lens on a 47 speedo should be
maybe its confusing cause its upside down ?
From my very limited knowledge the 47 needle was red at least for mph speedo's it was
also the center had a silver center fading to black to it
at least everyone i ever saw was and i bet i've seen 25-50 of them
i think chris' home made statement comes pretty close
if it is a home made one it was well done and done many yrs ago i'm sure
heres a factory pic of a 47 usa model thanks to a real asset to the sport
[not meaning me by any means]
notice the 1 yr only dash cover?

Image
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FlatHeadSix

Posts: 49

Joined: Tue Mar 03, 2009 9:45 am

Post Fri Apr 03, 2009 7:35 am

Re: Speedo

Scoot,
There is absolutely no doubt that the can is genuine Stewart Warner and not a repop, the big question lies in the face. I'm going to stick with my original guess for several reasons. I have 2 working unmolested 1947 speedos and everything you stated about them is true, but I have never seen an actual 1947 export unit in Kilometers so my guess is still a guess.
1. The crimp on the bezel of Keith's speedo looks perfect, I don't think it has ever been opened. If the can was opened then whoever put it back together must have used a lathe to roll crimp the bezel back onto it.
2. If you look closely at Keith's first picture you can see the window for the dash light, the "0" in the photo date on the picture is in the left end of it.
3. All of the 41-46 speedos had a bulls eye, civilian and military, this one has a plain circle in the center. As Scoot mentioned, the 47 faces were silver plated and the center circle had a fading shadow printed on it using a decreasing density dot pattern, Keith's does not but that is just part of the confusion.

Another puzzle is the number style which does not match either the 41-46 style or the 1947 mph style which used block shaped numbers.

Perry Ruiter would probably know, I stole this from his web site...
http://www.ruiter.ca/mc/info/SWSpeedoDating.html

look at his comment about the kilometer faces for 1947

I'm not trying to stir anything up here, I would like to know what it really is myself.

mike
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FlatHeadSix

Posts: 49

Joined: Tue Mar 03, 2009 9:45 am

Post Fri Apr 03, 2009 7:42 am

Re: Speedo

Keith
Look up above the 96--112 at the very top edge of the face, see if you can still read the stewart warner number printed on it and tell us what it is. You can just barely see it in your pictures but I can't read the whole thing. That's another reason why I don't think the face was home made, who would take the time to print Stewart Warner on the very top edge of a hand made face plate?
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FlatHeadSix

Posts: 49

Joined: Tue Mar 03, 2009 9:45 am

Post Fri Apr 03, 2009 8:28 am

Re: Speedo

here's a couple more things to look at. My original unmolested 1947 speedo is not quite as pretty as the picture that Scoot posted, the printing on the face has almost completely faded to a dull gray instead of the vivid black color it originally was, and the needle is now more of an orange than its original red. The can has never been opened and it still works as good as new.

The links show photos of the 41-46 style kilometer face and the back of the 41-46 style can.

mike
Image

http://members.shaw.ca/speedoshop/pictures/41-46B.jpg

http://members.shaw.ca/speedoshop/pictures/41-46%20in%20km.jpg
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