Speedometer wrong speed

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bieb
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Joined: Sun May 01, 2005 1:05 pm

Speedometer wrong speed

#1

Post by bieb » Wed May 25, 2005 1:38 am

I replaced a junky aftermarket speedometer with one that is suppose to be NOS.1962 duogluide, I am sure the gear ratio is wrong but not sure the best (least costly) way to deal with it. The readout on the speedo is about double what my actual speed is. Any help would be great!



Ente
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Re: Speedometer wrong speed

#2

Post by Ente » Wed May 25, 2005 9:30 am

Hey bieb..
I want that speedo, better than mine, I've done the same....
but my junk-speedo shows 5 times less actual speed....
I have been talking to a guy who works with speedos and he can fix it for
about 4 times what the speedo cost (approx. 10$).. *doh*
his solution is to change gears in it.
Probably the ratio for your speedo is 1:1,
but you need 2:1....
cheap is'nt always cheap...

FlatHeadSix
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Re: Speedometer wrong speed

#3

Post by FlatHeadSix » Wed May 25, 2005 1:58 pm

Bieb, Ente is right, the correct ratio for your '62 is 1:1, Harley switched to 2:1 ratio after the '67 model year. The only way you can be sure if your drive is correct is to pull the drive gear out of the transmission and count the number of teeth. If someone swapped the transmission on your bike for a '68 or later 4 speed you probably have a 2:1 drive and the the gear that sticks into the tranny will have a smaller diameter with fewer teeth.

Ente
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Re: Speedometer wrong speed

#4

Post by Ente » Wed May 25, 2005 2:26 pm

Hi..
I think I mean the other way around..
than you Panzerama
Because his speedo show the double-speed compared to actual speed.
The 2:1 ratio was between years 47-67 and 1:1 is the 'modern' ratio...
count the teeths on your gearbox-drive, if it's 11 or 13 you should have a speedo with 2:1 ratio and if it's 23 teeths the speedo needs a 1:1 speedo..
am I wrong or do I just think incorrect

Cotten
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Re: Speedometer wrong speed

#5

Post by Cotten » Wed May 25, 2005 2:32 pm

I think the ratio change was in the middle of '61, but anyway,...
Many cheapo batterypowered screwguns remarkably turn an exact 500 rpm, and can be reversed as the speedos require.
If I can get a chance to breathe today, I shall compare the two ratios to read a mph, and report back what I find. We can then use that to determine not only an unknown ratio, but a guess as to accuracy.
The early ratio is the expensive one when it comes to original units. I found it more practical to replace the two drive gears in one of my earlier trannys so that I could use a latemodel speedo with an earlier face.
Shamefull, I know.

But I also have a selection of delightful old auto speedos, which are the late ratio. At least they aren't modern, and it's no tragedy if they get damaged. (Came out of a bar one night to find my Police Special had been hammered into the dash by a jealous punk on a bicycle.)

Ente
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Re: Speedometer wrong speed

#6

Post by Ente » Wed May 25, 2005 3:10 pm

Hi again..
just increasing my post-counter...
or answering because I think I know...
The year-shift 61-62 was when the teeths changed from 11 to 13... but still ratio 2:1...
but that is (as you wrote) totaly irrelevant in this subject.....
Ride on.... and good luck Cotten with your testing.
The time in Sweden is 3 pm.. and good wheather... time soon to start kickin' and take the longest possible way home....

bieb
Posts: 18
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Re: Speedometer wrong speed

#7

Post by bieb » Wed May 25, 2005 3:57 pm

OOps I wrote/typed this thread this morning while I was still sleeping. I have a 1961 not a 62. Looks like I could have either transmission gears at this point? I just got the bike back together this past weekend after a long winter of rebuilding the motor. Can the spedo be sent out to someone to be recalibrated? Just seems easier than pulling the tranny. If need be I can put the aftermarket one back on until winter when I plan on doing the rest of the bike.
Who does speedo work?

panhead
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Re: Speedometer wrong speed

#8

Post by panhead » Wed May 25, 2005 5:24 pm

http://www.ruiter.ca/mc/index.html , but closed for 2005...

bieb
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Re: Speedometer wrong speed

#9

Post by bieb » Thu May 26, 2005 12:54 am

Thanks ante and panz,
Panhead, thats a little too long for me to wait. I wish I could take a year off work.
Cotton,
How much of a job is it to change the drive grears?
Not that I plan on taking it apart right now. I'm just glad it's running now and want to get it broken in. But I know the wrong speedo will really start bugging me again some day and will want it to be "right".
Oh by the way...........that specalty float you sold me is installed and everything is working great! Thanks again.

Bieb

Cotten
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Re: Speedometer wrong speed

#10

Post by Cotten » Thu May 26, 2005 4:19 pm

Bieb!

Since Perry is booked solid (I know what that's like), try Janus Naperalia (unfortunately, I haven't an address handy.)
(There is also an authority in Chicago who has tremendous Stewart-Warner capabilities, but I would have to find an address to find the address to find the address.)
Changing the drive worm on the countershaft cluster gear within the tranny is a press-off-press-on operation, however it must be carefully trued on a lathe with an indicator.
I compared three late ratio'd speedos at 500 rpm (a '65, a ~70s, and a ~70s calibrated Police Special) and they all showed 29 mph. So did a Ford Econoline crammed into a HD bucket.
Alas, the early ratio speedos barely bumped to 15, so 500 rpm is not accurate for anything but identification.

Ente
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Re: Speedometer wrong speed

#11

Post by Ente » Thu May 26, 2005 5:03 pm

Hmmm.... very nice indication-tool.. and handy...
And that explain... why my 2:1 speedo shows the other way around...
when I drive for example at 100 km/h the speedo shows only half of that speed.
And my gearbox is a '65... and should according to your test be a late model and need a speedo with a ratio of 1:1,
but my speedo is a 2:1 because I thought that the ratio-switching was '67.
That explains it all....
Thank Cotten... even that you did'nt test it for my sake

bieb
Posts: 18
Joined: Sun May 01, 2005 1:05 pm

Re: Speedometer wrong speed

#12

Post by bieb » Thu May 26, 2005 10:01 pm

Apparently what I have is a later speedo rebuilt with an earlier face (4 digit trip instead of 3 digit trip). I talked to someone in the Denver area who rebuilds them and come to find out that you can't change the gearing in the speedo from 1:1 to 2:1. Although you can go from 2:1 back to 1:1. a little confusing, but that is what he is saying. I will check around some more though. I'm learning more each day about this old stuff I just wish the mistakes were not so costly. It will be going back on Ebay if it can't be made to work. Looks very pretty though.

panhead
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Re: Speedometer wrong speed

#13

Post by panhead » Thu May 26, 2005 10:23 pm

Here's another address (in Holland). he repaired a speedo for me, great work: http://www.hd-shop-oldtimer.nl/

Perry Ruiter
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Re: Speedometer wrong speed

#14

Post by Perry Ruiter » Mon Jun 13, 2005 8:19 am

Bieb - to change from 1:1 (60=1000rpm) to 2:1 (60=2000 rpm) involves changing two internal gears. Obviously if you can go one way, you can also go the other. 1:1 gears are a lot more plentiful then the 2:1 gears hence the "fib" that you can't go the other way. I suggest dealing with reputable folks that don't fib. As an aside if you can run your speedo at 1:1 it's better for it as the magnet is spinning at half speed. It's not uncommon to find a broken magnet in a 2:1 speedo. It's very unusual in a 1:1 speedo ... Perry

51Hog
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Re: Speedometer wrong speed

#15

Post by 51Hog » Thu Jun 16, 2005 8:45 am

I just checked my odometer to a measured mile on the highway and it was correct to within several yards.
The speed however is off by 10 mph. I indicate 65 and am actually doing 55 mph. How can this be? Tires are stock height. Gears and sprockets are factory.--51 FL
Thanks

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