Author Topic: Front wheel speedo  (Read 290 times)

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Offline Pat

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Front wheel speedo
« on: February 24, 2016, 01:19:12 PM »
Does anyone have any pics or drawings of the front hub gears for a front wheel speedo? I can't find any info. Thanks.

Offline seetwelve

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Re: Front wheel speedo
« Reply #1 on: February 24, 2016, 01:56:35 PM »
Can you supply more information please Pat.  My NSU Max has a VDO front-hub driven speedometer 'gearbox' as do some British lightweight models of the 1950's.  Are you after information on veteran/vintage type hub mounted gears?

Em

Online hampshirebiker

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Re: Front wheel speedo
« Reply #2 on: February 24, 2016, 03:09:23 PM »
On a 1950 James Comet, if it's any help Pat.
Postal - Liphook Hants - But just into West Sussex.

Online hampshirebiker

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Re: Front wheel speedo
« Reply #3 on: February 24, 2016, 03:11:07 PM »
Sorry, missed one. I assume it's a worm drive inside the little box.
Postal - Liphook Hants - But just into West Sussex.

Online Owen

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Re: Front wheel speedo
« Reply #4 on: February 24, 2016, 08:54:00 PM »
Are you talking about a girder C model with the speedo drive on the front wheel or the type described by HB?
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11

Online MilitaryRon

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Re: Front wheel speedo
« Reply #5 on: February 24, 2016, 09:44:23 PM »
Ha Ha! Then there are two types for the Girder C. The angle type like mine. Then the later version on the N/S. Ron

Offline timsdad

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Re: Front wheel speedo
« Reply #6 on: February 25, 2016, 07:29:02 AM »
The later ones come in clockwise and anti-clock rotation, depending on whether they're for the nearside or offside of the hub, and also in different ratios. To check if it's the correct rotation drive box, the road wheel has to turn the cable in the same direction as the speedo needle needs to go.

Ray
Just a motorcyclist.

Offline Pat

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Re: Front wheel speedo
« Reply #7 on: February 25, 2016, 08:02:21 AM »
Thanks Ron, I will need an angled type. All I have is a NOS brake plate with screw in plug where the speedo drive would go. I guess that would make it a '38-'39 issue. The more I investigate, the more I find the early C's are different. Thanks for the info.

Online MilitaryRon

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Re: Front wheel speedo
« Reply #8 on: February 25, 2016, 09:01:23 AM »
The later ones come in clockwise and anti-clock rotation, depending on whether they're for the nearside or offside of the hub, and also in different ratios. To check if it's the correct rotation drive box, the road wheel has to turn the cable in the same direction as the speedo needle needs to go.

Ray
Yes Ray, and the ones we use on the front N/S are very hard to find. I always pick them up at jumples and check the rotation. Turn the two drive dogs clockwise and the cable drive should also turn clockwise. 999 out of a 1000 turn anti clock.

Pat, yes I can list quite a few differences between the 38/39 and 40 C's and on some BSA's they used the same brake plate when they fitted the later speedo drive and just fitted a blanking plug. Also the BSA angled drive is different from normal as it doesn't have a thread. It has a plain shank that pushes into a boss in the brake plate and held by a clamp. Although a standard angled speedo drive can be used with a machined bush to go over the thread. To my Knowledge, all these speedo drives are 2 to 1 ratio.  Ron

Online chaterlea25

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Re: Front wheel speedo
« Reply #9 on: February 25, 2016, 10:11:31 AM »
Hi All,
THe angled drives vary in that the cable drive piece can be in front or behind the drive that goes into the brake plate ??
Does this reverse the rotation or are the worm gears cut in the opposite direction ??? (or both??)

For the C and other bikes you also need to know the gear teeth number that goes on the inner end and hub
Fkn expensive pieces when you can find them  >:(

A while ago I needed one for a friends Norton mod 18, the hub gears come in right and lefthand threads,
The correct thread one could not be got so the inner threaded portion was machined out and the worn teeth machined off the old one and the two mated up and pegged in place ::)

John

Offline timsdad

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Re: Front wheel speedo
« Reply #10 on: February 25, 2016, 04:54:29 PM »
I think the girder-forked C speedo drive, for the left hand side of the front hub, is the same drive box as that fitted to the early post-war Cs that had it fitted to the left hand side of the rear wheel. These are the tele-forked bikes that had the 3 speed box as the later 4 speeders had the cable drive in the gearbox. My '40 350 C12 has the speedo drive box from a 1948 C11.

Ray
Just a motorcyclist.

Online Owen

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Re: Front wheel speedo
« Reply #11 on: February 25, 2016, 05:15:30 PM »
So the later type being.

1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11

Online MilitaryRon

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Re: Front wheel speedo
« Reply #12 on: February 25, 2016, 08:35:05 PM »
Hi All,
THe angled drives vary in that the cable drive piece can be in front or behind the drive that goes into the brake plate ??
Does this reverse the rotation or are the worm gears cut in the opposite direction ??? (or both??)

John

John I have at least a dozen bikes with the angled drive on either side and the the outer castings are all identical, with the worms cut in opposite directions, although some do have a longer thread, depending whether the cable has to clear a mudguard stay. I have only ever seen one (a picture) of an angled drive with the cable piece in the opposite location and never did find out what bike it might have belonged to. Ron

Offline timsdad

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Re: Front wheel speedo
« Reply #13 on: February 26, 2016, 07:39:08 AM »
That's the one, Owen. I've messed around in the past swopping gears and worm drives in these speedo drives to get the correct ratio or direction of rotation.

I didn't realise the left hand fitments were hard to find so their rarity may well be partly my fault! Has anyone found a source for the big grease seals for these drive boxes?

Ray
Just a motorcyclist.