The Marston Sunbeam Club & Register Forum

General Category => Technical Discussion Forum => Topic started by: VicYouel on December 14, 2016, 10:19:07 AM

Title: Speedo drive gearbox
Post by: VicYouel on December 14, 2016, 10:19:07 AM
The 1930's Models use a Smith's gearbox  brake plate mounted drive which I think has a ration of 1.5:1 but comes in two varieties. One reverses the direction of rotation and  the other does not. Currently I am trying to help a member in Japan but am unable to dismember my machines to determine which is correct and I never kept notes of my rebuild
Can anyone advise please.
Vic
Title: Re: Speedo drive gearbox
Post by: singleminded on December 14, 2016, 03:07:39 PM
If it has a 433L then it needs a clock in and clock out same as a Vincent,thats what i have on mine, The direction is with the input facing you and looking down on the output. I think that the 433 needs a reversing box.
I may have a clock in and anticlock out but I would have to check..John
Title: Re: Speedo drive gearbox
Post by: VicYouel on December 14, 2016, 04:30:07 PM
Thanks John, I think I comprehend but I always seem to get confused!! The input drive to the box is clockwise and the output is also clockwise when viewing the output. OK?
Vic
Title: Re: Speedo drive gearbox
Post by: singleminded on December 14, 2016, 04:51:40 PM
Yes that's right clock in looking at the drive gear and clock out looking down on the output, at least it is on mine..john
Title: Re: Speedo drive gearbox
Post by: singleminded on December 14, 2016, 05:06:27 PM
Norton used a reversing speedo gearbox because it was mounted on the left of the hub, that gives anti clockwise input to clockwise output. The norton box cannot be used on a Sunbeam, unfortunate as most of the reasonable speedo gearboxes that turn up are norton ones, lots of WD stock around. As soon as a seller realises that a non reversing box is needed on a Vincent the price goes up :-[..At one time you could get internals from Gagg motorcycles but i don't know if they still supply them..John
Title: Re: Speedo drive gearbox
Post by: VicYouel on December 30, 2016, 10:17:27 AM
John,
I think I will use this for the next Beaming spares column.... Cornucopia still sells the large and small front hub gear components.
Vic