Perfidious Albion

vibrac

Well Known and Active Forum User
VOC Member
I am having some difficulty calculating the internal ratios of my Albion Box in a form normally accepted and shown in books. In the past like many others I just read the ratios from a book and calculate speeds via sprocket ratios and chose accordingly but of course with an Albion box who knows what I have.

I thought it would be easy count the clutch shaft turns for one turn of the gearbox sprocket and express the result with top as unity 1:1 hoping for a result of say1:1 top, 1:2, 1:5, 2:0 bottom
However (with the box detached) in each gear I get :
For one turn of the gearbox sprocket shaft the following turns of the clutch shaft(approximate)

Top 1.75

Third 1.33

Second 1.2

First 1.0

Or (and this is one of the things not clear to me) it could be expressed as turns of the gearbox for one of the clutch (reciprocal)

Top .57

Third 75

Second .83

First 1.0

Assuming it is the first method and expressing top as unity I get

Top 1:1 third 1:1.3 second 1: 1.4 bottom 1:1.75

This is clearly wrong or I have a strange set of ratios….
 

highbury731

Well Known and Active Forum User
VOC Member
I am having some difficulty calculating the internal ratios of my Albion Box in a form normally accepted and shown in books.

... expressing top as unity I get
Top 1:1 third 1:1.3 second 1: 1.4 bottom 1:1.75

This is clearly wrong or I have a strange set of ratios….
The accepted method is your last one.

If the ratios are correctly calculated, you do indeed have an odd ratio set. With the other ratios, you would expect third to be somewhere around 1.1:1 or 1.15:1 Best way is to count the tooth numbers and multiply it out. There may be an Albion third gear ratio pair which can give you a suitable result.

Paul
 

davidd

Well Known and Active Forum User
VOC Member
I can't do the math, so I do it this way:

Albion Ratio Chart.JPG

AlbionHTT031.jpg


Starting with first on the right, then bottom to top: 29/19, 24/24. 22/26, 20/28 which means this is a No. 5 box. This would be the usual Grey Flash ratio for the non-KS magnesium box. The aluminum No. 16 box was provided for KS Flashes. What shows up at flea markets could be anything.
Credit goes to Jim Richardson for the lovely exploded photo.

David
 

vibrac

Well Known and Active Forum User
VOC Member
Thanks for that David I must strip the box and start counting but it does look like the first gear pair is my problem. I note that both the K/S and non K/s boxes first gear pair both add up to 48 and I do have a couple of K/S Boxes I got before I found my racing box when I was contemplating building a racing box replica (I think it could have been done with some welding as I have a small racing outer cover) .However since the kick start is obviously next to the bottom gear pair I suppose they may be different in design so I may not be able to swap a K/S pair (18/30 or 17/31)into my racing box, the other thought is Enfield gears although the tooth form/pitch may be different they work in pairs and after all its the PCD that matters... Enough I must strip the box.
 

vibrac

Well Known and Active Forum User
VOC Member
Hold on -see what I mean about perfidious! the tables go Ratio side 4321 Gear side 1234 so above that should read K/S pair(31/17 or 29/19)
To add to my confusion I thought the outer pair nearest the kick start were the (1) bottom set:confused:
Also amend the comment "strip the box" to "strip the RH side of the bike then strip the box":(
 

vibrac

Well Known and Active Forum User
VOC Member
UPDATE
I have stripped the box and on the layshaft starting at the drive end I have 21 24 26 28 which using the table supplied by David gives me a No 3 box
to make it a No 5 box I shall need a 29/19 (some hope!) I note a 'standard box' is 30/18 which if I have got things the right way round is a little lower at 2.78 than the No5 at 2.13*. So now I shall raid my store of Albion boxes and strip one down to see if its any good (I will be getting good at working on these boxes soon...)

* That wont be too bad because of the stupid chicanes they have added to the UK circuits to slow down the super bikes which the ACU in its 'wisdom' force us to keep for reasons unknown to man for Historic racing as well.
 

roy the mechanic

Well Known and Active Forum User
VOC Member
Vibrac, the reason we have to use the chicanes is down to the a c u. Each circuit has to have an a c u certificate, If you remove them it becomes a different "circuit" and requires a second cetificate, the folks that do the certification just won't be bothered with it.
 
Top