Who can supply such a snail cam?
What are you thinking about?
my newest crack:
Mine broke out entirely at that point due to fastening the bolt when not good in position (it did not sit properly in the recess at the back). I had it welded.
The snailcam is a good idea, I will certainly try that when I rebuild my Flyer.
my setup (but I think there is no space for a snail cam like the design above – or am I wrong?):
Just curious Alex, what is the purpose of the top hole in the black bracket (with the grease nipple)? On my 27 Flyer I have another bracket.
And you are right, not much space for such a snail cam.
PS: in one of the pictures you can just see the picture with the snail cam on your screen :o)
purpose of the top hole: for the brake shaft – from the left (where the pedal is) to the right side, where the anchor plate is
It’s a 1938 598 cc Flyinq Squirrel TT Replica
I’m thinking about making a snail cam with its center at the right hole
from the (I do not know the name – maybe the sprocket carrier?).
Oh, that is what the hole is for! My Flyer was also converted to LH brake when I bought it but this was by cable. I did no know Scott also used a cross over shaft for this purpose.
The snail cam is intended to prevent the outrigger bracket to be pulled to the rear by the drive chain. I order to do it has to be facing forward as in the picture in the newsletter.
In my opinion you could get the same result by reversing it (so facing backwards) and then mount in on the rear hole of the outrigger bracket. The black bracket looks strong enough for the snail cam to push against. I think the first method is a bit stronger but I guess second option will work as well.
You may not even have to make a snail cam yourself. I know several bikes that use such a cam for tensioning the drive chain. Maybe it is easier to adapt such a cam.
You are quite correct. There is no space to fit a snail cam normally
It is necessary to remove some metal by machining to make space.
3mm or 1/8″ inch should be enough, if you have, or know someone with machinery. I am building a bike, so I just followed what we have done before. If you do not have access to machinery or prefer not to change anything, you can file a metal spacer to fit in the front side of the front slot between the slot end and the bolt. You then put a washer over the top to prevent it falling out. As Erik says, there are other methods.
The most important thing is to realise the problem exists and do whatever you can to keep the outrigger in position. The photo of the welded undertray clearly demonstrates the results. I have seen so many worn high gear bushes and cracked undertrays, I thought it was worth while trying to focuss attention on this problem. Kind Regards Roger
When I was a young engineering apprentice, I noticed that one experienced milling machine operator always put a sheet of newspaper on the table of his machine and then put his vise on top of the paper.
He explained that the friction value of metal on metal was low and putting a sheet of newspaper between the faces very much reduced the tendency of the vise to slide from its position under heavy cutting loads.
Logical really, after all, we do not run metal upon metal in braking systems.
So my suggestion is that if you do not have opportunity to fit a positive adjustable stop for the outrigger, then just cut out a paper gasket to go between the faces. I can not claim absolutely that it will solve the problem, but it will definitely help.
Another thought on the subject is to scribe a line around the front edge of the outrigger on to the undertray after resetting the outrigger. You can then have a look after your ride to see if there is any evidence of movement. Kind Regards Roger
If there’s not enough room or indeed if you do not have the machinery to make that rather neat snail cam stop there another possibility. It’ll need a bit of elbow grease with a file if nothing else is available.
I can’t see anything wrong with making a filler to occupy the space in the slot not occupied by the bolt. This will mean measuring up the slot and everything associated with it as accurately as possible before assembly and then determining the position of the bolt relative to the ends of the slot when assembled and adjusted.
From the photographs a dimension taken from the O.D. of the washer to one end of the slot should locate the centre of the bolt if done carefully. (Hence the reason for measuring everything.) From the obtained dimensions it should then be a fairly simple job to first drill a suitable close fitting hole for the bolt in a scrap of material and then file it up to fit closely in the slot.
The only down side I can see is that any resetting will require another spacer to be made, on the up-side, (tongue-in-cheek), there is a small weight saving to be made for the racier minded owner, not that it is an issue for me as I probably weigh more than my bike anyway!
Just to confirm that I used the method of putting a close fitting filed up piece of aluminium between the left hand bolt and the LH end of the slot for years with total satisfaction. The only drawback for me, was the need to change the packing piece when I changed the outrigger.
When racing, you need to be able to change final gear ratios quickly. I carry three outrigger brackets with 18, 19 and 20 tooth sprockets already fitted to self aligning bearings.
I converted the Enfield rear hub to take an aluminium carrier that then will accept interchangeable aluminium plate sprockets. I mostly use 34 and 35 tooth and this gives me a smaller increment of change. The chain has two split links and I insert one of several different short lengths of chain to make the final length when I change the gearing. In my tool box there were a variety of aluminium packing pieces. It was this need to make ratio changing more efficient that gave me the idea of the snail cam. You are quite correct in that a little time with a file can produce the 3mm clearance needed to fit a snail can and the cam itself is easily produced with a hack saw, a power drill and a file.
I am very conscious that my fascination with making things can carry me away. I love machinery and workshop machinery or motorcycles are just examples of beautiful mechanical logic that we can play with. The snail cam example was put down in case someone like me might enjoy making one themselves. Otherwise they can be made economically on CNC machinery if enough folks were interested. Ok I have rambled on enough when I should be working! Kind Regards Roger
I try to concentrate on engines and Eddie does all transmission work as well as many other things. I talked to eddie about the snail cam advantage and we agreed that if this was to be made on a CNC machine, it could be made economically, but price would depend on quantity. I think a small maching modification would be necessary to the side of the undertray to fit it, but once fitted it solves a significant problem that has existed since vintage times.
Use of the snail cam will safeguard your high gear bush from wear and associated power losses and protect your undertray from breakages which are common. May I suggest that anyone who is interested in this upgrade contacts Eddie to register your interest so that some idea of possible quantities can be judged. Eddie’s email is email@example.com
Kind Regards Roger
To repair/prevent such a crack it should be possible to shape up a strip of stainless steel to as close a fit to the casting edge profile as possible extending well in front and below the hole, (as seen in Erik’s photograph), the strip to be fixed to the casting with a pair of suitable screws at each end. It would be advantageous if the edge of the casting and the mating side of the strap could be sand blasted clean just before final fitting and a layer of slow setting Araldite introduced to fill all the gaps. If the strap is made a substantial thickness, say 2mm, then it should add sufficient strength even if the casting is already cracked without being visually intrusive. It also removes the need to find a proficient welder to do a repair.
If there isn’t sufficient room for the snail cam how about replacing the rear washer with a quadrant of the same thickness? There is even a decent area of flat on the casting shown in the pictures ahead of the rear hole that could have been made for the job! The idea is that the quadrant is made with a set of close spaced holes set on progressively increasing radii relative to the bolt hole, ideally a difference in max/min radius of half a chain link is to be aimed at. The casting would have to be drilled and tapped for a suitably placed bolt hole, the bolt need not be large, ¼in. (6mm) should be plenty strong enough as it is in shear. So that’s job done without the need of more than a vice, drill and file I reckon. The only down side I can see is that the adjustment is not progressive as it is with the snail but I don’t think small steps would be a problem in this instance. I’d include a drawing but I can’t get my head around the doing of it! I can manage e-mail if anyone is really keen and can’t understand my above ramblings.