Cush drive Mk1 how oes it fit

[JohnnyBeckett]

hi i think you have got a part or parts that is wrong the parts should just fit together with no hammer or they need a lot deburring my one just slides together the spring can make it hard to get nut on sometimes

[Graeme.crawley]

Hello again Roger
I already wrote a reply to your helpful photos but it seems not to be showing. Anyway you are right, that sleeve has a bigger section where the sprocket runs than the actual spline and if my photo of the turned out sliding member is visible somewhere on this site, you can see it was not just a few burrs stopping the thing fitting. The sprocket is not the same as yours but does fit that fatter boss on the sleeve, a tad loose really. Hopefully the alignment to the clutch is correct.

Anyway I see your Spring retainer in one of your pictures. If that is handy would you be able to send me the dimensions of that please - looks like the one I have is not right for sure so will have to make a new one - already made one for another bike, will be getting good at them at this rate. It might be useful to know the length of your sleeve (the cush drive that is, I am not planning on knitting anything) as mine does look pretty short but the spring retainer is dished so it is deceiving probably. Graeme

[Graeme.crawley]

Hello Roger, Looks like my long winded reply vanished into the ether. In the end I machined out the Moving ramp to go over the Sleeve. You and others were right, that sleeve has a raised boss that the sprocket is running on. It was not just a few burs. Some pics attached, hopefully will work this time
Many thanks for all your trouble with the pictures, they are most helpful. I was told by a friend who does SQ$'s that he had some similar problems and the bits turned out to be BSA - he machined them as well. The sprocket is 24 teeth, fits that raised boss on the sleeve - too loose on the other sleeve hence I machined the slider, alternative would be to bush the Sprocket - looked like not that practical as the bush would be very thin
Graeme

[roger.fellows]

Hi Graeme, this ought to be a photo with arrows and scribbles, but that's beyond me.

Sleeve length looks like 1 27/32" or a shade under 47mm.

Washer OD 2", .. OD to fit inside spring 1 21/32", .. ID of nut recess 1 1/2", .. hole for narrow section of nut 31/32".

Overall depth 13/32", .. nut recess 6/32", therefore depth around narrow part of nut 7/32", there is a shallow machining to the inboard face of the washer - possibly 1/64" - which is a loose fit for the outboard end of the sleeve, .. the 'shoulder' which sits on the end of the spring is 1/8" deep, there is an even shallower machining for the bearing face of the nut.

If any of this does not make sense, please say. The components you are going to use will dictate some dimensions. There are chamfers except under the outer edge of the shoulder, and the hole edges and outer edge of the nut recess are not sharp, but very lightly relieved.

[roger.fellows]

I don't know about hardening, if any. It is a very different item from the pressing shown on Simes' Amelia blog.

The relationship between sprocket, shoulder on whichever sleeve you use, and whatever surface the assembly tightens onto will need careful thinking about to get sprocket alignment. The gearbox question you have adds another variable.

[nevhunter]

The BAP gearbox casing used in a Sq4 has different machining of the mounting lugs to locate it further to one side. . Nev

[Graeme.crawley]

Thanks for the dimensions - blimey I have not used 32ths for years. They will do just fine, perfectly understandable. Actually my sleeve comes exactly to the end of the crank spline so the spring retainer will correctly, (based on my other Ariels), clamp against the crankshaft end where the thread meets the Spline. I will check the measurement provided but hopefully it is all good despite the mysterious extra diameter on the sprocket boss. Your picture of the Spring cap will be my guide to chamfering.

Yes I have one of the pressed spring caps which has completely blown out the base of the cup but it is not the same as the one in Roger's photos anyway so not worth welding. I imagine that spring caps do not need to be hardened, nothing much is wearing againt this item. Looks like the nut has to be made as well but my Huntmaster has the same arrangement with normal albeit thin nuts x 2 from memory. I will look at this as an approach first becauseI am not sure if I have a cycle tap big enough. The nut probably should be high tensile, they get done up pretty tight even though the shaft has a split pin hole, but I will try mild steel.

I have given up finding a gearbox casing - found one that turned out not to be one, very dissappointing so I will have to cut the lugs back about 6mm to 8mm off the one I have and alter the gearbox adjuster mounting to re-align with the engine mount or alter the engine mount - what a pain. I am told one can simply pull the little peg that the adjuster fits into further out but that sounds a bit risky if someone does not fully losen the gearbox bolts then tries to adjust the primary chain. Anyway many thanks everyone for the help. Graeme

[roger.fellows]

The castellated nut is available on ACME Stainless.

[Graeme.crawley]

I think I am at the bottom of this
The sprocket I am pretty sure is Fieldmaster based on a picture I saw of one but more likely BSA - the ramp profile is steeper than my sliding member and in fact the sprocket will not be useable. I say more likely BSA because the sleeve has the raised boss and the sprocket fits it and I know that Ariel ones do not without machining the boss down and it is hard as hell.
The sleeve has the raised boss and a friend here had the same issue and did in fact manage to turn off the extra boss diameter so his Sq4 Sprocket would fit on. Someone said the diameter should be the same the whole way along and that is correct. It looks like the raised boss ones are BSA but who knows.
I think my sliding member is correct - the profile looks like the one in the Amelia Squariel photo - very hard to tell the ramp angles in photos. Certainly much more gentle than the Sprocket I have unfortunately.
So if I turn up a new sprocket from a blank I should be in! Not going to be very easy to get that ramp filed out but not impossible. 2 questions 1) Is there a recess on the engine side of the sprocket and if so how deep is it. I was told that the "dish" effect is about 6mm but that seems a lot. This I was told moves the chain towards the engine and assists with lining up the clutch sprocket. However looking at the only picture I can find of the non-ramp side of the sprocket (attached) it is dished alright but does not look to be more than 4 mm and there seems to be a boss protruding out by about the same amount that would preclude the dishing being effective. 2. How many teeth? Several numbers are mentioned in this thread and I have seen sprockets on ebay with 23 teeth and elsewhere mentions up to 26 teeth. I like the idea of slightly higher gearing but all esle fails I do have a clutch sprocket with 4 teeth less that I tried on the Huntmaster (it could not pull it over our hills so came off and reset back to the original). This is a solid sprocket and it literally pumps oil out of the primary into the clutch - seems those big holes in the original flung the oil off better. I would rather not use it if possible so any recommendations on a goodly teeth count for my new sprocket would be appreciated assuming the standard clutch sprocket no sidecar. I am thinking 25 might be good! - thanks Graeme

[Graeme.crawley]

Hello again - Sorry Roger, just reviewed your photos and I see you did send a back view of the sprocket and it does have a dish effect but from your photo, it looks to be entirely offset by the boss extending out by the same amount. I wonder why they went to the trouble to do that. Also if a Huntmaster sprocket done up scraped on the primary case as suggested above, then there is no way the sprocket could be offset to assist lining-up with the clutch - I mean it was suggested by someone local here that this is why the gearbox looks like it needs to move over but I think we all agree that the lugs of the gearbox will need to be altered, no getting around it using sprocket offset unfortunately