PD: Primary Drive Rapide Chain Problem

[bmetcalf]

What surface do you refer to as the face? Is it the tooth sides or closer to the center?

Edit: or is it the surface that contacts the rollers?

 

[vibrac]

. Or else, as long as the Spares Co is ignorant for redesigning the non-working ESA

I don't feel qualified to discuss ESA drives from BMW or anywhere, but one thing I do know its the Club Drawing committee who do any design changes or bless any standard Vincent parts that are sold by the Spares Company not the Spares Company

 

[oexing]

Yes, certainly the drawing committee is the authority for redesigns. But even so, they are obviously not interested in real improvements. And it puzzles me how ignorant they can be not to see the problems - for decades. I could add lots of examples of BMW type ESAs in Japanese shaft drive engines, not one of them in olde British designs as there is no progressive damping in them. There is no benefit of having both halves of ESA cams in same shapes, you only lose space for the progressive shapes you´d like to achieve. And you don´t have cheaper machining from this as one side of BMW type is very simple CNC milling the male radii, 3 each, the corresponding side with the funny valleys is a bit more complicated to do but not more difficult than the old shape, same complication to machine. Only the logic to get perfectly matching faces is no rocket science once you follow my thinking, inspired by the BMW parts. I had complete success in machining the first alu test ESA for checking my thinking, milled on my manual mill with DRO and dividing head plus digital readout on that for having fractions of degrees for safe angle positions. So it should be easy enough for younger staff to do same on modern machinery in 15 minutes for a pair of ESA halves. Well, not my business, Maughams more likely to see into this possibly . . .
Roy, what do you see as root of the broken sprocket teeth and split rollers of middle chain run ? Fretting at the face tells me that there is micro motion between parts from shocks onto them. It cannot be the tremendous power of the alternator or Miller dynamo with hardly a quarter hp. So only cause might be the mass of the rotor trying to resist uneven speeds in the triplex chain - from the ESA bashing effects ??
Laverda 750 and 1000 plus Commandos got their triplex chains as well, same type. I have not come across tales of exploded primaries in these, at least no wrecked chain rollers from the dynamos in these.

Vic

 

[greg brillus]

I agree with you Vic about the ESA, the more loads put on it the worse it behaves.......the only way to overcome that issue is to have a good CNC machine shop produce a batch of them to your design, Vic, then price them up and on sell them to Vincent folk who want one. It's just like the modified stem kits that Norman has made, why most all Vincent's with girdraulics don't have this mod done is beyond me........

 

[oexing]

Well, Vincent Speet and son have designed their own ESA type, with same shapes on both halves. I think it is too much time spent on CAD shapes as all faces get milled in small steps and lines - typical for CAD jobs. The BMW type is three simple 6mm radii / 12 mm wide male cams, can be milled with standard end mill in minutes real smooth. Just have a dividing head for 3 positions to do 3 cams. The corresponding funny valleys get milled by an end mill with 6mm radius / 12 mm standard end mill . But for these you need a dividing head, best get a NC type hooked up to the CNC mill. So there you enter a file of positions I got from a DRO that does circle pitch jobs. Basically I had a circle of 34 mm dia. (I think) drawn around the o.d. circumference of the ESA . One position in X axis is from the circle pitch data, the other y axis has to be dialled in by the dividing head in degrees , calculated with pocket calculator and pi 3.14 . I did 0.5 mm steps along the valley shape, so maybe 100 positions to enter in a CNC program. That way the mill would do the job in 10 minutes for three valleys in a smooth operation.
These days you could have stepper motor small mills with Mach 3 CNC program . You´d have an electric dividing head with stepper drive too and hey, off you go. Yeah, that machine would have to be a bit more massive than types for hobby uses, certainly. But just saying, the job is definitely no rocket science. If it were, I would never have managed it with my old brain.
The easier way to avoid chain troubles is to have a sort of cush drive on the dynamo sprocket . Alton did sort of crankshaft o-ring ESA on their electric start kit I think. This skips the old ESA so is great as the original ESA is the root of the problem. When keeping the old type you better have the o-ring damper on the dynamo sprocket - or a friction plate absorber like I did . Norman´s belt drive alternators provide same slip protection for the sprocket and triplex chain, if you accept the looks .

Vic

 

[greg brillus]

Question for Bruce.........does this bike have an electric starter........Looking at your picture, the small round head thingy at the lower right of the picture showing all the shrapnel.......Then I realised it is the small knob off the end of the primary chain adjuster.......see how in the pic the forward abutment is sitting lower.......also the aft end of the tension blade is bent........this is a sign of an overload from the starter.

 

[Bill Thomas]

Many years ago there was a batch of bad primary chains,
Because a lot of us don't do high mileage, I know I was afraid to change mine,
I Just make sure the is no whine from the chain / Dynamo drive ,
The adjustment can look OK , But if there is a lot of wear on the big wheel bushes,
Too much mesh can happen,
I check the oil levels , More or less every time I go out,
So I have a look at the chain via the filler hole.

 

[chankly bore]

I also wonder whether the head breaking off the tensioner adjustment screw, PD11, was cause or effect.

 

[delboy]

I would point out that the drawings team are NOT an authority for re-designing parts. Quite the reverse.

It was set up with the aim to draw parts, as near as possible to the original spec', so as to have a base line to follow and to archive drawings for the club, and the Sp.Co. to follow and improve quality and consistency.
This was due to the deal for the original factory drawings falling through, many years ago. However many factory drawings have been donated from individuals over the years, for which we are truly grateful.

Thanks for saying we were Ignorant, by the way.
delboy.

 

[bmetcalf]

No electric start. I did not notice that little knob! I'll take a look, thanks!

The broken rollers look like they have jagged breaks, no smooth edges like an un-welded tube might have.