ET: Engine (Twin) Ditch the ESA ?

[Mark Fisher]

Perhaps a better answer is to do away with the ESA altogether and design a Cush drive similar to those on a bevel drive Ducati, which actually operate within a drum (with vanes in it) that bolts to the rear wheel in a similar way to the vincent brake drum bolts to the rear wheel. Someone who is more talented than me could probably come up with a design that looks a lot like the standard rear brake so it wouldn’t look out of place. The downside of course is that you lose one of the rear brakes. This system woks well on Ducati’s, mk111 commandos and many others and is easy to maintain, pretty much limited to replacing the rubber “spider” every few years. Not running in hot oil really helps the rubber to last! No doubt, cost and lack of demand would be issues but it’s something to consider. I’m sure I’m not the first to suggest this but since I have a shadow With the usual ESA and several bikes with rear wheel Cush drive , I know which I prefer.
mark

 

[Howard]

My welded up ESA is doing well, the one thing I've noticed that's very strange after 46 years, is that the engine seems more connected to the rear wheel - yes, I know that sounds strange, but it's the best way I can describe it.
Throwing my two pennorth into the secondary discussion that's developed here - Torque limiters and shock absorbers should be installed as close to the load as possible, which in this case is the rear wheel, where it can protect final drive, gearbox and primary drive.
Why not build a cush drive in the sprocket side brake drum, and settle for one rear brake like the Ds?
Howard

 

[stu spalding]

Whether my spring reshuffle was ideal in terms of spring rate etc I've no idea. It was a bit stronger than standard but what I was aiming for was the elimination of PD27 so I didn't have to worry about spring breakage and in this it has been entirely successful. Cheers, Stu.

 

[vibrac]

Perhaps a better answer is to do away with the ESA altogether and design a Cush drive similar to those on a bevel drive Ducati, which actually operate within a drum (with vanes in it) that bolts to the rear wheel in a similar way to the vincent brake drum bolts to the rear wheel. Someone who is more talented than me could probably come up with a design that looks a lot like the standard rear brake so it wouldn’t look out of place. The downside of course is that you lose one of the rear brakes. This system woks well on Ducati’s, mk111 commandos and many others and is easy to maintain, pretty much limited to replacing the rubber “spider” every few years. Not running in hot oil really helps the rubber to last! No doubt, cost and lack of demand would be issues but it’s something to consider. I’m sure I’m not the first to suggest this but since I have a shadow With the usual ESA and several bikes with rear wheel Cush drive , I know which I prefer.
mark

Well you certainly could loose a rear brake drum on a Vincent
As for ESA I suppose its to early to see what the long term performance is of the electric start comet system because for sure he has got rid of the ESA and made a shock absorber in aprox 3/8" width

 

[greg brillus]

Again I think this is a case of us all over thinking the issue.........On older machines where these components are badly worn the parts should simply be replaced. Unfortunately these parts are collectively expensive, and so most folk will avoid this if they can. The 22 spring ESA is fine for most all road going Vincent's, but any big capacity high performance engines should have some type of upgrade here........The rear cush drive hub probably the best answer, but I agree with Vic on his findings........there are countless things on these bikes we can fettle and make better if we want to, but they have survived quite well up to this point especially if they haven't been owned by butchers in the past (or present).......It is not something I would loose sleep over.

 

[ray vinmad]

Something I don't think has been mentioned is that the ESA is a centrifuge. The fast the engine is running the more the counter wound inner springs are trying to `mingle' outwards into the outers & with constantly changing loads I'm not surprised they break up.
Secondly, a few years ago at one of our club nights, someone (I can't remember who) brought along what looked line a pretty normal rear brake drum assembly. On closer inspection it was a rear cush drive unit, probably built years ago.
Ray

 

[Comet Rider]

You used to be able to get a torsion sprocket with a cush drive built in.
I had one on my race bike, many moons ago.

It would be easy on a Vincent as you would be able to replace 1 rear drum

 

[Gary Gittleson]

It would be easy on a Vincent as you would be able to replace 1 rear drum

Yeah, but what if your bike (a D like mine) has but one drum to begin with, mounted in the very position of the would-be cush drive? Could be done for sure, but it'd be a project.

 

[highbury731]

Surely the Series D rear hub is the same, just has short bolts on the left side. Just mount that single D drum on the left, and a cush drive on the right.
Paul

 

[vibrac]

Yeah, but what if your bike (a D like mine) has but one drum to begin with, mounted in the very position of the would-be cush drive? Could be done for sure, but it'd be a project.

You would not be the first with two rear drums on a D