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ET: Engine (Twin) Engine Shock Absorber

erik

Well Known and Active Website User
VOC Member
The reputation of the BMW for durability founds mostly on the poor power output of these bikes for the days when they were built.And for this low power output ,60 to 70 PS, with 1000ccm the gearboxes were to weak.My R75/6 had only 50 PS and the live of the gearbox was not really long.Not a german masterpiece in engineering,sorry.Erik
 

oexing

Well Known and Active Website User
VOC Member
Just to be clear, I am not a BMW taliban, nor am I a Vincent fundamentalist. But when I find crap designs I say so, and crap you find in ALL types of machinery. So from long experience with many types of bikes I can tell what works and what doesn´t - from gut feeling and drawing conclusions not maths . And I do not want to say this or that brand is great but try to draw benefits from all types to achieve reliable results. So when pointing to this BMW type ESA - or the Kawa 1300 version - I had reasons to do so. The Vincent ESA is crap - period - and some more details as well . No matter how you paint it, there is scope for improvements with a radical change as I have tried to explain - and am a bit puzzled that my views seem a bit hard to follow ?
Yes, with BMW or Kawa ESA there is some axial loads from springs acting at bearing inners and some wear as well, but nothing like with the Vincent miserable flat lobe shapes when only very heavy spring loads are meant to stop the twisting motion within the ESA. The BMW lobes rise to a steep gradient over 45 degrees so when remembering force vectors in school you may get the idea that most of the torque is contained in the lobes unlike in the flat Vincent ESA lobes , that turns all forces into extremely high axial loads via the sprocket onto the inner race of the outer bearing - with a lot of wear - and which you do not get in BMW gear boxes.
In Vibrac´s project , using a belt drive (?) I see a problem with durability like Vincent Speet said above: The twisting motions in the poly dampened design will produce either wear in the cylindrical sprocket fits or seizures when no oil lubrication due to belt drive there.
Seizure is no big problem in a chain/belt drive machine I think, no non-effective ESA so no problem. But wear will be bad for the drive and not easy to avoid without oil lube. So not yet a finished design.

Vic
 

erik

Well Known and Active Website User
VOC Member
Vic I can follow your arguments for 100% about the lobes of the ESA .Pre war NSU had the same design like the Vincent. Erik
 

Vincent Brake

Well Known and Active Website User
VOC Member
Have a look at the Triumph T140 clutch hub.

Thats the way to go.
Bit reengineering as the wear can be high.

Them little pins on the comet s sprocket are too small for effective surface.

Put in a black spider....
 

Bill Thomas

Well Known and Active Website User
VOC Member
Bill, there are belts and then there are BELTS. Some of the stuff I have seen will take hundreds of horse power. Different animals to cam belts all together.
I have seen those stupid looking things on H.D Specials, About 3 Inches wide, Would not like to get anything caught in one of those !.
 

stu spalding

Well Known and Active Website User
VOC Member
The 3 inch belt driving a 6/71 supercharger on a top fuel drag engine is transmitting about 300 bhp. Cheers, Stu.
 

MartynG

Well Known and Active Website User
VOC Member
There seems to be two (or more) topics here.

Just to be clear the Alton electric starter/ESA combination IS NOT suitable for use with a belt drive primary. It was designed around a Burman clutch but works equally well with a Conway's Honda clutch. The 'redesign' of the ESA by Alton (see posts #9 and #11) was a necessary change in order to ft all the bits onto the mainshaft while staying within the confines of the original primary cover.
 

vibrac

Well Known and Active Website User
VOC Member
Not two topics you should.be on the thread 'comet electric start ' this thread was started when BMW shock absorbers took over :)
 

BigEd

Well Known and Active Website User
VOC Member
VOC Forum Moderator
There seems to be two (or more) topics here.

Just to be clear the Alton electric starter/ESA combination IS NOT suitable for use with a belt drive primary. It was designed around a Burman clutch but works equally well with a Conway's Honda clutch. The 'redesign' of the ESA by Alton (see posts #9 and #11) was a necessary change in order to ft all the bits onto the mainshaft while staying within the confines of the original primary cover.
I think Martyn's post is probably relevant to both threads so I've added a copy to the "Comet Electric Start" thread.
 

Chris Launders

Well Known and Active Website User
VOC Member
This is slightly off tangent but possibly relevant to the ESA topic. My Brough does not run an ESA but a cush in the clutch (Norton) and back wheel (Enfield), the back wheel has the sprocket one side and the drum the other but the later Enfield wheels have a drum/sprocket on the drive side and just a spoke flange on the other side.

So I wondered about fitting the later drum/sprocket type hub , pressing the other spoke flange off and fitting a spoke/drum flange to take a Vincent drum, giving drums both sides, and what were the chances of this contraption fitting in the back of a Vincent.

Well, very good actually, the post war early heavyweights have a 7" drum, same as the Vincent (so a Vincent brakeplate could be used) the chain line is about 1/4" out but the hub could be mounted offset. The Brough drum uses the same flange dimensions as a Vincent other than 6 bolts instead of 5 and has the same inwards taper (for the spokes) so a new flange to take the Vincent drum is easily made and fitted (the cush unit and spoke flange are pressed on, not one piece or welded)

For cheapskates the Bullet hub uses the same cush unit but has a 6" drum and smaller diameter hub so you would have a 6" and a 7" drum and couldn't use the chain side Vincent brakeplate, but they are available new, cheap, complete from India.
 

vibrac

Well Known and Active Website User
VOC Member
Royal Enfield cush rear hubs go back pre war they sold the wheels wholesale to Panther and Scott amongst many others. In fact when I was rebuilding my 3 speed Scott (It had a wheel but no drum) I was so put off by the cost of the ribbed rear brake drum that I used a Vincent one! The 6 holes were on the same PCD as the Vincent so I had one through bolt and four bolts into a common spacer held by 5 bolts from the RE hub and the extra rib caused consternation with the Scott rivet counters (Of which there are thankfully few)
 

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