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Aluminium Specs


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Pushrod Twin

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Is the depth of those splines tapered? If so, as a non-machinist, that seems quite a challenge to make the mating component fit with full contact. I suppose CNC machines would go a long ways for that. How the Hirth crankshafts are made to have the throws in phase has always mystified me.
No mysteries regarding Hirth cranks having throws in phase, its about cutting the splines starting from the same datum. The system gave Ing Carcano & his team the opportunity to alter the phase of the crank pins in the Moto Guzzi 500cc V8.
 

greg brillus

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When I built the rear hub for the twin racer I used close tolerance titanium aircraft bolts, and reamed the holes one at a time. These bolts also come in over sizes so you can go slightly larger if needed. The whole assembly was very light, when you consider 20 bolts with nuts.........It is lots of small changes that make for a light weight machine........I'm sure Phil told me the bike came in at 152 kg's.
 

Marcus Bowden

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I do wheel hubs with Helicoils in the flanges and Alan screws through drums & spoke flanges, shorter bolts and no nuts, lightness all round with holes through the Alan heads for wiring.
 

Glenliman

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When I built the rear hub for the twin racer I used close tolerance titanium aircraft bolts, and reamed the holes one at a time. These bolts also come in over sizes so you can go slightly larger if needed. The whole assembly was very light, when you consider 20 bolts with nuts.........It is lots of small changes that make for a light weight machine........I'm sure Phil told me the bike came in at 152 kg's.
The Vincent engine with exhaust system is right around 100 kgs.
The 1360 with its heavier Molnar cases and porkchop crank but lighter Newby belt drive was about the same weight as the 1000 engine +-2 lbs
I saw mention of building a racer at 130 kgs. This would be a feat!
This leaves 30 kgs for frame, front forks, wheels, tires, brakes, fuel tank and everything else.
I don't think it's possible, especially if want it to look like a Vincent.
I got the weight down to 155 kg dry on the Egli but had to really struggle to get it there.
The biggest weight saving vs stock Vincent was in the front end and wheel.
A modern GSXR front fork and tubeless wheel is about 40 lbs lighter than the girdraulic with stock Vincent type wheel.
The monoshock rear frame and GSXR wheel knocked off another thirty pounds or so.
The Egli upper frame was good for another 10 pounds or so of weight saving. The alloy tank knocked off about 8 pounds vs steel stock.
The rest of the saving is in the stuff you don't put on the bike, same as with a racer.
When all done it's a lot of weight chopped, but of course there is no Vincent remaining in the rolling chassis.
Not much in the engine either, but it does have the approximate architecture of a Vincent engine, and the great bloody weight!


There is a bit of road equipment on the Egli, but it's not much, maybe 5 lbs, the lightest stuff I could find.
Magnesium cases would shave a further 12 -13 lbs off, but the durability there is a big question, especially for a race bike.
Andy Molnar felt that the Vincent cases done in magnesium would not stand up.
He said they have a hell of a time with the Mg Manx cases, and they are heavily webbed for strength.
So a lot depends on whether it is built using original Vincent parts or not.
Sure some lightening can be done here and there, but these are still quite heavy components by modern (racebike) standards.

Building things as light as possible is great fun, it does add a challenge.
The result is quite pronounced. 120 pounds removed is roughly equal to a 20 bhp gain and unlike with tuning, the performance gain is all across the rev range, plus there are the handling and braking benefits.



Glen
 
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Glenliman

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Things did change a bit with the big motor.
That video was with the revs and throttle limited during break in.

Now that it's broken in and full rpm can be used, its a lot of fun.

Glen
 

Glenliman

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Speaking of aluminium hubs cracking-
this is going on a lightweight Norton as a cush drive, but perhaps the idea could be adapted to a Vincent.
The cush is 80 a durometer abrasion resistant polyurethane, available at McMaster Carr.
Freeze to machine.
 

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Cyborg

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Do you have some sort of clandestine way to spirit McMaster Car bits across the 49th parallel without upsetting the pentagon? The fallout from my last order sounded like it was getting close qualifying for a one way trip to Guantanamo Bay.
 

vibrac

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Speaking of aluminium hubs cracking-
this is going on a lightweight Norton as a cush drive, but perhaps the idea could be adapted to a Vincent.
The cush is 80 a durometer abrasion resistant polyurethane, available at McMaster Carr.
Freeze to machine.
I guess its some sort of material like that used in the engine shock absorber on the Comet Electric start all I know is its yellow.
Most of those weight saving dodges mentioned by Glenliman were tried with our Egli Racer. This time however the twin has to look reasonably standard so it will be interesting to see what it comes out at. Since the new style front end was intended for the road Comet its in steel not alloy but beggars cant be choosers.
 

Glenliman

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Do you have some sort of clandestine way to spirit McMaster Car bits across the 49th parallel without upsetting the pentagon? The fallout from my last order sounded like it was getting close qualifying for a one way trip to Guantanamo Bay.
They are definitely tricky to buy from.
eBay has lots of polyurethane in rod form and tubing, short pieces etc.
All different durometers.
80 on the Shore A scale is supposed to be ideal for this application.
Time will tell!
 
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