All automotive engine manufacturers been using them for many years now. Some are a tight interference fit on the crank, whilst others are a nice slide on fit using a good sized keyway and a descent sized bolt and washer to retain them.
Running without ESA
- Thread starter Howard
- Start date
Both you and Greg are correct, they are/were designed to damp out torsional vibrations to minimise crankshaft fatigue failure. DMFs are intended to protect the gearbox/transmission from torque fluctuations from the engine firing strokes , lighten the clutch effort and smooth out the gear change especially when the driver accelerates hard from low revs in a high (ish) gear when the engine can be generating around 60 to 75 percent of max torque. This is particularly the case for 4 cylinder diesel cars but at the other end of the spectrum it also applies to high power v6 and v8 manual box petrol engines. In the family, we have an Aston Martin v8 Vantage and an Audi RS4 both of which generate around 70 percent of their max torque at 1500 revs even though max revs are 7200 for the AM and 8000 for the Audi. These cars don't appreciate being driven like Miss Daisy. I'm not talking about tyre smoking antics but ambling along in 4 th gear at 20 mph which they will do, then accelerating hard in the same gear is bad news. In contrast to the Vette, their clutches and gear changes are light.
Valeo make solid flywheel replacements for DFMs and if you go to their site you can see video of their products in operation. They also make DMFs. The solid flywheel replacements have a clutch plate which incorporates an integral damping weight mounted concentrically on the plate and damped by ( relatively) long radial springs so they are not as complex as DFMs but more complex than ordinary clutches. Phew!
Another cost issue with clutch replacements these days, because of the labour involved, is that on many cars, the clutch slave cylinder and its integral release bearing are inside the bell housing so are replaced when a new clutch is required
After all this, considering firing pattern on v twin motor bikes, on road bikes at least, ESAs are essential.
I keep looking at this ESA that was in the Honda Clutch thread and thinking "can I make one of them" for my belt drive.
If I used a steel pulley I could mill the outer section in one piece and maybe weld vanes on a standard ESA sleeve for the inner ?
If I used a steel pulley I could mill the outer section in one piece and maybe weld vanes on a standard ESA sleeve for the inner ?
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Interesting thought Chris. Several years ago there was a fashion for using Suzuki clutches and fitting then to Vincent twins. I got one from a breaker and it has two sets of springs, one to take up the strain while accelerating and the other for the overrun. Rather like car clutches. The helical gears are part of the back plate and that is interfaced to a matching gear on the engine main shaft. No belts, chains or whatever. It has seemed to me for years that a sufficiently talented machinist could cut off those helical teeth and shrink on some straight cut teeth. These could then be used to interface to a pre-engaged or Bendix type starter where the dynamo normally sits. This would then leave our engine main shafts, now unencumbered by an ESA to take an alternator. The Horner bros in Australia already use gears in their primary drives so it does not even need a lot of creativity to replace the chain or belt.
I imagine that it would go where the dynamo normally goes and be fastened to a modified FT5.
I see it more like a shear pin in agricultural machinery. The position of the shear pin isn't critical, it just needs to be sized correctly, made of the appropriate material and be in the drive line somewhere between the power take off and the main load.
In this case, the power take off is the end of the crank and the main load is where the rear tire meets the pavement. Rather than position the important thing would be to have an effective cush. The use of a Norton Commando rear wheel cush drive was mentioned- all of those up to the Mk3 850 were pretty ineffective, especially as the rubbers hardened up with age. The MK3 version is a totally different unit and offers a lot of cush to the drive train. Norton must have recognized some problems due to inadequate cush which prompted them to do the redesign for the MK3 rear wheel, which is the only cush on the bike.Torque output is similar or a bit greater than a standard Vincent.
Glen
In this case, the power take off is the end of the crank and the main load is where the rear tire meets the pavement. Rather than position the important thing would be to have an effective cush. The use of a Norton Commando rear wheel cush drive was mentioned- all of those up to the Mk3 850 were pretty ineffective, especially as the rubbers hardened up with age. The MK3 version is a totally different unit and offers a lot of cush to the drive train. Norton must have recognized some problems due to inadequate cush which prompted them to do the redesign for the MK3 rear wheel, which is the only cush on the bike.Torque output is similar or a bit greater than a standard Vincent.
Glen
but have the parts running on each other in hardend steel.
its a bit like a triumph t140 clutch thing.
Rotational speed of the engine is higher than on the clutch, which rotates faster than the real wheel. This means that moment is highest at the rear wheel and less at clutch and least at engine. Everybody knows that (hopefully). This means that RWSA has much more load to handle than an ESA.
Norton moved SA from clutch to rear wheel when introduced the Commando, where the new clutch didn't have place for a SA. The higher output of the 850 forced them to improve the RWSA. In my opinion a proper designed SA can be placed anywhere in the drive train.
An old TT-rider said that you should not jump too high over a hump bridge to save the chain. Sadly the guy who rode my Manx there in -62 didn't know that.
Norton moved SA from clutch to rear wheel when introduced the Commando, where the new clutch didn't have place for a SA. The higher output of the 850 forced them to improve the RWSA. In my opinion a proper designed SA can be placed anywhere in the drive train.
An old TT-rider said that you should not jump too high over a hump bridge to save the chain. Sadly the guy who rode my Manx there in -62 didn't know that.