Running without ESA

[Howard]

Best place for a safety device (shock absorber, shearpin, torque limiter) is as close to the perceived problem as possible. Breaking a rear chain on a hump back bridge would be a load produced by the rear wheel, so a rear hub cush drive would be the way to go. What I hadn't considered, until this thread, was the engine pulses (I'm used to electric motors) so if the engine is producing shocks in the transmission we need an ESA (or clutch cush) as well.

I used to design drive systems, some of them had less than 1/2 hp electric motors, but the output speed of the drive could be as low as 0.05 rpm with a torque of well over 100,000 Nm (sorry, don't know how many lb.ft). The motor was the smallest practical for the application, and not only was it oversized, but under load it could exceed its design power by 2.5 times. 100,000 Nm torque limiters are as available as hen's teeth and about the same price as a Rapide, so competitors would use electronic torque limiters on the motor - sometimes if there was a problem, the only reuseable part was the electronic torque limiter ). We fitted an affordable unit in the drive train which never caused a problem - a bit like a cush clutch, but the overload was unidirectional.

Just a ramble - it's cold and damp today and I'm building up to going into the garage for Winter maintenance (the bike's being maintained not me) - may take a Honda (oops) out for a spin on these awful salty roads instead.

H

 

[Pushrod Twin]

I am a fan of cush drives wherever they may have been fitted by the designers. Moto Guzzi Vee twins traditionally had a spring loaded ramp assembly, not unlike a Vincent ESA, hiding in the gearbox input shaft right from their inception in the mid '60's, using a single coil spring. In the '90's they uprated it by replacing the coil spring with a stack of belville washers to account for the extra HP & torque of the 1000 LeMans. In between, 1974 to be precise, they added a rubber cush to the rear wheel. Rumors abounded that it took some of the bite out of the reputedly nasty gear change. It didnt take long before more rumors suggested that it could be made to work better if 1/2" holes were drilled through the generously sized rubber segments which allowed the rock hard rubber to actually flex & do its job. I have drilled a number of Guzzi cush rubbers over the years & can confirm that it certainly improves the action of the drive train. My V7 Sport was built with the solid rear wheel, the male drive spline mates into the female crown wheel spline with no cush. I fitted an 850T rear wheel, the only model with a drum brake & a rubber cush, & drilled the rubbers per standard practice. Undeniable improvement, not only smoother gear changes, but also less wear on universal joints & drive shaft splines.
I built my first Vincent with a D style ESA because it was with the kit set, and a cush rear wheel. However, for my second engine I am keen to try the single coil spring mod detailed in 40 Years On. I have already tried to identify the BSA spring by the published part number, but no BSA experts down here can find it. I dont think its critical, I am sure an AMC or Guzzi one will be close enough!

 

[bmetcalf]

Do I remember correctly that Maughans were looking at designing a belleville washer ESA?