E: Engine Comet for the 2020's

[Martyn Goodwin]

Moving to the front in preparation for the forks and the new steering stem I am fitting a couple of old racing alloy brake plates in place of the steel ones. My experience of alloy plates is mainly track orientated so I had no speedo to worry about

Taking the speedo drive off the steel plates the gear did not pass through the hole in the plate ,I cant recall if it was intended too, but I think not, since there is/was enough clearance because of the thinness of the steel plate to remove the speedo gear split pin after the two retaining screws were removed. (The speedo gear is a black nylon gear)
When I come to fit the gear again in the aluminum plate the plate is obviously too thick to allow me to refit the split pin in that manner so the gear needs to be fitted to the spindle with the split pin before the assembly is passed through the alloy plate and the drive secured. the gear and the hole in the alloy plate have a 1/16th interference my inclination is to skim 1/32 off the tips of the nylon gear rather than open the aluminum hole especially as the securing holes are so close to the hole edge and the speedo brass casting has a raised rim that sits in the hole. has anyone else found this hole/gear problem with alloy plates?

Alloy plate on my Comet - and the brass speedo gear passes through the hole - no problem.

Martyn

 

[Hugo Myatt]

Alloy plate on my Comet - and the brass speedo gear passes through the hole - no problem.

Martyn

In my experience the black nylon ones grow after a little usage and no longer pass through the hole.

 

[Martyn Goodwin]

Slightly off thread - but does relate to building a Comet. Just had my crank/flywheels dynamically balanced to Bal Factor of 66%. Turned out that each flywheel was 'dynamically' different and required different correction. You would never discover this with static balancing.

 

[vibrac]

I recently swapped out the original front brake plates on my Rapide with lightning style ones. The (used) VOC nylon speedo gear was a snug fit through the hole but did pass through.

I would turn the gear down to fit.

Well I took the advice and took a touch off the teeth and it squeezed though, however now I see it in situe I see another problem a quick measurment (its cold in there tonight) gives me .179" flange of brake drum to face of inner ring gear while the drive gear protrudes .317" from face of plate
So 317"-178""= .139" engagement of teeth But I need clerance twixt plate and drum face to be fair I would be lucky to get 39 thou without touching and scraping so the question is can less than 1/8" ( .100 max) be enough engagement for the gears or is there a longer spindle for the drive or modified taller stemmed gear ?

 

[bmetcalf]

Can the ring gear be moved out on the hub?

 

[nkt267]

Well I took the advice and took a touch off the teeth and it squeezed though, however now I see it in situe I see another problem a quick measurment (its cold in there tonight) gives me .179" flange of brake drum to face of inner ring gear while the drive gear protrudes .317" from face of plate
So 317"-178""= .139" engagement of teeth But I need clerance twixt plate and drum face to be fair I would be lucky to get 39 thou without touching and scraping so the question is can less than 1/8" ( .100 max) be enough engagement for the gears or is there a longer spindle for the drive or modified taller stemmed gear ?

The series D drive is longer. could you slim the oval plate to give more depth..John

 

[timetraveller]

But the 'D' drive rotates in the opposite direction to the 'B' and 'C'.

 

[nkt267]

But the 'D' drive rotates in the opposite direction to the 'B' and 'C'.

Did not know that..thanks for the info..John

 

[Bill Thomas]

But the 'D' drive rotates in the opposite direction to the 'B' and 'C'.

Would it turn back time !!. Cheers Bill.

 

[vibrac]

Now the suns up I had a closer look and more fun can be seen I think sex apendages of knats could be involved because I only have a slight inwards movement and I reach the brake shoe underside.
The ring gear may come out 20 thou or so and I have just invested in a milling machine so I could reduce the face of the plate a bit as well- thanks guys
However I also note that I can move the drive spindle in and out of the drive housing a short way (my measurements were taken with it out) is this movement normal? perhaps the pressure of rotation of the internal gears (helical? bevel?) keeps the spindle extended??