Wednesday, December 21, 2011

Fitting a steering damper to an Indian Royal Enfield

1997 Royal Enfield Bullet
A few months ago I bought a nicely aged sixties Watsonian Monza sidecar to fit to my '97 Indian Bullet. I've always wanted to have a go at sidecar piloting and a budget chair tacked on to a hack bike I already own seemed the cheapest way of doing it. In the first flush of enthusiasm the chair was duly attached without too many difficulties. However despite being reasonably well set up the handling was dangerously evil. The front end broke out into violent shakes from walking speed onwards. Old hand sidecarists have told me that you should ride through it and it will smooth out. In this case though the shakes were such that the chances of riding through them and getting out alive at the other end were negligable.

So, off came the chair and it was back to the drawing board. A friend lent me a set of original Redditch sidecar fork sliders with extended trail. These would have been great except I've got a disc front end on my Bullet and getting the sliders to fit would have involved making a mounting plate for the disc caliper, lining it up and sorting out a new mudguard. And when the job was done I wasn't sure that the extra braking of the disc combined with the greater trail wouldn't have resulted in excessive fork twisting under braking.

Royal Enfield Bullet with steering damper fitted.
I moved my thoughts on to getting a hydraulic damper. This would have worked well enough but look a bit incongruous and in the time I was looking no decent quality damper came my way at a reasonable price. What I did chance upon though was an original Redditch fork bottom yoke with integral friction steering damper. In the meantime I sourced a pair of sliders for very cheap from a bike that had been in a front end smash - the stanchions were bent but the sliders seemed good. New stanchions came from Hitchcocks and head bearings I had in my spares box.

The front end was duly stripped down. It looked like everything would go together simply. The Indian Bullet already has a lug on the front downtube for the friction damper anchor point. Not sure why they still leave that lug there as it serves no purpose and they don't go as far as to drill and tap it. Out came the drill and I carefully drilled a 6mm hole into the damper lug. If anyone tells you that Indian Bullets ae made with poor quality metal don't believe them, this lug was hard as rock. Next step was to run an 8mm tap down the hole.
Royal Enfield Bullet stereing damper bottom yoke view. Note lug on the frame.

With the Indian bottom yoke out and the casqette flapping around I could knock out the old steering bearing cups. To cut a long story (bearings in, swear, hammer, bearings out, repeat) short I discovered that steering bearing cups from a Redditch Bullet will fit into an Indian frame however the inner races / cones will not. You may then suspect that the cone that fits on the Redditch bottom yoke would work fine with the Indian cup. Nope, the British ones are ever so slightly different and though they seem to fit the ball bearings are not quite running on the bearing surfaces correctly. So, in the end, the correct configuration is: Indian bearings at the top in the casquette and in the top cup. British bearings in the bottom cup and on the bottom yoke. The balls are the same size for both.

This figured out I put it all back together discovering that the British steerer tube on the bottom yoke is slightly longer than the Indian one. This is probably because it was designed for the later pattern casquette and the steerer nut would have sat proud and the damper knob would sit straight down on to it. To get over the problem I raided my box of bicycle spares and fitted a mountain bike 1 1/8" head set spacer over the Enfield recessed steerer nut. To space out the damper adjuster rod correctly I used an axle spacer from a cycle rear hub. The Indian steerer tube top lock nut had to be drilled out to allow the friction adjuster rod through. It was a little fiddly bolting the fixed plate of the friction damper mechanism to the newly tapped out frame lug but once that was done it all went back together a treat.
Royal Enfield Bullet steering damper fitted with help from a couple of mountain bike parts.

Whilst it was all apart I decided to spoil the bike with a few other goodies. A new Indian speedo with a Smiths Chronometric type face and a retro style ammeter. A sixties handlebar fairing in preparation for February's planned ride up to the Dragon Rally and a fork brace from Hitchcocks. The fork brace was pricey but since fitting the disc brake the forks have suffered from twisting under braking and I thought with all the new parts on and the imminent sidecar fitting I might as well try and get it all as good as possible. The fork brace is beautifully made (as well it might be for the price), was a doddle to fit, looks good and does exactly what it is made to do.

Road testing the damper it all works well and is adjustable over a wide range from off to solid. The Bullet is a sweet enough handling and low powered bike that solo it has no need of the damper at all, in truth it felt a bit strange with it screwed down. Truth will tell when it has the chair on the side, hopefully in time for the Dragon.....

Mr Hitchcock's very nice Royal Enfield fork brace.

1 comment:

  1. Extended trail ???? Decreased to the point of having none I think you will find, done to make them turn easy