Head stady upgrade

Dear Sirs,
Someone could kindly help me to mount well the head stady spring retainer plate and the spring tensioner of the 1975 ES Commando.
I do not understand the way of the spring and if the plate must be mount on which of the bolt up the coils mounting brackets.
Iould receive ome photos.
Thanks and ciao.
Piero
Italy

Its a wkend so many may be away from their 'Commando' work stations but there are a hand full of threads/photos on this to try forum serach or Google search which generally finds stuff better than forum search engine. I'm putting a spring on my special with heavy engine so keeping track of details too. I'm off to work though but found this on google to get ya warmed up.

mk3-head-steady-adjustment-t8299-15.html

Here is a photo (not mine) that clearly shows the installed assembly-



The flat "L" bracket with two bolts, connects to the front of the standard box type head steady. In this photo, it is a Production Racer type steady, but same connection point.

L.A.B. replied further on, that in the photo, the spring orientation is upside-down. In other words, the loop that goes over the saddle should eminate from the coils at the lower orientation, not the upper side.

I hope this helps.

A bit surprising that somebody fits the Production Racer Headsteady (beware of imitations sold under different name!) with the spring.

No spring on my original 1970 Production Racer, and certainly no spring on my Shortstroke Roadster or my son's 750 Roadster using the Andover Norton Proddy racer headsteady. Nor on our "Family Racer" using an older version made by a Norton specialist whose name suddenly escapes me, but if you see the sorry structure with the "Wave" base plate you will know why...

Ah, and while we are at it- no spring on the Peter Williams drawing dated 1969 in the Andover Norton files either.

Wasn't the spring in the standard head steady a Mk III upgrade? I believe it was to take some engine weight off the isolastics, part of the re-think of the isos that came with the Mk III, hence a '75 or newer thing. If it works, why not retrofit to a PR head steady?

I ordered my Dave Taylor with the spring, as it was available that way, and I like it. Haven't run the DT without the spring, so I don't know how much difference it makes, but a definite improvement over the 850 Mk I set-up.

Would this help?



Ken

Norton must have been joking to use the head steady in that way - to me it looks like appalling engineering. I would rather modify the frame to pick up the ends of the pivot bolt with a couple of silentbloc bushes , and cop slightly more vibration. The motor and gearbox assembly would then rotate around the pivot bolt, when the motor is running and vibrating up and down, and the swing arm wouldn't be able to move laterally and flex the engine plates or move the assembly. You could then use rods with rose joints on the top of the head to stop fore and aft movement as the load comes on under acceleration, and under engine braking. Most of the vibration must then come in a vertical direction, from the heavy pistons and the necessary crank imbalance . It would still be damped by the isolastics.

I've really enjoyed seeing all the variety of top steadies and ingenious third/fourth rear/bottom links.

Here's my Rube Goldberg arrangement with my home made head steady. I had to fabricate a plate to fasten the spring on the head.



The spring may not have been on the early bikes, but I think it's a good improvement. It was worth the $20-$30.

Dave
69S

I replaced the ubious stamped three bolt (hole) sideplate triangular things with 5mm Duralamin plate to same outline . Seems a trifle more ridgid laterally in fact .

Why has the head steady in the photo been set up to stop sideways movement ? I don't understand what the spring is supposed to do. If you think back a few years to the featherbed frame,replacing the silentbloc bushes in the swing arm with bronze bushes used be the go, because you could feel the movement in the silentbloc bushes when the bike was ridden hard. A few thou movement in the swing arm bush translates to millimetres at the rear tyre contact patch. A firm relationship between the handlebars and the contact patch is critical if you want to feel confident when riding quickly.
When Peter Williamns was at Norton and the short stroke 750cc production racer was produced, did it have isolastics ? I know that one of his designs involved fitting the swing arm outside the engine plates instead of being supported at its ends, to get the bike narrower, - I believe it was a fail. The isolastics setup seems to be an extension of this idea.

Alan you don't seem familiar with the isolastic function and head steady. Must allow vertical engine arc or vibes get through and head steady in isolastics should not carry any engine mass nor allow much side/side motion from the twist of swing arm through isolastics. The engine moves most at idle-low rpm as next stroke ain't soon enough to stop the rubber compression distances bottoming somewhat. Spring helps support engine off compressed isolastics so less rubber compression state to allow sooner better isolation onset. The real mystery to me is the reason for the smaller doughnuts as they are like 1/4" below the big one and the most I've ever seen front iso most in one direction is 1/8" and rear too from road loads though not engine.
I'm not sure how I'll handle Peel's extra heavy engine+Drouin, maybe air bladder or dense foam under the cross tube. By logic the extra pull up of spring would allow engine to rise up a bit higher so maybe two springs best, one lifting the other limiting lifting.

acotrel said:

When Peter Williamns was at Norton and the short stroke 750cc production racer was produced, did it have isolastics ? I know that one of his designs involved fitting the swing arm outside the engine plates instead of being supported at its ends, to get the bike narrower, - I believe it was a fail. The isolastics setup seems to be an extension of this idea.

Click to expand...

The only short stroke 750 production racer I know of was the "Thruxton" Club Racer, of which very few seem to have been produced. Like all the earlier factory 750 (89 mm stroke) Production Racers, it had isolastics. The PRs all had an isolastic top mount, which the normal Commando did not have, and they also used a slightly different set of rubber dampers in the isolastic tubes.

As far as I know, all the John Player Norton F750 factory race bikes, from the first conventional framed design to the monocoque to the "birdcage" all used isolastic mounts. I'm not so sure about the monoshock design PW tried in '74, that was originally meant for the Cosworth engine, but went racing with a 750 twin because the Cosworth wasn't ready in time. I'm not sure on that one, so I could be wrong, but I think it did not have isolastics.

Ken