Head steady on FH.

[Leslie.Ore]

Can of worms time,are the head steadies on a Huntmaster absolutely vital? I've seen a few around without them.Cheers...

[dave.owen]

It will vibrate without them.

Dave

[Simon.Gardiner]

It will vibrate without them.

I have a sneaking suspicion it'll vibrate with them too

I'm not over-confident about the Ariel version of the head steadies, I suspect that if the engine really wanted to move about it would make short work of the screw threads that go through the tube ends (which are probably slightly oversize/loose to start with.)

However as I've also seen a number of swing-arm frames fractured at the bottom of the front cradle tubes (at least one of which was on a 650 that might have been running without head steadies) I tend towards the 'don't mess about with the standard setup' position.

SG

[will_curry]

The Huntmaster head steady is the same as used by BSA on the plunger A10.
Swinging arm A10's had a much more complicated effort on top of the rockerbox
which if Ariel had adopted would have meant the end for the access hole in the
top of the Ariel rockerbox for doing the pushrods.

I've had both plunger A10's and Huntmasters solo and sidecar and couldn't
keep the head steadies tight until another Ariel owner suggested wrapping a layer
of inner tube around the frame tubes and modifying the clamps to suit. They stayed
tight from then on and didn't seem to vibrate any more and nothing broke which might
be due to the modification.

It was considered necessary to use a 'thick-flange' barrel if any attempt was made to
tune the A10 otherwise the barrel flange would fail. I've seen the wreckage of a few
A10's over the years usually running the 8:1 pistons. Did Cyclones break their small-flange
barrels? I ask because I ran a plunger A10 for a couple of years on a chair with 8:1s
and a thin-flange barrel and it didn't break - could be due to the different headsteady
between the plunger and swinging arm BSAs?

[alan.moore]

Les
I think all the twins of this era (Triumph, Norton, Bsa etc) had head steadies to dampen out the secondary high frequency vibration inherent in these twins. It is this high frequency vibration that tends to damage engine mountings and the steadies direct this into the frame where it is dissipated. Some later Triumph's had them attached to the front and rear rocker boxes to dampen out the increased vibration that came with the higher tuned motors.

This high frequency vibration increases as revs rise ...so if you only ride around at 'normal' speeds and don't rev the nuts off the engine through the gears it may not be much of an issue.

The addition of a rubber sleeve at the frame mount really defeats the object, yes it stops the steadies coming unbolted but that's because they are not transferring the vibration through to the frame.

I would suggest that fitting them can do not harm, and that's how Ariel designed it. Application of a decent thread locking fluid to the bolts (applied correctly) should prevent the fixings coming loose.

Cheers
alan

[will_curry]

Alan,

As Leslie says 'It's a can of worms'

It's going to vibrate whatever you do. No balancing and the vibration is vertical.
As you add weight to counter this vertical vibration you introduce horizontal
vibration.

The purpose of the headsteady is to 'dampen' this vibration so that things don't
get broken. Whether this is done by firmly coupling the engine to a mass large
enough to dampen - absorb - the energy or whether the mounting itself absorbs the
energy by flexing - the rubber bushes in a Norton Commando or Sunbeam S7 or S8
and which probably get quite warm, doesn't matter.

The energy goes up as the square of the revs: double the revs and you
get four times the energy, hence the issue with 'tuned' engines which usually
need more revs to develop their power.

The frequency of vibration is such that at much over tickover the thin layer of
rubber I used around the frame tube was I think effectively rigid and so functioned
as Ariel intended.

Harmonic resonance is the absorbing of energy at a specific frequency and this
isn't necessary a high frequency. Velocette Vipers and Venoms would break the
rear mudguard stays if the tickover was set too slow.

Will

[Leslie.Ore]

Thanks all,have fitted them now.

[nevhunter]

A few people who's opinions I respect are blaming extra strong head steadies for cylinder base failures. If they are bolted up rigid the stays need to be strong or they fracture. That's telling you something. Nev