MK III head steady mount questions

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Mounting an 850 Mk III type head steady, and need some help. I've found that the measured spring length should be approx 1.5", and that the thread exposed from below the trunnion is approx .5"

However, where do you tighten the "box section" of the head steady itself --- first? Pushed all the way forward, all the way back, or centered; and then tighten the three bolts to the head ??? I'm guessing that must be done first, and "then" you do the spring length/tension adjustments. Did a copy and paste from below website article:


Finally, with the bike supported off the centerstand so as not to load the Isolastics, set the tension on the head steady spring by adjusting the nut on the trunnion until the spring coil is extended to approximately 1.5 inches. There should be approximately 0.5 inches of thread showing below the trunnion. Check the Isolastics for proper adjustment and you're done.
 
I followed those instructions when I added the MK3 spring, I just put the head steady on the head as normal, fitted the side plates and made sure all the studs, nuts and bolts would start, and tightened the 3 allen bolts followed by the rest. I then set the spring tension to the advised figures and it works as the vibration at the lower end is less. If I was doing it again I would push the head steady forward as the spring wants to pull it forwards but I doubt it makes any difference, the tension sets the force which offsets the engine weight.
 
I fitted one to my 750 recently.
I fitted the head steady as far back as I could and tightened this down. Fitted the side plates with new rubber mounts, but kept the nuts loose at this stage.
I found that the spring looked better lined up using the front hook on the spring mounting plate.
With regards to the spring tightening, I loosened the front isolastic bolt and then tightened the spring until I could move the bolt back and forth by hand, figuring that this proved that the spring was supporting the engine fully.
Then tighten the mounting bracket nuts.
It seems to have made a difference for me. Vibration goes at around 2500 to 3000rpm and at tickover my silencers now vibrate on their mounts whereas before this my rear mudguard would vibrate quite badly.
 
Well, I have a Mk2 850 and am in the process of fitting the Mk3 head steady spring - to compensate for the mass of the engine, which I don't believe the isolastics were, ideally, intended to deal with.
Anyway, the bits are here from Andover (great service!) but I have a question:
The manual says to extend the coil part of the spring to 1.5" (38mm) from the free length of 24mm (as I measured it).
The alternative, which I have read somewhere (here?), is to loosen the front isolastic stud, then tighten the spring nut until the isolastic stud slides freely.
The latter method makes more sense.
Does anyone have good advice on which is the better practice?
 
Iso makes more sense as it takes any weight differences out of the equation, like using bolt stretch instead of nut torque or rim offset on a front wheel when it just needs to be centered between the fork legs.

This is especially true when fitting to a pre MK3 where the starter is not present.
 
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I did the 1.5" spring method and found the front bolt freed up as I got to 1.5". I left it at that.
Same here. 74 Mk2 850.
Had to move the spring to the forward position on the frame clamp to get the 1.5".
Once set, the front Iso bolt lossened up. Must be the magic number.
 
No one is talking about whether on the side stand or center stand to set this up.
It makes sense for it not to be on the centre stand,
Probably the ideal is for a trusted mate to hold it vertical - but on a "chocked up" side stand would be acceptable (in my view)
 
snipped

However, where do you tighten the "box section" of the head steady itself --- first? Pushed all the way forward, all the way back, or centered; and then tighten the three bolts to the head ??? I'm guessing that must be done first, and "then" you do the spring length/tension adjustments. snipped
Late to this conversation. Regarding where to locate the head steady, fore/center/aft in reference to the slotted holes. The slotted holes are to allow you to mount the head steady without placing side loads on the rubber mountings [item #10 linked below].

https://andover-norton.co.uk/en/shop-drawing/136/engine-mountings-spring-head-steady-

First loosely assemble the head steady to the engine and frame, without the spring attached. Next, tighten the fasteners at the rear of the head steady, items #10 thru #15 linked above. Next, tighten the SHCS [socket head cap screws aka Allen Head bolts] Items #16 linked above. This method will ensure a longer life for the item #10 rubber mounts. Lastly, install and tension the spring.
If tensioning the spring places a side load on the item #10 rubber mounts, loosen the item #16 SHCS. Slide the head steady as needed to remove the side load on the item #10 rubber mounts. Retighten the 3 SHCS.
 
Has anyone figured out a way to get at head bolt #1 after this head steady is installed?
 
Well, I have a Mk2 850 and am in the process of fitting the Mk3 head steady spring - to compensate for the mass of the engine, which I don't believe the isolastics were, ideally, intended to deal with.
Anyway, the bits are here from Andover (great service!) but I have a question:
The manual says to extend the coil part of the spring to 1.5" (38mm) from the free length of 24mm (as I measured it).
The alternative, which I have read somewhere (here?), is to loosen the front isolastic stud, then tighten the spring nut until the isolastic stud slides freely.
The latter method makes more sense.
Does anyone have good advice on which is the better practice?
The guidance on tensioning spring is a ballpark initial setting. Don't sweat it. You can fine tune it based on where vibrations dictate later.
 
Has anyone figured out a way to get at head bolt #1 after this head steady is installed?
As I have a Mk III, I did not initially realize the issue you bring up. Using the method described in the MCC article, causes the problem. Removal of the tensioner bracket, item #2 second link below, is required to access that center bolt.

MCC Head Steady Upgrade

This method makes removal of the head steady tensioner bracket cumbersome. See item #2 linked below

https://andover-norton.co.uk/en/shop-drawing/136/engine-mountings-spring-head-steady-#

Three variations on this method will make access to the center cylinder head mounting bolt a bit easier.

#1 Insert the two 1/4" X 5/8" long UNF bolts from the rear and spot weld them into place. This is the method used by the factory on the Mk III head steady.

#2a Weld or braze two 1/4" nuts onto the rear side of the holes you drill in the front of the head steady, per the article above.

Down side on the above methods is limited space to do the welding/brazing

#2b Install two K1000-4 [aka MS21047L4] nut plates to the back side of the drilled holes. These are 1/4" 28 TPI [UNF] nut plates.

Aircraft Spruce Nut Plates

Down side is you will need to counter sink the drilled holes to allow flush installation of the 3/32" flush blind or solid rivets.

97517A196 Flush Blind Rivets

MS20426AD-3-4 Solid Aluminum Rivet

You can easily obtain small numbers of the solid rivets at your local airport FBO [fixed base operator]. Odds are, if you ask an aircraft mechanic or kit plane builder, they will gladly give you a few.

#3 Create a threaded plate out of 2" X 1" X 3/8" 6061-T3 aluminum or mild steel plate. Drill and tap the two holes to match those on the tensioner bracket. Tap for 1/4" 28 tpi [UNF].

Down side. Will be a bit of a fettle to line up when you go to re-install the tensioner bracket.

Just a suggestion and worth exactly what you paid for it! :rolleyes:

PS I note that Andover Norton's replacement Mk III head steady does not have the 1/4" UNF X 5/8" long bolts spot welded in place, like the original items.
 
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