Isolastics and Dave Taylor head steady

Don't know re the headsteady but, yes, adjust threaded collar until when the bolt is torqued up you have 0.006" clearance or whatever you want. Remember you have to force the isolastic assembly over to the opposite side from where you are measuring for clearance,

Simon.

Chris,

re engine offset, or more specificly wheel to frame alignment, Google "Worlds straightest Commando". This article has step by step instructions on Commando frame alignment. Due to production methods, factory tolerances and quality control (or lack of) there are no definitive frame dimensions for checking alignment. I assume the blueprints would have included +/- tolerances but what these were or if production frames were any where near I don't know. I don't think any two Commando frames are the same, or Featherbeds for that matter,

Simon.

The frame lugs for the front and rear isolastic mounts are supposed to be central to the steering head. ie a centre line through the head spindle should coincide with a line drawn through the centre of the two pairs of isolastic lugs on the frame. Fact. The engine/gearbox plates are 3/16" across to the left of centre. the rear wheel rim is offset to the right to bring the rear wheel in line with the steering head. Seemples

Alright Tony, checking for clearance is as per the manual.

Dave,

I have found that unfortunately you can't assume anything, especially when it comes to a Commando frame. Whatever the orientation of the isolastic brackets are supposed to be in relation to the frame centre line (I'd like to have a look at the drawings you've seen), without establishing a reference point for the frame centre line how do you know what the relationship of the brackets are? Where's the centre line on your frame? You also haven't taken into consideration that the iso. bracket bolt holes aren't perpendicular in two planes to the steering head. These errors result in the swinging arm spindle also not being square in two planes to the steering head and subsequently move the rear wheel further away from alignment. Without a frame centre line reference you can't accurately centre the rear wheel. Whilst in Northumbria at the National rally, I conducted some testing (on a private B road of course). With a barely legal rear tyre and part worn front tyre the bike ran straight with gusting winds and the speedo indicating 100mph. You mentioned your bike developed a weave at 75mph encountering side winds on the M6. How come? Your rear tyre also indicates lean angles not far off vertical. Are you sure your wheel to frame alignment is as it should be?

Simon.

Hi Tony,

the M6 weaving I refered to was in reply to Dave Evans message. You're correct ref. to adjusting the front iso. For the rear I push on the rear wheel from the drive side to check clearance. One thing you can do is lock the rear iso after first removing the collars and ptfe washers from the front iso and check clearances between iso tube ends and inside front iso brackets to make sure the assemblies each side are the same width as the space available. Machine and shim as required. Best to do this before fitting the head steady. It helps to get the front and rear iso's somewhere near parallel. Obviously adjust to 0.006" clearance afterwards,

Simon.

My M6 weave I put down to the standard issue of most of my weight being on the rear. In addition I notice that when the weave builds up and I removed one hand from the bars the weave reduces. I put that down to what is known in the flying world as PIO or pilot induced oscillation ie. the wind on my chest is creating an alternate pulling force on each side of the bars.

So, nothing to do with wheel to frame alignment then. My unfaired bike was loaded similarly but doesn't display the symptoms you reported your bike suffers from. As I assume you were seated normally, then most of the weight distribrution would be as solo, unless you were carrying 14 stone of camping equipment. Also, adjusting shock absorber preload would compensate for any additional rear loading,

Simon.

Hi Tony,

I think the best way to check is support the bike on the lower frame rails so it is near enough vertical, with the rear wheel off the ground. Then with the rear iso locked up i.e zero clearance, rear iso bolt torqued up and the front iso refitted minus adjuster and fixed collar etc measure the gap between the front iso tube end and inside bracket on each side. Now measure the thickness of each assembly removed from the front iso and compare with the iso tube to bracket dimension. Note that the adjuster and fixed collar are different thicknesses so the iso to bracket gaps will not be equal.

Any difference between assemblies and gaps needs to be corrected by removing metal from an adjuster or collar by machining or adding metal with shims or spacers as required. Hope this is clear, the procedure is described in Worlds straightest Commando also,

Simon.

Lock the collar against the tube and then insert the rubber assembly into the mounting tube, silicon grease helps, and push in until you have 0.003" clearance. A bit fiddly, but essential to get it right. You can pull it through a bit for fine adjustment using spacers and a nut on the other end of the threaded tube,

Simon.

Sorry Tony, I'm confusing the issue. There's no need for you to insert the rubber assembly into the mounting tube if you haven't taken it out.

If the clearance between the fixed collar and thrust washer is greater than 0.003" then you can add shims underneath the mounting tube end cap. If the clearance is less then you can add shims between the fixed collar and threaded tube end. There's a grub screw which locks the collar to the tube, which then screws off. It will probably be quite tight due to corrosion. Alternatively move the rubbers/tube within the mounting tube - that's the fiddly bit.

Simon.

Tony,

just to clarify. If you want 0.006" total clearance then effectively each side is set to 0.003". The fixed collar is set at 0.003". When checking clearances on the bike the isolastic assembly is temporarily pushed over to one side to take up the 0.003" clearance, turn the adjustable collar until the gap you measure is 0.006" when the mounting bolt is torqued up, which should equate to 0.003" per side when the iso assembly returns to it's free position,

Simon.

Tony, I have a DT head steady on mine. Which unscewed itself a couple of times. You may find you need to use a little threadlock on the rose joint coupling screws.

It was avery tight fit indeed on mine, no clearance at all for the upper frame member collar, but the important thing as I understand it is the parallelism of the actual arm that runs from the cykinder head assembly to the frame. That took me a while and some manipulation, but I eventually got there.

When it runs it seems to move a ridiculous amount at tickover, then you rev it and all movement seems to disappear!

I think it is now right, but I am not sure, and I can't tell you what it is like on the road as I can't get the damned clutch to work!!! It's sulking because I got the starter working

Good luck,

Jack