Hemmings Isolastic Adjuster

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Tornado

Tornado

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Anyone using the Mick Hemmings isolastic adjuster having trouble with it staying where you set it? Mine (rear iso only) does not want to stay put with two nylon tipped set screws wound in as much as possible before the hex key strips the set screw. A 20 min ride and the adjuster has loosened two or three holes out.

Thinking maybe to drill out the M4 set screw holes and re-tap to something larger. Are there other solutions people have used?
 
Hi , I'm not familiar at all, if those nylon plugs are there to protect the thread ? , can you change them for brass , ? Brass is quite often used like that . Can you stack another set screw on top , common as well .
 
Shelby-Right said:
I'm not familiar at all, if those nylon plugs are there to protect the thread ?
Click to expand...
Yes (nylon-tipped grub/setscrew).
The Hemmings front and rear vernier adjusters, rear on the left:
Hemmings Isolastic Adjuster


isolastic query

Hi, i'm a new commando owner (1973 mk 5) and novice mechanic trying to acquire the skills to maintain my machine as a regular user. My current issue is with the rear isolastic and my vague understanding of the mechanics of the thing. The bike appears to have had vernier type isolastic adjusters...
www.accessnorton.com www.accessnorton.com
 
Tornado said:
Anyone using the Mick Hemmings isolastic adjuster having trouble with it staying where you set it? Mine (rear iso only) does not want to stay put with two nylon tipped set screws wound in as much as possible before the hex key strips the set screw. A 20 min ride and the adjuster has loosened two or three holes out.

Thinking maybe to drill out the M4 set screw holes and re-tap to something larger. Are there other solutions people have used?
Click to expand...
I've never used the nylon tipped screws
I only lightly tighten mine
They never move ,I have never heard of your problem before
I'm wondering if something else is wrong?
 
baz said:
I've never used the nylon tipped screws
I only lightly tighten mine
They never move ,I have never heard of your problem before
I'm wondering if something else is wrong?
Click to expand...
The set screws are quite a fiddle to handle being so small and in the limited access around the adjuster. I've managed to damage two of them with 2mm hex key stripping out the hex section in the screw. Have managed to get two fresh ones tighten enough to hold adjuster from turning by hand force, but when riding, with vibration etc, the adjuster backs off several holes.

Maybe it needs more than two set screws at once. Problem there is trying to get access around adjuster to fit more, battery tray bracket in the way.

Larger diameter set screws or even full nylon bolts should improve friction force on adjuster.

Yes full metal set screws should hold but likely to damage adjuster thread. Are there brass M4 screws out there?
 
The nylon tipped grub screws are useless to be honest as it gets chewed up by rotating on the tip of the threads. I know some folks have removed the thread from that part of the inner collar so the grub screw bears on a plain surface rather than a thread. When I get around to it I plan to use brass M4 screws instead.
 
The andover iso's don't have a set screw on the "adjustment end" and relies on the main through bolt , to hold the setting , have you tightened this enough . Throw the screws away ? I just put some AN vernier ones in , last weekend .
 
Last edited:
Tornado said:
Yes full metal set screws should hold but likely to damage adjuster thread.
Click to expand...

The original Brian Tyree patent has a different locking method where a "pin" is inserted through the appropriate hole in the outer adjuster ring into what appears to be a longitudinal slot in the inner sleeve so locking the adjuster in position.
The pin doesn't appear to be threaded and there are no details on how the pin is retained although there is mention of an alternative "...Allen screw, rivet or the like..." so a longitudinal groove could be cut in the threaded sleeve and a solid grub/setscrew used in a similar manner to how the Lockheed master cylinder barrel assembly is locked to the casting.


Shelby-Right said:
The andover iso's don't have a set screw on the "adjustment end" and relies on the main through bolt , to hold the setting , have you tightened this enough . Throw the screws away ?
Click to expand...

The Hemmings adjuster, however, does not in any way rely on the tightness of the front Iso. bolt or rear stud to lock the adjuster as it does with the factory-type vernier (either pre-Mk3 conversion or Mk3).
 
Tornado said:
The set screws are quite a fiddle to handle being so small and in the limited access around the adjuster. I've managed to damage two of them with 2mm hex key stripping out the hex section in the screw. Have managed to get two fresh ones tighten enough to hold adjuster from turning by hand force, but when riding, with vibration etc, the adjuster backs off several holes.

Maybe it needs more than two set screws at once. Problem there is trying to get access around adjuster to fit more, battery tray bracket in the way.

Larger diameter set screws or even full nylon bolts should improve friction force on adjuster.

Yes full metal set screws should hold but likely to damage adjuster thread. Are there brass M4 screws out there?
Click to expand...
Maybe something like this would be the answer ?

www.ebay.co.uk

Brass Knurled Thumb Screws M3 M4 M5 M6 M8 M10 High-type Hand Grip Knob Bolts | eBay

Thread Pitch: M3 0.5; M4 0.7; M5 0.8; M6 1; M8 1.25; M10 1.5. High-type Knurled Thumb Screw Hand Grip Knob Bolt. Material: Solid Brass.
www.ebay.co.uk
 
Tornado said:
Anyone using the Mick Hemmings isolastic adjuster having trouble with it staying where you set it? Mine (rear iso only) does not want to stay put with two nylon tipped set screws wound in as much as possible before the hex key strips the set screw. A 20 min ride and the adjuster has loosened two or three holes out.

Thinking maybe to drill out the M4 set screw holes and re-tap to something larger. Are there other solutions people have used?
Click to expand...
Tornado,
I have the Hemmings adjusters on mine and I replace the grub screw every time I make a change. I have not had any problems so far.The rear is a PITA.
Mike
 
YING said:
Tornado,
I have the Hemmings adjusters on mine and I replace the grub screw every time I make a change. I have not had any problems so far.The rear is a PITA.
Mike
Click to expand...
what is the size of that grub screw , is it the same as the MK3 vernier (cause I have both on the same bike :rolleyes:, one mk" at the front and one hemmings rear !)
 
Never had an issue with them loosening off on two of my bikes. Perhaps they were previously overtightened and the nylon tips were mangled beyond use? A visual inspection should confirm this. Suggest you try some new ones, not overtighten, and see if this helps.
 
Stephen Hill said:
Never had an issue with them loosening off on two of my bikes. Perhaps they were previously overtightened and the nylon tips were mangled beyond use? A visual inspection should confirm this. Suggest you try some new ones, not overtighten, and see if this helps.
Click to expand...
To clarify it is not the set screws which loosen, its the adjustment collar that back off from where the set screws had located it. But, yes, the set screw nylon tips may have work/abraided etc and are no longer holding correctly.

Think I'll get some brass types to see how they hold up. Worse case if the adjuster thread gets damaged, can clean it up at some point later I guess. Not like it needs a lot of adjusting once happy.
 
I had this same problem on my own bike years ago. I used some .023" safety-wire, wrapped from the grub screw, twisted, and tied to a point on the bike (battery tray tab), and it stopped the screw from backing out and holds the vernier from rotating. Still there 20 years later.

-Kenny
 
Tornado said:
To clarify it is not the set screws which loosen, its the adjustment collar that back off from where the set screws had located it. But, yes, the set screw nylon tips may have work/abraided etc and are no longer holding correctly.

Think I'll get some brass types to see how they hold up. Worse case if the adjuster thread gets damaged, can clean it up at some point later I guess. Not like it needs a lot of adjusting once happy.
Click to expand...
Make sure you either use a nickel based anti-seize or Loctite blue (which will fill the thread voids and prevent both seizing and backing out) on brass/steel interfaces.
 
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