isolastic replacement suggestions for a 72 interstate

10drum

10drum

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May 10, 2020
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Greetings,

I am replacing the isolastics on my 72 interstate. I am in the US and would like recommendations for the best kit, or is it best to buy the individual parts?

Thanks for all replies.
 
"Best" is probably CNW's

coloradonortonworks.net

cNw Mk3 Style Isolastics Conversion

Both front and rear new internal rubbers Front and rear new PTFE friction washers Complete stainless Isolastics kit with Adjusters, Abutments and Cups All stainless parts are show polished Machined, powder coated (Gloss Black) and prepped front engine mount The front mount is assembled and ready...
coloradonortonworks.net coloradonortonworks.net

RGM makes a Mk 3 version as well
 
Some isolastic rubber is too hard, and will vibrate at all rpms.
Find a source that sells rubber with the correct hardness/softness/durometer #.
 
Stephen Hill said:
Some isolastic rubber is too hard, and will vibrate at all rpms.
Find a source that sells rubber with the correct hardness/softness/durometer #.
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I think this is the key issue, and I'd certainly like to hear of any recent comparative testing (Dynodave has previously posted some testing he'd done some years ago) or feedback on isolastics from the various sellers. Given the number of Commando users on this forum it should be possible to narrow down the choices.
 
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I installed and sold over a dozen sets purchased from Carl (racingnorton) and ALL were very well received.
 
I only looked at what L.A.B. posted and would agree , I have a ‘72 roadster and switched/upgraded the isolastics with the no mod front mount kit with the vernier adjusters all round and am pleased with result .... I would suggest at same time you splurge for Dave Taylor type headsteady ( with spring) at the same time ... once everything adjusted to your ride style you will be glad you did ....
 
Craig said:
I only looked at what L.A.B. posted and would agree , I have a ‘72 roadster and switched/upgraded the isolastics with the no mod front mount kit with the vernier adjusters all round and am pleased with result .... I would suggest at same time you splurge for Dave Taylor type headsteady ( with spring) at the same time ... once everything adjusted to your ride style you will be glad you did ....
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How much difference does the spring make?
 
robs ss said:
How much difference does the spring make?
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More than enough to make the cost worthwhile!

It saves the iso rubbers from excessive compression (and resultant non-concentric mis-shaping) as a result of weight-bearing instead of simply vibration isolation.
 
grandpaul said:
More than enough to make the cost worthwhile!

It saves the iso rubbers from excessive compression (and resultant non-concentric mis-shaping) as a result of weight-bearing instead of simply vibration isolation.
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Just by way of conversation, rather than confrontation, is this spring really 'weight bearing?' Given it's angle of mounting and size I would suggest perhaps it serves as a damper rather than a support. Though it is referred to as 'suspensory'.
But happy to be proven otherwise :)
 
It does appear to be weight bearing. I fitted one to my 750 and tightened it until I could move the front iso bolt back and forth by hand, so certainly the load was taken off the front iso. It doesn’t take the load off quite as well at the back, but it does reduce it.
Definitely worth fitting in my opinion, reduced my tick over vibrations - no more mudguard (fender) shakes at idle.
 
Yes, definitely not doubting it's effectiveness (I own a Mk3), rather how it achieves it.....
 
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I kept it stock and used the rubbers from Andover Norton. Vibration same. Fairly easy job using a variation of the Mike Taglieri method. I didn't want to take the bike halfway apart to install vernier isos.
 
EstuaryBoy said:
Yes, definitely not doubting it's effectiveness (I own a Mk3), rather how it achieves it.....
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If properly adjusted, the engine is sat in place even if you extract the front mount bolt. Of course you can not operate the bike without the bolt, but the spring (and top isolastic coushions) are indeed suspending the engine. Remember that the engine is counterbalanced on the rear isolastic pivot, by the swingarm and rear wheel/tire assembly.
 
Thanks for the replies. I am waiting on a reply from Matt. I installed his electric start on this bike, and I'm really impressed with it. This is a survivor bike, and his kit comes with a stainless or powder coated front housing which would stick out like a sore thumb.
 
While I really don’t completely understand exactly why the spring on DT style head steady improves handling and ride ... I can say I did the vernier isolastic upgrade first , with the “no mod” front mount , I don’t remember taking my completed ‘72 mostly apart to install this upgrade , remember a couple hours of fiddling in shed one wet afternoon .... rode bike for a couple hundred miles and thought maybe the DT head steady would improve things more ( based on reading I had done) .... installed the H. steady with spring and gradually over another couple/few miles I adjusted spring to take more load until I got the eureka moment .... been smooth well controlled riding ever since .... I should also note I have steering damper mounted as well , I installed that along with tapered steering head bearings a while before tackling the isolastics and headsteady .... the Commando behaves very well these days out on the road at all speeds I care to travel , on our poorly maintained back roads .... not scientific but is my experience , hope this info helps ....
 
Craig said:
.... installed the H. steady with spring and gradually over another couple/few miles I adjusted spring to take more load until I got the eureka moment .... been smooth well controlled riding ever since ....
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That "Eureka Moment" is easily arrived at by installing the isolastics (with no main bolt thru the front mount), then installing the sprung top steady, then you adjusting the spring 'till the front isolastic tube lines up with the holes in the frame tabs. Then, install and snug up the bolt and ride away happy.

I'm not positive, but I believe you should set the bike on it's tires with support on both sides to adjust the spring (unless the book says to use the centerstand).
 
Spring adjustment was done (in my case) with bike on wheels with assistance from my long suffering wife ....
 
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