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Front Isolastic

Submitted by steve_nairn on Thu, 11/08/2016
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Commando

Hi - rebuilding a Mk2a that I got in bits, and having a problem with fitting thefront iso mount, probably something basic I am not seeing.

Replaced old iso with RGM vernier upgrade, fitted the rubber & sleeve internals OK (centred in mount) this assembly fits in frame with approx 1/4" gap, Fitted the new caps, the polyeurethane washer, and the threaded collars. The 'vernier' collar can be tightened on the washer,with the internal sleeve end almost flush with the collar, but the grub screw collar side bottoms out on the sleeve and I cannot tighten it up on the washer - there is about a1/4" gap.

I can pull through the internal sleeve on the vernier side to close gap on grub screw collar but that will off centre the mounting.

How do I set this up so I can get both collars tightened to the correct gap and keep it centred, and how tight should the collars be in the frame? Does frame lug fit hard up against collarswhen the frame bolt is tightened?

Submitted by david_evans on Thu, 11/08/2016

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The plates on the mount are not centred in between the frame lugs. Let me come back to you with some dimensions from my bike.

Submitted by john_holmes on Thu, 11/08/2016

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Which upgrade did you buy as there are 2.

1. The MK3 version made for front iso tube which is short on both sides.

2. The retro fit for pre MK3's where the iso tube has one long side and one short side.

If you iso mount is original to your bike then you need no 2.

The difference in lengths is 1/4" so could be the cause

Submitted by david_evans on Thu, 11/08/2016

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The measurement between the inside edge of the frame lug and the outside face of the isolastic plates are 1.054" on the LHS and 1.272" on the RHS. a difference of 0.218" i.e. the iso mount is 0,109" across to the left on my bike.

Submitted by steve_nairn on Thu, 11/08/2016

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Thanks to you both.

I bought (or ordered) the pre Mk3 set up, but the tube distance either side of the one I gotlooks to be thesame? I can shorten the tube ongrub screwside easily enough if thats all it takes.

Or, I think I can pull through enough to get both sides snug, and if a slightengine offset (as Davis has) will not cause any problems I think I can do this.

I will call RGM and make sure I got the right bit.

Steve

Submitted by steve_nairn on Tue, 16/08/2016

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Problem solved, it turns out that it was a Mk 3 mounting I had - not Mk 2, got the correct end collars and it all fits.

Thanks for your help. Steve

 



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