75 Mark III refurb/mod project

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Re: 75 Mark III refurb/mod project

Postby grandpaul » Thu Jan 21, 2010 3:42 pm

JE Pistons and "gapless" rings installed-

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Radiused tappets to mate with the Megacycle cam-

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I still remember the first top end job I ever did on a Norton. Ever forget to lockwire the cam followers in place before you lower the jugs onto the block? It's a nightmare to wire them in place with the pistons at the top of thier stroke and the cylinders blocked up with custom-fit 1x4 to leave room to safety wire!

Anyway, I learned my lesson way back then...

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Just need to wash off all the fasteners and nip it all up-

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Re: 75 Mark III refurb/mod project

Postby grandpaul » Wed Feb 03, 2010 4:22 pm

Just an update on this project, as it would appear that it's been "waiting" for a while:

1. Wheels should arrive today

2. Revised design of swingarm to allow full clearance for rear disc brake caliper mount to adjust all the way forward is in-work. Final design will be built next week.

3. Engine is complete and ready for installation in the frame, as soon as the swingarm is mounted.

4. Rebuilt forks will be on the bike next week.

So, starting next week, there should be steady activity right up to completion. Target date to deliver the bike to the West coast is late April, so there's plenty of time go step-by-step
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Re: 75 Mark III refurb/mod project

Postby grandpaul » Wed Feb 03, 2010 8:07 pm

Wheels just in from Buchanan's (no, it's not a copy of the photo from the '74, they are identical)

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Re: 75 Mark III refurb/mod project

Postby grandpaul » Thu Feb 04, 2010 1:03 pm

Cleaned up the rear hub components and re-packed the bearings & speedo drive-

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Installed rear hub & brake disc, mock-up shot just for grins-

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Re: 75 Mark III refurb/mod project

Postby rond944 » Thu Feb 04, 2010 3:42 pm

Paul , are those the 10.5 to one JE's from Kenny ? If so please let us know how they work . I think I've got Leo talked into milling the domes down on mine a bit . I'll feel more comfortable if we hold it down to 10 to one .

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Re: 75 Mark III refurb/mod project

Postby grandpaul » Thu Feb 04, 2010 4:52 pm

Yep, those are the 880s.
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Re: 75 Mark III refurb/mod project

Postby grandpaul » Thu Feb 18, 2010 5:11 pm

Frame mods are done; they do not affect a return to original configuration nor do they disturb any standard parts fitting. Just two simple tabs welded up against the webbing, with holes for the monoshock's top mount bolt-

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Re: 75 Mark III refurb/mod project

Postby grandpaul » Thu Feb 18, 2010 5:15 pm

Swingarm is also done, this is the "Plan B" model, my second iteration. This time I boxed out the front section and eliminated the left side upper leg so I can retain the stock chain guard. As it is, it's still over-designed for the base mounted rising rate linkage that forms the bottom monoshock mount-

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Re: 75 Mark III refurb/mod project

Postby grandpaul » Thu Feb 18, 2010 5:18 pm

One more shot of the swingarm-

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Sanded and touch-up painted the frame, stripped and painted the swingarm-

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This day has been a long time coming!
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Re: 75 Mark III refurb/mod project

Postby grandpaul » Mon Feb 22, 2010 1:27 pm

I've had to go to an alternate design in the rising-rate linkage in order for it to co-exist with the box-section front assemblage on the new swingarm. On my previous design using tubular uprights on each side, there was a space in the center where the bottom hinge point of the linkage and tail end of the rotating cradle connection could "slot" into; now, that's gone.

No big deal, it's all worked out. Just going to take an extra day to fabricate the new link plates, test fit them, then paint and install.
Last edited by grandpaul on Thu Mar 04, 2010 5:41 pm, edited 1 time in total.
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Re: 75 Mark III refurb/mod project

Postby grandpaul » Wed Mar 03, 2010 2:04 pm

Well, it took more than an extra day to get it done, but here's the new setup. Just waiting on the forks to get back from overhaul to set up the rolling chassis and verify range of motion before pulling it back apart for final spacer & hardware fitment.

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Re: 75 Mark III refurb/mod project

Postby Coco » Wed Mar 03, 2010 2:08 pm

Cool.
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Re: 75 Mark III refurb/mod project

Postby swooshdave » Wed Mar 03, 2010 5:12 pm

Maybe I can't keep them straight but what's the difference between the two monoshock projects you have going on?
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Re: 75 Mark III refurb/mod project

Postby grandpaul » Wed Mar 03, 2010 5:58 pm

This one is a Mark III which has a square section main web front section. From there, I've built up the box vertically, and attached only the front and right leg of the second swingarm instead of using the left leg and chopping into it to clear the chain. This allows me to retain the OEM chain guard. Other than that, they are essentially the same with a bit different geometry on the rising rate linkage..
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Re: 75 Mark III refurb/mod project

Postby grandpaul » Thu Mar 04, 2010 5:34 pm

I still need to pull the rear end loose and replace all the temporary hardware with the grade 8 stuff, paint all the rising rate linkage bits & spacers, install the
swingarm spindle set pins, and the isolastic rubber booties, but I just had to assemble the rolling chassis temporarily after getting the forks back from overhaul.

Rear wheel first-

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Front forks, after cleaning up and re-painting the lower sections-

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Then the front wheel-

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Note: the photo with both wheels shows the bike lift still had the wheel off the ground, that's the reason for the "headed downhill" appearance;
the static suspension settings will see the bike level & true once everything is nipped up right & proper.
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