G15 Fork Length

Information relating to the Matchless G15 or AJS Model 33 750cc twin. This also includes the G15 Mk II and the G15/45
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G15 Fork Length

Postby Mick D » Mon Oct 19, 2020 1:39 pm

Hi

I'm after a sanity check if anyone can help me please.

Having stripped, inspected and re-assembled a set of roadholder forks for my G15CSR things don't feel correct when I fit them. In order to attach the damper rods to the top nuts I have to compress the forks by about half their travel which then really restricts the fit and function of the gaiters.

Before I strip the forks down to measure individual components could anyone measure the distance from the top of the upper crown to the wheel spindle centre when the fork is fully extended please? I have 29"

Regards Mick

Edited to say: The forks will be stripped again tomorrow, I suspect I have the wrong dampers, 7 5/8" as opposed to 10 3/4", fitting the correct ones would result in a fork length of about 32" - does that come close?

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Re: G15 Fork Length

Postby Peter Morris » Mon Oct 19, 2020 9:13 pm

Check out Andover Norton site, forks page Mick, if no joy give them a call, they're very helpful.

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Re: G15 Fork Length

Postby clive » Tue Oct 20, 2020 7:58 am

Cannot help with the measurement I am afraid as the G15 is firmly strapped down on the bike lift awaiting replacement of the magneto.
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Re: G15 Fork Length

Postby Mick D » Wed Oct 21, 2020 1:56 pm

Hi

A bit further with this one now. I was using the AN website as a reference Peter but couldn't find all the info I needed, on your advice I spoke to one of their Technical help guys, (brilliant service), and determined that I have early Commando damper tubes - too short.

New items on order - should increase the length of the forks by around 2"

Another step forwards - I hope :)

Regards Mick

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Re: G15 Fork Length

Postby clive » Thu Oct 22, 2020 10:38 am

"and determined that I have early Commando damper tubes - too short" so now you know how to describe them when they go on ebay Mick! :roll:
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Re: G15 Fork Length

Postby Groily » Thu Oct 22, 2020 11:03 am

Enfiield resting 001.JPG

Faced with exactly the same problem on one Road-Holdered machine I used to have, which was a bit non-standard to say the least, I made up some 1.5" extensions for the rods so that the springs weren't compressed on assembly. Probably not the best way, but it worked fine.
Sorry the pic is so darn BIG - but you can see at least that the fork length looked about right after surgery. Before, the gaiters were well-squished.
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Re: G15 Fork Length

Postby Mick D » Thu Oct 22, 2020 12:02 pm

clive wrote:"and determined that I have early Commando damper tubes - too short" so now you know how to describe them when they go on ebay Mick!


Hi Clive - I prefer to look at them as the start of my Commando restoration :rofl:

Hi Bill - Funny old world - I've drawn up a set of modified damper rods just in case the longer damper tubes don't fully resolve the issue. Should keep the springs and dampers functioning the same whilst extending the forks a tad ;) ;)

Regards Mick

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Re: G15 Fork Length

Postby Groily » Thu Oct 22, 2020 12:55 pm

"I've drawn up a set of modified damper rods just in case the longer damper tubes don't fully resolve the issue. Should keep the springs and dampers functioning the same whilst extending the forks a tad "

That was my thinking Mick. . . . . Great minds thinking alike - or Fools seldom differing??!! (Oh, and it's a no-cost get round, which is obviously the best sort when far too much has already been 'invested', ha!)

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Re: G15 Fork Length

Postby clive » Thu Oct 22, 2020 8:19 pm

Mick D wrote:Hi Clive - I prefer to look at them as the start of my Commando restoration :rofl: Mick


and I have the first nut towards my AJS Porcupine build...... :rofl:
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Re: G15 Fork Length

Postby Peter Morris » Thu Oct 22, 2020 9:23 pm

There was 2 types of Roadholder forks, long and short.

The G15's had the long version

From Norvil website (forks page) ...... https://www.norvilmotorcycle.co.uk
STANCHION - FORK - PAIR - 24.93" LONG - G15 ETC

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