Rob North Framed Commando

HondaRC30 fork tube showing inner damper rod stop, these usually have to be machined out for additional clearance for the cartridge kit
. Our current stock of Ohlins Cartridge kits and some springs. It helps to have a selection of parts to pick from

gortnipper said:

The length of the stantion tube itself is 23 1/8".

Overall length installed is approx 29" from axle center to top of triple tree.

I dont know if this is if interest or helps re springs

Progressive Fork Springs

The link I posted earlier was interesting It said if you place the close coils at the bottom the extra coils can take up oil capacity in the fork leg! Something I'd never considered before? That has to be the best reason for the close coils at the top, like Nigel said, you would have to be...

www.accessnorton.com

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29 inches makes more sense, that is 736 mm, I just finished a RZ350 which was 740 mm, so that is easy
You can see one of the problems with those long progressive springs, they bend out side to side, that rubs against the fork tube, causing friction, noise and wear. The wear makes the fork oil get dirty

You can see Ohlins uses a fork spring internal guide to try and avoid this, this is done in all Ohlins forks.
The Ohlins spring is much shorter.
ALL Ohlins fork springs are straight rate, NOT progressive.
We can discuss why that is, but just start with the spring is progressive and the Damping is not, so the damping curve cannot follow the spring rate.
The progressive spring can be used over a wider range of rider weight,.
A straight rate if it is correct for the rider weight along with the correct amount of preload, will work better.

I never thought that fork internals could look so sexy !!

Thanks for posting the pictures, Dan. I think I'll give it a try, and take you up on your offer to help. I'll get back to you on it. I'll start a new thread to cover the project. One question I have at the moment is the diameter of the damper tube and the bits at the ends of it. The Commando stanchion is only 26.12 mm ID. Will the NIX 22 cartridge fit? I'm assuming I'll have to turn down the nut at the top end and maybe the extension at the bottom end of the cartridge body.

For anyone interested who hasn't seen it already, this is a link to a thread several years back that I posted on the F4i conversion, and it also has some info on other conversions for the Commando forks. There are corrupted or missing images because of the Photobucket disaster back then, but the basic info is still there.

Ken

Sorry, I left out the link I referenced above. It is


Ken

For sale in The Netherlands.
(Not mine, then it wouldn't hbm e for sale)

Ooh...ahhh.

lcrken said:

Just a heads up for anyone interested, I posted today on the Other Nortons forum with pictures and questions about the current status of bikes built with Mick Hemmings Rob North frame kit for Commandos. It's not a Commando, just uses that engine, so I wasn't sure where to post it.

https://www.accessnorton.com/NortonCommando/where-are-the-rob-north-northtons.30270/

Ken

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My friend Jarmo Hirvasoja has an original Mick Hemming Rob North frame with Norton Commando. Jarmo is 1990 world champion in ice speedway and is a long time British bike owner. The frame number is 00269. I will ask him to post some info about it.

Karkka said:

My friend Jarmo Hirvasoja has an original Mick Hemming Rob North frame with Norton Commando. Jarmo is 1990 world champion in ice speedway and is a long time British bike owner. The frame number is 00269. I will ask him to post some info about it.

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I'll look forward to seeing it. Always good to find out the fate of another one of the bikes.

Ken

I found one on Facebook Ken. At least I thought it was I will find the post.
Chris

Here it is Ken

Thanks, Chris. I haven't seen that one.

Ken

Fast Eddie said:

Absolutely right Chris.

I don’t know what goes on down in Oz, Al makes the organisers there sound like morons. That’s for our other Oz members to comment on, not me.

But, as regards building a race bike...

Building what you want, irrespective of rules, and worrying about the rules afterwards is just plain shoddy. Someone who does that deserves every rejection they get!

Understanding the rules in advance, and building a competitive machine WITHIN the rules is all a part of racing, just as much as good tuning and good set up.

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I completely agree, if from the outset you are building a race bike for historic racing here in OZ, why the bloody hell would you not build it to the required spec. If you don,t build it to the required spec and you are not eligible to race due to this, tuff luck for you. Is the house you live in built to code a guess it is, if it wasn,t you would be having trouble with the governing body would you not, whats the difference?.