Rob North Framed Commando

Chris

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Hi Steve Storm
Mk4 has a ladder bolt on down tube. The head steady is two small strips that attach the plate bolted to the head to two small brackets next to the ladder mount. I was making up a new pair as the holes were elongated. AND I didnt do it! Aah
Silencers were rubber mounted. Down pipes came away below the rose & knackered the threads in the head.
 

grandpaul

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On a Commando as we know, ... the head steady is the only point that mounts the motor to the frame as the other points mount it too the engine/plates/swinging arm assembly.
You are forgetting the front Iso mount...
 

MichaelB

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That's interesting, but not relevant to a rigid mounted motor! ...
So as I understand it what Kenny Dreer did when he removed the head steady was in effect to move the 3rd iso mount!

Yes, very true...
Saw the head steady and assumed it was rubber mount.
I'll return to my corner and observe quietly...
 
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If the handling of your motorcycle depends on the head steady, you have a real problem. All mine does is stop the frame from cracking./
 

Roger Middlebrook

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For any one interested the Rob North Norton has a pissie light weight piece of renolds tube attaching the head to the head stock, compared to a Norvil head steady more a token gesture than an attempt to smooth out the ride. Non the less took RNN to the local track this weekend for a tuning day. Second outing for the bike and pleased to report had a full day of tuning and tewaking with out a glitch. Only pushing was back to pits after plug chops.
On the Vibes front, being solid mounted 920cc there was never any doubt that it would detach the retina from the iris and pleased to report lived up to the expectation, vibes started at 4K and didnt smooth out, seemed to be just as alive at 4k as it did at 6.8K. Vibes were down low through the foot pegs, noting in the seat or bars so very ride-able. Being used to big pommy twins didnt phase me and I have my fillings double lacquered to save Monday after race day revisits to local dentist :)

Fast Eddi asked some time back for a track side comparison between the RNN and the Wide line Feather bed Norrish Weslake Twin I used to race so to summarize the two in a non scientific mannor.

RNN
Low CoG
Neutral handling
Compact riding position
Nicely balanced weight distributing with the fwd slanting engine
Well matched front and rear end suspension
Reasonable breaks
Forks worked well no funny stuff mid corner

FB Noirrish Weslake (excuse the 80's Front forks didn't make any improvement over the road holders to be honest)
Higher CoG
Sharp steering tips in nice but under steers coming out (have lost front end in the wet in the past)
Longer stretch to the bars
Weight distribution further back due to full length manx style tank
Didn't give full confidence mid corner on faster sweepers.

In saying all this main take away is the CoG of RNN is better than the FB Weslake, breaks and suspension far superior on RNN. I am sure the Norrish Weslake in a Manx frame with better suspension would have been a better match up to the RNN but out of the box the RNN has my vote all day. And man it sounds soooo good !! Sorry cant share a sound file with you all :-(

couple of pxts below
Norrish Weslake in a standing 1/4 mile 11.3 sec. if front wheel would stay down probally would have shaved another 0.1sec
 

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Chris

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Well done Mike
Great to see it out on track.
Thanks for the photos
 
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What has Herb Becker done to the ISOs on Doug McCrae's bike ? - 'Racing improves the breed' ?
If I was going to race a normal Commando, the first thing I would do would be to speak to them.
ISOs were invented to make the Commando as smooth as a CB750. However the Atlas and the 650ss were both very good bikes. I rode a CB750 when they first came out - I would not piss on one.
The Commando with the ISOs is good, but I would much rather ride a Norton Manxman. What surprises me about the Commando is my mate used to do the pre-delivery on them. They used to take them to a local boulevard to test them. They are as quick as the H1 and H2 Kawasaki two strokes.
I just wish I had known that when I built the Seeley 850, because I never believed in it. It was just a good thing to build.
 
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Roger Middlebrook

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After a racing incident where the cush drive came to bits locking wheel to swing arm mid corner ditching bike and rider its time for some more shed time tinkering with the RNN.
Re work back wheel mounting, fork upgrade, carb work over or replacement yet to decide.
 

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After a racing incident where the cush drive came to bits locking wheel to swing arm mid corner ditching bike and rider its time for some more shed time tinkering with the RNN.
Re work back wheel mounting, fork upgrade, carb work over or replacement yet to decide.
Looks like Ohlins shocks on the rear, is that correct?
Care to share any spring info? Damping specs?
What are you using for front forks?
What mods are you doing with the forks?

Thanks
Dan
 

lcrken

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After a racing incident where the cush drive came to bits locking wheel to swing arm mid corner ditching bike and rider its time for some more shed time tinkering with the RNN.
Re work back wheel mounting, fork upgrade, carb work over or replacement yet to decide.
Ouch! Hope it was only the bike that got damaged. I'm sure you will have it back to pristine condition soon. After all, isn't that why we have bikes, so we can work on them? :rolleyes:

Ken
 

Roger Middlebrook

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Looks like Ohlins shocks on the rear, is that correct?
Care to share any spring info? Damping specs?
What are you using for front forks?
What mods are you doing with the forks?

Thanks
Dan
Hi Dan, rear shocks are YSS RZ362 rebound adjustable by 21 position rotary knob at bottom, threaded pre load adjuster up top. Not fully set up yet as haven't had great success with the front end to really dial in the back.
Front forks are Marzocchi 38mm shortened by 45 mm to fit into RNN, cut off the Brembo caliper mounts and welded AP Lockheed caliper mounts, fitted Race Tech emulators and done the damper rod modification fitted dual rate Works performance springs shortened 45mm, still work in progress on the fork tuning, have taken all this out now and fitted to the Rickman Metisse, fitting a set of cartridge internals to the RNN forks
 

Roger Middlebrook

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Ouch! Hope it was only the bike that got damaged. I'm sure you will have it back to pristine condition soon. After all, isn't that why we have bikes, so we can work on them? :rolleyes:

Ken
Bit of steel work in the right wrist and big cup of concrete will see both bike and rider back track side sooner than later, bike is only superficial new upper faring section and bit of panel work on tank and exhaust and we be racing. :)
 
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Hi Dan, rear shocks are YSS RZ362 rebound adjustable by 21 position rotary knob at bottom, threaded pre load adjuster up top. Not fully set up yet as haven't had great success with the front end to really dial in the back.
Front forks are Marzocchi 38mm shortened by 45 mm to fit into RNN, cut off the Brembo caliper mounts and welded AP Lockheed caliper mounts, fitted Race Tech emulators and done the damper rod modification fitted dual rate Works performance springs shortened 45mm, still work in progress on the fork tuning, have taken all this out now and fitted to the Rickman Metisse, fitting a set of cartridge internals to the RNN forks
We are currently fitting a set of Ohlins cartridge kits to a Ducati 900SS 1980, which also uses Marzocchi forks.
In this case the cap is 34mm X 1.5mm threads.
The nice thing about the Ohlins kit is they already make a 34 X 1.5 cap so no mods there.
This is an easy fit for the Ohlins 22mm NIX kit, these kits have adjustable spring preload, adjustable rebound and compression damping.
Adjustable shim stacks, with Ohlins predetermined steps in increase or decrease of damping.
The same 22 Nix kit allows quick change on the springs, less than 2 minutes with the forks on the bike. The spring range 6 Nmm to 9 Nmm, in the small diameter springs and up to 13.0 Nmm in a larger diameter spring
We have done custom Ohlins kit for at least 15 different types of forks. , just finished a 35 mm RZ350 fork, for a Bultaco Astro flat tracker
A week ago finished a Honda RC30 (VFR750R) 30 MM NIX kit
 

lcrken

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Hi Dan,

Do you think it would be possible to fit the NIX 22 kit to the standard Commando 34.5 mm forks? I've fitted the cartridges from a Honda F4i into them, but it's a pretty tight fit, and requires a funky sort of adjutment process to change the compression damping, requiring front wheel and axle removal to get to the needle, but it works quite well. The total parts cost was under $200 for a pair of bent F4i forks on eBay. We used a pair of springs I already had, shortened 250 ninja springs, if I recall correctly. The cost of the NIX 22 kits on your web site looks like $750 or so, which seems reasonable, if they could be adapted to the Commando with relatively simple machining. like the idea of using the Ohlins for a couple of reasons, the eas of adjustment from the fork tops, the high quality of Ohlins products, and the availbility of shim and spring info and parts.

I couldn't find enough info on-line about NIX 22 configurations (dimensions and such) to know which one would be a likely candidate for a Commando. I looked at the list of applications for the NIX 22 kits on your web site. Is there a particular kit that you would recommend for adapting to a Commando? I'm thinking I might like to give it a try.

Ken
 
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Hi Dan,

Do you think it would be possible to fit the NIX 22 kit to the standard Commando 34.5 mm forks? I've fitted the cartridges from a Honda F4i into them, but it's a pretty tight fit, and requires a funky sort of adjutment process to change the compression damping, requiring front wheel and axle removal to get to the needle, but it works quite well. The total parts cost was under $200 for a pair of bent F4i forks on eBay. We used a pair of springs I already had, shortened 250 ninja springs, if I recall correctly. The cost of the NIX 22 kits on your web site looks like $750 or so, which seems reasonable, if they could be adapted to the Commando with relatively simple machining. like the idea of using the Ohlins for a couple of reasons, the ease of adjustment from the fork tops, the high quality of Ohlins products, and the availbility of shim and spring info and parts.

I couldn't find enough info on-line about NIX 22 configurations (dimensions and such) to know which one would be a likely candidate for a Commando. I looked at the list of applications for the NIX 22 kits on your web site. Is there a particular kit that you would recommend for adapting to a Commando? I'm thinking I might like to give it a try.

Ken
I just missed getting an extra set of Norton forks.
As I would like to do it as well

It really depends how many you are going to make, one or two by manual machines, means either a lot of extra work, or deleting some features.

There are a few problems, that I have looked at already.
First: as the cap is not a metric thread so a cap has to be made.
As the cap diameter is so small due to the tapered end of the fork as it fits into the upper triple without any clamping bolt.

Second: This small size is slightly to small to use the current small Ohlins forks springs, which I really wanted to use, due to their selection, 6.0, 6,5, 7.0, 7.5, 8.0 and 9.0 Nmm
This can be overcome by using another brand of spring

Third: Again as the cap diameter is so small that the Ohlins parts to adjust the spring preload will not fit.
There are a number of ways to overcome this. If I was making enough of them, I would have the parts CNC
If I was just doing a few, as I have done in the past, make a simple cap to house the compression adjuster and NOT have an outside spring preload adjuster, it is very easy to add or subtract spacers to add or subtract preload

Everything else is pretty easy.
Determine the length and stroke, fine a kit that is close.
Determine the bolt size on the fork.
It needs to be either 8mm or 10 mm or more work to convert the Ohlins parts, or make new ones.

If you want to work with me on this I am in.

I will post some pictures of other fork parts, that may give you some ideas.

I have not looked, do you know the fork length?
Measured from the center of the axle to the top of the fork tube, not including the cap.

The fork stroke?

I just took a quick look
This is what I found

I do not know if it is correct

Fork length 23.161 inches 588.29 mm That is very short
Fork stroke 6 inches 152.4 mm this sounds wrong, if it is right, I would change it to 130 mm
Stock spring rate 36.5 Lb/in 4.12 Nmm
 

gortnipper

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I just missed getting an extra set of Norton forks.
As I would like to do it as well

It really depends how many you are going to make, one or two by manual machines, means either a lot of extra work, or deleting some features.

There are a few problems, that I have looked at already.
First: as the cap is not a metric thread so a cap has to be made.
As the cap diameter is so small due to the tapered end of the fork as it fits into the upper triple without any clamping bolt.

Second: This small size is slightly to small to use the current small Ohlins forks springs, which I really wanted to use, due to their selection, 6.0, 6,5, 7.0, 7.5, 8.0 and 9.0 Nmm
This can be overcome by using another brand of spring

Third: Again as the cap diameter is so small that the Ohlins parts to adjust the spring preload will not fit.
There are a number of ways to overcome this. If I was making enough of them, I would have the parts CNC
If I was just doing a few, as I have done in the past, make a simple cap to house the compression adjuster and NOT have an outside spring preload adjuster, it is very easy to add or subtract spacers to add or subtract preload

Everything else is pretty easy.
Determine the length and stroke, fine a kit that is close.
Determine the bolt size on the fork.
It needs to be either 8mm or 10 mm or more work to convert the Ohlins parts, or make new ones.

If you want to work with me on this I am in.

I will post some pictures of other fork parts, that may give you some ideas.

I have not looked, do you know the fork length?
Measured from the center of the axle to the top of the fork tube, not including the cap.

The fork stroke?

I just took a quick look
This is what I found

I do not know if it is correct

Fork length 23.161 inches 588.29 mm That is very short
Fork stroke 6 inches 152.4 mm this sounds wrong, if it is right, I would change it to 130 mm
Stock spring rate 36.5 Lb/in 4.12 Nmm
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

 
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Spring Diameter above

Spring Length

Standard Ohlins NIX 22 Fork caps Showin cap and inner spring adjuster it uses the hex drive to turn the adjuster which is threaded


Above Cart kit showing spring guides removable lower mount, these come in a few different lengths, as well as 10 mm or 8 mm bottom mount

Above machined nut to reduce diameter to fit into a 35 mm fork tube
 
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Below custom caps 31mm X 1.5 mm for RZ350 forks No inner threaded portion, so not outside adjustable spring preload


Ohlins internal in custom cap, retaining adjustable damping

 
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