Transform Roadholder Commando to external spring

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gillou

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Hello,

I want to transform my Commando Roadholder standard spring to external spring. It's for my racer Commando.
I find part to tranform it in RGM shop :

ALLOY FORK SEAL RETAINERS FOR EXTERNAL SPRINGS MANX 050004M
SHORT FORK YOKE SHROUDS 1 1/4" LONG, ATLAS, COMMANDO(PR) 030041

But i don't know what spring buy : i think it's the : EXTERNAL FORK SPRINGS CHROMED MANX/TRITON 9 1/2" DUALRATE 080001 first, but i don't want dualrate sprint, it to race and second what length ?

Can you help me?

Gilless
 
I think you will find the Manx /triton to short on a Commando. but a couple of plastic spacers to give 1/2 static ride hight should be OK. External springs are a bit tricky to get what suits you. RGM only do one lenght/weight.
 
John, do you have any suggestions for front fork springs for an ironhead Harley Sportster engine in a Slimline frame with Roadholder forks? I suspect the weight gain may be almost 100 lbs, but wont know until I can weigh everything.
 
Dave, Sounds like stock Norton internal and add a external from a light weight ?

dave M said:
John, do you have any suggestions for front fork springs for an ironhead Harley Sportster engine in a Slimline frame with Roadholder forks? I suspect the weight gain may be almost 100 lbs, but wont know until I can weigh everything.
Click to expand...
 
Robert, having weighed everything doing an internet trawl from the comfort of my couch, it looks more like a difference of around 50lbs when I include the Norton Gearbox and primary drive into the mix.
 
Norton Roadholder standard red painted spring [if any remains] is 36 lb/inch when new. Off the shelf progressive rate spring only reach factory level after a nose dive first. Cutting springs, ie: shortening them increases their spring rate though I don't know how much per slice off. The suggestion to try additional exterior springs as back up makes a lot of sense. Internal spring can be chopped short and another spring spacer dropped in. I found valve springs that worked a treat for me there. I've seen yellow paint spring shopping 2 decades ago but forget their rates. I think there may be an orange or green rate too.
 
Steve ,is there a sidecar spring ,i would guess the factory back in the sixties offered an up rate for a double Adult chair ?
But who would stock them? As Dave as said 0nly another 50LB ..depends on His weight ..perhaps he will get away with original?

hobot said:
Norton Roadholder standard red painted spring [if any remains] is 36 lb/inch when new. Off the shelf progressive rate spring only reach factory level after a nose dive first. Cutting springs, ie: shortening them increases their spring rate though I don't know how much per slice off. The suggestion to try additional exterior springs as back up makes a lot of sense. Internal spring can be chopped short and another spring spacer dropped in. I found valve springs that worked a treat for me there. I've seen yellow paint spring shopping 2 decades ago but forget their rates. I think there may be an orange or green rate too.
Click to expand...
 
Dave, the Lansdowne dampers have the compression control ,which in effect stiffens up the fork spring on braking..
Try a SAE 15 fork oil aswell.. Crash diet adds to the result :lol:

dave M said:
Perhaps standard springs and a crash diet!
Click to expand...
 
I was supplying external spring kits for pre Commando, I still have some springs and they are 9-1/2"
just comparing them against my Commando, it looks like they would have about 1-1/2" preload on them
while the wheel is off the ground. but I think as some one suggested, what might suit you might not suit someone else. not much help I guess.
 
Gillou says this is a racer....

So, one, lets forget progressive springs.

Two, lets forget using two springs together, you are going to have great problems calculating the effect of both springs and friction. The concept of teh external spring allowed racers in the '60s to change springs easily from the range then available. Those springs are not available as easily today so you would need to look at custom wound springs to have a real choice.

Three, the correct spring is a derived from a calculation of bike and rider combined weight and front to rear weight bias and is affected by rider style and preference, and braking technique!

Four, modern race bike suspension supply firms (e.g. K-Tech) make a range of springs of a set ID/OD and length but different rates allowing you to fine tune to meet your own needs. You install these springs with spacers and adjust the spacer stack to get your static sag.

(These springs are not progressivly wound, which are a road biased compromise no matter how much they were touted for race use some years ago)

If Gillou is serious about his racing he needs to go down this route.

And all of this has little to do with the damping, for which as we know Lansdowne do a product that a lot of riders are having success with and is an easy fit on Commando forks, but successful riders/tuners are sorting their springs properly too.

Another approach is to take the fork sliders to Maxton and have them rework to fit stanchions, bushes and cartridges and springs. They will tell you that the bushing system will still leave the forks compromised......but then again they do sell their own complete replica Ceriani fork legs with CBR600 style cartridges set and sprung to the data you provide....you pays your money.....
 
SteveA said:
Gillou says this is a racer....

So, one, lets forget progressive springs.

Two, lets forget using two springs together, you are going to have great problems calculating the effect of both springs and friction. The concept of teh external spring allowed racers in the '60s to change springs easily from the range then available. Those springs are not available as easily today so you would need to look at custom wound springs to have a real choice.

Three, the correct spring is a derived from a calculation of bike and rider combined weight and front to rear weight bias and is affected by rider style and preference, and braking technique!

Four, modern race bike suspension supply firms (e.g. K-Tech) make a range of springs of a set ID/OD and length but different rates allowing you to fine tune to meet your own needs. You install these springs with spacers and adjust the spacer stack to get your static sag.

(These springs are not progressivly wound, which are a road biased compromise no matter how much they were touted for race use some years ago)

If Gillou is serious about his racing he needs to go down this route.

And all of this has little to do with the damping, for which as we know Lansdowne do a product that a lot of riders are having success with and is an easy fit on Commando forks, but successful riders/tuners are sorting their springs properly too.

Another approach is to take the fork sliders to Maxton and have them rework to fit stanchions, bushes and cartridges and springs. They will tell you that the bushing system will still leave the forks compromised......but then again they do sell their own complete replica Ceriani fork legs with CBR600 style cartridges set and sprung to the data you provide....you pays your money.....
Click to expand...

I don't have so many money to spend in Maxton... and i know Lansdowne product, but know i had to rebuild my engine, broken on Magny Court tracks... Crankshaft, cylinder, piston .... too expensive...

Then i have already modify damper like this :

Transform Roadholder Commando to external spring

And change bush like this :

Transform Roadholder Commando to external spring

Now the spring are not enough hard. My head weight bike now 84kg and rear 90kg and me all with equipement about 90kg. The bike weight continu to decrease i think for the next season race being betewen 165 and 170kg.

A friend say me whith calculation, that the spring had to be about 8.5kg per cm and standard spring Commando are 6.5kg/cm... 36lbs/inch it's why i wanted to fit external spring.
 
Gillou,

Reach out to Andy Molnar in the UK.
He has stainless external springs in a few different lengths. It's been quite some time, but I measured a set I purchased several years ago and if memory serves, they came to about 35lbs per inch.
 
Ponder this…. for different race tracks you may want to alter fork spring preload or ease it off, with external fork springs you need to remove the top fork sanction nuts loosen the clip-ons, then remove the top fork yolk & drop the sanctions after removing the front wheel, all this in order to get at the external fork springs. :!:
To do the same thing with the normal set-up you just need to remove the top sanction bolts in order to add /remove preload spaces………….

Try adding some preload spaces to your present set up-you do not need to go too hard or you will have no play in the springs to absorb the bumps :!: :(
 
Holmeslice said:
Gillou,

Reach out to Andy Molnar in the UK.
He has stainless external springs in a few different lengths. It's been quite some time, but I measured a set I purchased several years ago and if memory serves, they came to about 35lbs per inch.
Click to expand...

I've written to Molnar Precision, i wait the answer.

Tahnks
 
No spacers required with the Lansdowne Kit. simply screw in the compression needle ,this restricts the oil flow..in effect adding to compression ressistance.. Re- drilling the original dampers is a complete waste of time, think about it. The hole on the lower damper base ,when its moved the oil just travels up the stanchion 20mm early RIGHT AT THE END OF STROKE! has zero effect on the rebound. .. just spoken to Robert Mceever , we both agree the Original dampers are next to useless, he's going to try the original v Lansdowne ,carn't wait. and he as 4 racing Manx's.

Bernhard said:
Ponder this…. for different race tracks you may want to alter fork spring preload or ease it off, with external fork springs you need to remove the top fork sanction nuts loosen the clip-ons, then remove the top fork yolk & drop the sanctions after removing the front wheel, all this in order to get at the external fork springs. :!:
To do the same thing with the normal set-up you just need to remove the top sanction bolts in order to add /remove preload spaces………….

Try adding some preload spaces to your present set up-you do not need to go too hard or you will have no play in the springs to absorb the bumps :!: :(
Click to expand...
 
john robert bould said:
No spacers required with the Lansdowne Kit. simply screw in the compression needle ,this restricts the oil flow..in effect adding to compression ressistance.. Re- drilling the original dampers is a complete waste of time, think about it. The hole on the lower damper base ,when its moved the oil just travels up the stanchion 20mm early RIGHT AT THE END OF STROKE! has zero effect on the rebound. .. just spoken to Robert Mceever , well both agree the Original dampers are next to useless, he's going to try the original v Lansdowne ,carn't wait. and he as 4 racing Manx's.

Bernhard said:
Ponder this…. for different race tracks you may want to alter fork spring preload or ease it off, with external fork springs you need to remove the top fork sanction nuts loosen the clip-ons, then remove the top fork yolk & drop the sanctions after removing the front wheel, all this in order to get at the external fork springs. :!:
To do the same thing with the normal set-up you just need to remove the top sanction bolts in order to add /remove preload spaces………….

Try adding some preload spaces to your present set up-you do not need to go too hard or you will have no play in the springs to absorb the bumps :!: :(
Click to expand...
Click to expand...

John the reference to spacers is only the spring preload adjustment not the damping adjustment.

But, to Bernard, once the preload suits your weight/style, this is a static set up, you might want to try a different set up on a test day, but it should only be the damping you would want to adjust on race day.

I sympathise with Gillou's budgetary issues.....you don't have to spend money with Maxton, but in the value of a racebike really good suspension for the price of a Fullauto head has to make sense.

You should be able to get a very effective set up with a Lansdowne kit and the right rate of single spring. 8.5kg would seem in the ball park and 6.5kg too light.

It would be easier to get the spring rate right and do a static set up with spacers than to fit extra springs and components, and I can't see how it costs any more than an external spring set up. Last time I bought K-tech springs they were £100 pair. They do them in 0.5Kg steps, but you will need to check for suitable ID/OD and a length you can work with. I did this with Suzuki forks and had a 4" spacer in each leg as compensation for the difference in spring length to teh standard ones, then a few washers stacked to get the sag right.

Andy Molnar externals plus the cups are likely to be very similar price or more.

I also put more weight on the front by using a longer shock to raise the rear ride height, which is something you need to consider with the 6kg rear weight bias you indicate.
 
SteveA,

With little surch and reading this afertoon on the Web, i think your are on the right with Lansdowne Kit.

All the parts i need to fit external spring with standard damper (bad damper...) cost about 231€ and the Lansdowne Kit 307€. I think i waiting just little time and buy it.

For the spring spacer to change the préload i have made this plate :

Transform Roadholder Commando to external spring
 
Our Ludwig ,states spring spacers only change the static hight, the spring rate stays the same,as the spring as a fixed rate this makes sence? if your spacer is 5mm eg the fork will compress 5mm less with the same "weight " appled
Only a change to wire gauge or dia or spring coils rate will alter the fork action. Spacers will only raise the ride hight..sorry!
gillou said:
SteveA,

With little surch and reading this afertoon on the Web, i think your are on the right with Lansdowne Kit.

All the parts i need to fit external spring with standard damper (bad damper...) cost about 231€ and the Lansdowne Kit 307€. I think i waiting just little time and buy it.

For the spring spacer to change the préload i have made this plate :

Transform Roadholder Commando to external spring
Click to expand...
 
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