Commando Fork Damper Info

Woolant · Feb 14, 2009

Hi
I am currently rebuilding a 1969 750S (as a roadster) and I am seeking information or the sizes of the piston and tube of the fork damper or the clearance between the two.
I know they are still available new, but do not wish to purchase a set just for dimensions as I am experimenting with making all the Bushes, Caps, and Pistons out of Oilon (oil impregnated Nylon) to reduce stiction.
Any and all help will be greatly appreciated.
Cheers
Tony

L.A.B. · Feb 14, 2009

Welcome to the forum, Tony,

The only unused part of those that I have available to measure is the damper cap of which the damper rod bore (damper rod/cap clearance affects rebound damping) is exactly .375" (3/8").

Woolant · Feb 14, 2009

L.A.B. said:
Welcome to the forum, Tony,

The only unused part of those that I have available to measure is the damper cap of which the damper rod bore (damper rod/cap clearance affects rebound damping) is exactly .375" (3/8").

Thanks L.A.B you guys have some great content here.
I have managed to get pretty well all the other dimensions from various web atricles, just nothing on the piston clearance. I'll keep trying though.
Cheers
Tony

marinatlas · Feb 14, 2009

Hi may be could be helpfull
http://www.members.shaw.ca/randell/dimensions.htm

Woolant · Feb 15, 2009

marinatlas said:
Hi may be could be helpfull
http://www.members.shaw.ca/randell/dimensions.htm

Thanks so much Marinatlas, that was perfect both dimensions were listed. Cheers
Tony

cash · Feb 15, 2009

Tony,
I've had a bit of experience with materials like Oilon, during service it can take up moisture/oil and swell. Contact the manufacturer and they should be able to give all the help you might need.

Best of luck.

Cash

Woolant · Feb 15, 2009

cash said:
Tony,
I've had a bit of experience with materials like Oilon, during service it can take up moisture/oil and swell. Contact the manufacturer and they should be able to give all the help you might need.

Best of luck.

Cash

Cash
The guy that sold me the material did inform me of this although he could not be precise as to waht extra tolerances should be added to allow for expansion. I infact purchased the food grade version which is less likely to swell. I will machine up the parts and leave them sit in oil for a couple days before I assemble the forks. the top bushes will not be a problem if they are a fraction tight, I can run a reemer through them, the bottom sliders I may have to hand finsh if they are too tight; at worst I will have to start again. Thanks for the advice and heres hoping

Cheers
Tony

Seeley920 · Feb 15, 2009

FWIW., Maxton use nylon bushes when they convert roadholders, might be worth giving them a call

http://www.maxton.netspinners.co.uk/

Woolant · Mar 1, 2009

Hi
Well I have reassembled and workshop tested (not ridden) the forks with good results. They work more freely with a lot better action compared with the old steel and phos bronze bushes. I will keep you posted once ridden, thanks agin for all your help.

Cheers
Woolant

Woolant said:
cash said:

Tony,
I've had a bit of experience with materials like Oilon, during service it can take up moisture/oil and swell. Contact the manufacturer and they should be able to give all the help you might need.

Best of luck.

Cash

Click to expand...

Cash
The guy that sold me the material did inform me of this although he could not be precise as to waht extra tolerances should be added to allow for expansion. I infact purchased the food grade version which is less likely to swell. I will machine up the parts and leave them sit in oil for a couple days before I assemble the forks. the top bushes will not be a problem if they are a fraction tight, I can run a reemer through them, the bottom sliders I may have to hand finsh if they are too tight; at worst I will have to start again. Thanks for the advice and heres hoping
Cheers
Tony

cash · Mar 1, 2009

Tony
Good to hear, I hope it all goes great cos I've found a bar of the stuff while cleaning out the garage (moving stuff about). I reckon the top bush could be made a bit longer too.

Cash

Woolant · Mar 1, 2009

Hi Cash
I did that, made them 1.5" longer. then used plastercene to gauge the stroke length in the top of the damper tube before cutting them off, thus creating a bump stop with the bush also.
Cheers
Tony

cash said:
Tony
Good to hear, I hope it all goes great cos I've found a bar of the stuff while cleaning out the garage (moving stuff about). I reckon the top bush could be made a bit longer too.

Cash

Commando Fork Damper Info

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