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Front Fork Travel

Submitted by david_cowan on Fri, 25/03/2022
Forums
Commando

HI, I have a small problem with my Commando forks in that they seem to have too much travel when on the centre stand, main problem is that they pull on the lower flexible brake pipe and I believe this could actually stretch so much it would eventually break.

I have rebuilt the forks using new stanchions (measured correct) and everything seems to be correct as per the manual, is there any way I could have fitted something incorrectly that would allow the forks to travel probably about an inch too far.

Grateful for any help before I strip these back down.

 

Submitted by john_holmes on Fri, 25/03/2022

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Have you attached the damper rods to the Fork top nuts, this is what limits the full extension fork movement, if the rods are free the forks drop too much by 1.5".

Fitted by the book it also causes the top out clunk as the damper valve hits the underside of the damper tube top cap. The fix for this design issue is longer top bushes which takes over the role limiting of fork movement and gives a hydraulic bump stop at full extension.  

Hi John,

I was wondering about whether these were attached correctly, reason being I removed the top nut from one of the forks earlier and the rod stayed in place, I will check these out tomorrow and make sure both ae attached.

Are the longer top bushes readily available somewhere?

Thanks,

David

Submitted by peter_denham on Sat, 26/03/2022

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Following same problem M2a.

Submitted by john_holmes on Sat, 26/03/2022

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Longer top bushes

https://www.rgmnorton.co.uk/buy/extra-long-fork-stanchion-top-bush-stops-topping-out-2-9-74mm-o-all-lgth-pr_2298.htm

If rods are connected to top fork nuts then also check that the damper tube top cap is in place and the valve is on the bottom of the rod by pulling up fork top nut. If the nut comes up with the rod too far and the end shows then you need to disassemble and reassemble.

Only check one leg at a time unless you support the bike under the front under the engine. 

Submitted by peter_denham on Sun, 27/03/2022

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Many thanks John Bushes ordered.

Submitted by dave_taylor on Thu, 31/03/2022

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The longer slider bushes do indeed help, however there is another cause of the clonk. The damper top nut/bushes are made of aluminium and wear out quickly over time.

I would advise changing them at the same time as the slider bushes. And for longer life fit the RGM cast iron version. The cast iron version sometimes stiffens up the damping a little and may need a few miles running in to soften out but last for ever.

Regards,

Dave

Submitted by david_cowan on Sun, 17/04/2022

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Hi,

My apologies for not getting back on the forum sooner to thank the guys for their information, it was indeed as John had said that the damper rods required to be re-connected.

I assumed (wrongly) that they would reconnect themselves after I had removed the nuts to fit the clocks, unfortunately they simply fall down into the tubes.

All ok now so many thanks guys, I am posting another plea for information in regards to photo's or diagrams as to the layout of electrics.

 


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