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flying aceTue Dec-19-06 05:15 PM
Member since Mar 18th 2009
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"front fork too spongy HELP me!!"


  

          

Hello out there, I have come to the source of knowledge concerning the 'Unapproachable Norton"for aqdvice. I have a 72 commando that suffers from spongy, soft( too soft) front forks. I am thinkimg that "progressive" fork springs can aid in solving this problem.I weigh 230 lbs. The stock springs have at least 15,000 miles on them.I don't think that the fork oil is "at fault' Have any of you had any success with this "solution" concerning this "problem"??Your input/advice will be greatly appreciated! ace

  

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dynodaveFri Dec-22-06 07:53 AM
Member since Mar 18th 2009
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#1. "RE: front fork too spongy HELP me!!"
In response to Reply # 0


  

          

I have studied the commando front fork/damper a fair amount.
There are two areas of the front end to look at.
spring rate and damper rate.
The after market front springs by progressive are even softer (initially) than the stock linear wound springs.
Most people find the front springs stiff, considering the commando is actually a touring bike (in my opinion).

The dampers are a fairly crude piece with the damper piston controlling the compression bleed rate.
The extension damping is controlled by the damper cap which wears out quite rapidly if in the presence of a typical neglected/rusty fork damper rod. It eats the damper cap out like a file...
The clearance between the rod and cap is critical for the dampers to work.

Do you get bottoming or topping out? I'd look at the dampers first...and then the oil viscosity. last would be the springs.
I expect if you need to change the fronts, that the rear springs will have to be changed to match also.
Dave
Dave

  

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flying aceFri Dec-22-06 09:26 AM
Member since Mar 18th 2009
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#2. "RE: front fork too spongy HELP me!!"
In response to Reply # 1


  

          

Dyno Dave, I get both bottoming and topping out, as well as a soft feel in the front forks, What do you suspect and prescribe? And do you prefer stock or progressive front springs? ace

  

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dynodaveFri Dec-22-06 10:13 AM
Member since Mar 18th 2009
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#3. "RE: front fork too spongy HELP me!!"
In response to Reply # 2


  

          

If you say it is not the oil....then you must have changed and filled the front end with oil?
I'd suggest a tear down to see what you actually have?
Don't necessarily assume you have stock parts or if stock, that they are any good/not worn out.
There are lots of boy racer/mechanic/engineers(DPO)that may have modified/upgraded(sic) what you have inherited.
My pure stock rebuilt front end is stiff enough for me...I'm 200 lbs.
It only tops out when going on the center stand and that is normal.
Dave C


http://atlanticgreen.com/forks.htm

  

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