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Front Forks Rebuild

Discussion in 'Norton Commando Motorcycles (Classic)' started by tony Targett, Mar 28, 2004.

  1. tony Targett

    tony Targett

    Jul 18, 2003
    The front forks on my 850 MkIIa seem to bottom out with a nasty 'clang' over any decent pothole. They don't seem very compliant but I don't have anything to compare them with.

    Before I start anything I have some questions for the forum:

    1. What is the best source of information on disassembly & assembly? I like pictures!!
    2. What mods are are used to improve the roadholders?
    3. What fork oil & capacity are commonly used? I hear that complete disassembly is the only way to completely drain the old fork oil.
    4. What questions should I be asking?
  2. Ron L


    Feb 27, 2004
    Get a factory service manual and a parts manual. Both have pretty nice pictures and detailed description of how the forks work.
    Popular mods are progressive springs and the "Covenant" damper modification. I haven't done either, but I have had the same nasty "clang" on my cafe racer and plan to someday try both.
    Ron L
    '73 Roadster 750
    '73 Interstate 850
    '75 Production Racer replica 850
    '68 Fastback 750
    '69 P11A Ranger
  3. Jerry Doe

    Jerry Doe Admin

    May 21, 2003

    I rebuild my front end every year. It's pretty straight forward, and a manual will help.

    Fork oil should be 20 or 30 weight- I use 20.

    After this years rebuild the front end was clanking over bumps as you describe. I removed the oil and noticed I put twice as much (300cc) in each leg (too much homebrew :oops: ).

    The interesting thing is that I had read an article previously, which suggested too much oil will create bottoming out, but I did not believe it.

    The fact is too much oil in the fork legs will make them clank. Once I put the right amount in each leg (150cc) everything was perfect!

  4. norbsa48503


    Apr 7, 2004
    I got the Alum. damptner tubes from British Spares NZ. They already have the holes moved up the one half inch. Be carful if you use these they need a 8mm fine thread screw to hold them in the bottom of the sliders. This change prevents toping out not bottoming out. To solve bottoming use progressive springs and add washers to shimm these springs until you get the right amount of drop when you sit on the bike. Leak proof seals a "brand name" seem to last a long time. I run gators not scrappers. I like this set up have it on both Commandos. norbsa

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