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Restoring my Dads Fastback

Discussion in 'Norton Commando Motorcycles (Classic)' started by simonha, Aug 6, 2019.

  1. cliffa

    cliffa

    Joined:
    May 26, 2013
    Grüezi simonha, and welcome. As Martin mentioned i live in Wädi. Where are you living?

    I love your bike, but am quite surprised to see that you have an upgraded front brake already so I don't know why folks are suggesting a CNW brake to you. (It looks like a Norvil adapter plate to me). Do you know if it passed MFK with that fitted? If so and it's entered into the fahrzeugausweis I would definitely leave it as it is. I was forced to remove my Norvil brake and revert to the standard Norton Lockheed setup. :( Later I made my own brake upgrade, but still revert it for the MFK ( which it passed last week). I would take a look at the master cylinder, and see if it's been sleeved down to 13mm. If not get a sleeve kit from member madass140 or buy a brand new 13mm. one from Andover Norton (AN).

    Important - Check the rear brake lever has a return spring fitted. If it doesn't again get one from AN. If there is no spring and the cable snaps, the lever will instantly drop to the ground and you and potentially a passenger will both be launched into a low earth orbit.

    There are many upgrades you can do on a Commando, and us owners are extremely lucky that they are supported so well.

    The head steady modification is very worthwhile as it controls the lateral forces imposed on the whole isolastic system through corners (Personally i think the Comstock / CNW one is the best as it used the original mount points). The "Kegler" clamps on the swinging arm spindle are also recommended.
    If you still have the old shimmed Isolastics I would definitely recommend getting a vernier (as fitted to the MKIII Commando ) conversion kit. Again AN sell them, but there are other reputable suppliers such as RGM in the U.K. and as Martin also mentioned a few here as well. As the CHF / GBP exchange rate is so good at the moment I would advise comparing prices before placing an order with either.


    Cheers,

    cliffa.
     
  2. cliffa

    cliffa

    Joined:
    May 26, 2013
    I've just noticed it look as though you already have an upgraded brake master cylinder. ;)
     
  3. cliffa

    cliffa

    Joined:
    May 26, 2013
    I'd replace the plug caps if it was my bike.
     
  4. rvich

    rvich VIP MEMBER

    Joined:
    Jul 25, 2009
    Did some of the 1969 motors have the tach drive off the front of the case instead of off the end of the end of the cam?
     
  5. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    20M3S is the camshaft points/inboard tach drive engine. Early Fastback engine (with tach drive off the timing cover and points housing behind the cylinders) is 20M3.
     
  6. SteveA

    SteveA VIP MEMBER

    Joined:
    Dec 20, 2011
    Simonha, in case you don't know (though you probably do), the front brake you have is similar to the production racer set up having an AP Lockheed caliper and a splined floating disc. You could also have a 6 bolt hub for that disc, not the standard 5 bolt, so be wary what you buy or you may need a new front wheel to complete the job. From the photo it does look to me that you have 5 bolt hub, but check it, and I think that is a CP2696 4 Rib caliper rather than an '70s 3 rib (see below)

    Again, from the photo either your pads have overheated or the disc surface isn't 'clean'.

    Your dad already did a good upgrade from the original twin leading shoe drum (though even that can be improved from it's original performance), to something better than the original Commando disc set up.

    If it isn't working good try overhauling the set up you have before investing in another set up.

    If your master cylinder has a bore of 13mm in place of the original 5/8" bore you have the basis of a good brake. If not performance will be limited by the master cylinder, not the caliper. Check size of the master cylinder, and the condition and if it is 13mm already maybe just change the seals. You might replace the brake hose if it is old. With the caliper, maybe more recent pads can help but replace the seals anyway, making sure there is not any corrosion behind the seals making the pistons sticky. It is difficult to see if the actual caliper you have has a piston seal and a dust seal, but a CP2696 only has piston seals, no dust seal, but seals are readily available for both. Depending on the condition of the pistons they are available too, and in various metals including stainless! Pads overheat if they are stuck on even a little and braking degrades, that might lead to the disc colouration you have.

    The disc itself can be improved if you still aren't happy, either by a new production racer one from Andover Norton, or go with a modern style floating disc. There is a wide range of pads available for these calipers. For road use Ferodo Platinum or EBC green or SBS road should work well.

    The guys telling you what they fitted mainly will have started out with the original Commando road caliper and large bore master cylinder, and maybe even a plated disc. The upgrades they refer to are good, way better than a standard set up. I am not criticising other posters or the suppliers.

    But they had a different start point and are proposing something although potentially better than what you have, by a much smaller margin. What you already have can be made to work very well.

    So going straight to a CNW or Madass set up could be a lot of money for a little improvement.

    What you have is pretty much what I and many others have on our race bikes. And taking the overhaul route leaves you cash for other work.
     
    Last edited: Aug 14, 2019
    cliffa, rvich and baz like this.
  7. JimC

    JimC

    Joined:
    Oct 12, 2007
    Simonha, as for the front brake, the most important thing is to have a 27:1 or near ratio between the area of the caliper piston to that of the area of the master cylinder piston.

    The advice Steve gave you is spot on.
     
  8. rvich

    rvich VIP MEMBER

    Joined:
    Jul 25, 2009
    Thanks for the clarification. Although earlier you posted "The 1969 Fastback supposedly had the 20M3S engine from 133668." The original poster here says his number is 133504. So there seems to still be something not quite lining up. But its probably me. I'm just trying to help out here.

    So for the original poster here, make sure you also understand this when shopping for parts for that motor!
     
    Last edited: Aug 14, 2019
  9. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Yes, that's what I meant by 'supposedly'.

    The 20M3S engine was supposed to have been introduced on the '69 Fastback from (20M3S)133668.

    133504 appears to be a 20M3S engine so either the 133668 number isn't accurate or there's some other reason for 133504 appearing (slightly) too early to be a 20M3S Fastback.
     

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