+ Reply to Thread
Page 1 of 2
1 2 LastLast
Results 1 to 10 of 15

Thread: 851 M1r forks

  1. #1
    Join Date
    Jun 2007
    Location
    Asheville, NC
    Posts
    26

    Default 851 M1r forks

    Hi Folks,

    After having worked on a few sets of the M1r forks, I thought I would post up some detail on what we found.

    The M1R are an interesting fork and a sophisticated set of non cartridge type fork (I consider them damper rod forks).

    One of the legs has a rebound adjuster at the bottom and provides both rebound and compression damping. The adjustment range of the rebound damping is quite good as seen on the dyno test below:



    The second fork leg has only compression damping and is setup to provide position relative damping which is a harder thing to show on a simple graph:



    The compression graph is roughly showing the compression force vs position over the first 2" of travel while the rebound graph shows force vs velocity. While the tests were run with out a spring, it is not practical to do the runs without some effect from the air spring force in the fork. Some educated extrapolation and my choice of what I displayed here minimize this issue.

    Damping wise, these forks are not bad for the type. In working on these forks, I feel it is important to respect the engineering and design of the era and not irreversibly change those features. Today, we would not be looking to use a position sensitive damping profile. The total forces made by these forks are somewhat high in compression. we suggest non-destructive methods of reducing the compression fork (namely, using lighter oil).

    We have had custom springs wound for this fork that allows replacement of the OEM spring with the full retention of the stock internal parts (including the steel spring guide cup). With this knowledge and the correct spring, we are able to service and tune these forks to be suitable to a specific rider without losing the character that makes these bikes the classics they are.

    We found that fork seals are easy to come by but the dust scrapers seem to be unobtanium. We have seals and some additional custom springs in our stock.
    Last edited by NC Rick; 04-07-2011 at 10:08 AM. Reason: Spelling
    Rick Tannenbaum

    http://motocd.com

  2. #2
    Join Date
    Jun 2007
    Location
    Bris Vegas
    Posts
    3,371

    Default

    Thanks Ric, I have a set of M!R's for a bevel I'm going to get around to fitting one day. They are in need of attention. The bloke I brought them off was machining up different slugs for inside the rebound adjuster. Unfortunately I haven't pulled it apart to see what state it in at the moment.

    Griff

  3. #3
    Join Date
    Nov 2007
    Location
    Gothenburg, Sweden
    Posts
    668

    Default

    Thanks for the info.
    I have a spare 38mm and 41,7 on lav 500.

    Cheers
    Thomas

  4. #4
    Join Date
    Jul 2008
    Location
    Cottage Grove, Oregone
    Posts
    39

    Default

    Hello Rick: Dust seals are same as on the Guzzi 1100 sport of the 1990s with 41.7mm Marzocchi forks. I have order them from Moto Mecca spares in the UK. SAME.

  5. #5
    Join Date
    Jun 2007
    Location
    Asheville, NC
    Posts
    26

    Default

    I never put the Guzzi fork and the M1R thoughts in my head at the same time. I recently fit a pair of our 25mm fork cartridges into a set of the 1100 forks and ordered seals for them. I have a source for those. Thanks for the tip!
    Rick Tannenbaum

    http://motocd.com

  6. #6
    Join Date
    Oct 2010
    Location
    Frankfurt, Germany
    Posts
    169

    Default M1R dust seals on ebay

    there is a company on ebay based in the UK selling sets of oil seals and dust covers complete for a lot of different bikes, prices look good, but I haven't bought from them so I don't know about the quality. This is the set for Paso 906 1989 FORK SEAL DUST SEALS Set: 270634221923, they don't mention dimensions, but as far as I know are M1Rs.
    Here's the same thing in Australia: 390331057982
    and New Zealand: 190505202106
    all the best
    Ian
    Last edited by 851 tricolore; 08-30-2011 at 11:20 AM.

  7. #7
    Join Date
    Aug 2008
    Location
    Hastings, NZ
    Posts
    281

    Default

    M1R forks came in two diameters 38mm and 41mm (40.7) make sure you confirm the right size.

  8. #8
    Join Date
    Apr 2008
    Location
    midwest
    Posts
    888

    Default

    Quote Originally Posted by 851 tricolore View Post
    there is a company on ebay based in the UK selling sets of oil seals and dust covers complete for a lot of different bikes, prices look good, but I haven't bought from them so I don't know about the quality. This is the set for Paso 906 1989 FORK SEAL DUST SEALS Set: 270634221923, they don't mention dimensions, but as far as I know are M1Rs.
    Here's the same thing in Australia: 390331057982
    and New Zealand: 190505202106
    all the best
    Ian
    Be careful with Pyramid Parts as I had made an order previously for the M1R seals and they sent me 41mm instead of 41.7. I ended up using www.motomeccaspares.com as mentioned above and I got the correct dust seals (41.7) so I recommend them also.

    Quote Originally Posted by Claire4dukes View Post
    M1R forks came in two diameters 38mm and 41mm (40.7) make sure you confirm the right size.
    Actually 41.7mm

    Robert

  9. #9
    Join Date
    Jun 2007
    Location
    Bris Vegas
    Posts
    3,371

    Default

    We have loads of 41.7 fork seals on the shelf at the shop.
    Griff
    To infinity and.......

  10. #10
    Join Date
    Apr 2008
    Location
    midwest
    Posts
    888

    Default

    Well, the truth of the matter is I am not even going to bother with my M1R's as I've got a recently rebuilt pair of Showa 41usd that I am currently cannibalizing from one of my 900ss. I figured the M1R's will never be as good as the Showa's so why bother putting time and effort and $$ into them.

    Robert

+ Reply to Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts