Results 1 to 15 of 15

Thread: 1992 R100RT TOP Fork Nut

  1. #1
    Registered User b25bsaboy's Avatar
    Join Date
    Aug 2010
    Location
    Calgary, AB. Canada
    Posts
    522

    1992 R100RT TOP Fork Nut

    good day,

    started taking my front forks apart and all is going well. I am at the point that the large hex nut BMW part # 31 42 1 454 959 that sits on top of the upper bracket of the triple tree. Would someone on this board know what size this nut is, so that I can go to my local Princess Auto and get the proper socket. Thank you for your patience and wisdom
    Rick MacPherson
    Success is Not a Destination, But a Journey.
    Accredited Motorcycle Appraiser
    1968 BSA Starfire, 1976 BMW R75/6, 1992 R100RT, 2009 R1200RT

  2. #2
    Day Dreaming ... happy wanderer's Avatar
    Join Date
    Mar 2010
    Location
    Vancouver, B.C. Canada
    Posts
    2,509
    Just pop the plastic cap off the top and measure it. Should be 36mm. Crow foot wrench works best. Or the one in the tool kit... with a rubber mallet.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  3. #3
    Liaison 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    17,336
    On my /7, the nut is 36mm. Do you have a micrometer? Something useful to have...just measure across the flats. Or get your favorite crescent wrench, open it to fit, and go to the store and find something that fits that opening.

    If it's like the /7, it will be a thin nut. Typically, the socket will need to be ground down to eliminate the inside chamfer...you need ever bit of bite you can get on the nut. If it's not like the /7, well, never mind!!
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  4. #4
    Day Dreaming ... happy wanderer's Avatar
    Join Date
    Mar 2010
    Location
    Vancouver, B.C. Canada
    Posts
    2,509
    Quote Originally Posted by 20774 View Post
    On my /7, the nut is 36mm. Do you have a micrometer? Something useful to have...just measure across the flats. Or get your favorite crescent wrench, open it to fit, and go to the store and find something that fits that opening.

    If it's like the /7, it will be a thin nut. Typically, the socket will need to be ground down to eliminate the inside chamfer...you need ever bit of bite you can get on the nut. If it's not like the /7, well, never mind!!
    Not sure it is Kurt. I did a where used search. It was only used on the R65, R80RT, R100RS, R100RT and R80. Did not see the /7 in the list but it could be same size only slimmer. I just popped my cap off and measured 36mm on mine but the flats are pretty big so no problem getting a normal wrench on there. Even easier with the bars off.

    At first I was confused with the top nut which is 41mm I believe.
    Last edited by happy wanderer; 11-13-2016 at 09:50 PM.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  5. #5
    Registered User b25bsaboy's Avatar
    Join Date
    Aug 2010
    Location
    Calgary, AB. Canada
    Posts
    522
    Quote Originally Posted by happy wanderer View Post
    Not sure it is Kurt. I did a where used search Kurt. It was only used on the R65, R80RT, R100RS, R100RT and R80. Did not see the /7 in the list but it could be same size only slimmer. I just popped my cap off and measured 36mm on mine but the flats are pretty big so no problem getting a normal wrench on there. Even easier with the bars off.

    At first I was confused with the top nut which is 41mm I believe.
    Just finished the dishes and went and measured. Answer is 41mm. Thank you, and will pay a visit to Princess Auto our equvilant to Harbor Frieght in the 🇺🇸.
    Rick MacPherson
    Success is Not a Destination, But a Journey.
    Accredited Motorcycle Appraiser
    1968 BSA Starfire, 1976 BMW R75/6, 1992 R100RT, 2009 R1200RT

  6. #6
    Registered User 88bmwjeff's Avatar
    Join Date
    Aug 2004
    Location
    Walnut Creek, CA
    Posts
    2,723
    Quote Originally Posted by b25bsaboy View Post
    Just finished the dishes and went and measured. Answer is 41mm. Thank you, and will pay a visit to Princess Auto our equvilant to Harbor Frieght in the 🇺🇸.
    I had trouble finding that size as well. I ended up ordering a really big open/box end wrench/spanner on the internet. I
    Jeff in W.C.
    1988 R100 RT (the other woman)
    "I got my motorcycle jacket but I'm walking all the time." Joe Strummer

  7. #7
    Registered User lmo1131's Avatar
    Join Date
    Jan 2010
    Location
    Pismo Beach, CA
    Posts
    3,568
    41mm... odd size, probably 40mm.

    You don't have this tool in your roll?

    "It is what you discover, after you know it all, that counts." _ John Wooden
    Lew Morris
    1973 R75/5 - original owner
    1963 Dnepr

  8. #8
    Day Dreaming ... happy wanderer's Avatar
    Join Date
    Mar 2010
    Location
    Vancouver, B.C. Canada
    Posts
    2,509
    Quote Originally Posted by b25bsaboy View Post
    Just finished the dishes and went and measured. Answer is 41mm. Thank you, and will pay a visit to Princess Auto our equvilant to Harbor Frieght in the 🇺🇸.
    If that's the case the -190 part number you posted was for the top of the forks and the 41mm is for the center of the cross brace. Does it look like this? 31421232343_2_B.jpg
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  9. #9
    Registered User b25bsaboy's Avatar
    Join Date
    Aug 2010
    Location
    Calgary, AB. Canada
    Posts
    522
    Quote Originally Posted by happy wanderer View Post
    If that's the case the -190 part number you posted was for the top of the forks and the 41mm is for the center of the cross brace. Does it look like this? 31421232343_2_B.jpg
    Double checked and it's part # 31 42 1 454 959 Hex Nut. Here is a picture and it is 41mm. Went to Princess Auto and with a low level impact wrench, off it came.

    Do have a question for the masses, but I watched a Chris Harris and he reinstalled a spring retainer that has an o-ring. What he did was to rube alcohol on the o-ring prior to installing. As a retired factory representative who was involved in rubber polymers what is the purpose of this practice? This a new one on me and would be interested in why.
    Attached Images Attached Images
    Rick MacPherson
    Success is Not a Destination, But a Journey.
    Accredited Motorcycle Appraiser
    1968 BSA Starfire, 1976 BMW R75/6, 1992 R100RT, 2009 R1200RT

  10. #10
    Day Dreaming ... happy wanderer's Avatar
    Join Date
    Mar 2010
    Location
    Vancouver, B.C. Canada
    Posts
    2,509
    Chris Harris loves using rubbing alcohol to make all things rubber slide together much easier and it does work very well for any rubber parts that you want to slide on easily. My preference is to use red rubber grease on most O Rings as it does the same thing, is an organic compound and actually helps preserve the rubber whereas alcohol dries it out a bit as it evaporates I would think.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  11. #11
    Registered User b25bsaboy's Avatar
    Join Date
    Aug 2010
    Location
    Calgary, AB. Canada
    Posts
    522
    Quote Originally Posted by happy wanderer View Post
    Chris Harris loves using rubbing alcohol to make all things rubber slide together much easier and it does work very well for any rubber parts that you want to slide on easily. My preference is to use red rubber grease on most O Rings as it does the same thing, is an organic compound and actually helps preserve the rubber whereas alcohol dries it out a bit as it evaporates I would think.
    Thank you for the answer, as I thought alcohol might dry out the o-ring. I have always used a very small amount of synthetic grease and all is well.

    Thanks to everyone chiming in on some of my questions which is much appreciated😄🏍
    Rick MacPherson
    Success is Not a Destination, But a Journey.
    Accredited Motorcycle Appraiser
    1968 BSA Starfire, 1976 BMW R75/6, 1992 R100RT, 2009 R1200RT

  12. #12
    Registered User b25bsaboy's Avatar
    Join Date
    Aug 2010
    Location
    Calgary, AB. Canada
    Posts
    522
    Quote Originally Posted by happy wanderer View Post
    Chris Harris loves using rubbing alcohol to make all things rubber slide together much easier and it does work very well for any rubber parts that you want to slide on easily. My preference is to use red rubber grease on most O Rings as it does the same thing, is an organic compound and actually helps preserve the rubber whereas alcohol dries it out a bit as it evaporates I would think.
    Thank you for the answer, as I thought alcohol might dry out the o-ring. I have always used a very small amount of synthetic grease and all is well.

    Thanks to everyone chiming in on some of my questions which is much appreciated😄🏍
    Rick MacPherson
    Success is Not a Destination, But a Journey.
    Accredited Motorcycle Appraiser
    1968 BSA Starfire, 1976 BMW R75/6, 1992 R100RT, 2009 R1200RT

  13. #13
    Registered User lkchris's Avatar
    Join Date
    Mar 2003
    Location
    Albuquerque, NM
    Posts
    5,840
    Quote Originally Posted by lmo1131 View Post
    41mm... odd size, probably 40mm.

    You don't have this tool in your roll?

    OP's bike is a 1992, which has a complete K-bike front end. It should be obvious it didn't come with a tool last used for '84s.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  14. #14
    Registered User b25bsaboy's Avatar
    Join Date
    Aug 2010
    Location
    Calgary, AB. Canada
    Posts
    522
    Quote Originally Posted by b25bsaboy View Post
    Thank you for the answer, as I thought alcohol might dry out the o-ring. I have always used a very small amount of synthetic grease and all is well.

    Thanks to everyone chiming in on some of my questions which is much appreciated😄🏍
    Quote Originally Posted by lkchris View Post
    OP's bike is a 1992, which has a complete K-bike front end. It should be obvious it didn't come with a tool last used for '84s.
    Good point
    Rick MacPherson
    Success is Not a Destination, But a Journey.
    Accredited Motorcycle Appraiser
    1968 BSA Starfire, 1976 BMW R75/6, 1992 R100RT, 2009 R1200RT

  15. #15
    Day Dreaming ... happy wanderer's Avatar
    Join Date
    Mar 2010
    Location
    Vancouver, B.C. Canada
    Posts
    2,509
    Quote Originally Posted by b25bsaboy View Post
    Thank you for the answer, as I thought alcohol might dry out the o-ring. I have always used a very small amount of synthetic grease and all is well.

    Thanks to everyone chiming in on some of my questions which is much appreciated����
    As long as your synthetic grease is not silicone based no problems as long as it is never used anywhere around the fuel or intake systems. Even the tiniest amounts of silicone will contaminate your O2 sensor.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

Posting Permissions

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