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Steering Head Bearings

Discussion in 'Supersport (1974-2007)' started by Geo7863, Apr 17, 2012.

  1. Can someone please tell me the dimensions of the steering head bearings... I believe they are ID 26 OD 52... but dont know the depth... I am nowhere near my bikes so I cant check!

    cheers

    George
     
  2. Measuring one right now as I type this....

    Outer race depth: 12.7mm

    Outer race O/D: 52mm

    Inner race I/D:26mm

    Inner race depth: 14.28mm

    SKF Reference numbers: Outer 639172 Inner 639174

    As far as I am aware, SKF don't make this size anymore, but there is a supplier on Hayling Island (not much use to you, I guess) that has the equivalent and it appears so do these people.

    900 S Sport S Light 900 S Sport S Light 1993 - 99 Steering Headrace bearing Kit With Seal

    AL
     
  3. Cheers Al :upyeah:

    I dont actually need new bearings in this size, mine has new bearings, however to use the Paso Steering stem on my F1 replica which was made with a Monster 900 Steering head, (same size as the SS) I need a smaller ID of 25mm I know I can get ID 25 OD 52....wasnt sure about the depth required

    The SKF number helps as I can cross reference this with Simply Bearings a UK company who do just about all available bearings and ship abroad no problemo!
     
  4. I think you will find that Simply Bearings won't have them either.....that's why I got mine elsewhere and so did Nog and a few others...

    AL.
     
  5. I will have to wait till I get home and find one of the original bearing packets, I know they come as a complete unit, inner and outer race, you are right that Sinmply bearings dont have any with 14.2mm or 12.7mm depths so I need to know what the bearing depth is actually classed as.... inner or outer race? :frown:
     
  6. Just found on google 639174 is a common steering headstock bearing ID 26 OD 52 Depth 15mm!..... Simply bearings do that size! and ID 25 OD 52 Depth 15mm as well! (the Paso OEM bearing is ID 25 OD 47!)
     
  7. Seems to me that they are measuring the bearing ' assembled' then......

    .......but I am aware there are some difficulties obtaining the right combination of inner and outer race, but I can't recall what the issues are...and I can't recall who detailed the problem....it was on Ducatisti site quite some time ago.

    AL
     
  8. I dont know why there should be problems with disparity between the inner and outer races, I have only ever seen them sold as one complete item!
     
  9. Know it does not help in this case but I got a set last year from wemoto.co.uk
     
  10. You might find this useful (particularly posts 8 & 18)

    http://www.ducati.ms/forums/57-supersport/64925-head-set-bearings.html

    The oddity is the difference in the two reference numbers.....they are a mixed 'pair' and thus form an unusual size bearing.

    AL.
     
  11. Fraid I have to disagree there Al, the two posts just confirm that the outer race and inner race have seperate numbers, doesnt means that they are unusual or mis-matched. I will buy the bearings with the smaller ID and the same OD for the Paso stem I will be using, I bet the outer race has the number 639172!

    As long as the angle of the roller bearings match the inner face of the outer race, and fit proud of the upper edge of the outer race then it matters not what size the outer race OD is or the ID of the inner race for that matter... er .. I think!
     
  12. Ah...but I have an old hard copy SKF catalogue......

    However, those two reference numbers do have the correct angle bearings....

    What apparently happened with some people is that they fitted the 15mm depth bearing available from 'wherever' and the outer race was proud of the frame head recess.

    Still it doesn't really matter if you can get what you want, does it?....particularly as the information in my first reply was correct. :wink:

    AL.
     
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