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Head stem elongation

Discussion in 'Technical and Troubleshooting Torque' started by Traviss, Jul 31, 2008.

  1. Ive noticed on a fair few second hand bikes Ive dealt with that the head stem tube outer race mount has elongated ,Ive only noticed it on cast alloy frames top mostly ..
    Whats do you think the solution is apart from packing it and why does it always seem to be elongated from rh bottom to lh top.. :?:

  2. I am not sure I get what you are talking about!
  3. The bearing looks like its been loose and its bashed the Alloy tube so is ovaled out ( head stem bearing)when you put the new bearing race in (out side of the bearing) its got a gap at the top left of centre or move the race forward and the gap is at bottom right of centre Ive seen it on a few bikes now 90,s up all aluminium frames Mostly Suzuki's (that's who i worked for) But Ive seen it on an R1 and a ZXR ,Ive just found my rgv Track bike has ovaled as well ..I was thinking of putting a shim in to fix it But was wondering what other do to fix it..
  4. Sounds very strange. I can't say I have ever seen anything like that.

    Things like steering head bearings are extremely unforgiving when it comes to being out of round or loose.

    You sure it's not an optical illusion of some sort?
  5. Devcon make some excellent products that would be quite suitable for that particular purpose. Far better than anything you can buy from any hardware style shop. Visit your local engineering supply store for the good oil :) :)
  6. You could call it out of round its got a 1.5mm gap and the bearing race moves ..I wish it was an optical illusion..My last RGV had it too but worse..
  7. That must make the things just about unrideable!

    I'd love to see a picture.
  8. Caused by heavy landings..?
  9. very common with RGV 250's....when they have had a whack it elongates it out....ive also seen it done from improper straightening techniques..... it can be shrunk back to shape...we have a special part that clamps over the outside of the headstem to hold everything closed when straightening
  10. Fascinating. Can you take a picture for us?
  11. Its hard to take a photo of it that show what Im talking about I will give it a go with a micro camera tomorrow ...

    ylwgtr....Its never had a whack ,lots of heavy braking and Im no mono king ( well not on the V ) Its had loose bearing but not long enough to warrant the damage ( maybe 20 laps of the track 90km at most) It did have a long trip in the trailer with loose bearing tide down from the bars with those slide over the bars sock things ...
    How much do you think it would cost to fix..??
  12. you bought it new?
  13. Hi Travis, Interesting, the only thing I can think of as a cause is road camber. That is an asymmetry that bikes are subjected to over their entire life. Just a guess maybe malarkey :?
  14. Not the bike just the frame I had a spare .
  15. Oval head stem

    When I worked @ Bob Martin Engineering the bikes we saw with that problem had been crashed or heaps of monos. Early R1 Yams & T model GSXR's were the most common. We had a special former to hammer RGV steeing heads round again. Be careful using Devcon or such products as you need to know exactly what the steering head angle is as if it's too steep it will be likely to tank slap, & too shallow it will steer slowly.
  16. You most likely worked on the old frame it had a few trips to Bobby's... Anyone doing that sort of work know that you know of ???
  17. Frame work

    Only Dave Kellet in QLD. He used to work for Bob.
    I'll have a hunt around & see if anyone I know can do it that's a bit closer.
  18. I miss Bob Martin
  19. Me too...I also miss the Ute and trailer going around picking up the bikes ..The last time I saw Bobby was at turn 1 Phillip island during the gp and he always remembered me and my project bikes... RIP Bobby ..
  20. RGV

    Hey Trav, drop me your phone number in a PM. Steve Martin still has the gear & will have a look at it if you want. I'll pass your number to him & he'll give you a call. Duncan