The 101 Association, Inc.
For the preservation and enjoyment of 1928 to 1931 Indian Scout Motocycles
"You can't wear out an Indian Scout"

Steering Head Stem Clearance - Possible Modification

  • 05 Oct 2020 3:40 PM
    Message # 9285318

    Hi all,

    Time to work on the forks for the ongoing restoration.

    I have to sort out the steering head thread which is worn, so that's work in progress.

    I saw Tim's comment on replacing the whole stem, but I'm going to try replacing only the top part with the guys at Exactweld in the UK doing the welding/brazing. There's nobody better I know in the UK for TIG welding and brazing.

    Anyway to the point, I have screwcut a new threaded section to fit the top cone adjuster and there's a fair bit of "slop" between the thread and the handlebar casting.

    I was thinking that a better design would be to make a custom "Head Adjustment Cone Nut" N1512/17B3 with an extended thin-walled (and threaded) section that extends most of the way through the handlebar casting.

    Then slightly bore out the casting so it is truly round again to fit the new nut.

    This would negate the need for the lock washer as the clamp screws would clamp the centre nut and the outer fork stems.

    Question is ... what do you think??? Has anyone else done this? Or more to the point has anyone done this and found it hasn't worked!

    Also my original centre nut measures 1.300" across flats ... is this right?

    Comments appreciated, thanks Mick

  • 06 Oct 2020 12:55 PM
    Reply # 9287336 on 9285318

    I would not make a thin walled extended nut, that nut would not be as strong as it can be as the internal threads makes a crack instigation especially at the dimensional changes on the outside.

    If not changing the full stem, I would replace the top end of the stem with a reinforcement tube-in-tube in the center, then bore out the handlebar casting as little as possible, with a shallow recessed ledge to stop the insert from sinking further. Then turn a exact fitting steel insert with a rim, that is lightly pressed in. A couple of spot welds would prevent the insert halves from ever turn in the handlebar. Then cut the split slit. A standard stem nut would top that off.

    Last modified: 06 Oct 2020 1:35 PM | Carl-Erik Renquist
  • 07 Oct 2020 7:55 AM
    Reply # 9289161 on 9285318
    Tim Raindle (Administrator)

    Yep, agree with Carl-Erik on the sleeving of the stem tube, any reinforcement to the weld better. A decent weld should be as strong as original, but Bill Erickson had just such a repair completely fracture and his front end fell off last year.

    Personally, I would leave the handlebar clamping arrangement as stock, they generally seem to work quite well, and I would rather use a serrated lock washer than alter an original part, if possible. Maybe fit as is, and update down the road if you feel the need ?

  • 07 Oct 2020 12:27 PM
    Reply # 9289696 on 9285318

    Please be aware that the handlebar casting is an important part of the fork stability. When mounting the handlebar on the fork, the casting must fit snug on the both fork legs but there must be an ample gap between the hole in the handlebar casting and head stem in order for the headlight stem nuts be able to firmly clamp the fork legs solid!

    In the pictures can be seen an example where the headlight stem nuts was not tightened hard enough or tightened in the wrong sequence, the fork legs was moving and a sure sign of that is the red contact rust that developed in the gaps!

    Modern bikes has the upper triple tree, as it is called, made as a separate part but on the Indian the handlebar casting is that part. The headlight stem nuts clamping force that tie the fork legs (those that stick up on each side of the head stem) are most important, as that is the factor that stabilise the fork legs from moving about.

    Correct procedure and first important moment to firmly tighten the headlight stem nuts in order to clamp the legs solid without interference from the top nut, then the fork bearing is adjusted and after that the top nut is torqued.

    The fork bearings should be tightened down so there is no play and just, but no more than it is felt a slight smooth resistance to turn the handlebars from side to side. Modern bikes with tapered fork bearings are tightened down much harder and sometimes there is a set value of the resistance the handlebar should have to turn. Not so on the Indian with somewhat delicate ball bearings and races.

    The top nut is to tie the head stem and fork legs together and secure the top bearing from turning and upset the fork bearing adjustment.

    3 files
    Last modified: 07 Oct 2020 8:02 PM | Carl-Erik Renquist
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