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  • motorcycle stering stem?

    I am making a replacement stering stem for a springer front end i am putting on my chopper. What would be the best machineable and strongest materal to use in this application? I talked to Mondo from denver choppers and he said any steel would work since there is not lateral forces but i want decent machineable steel. I tried using i belive A36 just some junk cold rolled with mill scale. How would 1144 or 4140 or something else. I dont want to get into heat treating since i am not set up for that.

    thanks
    JAson

  • #2
    How about pre-hardened 4142? Will you be welding it or making a mechanical joint? Most stock steering stems are made of tube.

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    • #3
      Many modern stems are machined from aluminium alloy. My bike and my brothers bike both are. I certainly wouldn't make it from any hardened steel, as above mostly they are mild steel tube.
      Peter - novice home machinist, modern motorcycle enthusiast.

      Denford Viceroy 280 Synchro (11 x 24)
      Herbert 0V adapted to R8 by 'Sir John'.
      Monarch 10EE 1942

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      • #4
        If it goes wrong, have the widow post what you decided to use.

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        • #5
          What are you making the rest of the frame out of? Make it out of that. Somebody will point it out if I'm wrong ,but I dont think welding a CroMolly to just any old DOM is going to last.

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          • #6
            That is one of the most stressed parts on a motorcycle. Springer forks are also the most unstable arrangement ever conceived. There are lots of lateral and twisting forces on the steering head parts and they're not trivial. It is my opinion that the steering components can not possibly be over-engineered. There's a reason H-D recommends inspecting the bearings at 10K intervals.

            But I have to admit springers are the coolest looking forks for a chopper.

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            • #7
              How much engineering and thought do you think went into the aftermarket front ends that you can buy out of a catalog. Those things and aftermarket wheels made by some yahoo with a CNC mill scare me to death.

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              • #8
                The spring was the most widley used front end in history and are no more dangerous than moderan forks. Mondo the grandfather of the long bike (motorcycle with the very long front ends) and the nomber 1 springer builder says there is no lateral pressure on the stering stem even if the front end is 3" or 11" over stock. The stem will be one piece of solid ?? and screw into the bottom tree of the springer. This is the way the springer is now but it is for a different bike than mine so the berring races are different so instead of cutting the neck off i am replaceing a removable neck stem.


                thanks
                Jason

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                • #9
                  Evasive maneuvers put a lot of lateral and twisting stress on the steering head. I've chirped my front tire avoiding road hazards. It's even worse with stretched and raked front-ends with overbite (contact patch is ahead of the axle) that cause the bike to fall face down low-side.

                  Check out the maintenance recommendations and costs for a stock Harley springer.

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                  • #10
                    Ask "Mondo" where he got his engineering degree from, Is he a P.E., and what type of stress analysis was undertaken. I can guarantee you there are stresses in that system that must be qualified and quantified or the result will be less than desirable. Anybody can put something together for a show bike, but for a daily rider out on the ride the rules are a little different. Personally I would not ride one of those OCC "Bikes" to my neighbors house.

                    P/R

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                    • #11
                      I have worked one on one with engineers and most dont know anything about what they are drawing. I would rather trust somone that have been building and using the product for more than 30 years. I have seen many times where something was designed to where there is no way to build the thing.

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                      • #12
                        Originally posted by dilligaf
                        I am making a replacement stering stem for a springer front end i am putting on my chopper. What would be the best machineable and strongest materal to use in this application? I talked to Mondo from denver choppers and he said any steel would work since there is not lateral forces but i want decent machineable steel. I tried using i belive A36 just some junk cold rolled with mill scale. How would 1144 or 4140 or something else. I dont want to get into heat treating since i am not set up for that.

                        thanks
                        JAson
                        Stressproof (1144)would work well for this.

                        Guys, before we get all bent out of shape on the stress analysis
                        Draw the force vector on heavy decel - it's almost right up the fork tubes.... which means that the bearings take the guff, not the steering stem.

                        On steering transients, we get some side load - but again, the triple clamp & forks force this right into the bearings. The handle bars fasten to the top triple clamp - so the force is carried by the fork tubes.

                        The head set tube should be really strong, along w/ the frame that ties into it - but the piece connecting the two triple clamps isn't that loaded. Make it out of some strong tube (or solid if you must), and you'll be fine.

                        Engineer in some tapered roller bearings w/ good grease seals while you're there - that will keep the bike handling better for a long time.
                        Bart Smaalders
                        http://smaalders.net/barts

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                        • #13
                          I used stressproof 1144 for my steering pivot shaft. It is 13" long and it started at 1.375 dia. The nuts on the top and bottom are 1"-16 thread.
                          Used tapered rollers and labyrinth seals. Should survive hitting a tree.

                          --Doozer
                          Last edited by Doozer; 04-29-2009, 01:04 AM.
                          DZER

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                          • #14
                            I use grade 5 titanium but these are for race bikes and the stems are periodically inspected for cracks and wear.
                            Non, je ne regrette rien.

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                            • #15
                              thanks for all the replys 1144 it will be.

                              Jason

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