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Material for Motorcycle Axle?

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  • Material for Motorcycle Axle?

    One of my customers bought an ebay front end for his bike,unfortunately it didnt come with a front axle.This is a hidden type axle setup,and its proving to be an oddball size. Would be alot easier just to make what he needs rather than scrounging....what material is best for this?

  • #2


    • #3
      Who made the front end?


      • #4
        I'm no expert, but I would guess 4130. I don't know too much about motorcycles, but we used to use 4130 for all of the FSAE axles and the Baja car king pins/stub axles. The FSAE vehicle went to some exotic stainless alloys and nickel super alloys for the axles. PITA to machine, but they can be made smaller and lighter that way.

        I guess stress proof makes sense - the front axle on the motorcycle doesn't have to transmit any torque...


        • #5
          Hidden axle: Off ebay.??

          Probably a inverted tube front end from Midwest. (Ultima brand??)
          Good news is they are $30 or so.. bad news is they made several different designs of them.

          The axle on the front end here, seems it has a bearing preload adjustment on it, then it all bolts up into the "bullets" shaped covers on the lower legs.

          The newest sales flier, the triple trees are like $125 (117x237), and the tubes' and sliders (117x236) are $299

          THE crane cams hi-fire single fire ignition kit is a good deal this month too at dlr cost of $164.. all tuning parameters are adjustable.

          If you can provide Fork part numbers I will get a part # for the axle Monday for you through my rep.

          (I gave $750 for one of these just a year or two back)
          Last edited by Dawai; 05-02-2009, 04:49 PM.
          Excuse me, I farted.


          • #6
            Originally posted by David E Cofer
            THE crane cams hi-fire single fire ignition kit is a good deal this month too at dlr cost of $164.. all tuning parameters are adjustable.
            Quick sidebar - Crane Cams has been bought by S&S so at least the bike parts will continue. Dunno about the auto stuff.

            Anyway - a front axle is nothing to experiment with. I'd rather have swine flu than build one, but then I've stood over the open graves of a couple friends who broke front axles. There's a lot of science that goes into making them strong.

            I have a rear axle from my Harley in the garage - I removed and replaced it when I spun a bearing back there. It looks fine but I'm not going to risk it. If at all possible get a factory-built axle. If not, crack the books and see what kinds of treatment and metal is appropriate.


            • #7
              I built an axle for my former Harley Shovelhead motorcycle. I used a 3/4" 4130 rod. I threaded one end to 3/4-16 and welded a 1-1/4" stainless steel nut on the other end. It worked perfectly for the 15 years I owned the bike. I made it because I added some heavy 1/4" thick stainless steel washers on the outside of the swing arm to protect it. That caused the need for a 1/2" longer axle. I don't think you would need anything stronger or harder than 4130.


              • #8
                Probably a inverted tube front end from Midwest. (Ultima brand??)

                Hmmm...I swear he told me Mid Usa. I have no idea if its inverted or not,havent seen anything other than the caps for the lowers. He DID tell me he's already ordered 2 axles from they're part #'s and neither did the job.I'll agree an axle is nothing to play with,and I've mixed emotions about the whole setup. This is mainly due to the fact that he (and alot of others) buy this stuff from ebay,many missing pieces,and then come to me to sort out the mess. As much as I'd like to tell him to stick it where the sun wont shine,he's been a good customer,and I'd like to follow thru. I've done alot of bike stuff lately,got a BDL drive in the shop now re-doing races,but am not very comfortable with this axle this a liability issue? If so I dont think I need to be involved,we're a reputable shop with a good customer base,and I def dont want to endanger any of that.


                • #9
                  Proprietary axle fits that front end. It has a flat flange on one end and a nut on the other.

                  They come with the front ends normally, Have "customer" go through the supplier off ebay. Probably one came with the front end, laying in the corner and didnt' get shipped with it.
                  Excuse me, I farted.


                  • #10
                    4130 will do the job. It has the right combination of high yield strength and resistance to fatigue cracking. That is why it is used in the most critical parts of aircraft where failure is not an option such as wing spars, landing gear struts, control columns and engine mounts.
                    Free software for calculating bolt circles and similar: Click Here


                    • #11
                      As said before 4130 is a good choice, no doubt. I myself prefer the 4150 heat treated, or the 4150 heat treated,stress relieved. It has super strength, super wear resistance, plenty hard enough, and dosen't "brittle up" badly when welded on. I promise you that the original was probably 1118 since it machines easyer than the old common1018 carbon steel. Any chrome-molly is superior to any carbon steel. I make a lot of stuff out of 4150, sometimes a little tuff to machine. But in the end, makes a better part. I have seen chrome molly hold up long after the others failed.

                      Also, new member here, my first comment in the forums. New to computers too.

                      Your friend, Doggie


                      • #12

                        I used 3/4" O-1 drill rod. Fit my bearings nice and threaded nice as well.



                        • #13
                          Did a little research looking through catalogs I have, and on the net, and have found that most are made out of 4140.

                          Here's a link to a $6,300 Baker wide tire kit which also comes with a 4140 axle, just as an example that it's not a mickey mouse choice and probably has a bit of engineering behind it as far as choice of materials goes.

                          The Linky
                          Home, down in the valley behind the Red Angus
                          Bad Decisions Make Good Stories​

                          Location: British Columbia


                          • #14
                            Jap OEM hollow spindles are ususally made from some kind of mature cheddar, judging by how easy it is to round-off the corners of the hex part.
                            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


                            • #15
                              I'm waiting for the post that says no don't make one, it will break and every slimeball will sue you.
                              14 posts and it hasn't appeared yet ?

                              Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.