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Post by Just Plain Bill on Sept 8, 2008 1:02:27 GMT -5
I will be mounting a TX750 rear wheel which has a 20mm axle on my SR500. Presently I plan to put spacers over the SR500 axle to build it out to 20mm where it is inside the TX750 wheel and leave it at 17mm where it slides in the swingarm. (I'll use a short spacer in the brake drum part and a longer spacer in the wheel hub portion.)
I've found a source (in England) of EN AW 6060 aluminum round tube with a 20mm OD and 17mm ID, which would eliminate machining concerns except for cutting to length. I've also found a length of carbon fiber tube with an OD of 20.6mm and ID of 14mm. Obviously, the aluminum tube would be easiest since I am not the world's greatest machinist and have never worked with carbon fiber, but are there any physical properties of the two materials that would make one better or worse for the intended purpose over the other? My gut says use the aluminum and be done with it.
Bill
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Post by solo2racr on Sept 8, 2008 1:20:45 GMT -5
Stick with your gut. The carbon FRP is the wrong size and can't be machined. There would really be no real benefit to using it anyway. Even if it was to correct dimensions. Get some 1" (25.4mm) round bar and drill the inside close and bore out to the correct size. Machine the outside and leave a bit of a lip. Leave the OD just a bit (.0005) over size so to get a bit of a press fit. With that little bit of difference, you should be able to put the spacer into the freezer over night and it should practically drop in.
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Post by StewRoss on Sept 8, 2008 1:59:52 GMT -5
Hi, I am a little unclear of what exactly you are planning on doing so it's a little difficult for me to comment...I have fitted a TX rear drum to my black cafe racer and I made top hat bushes to sleeve the bearing ID down to 17mm and I made a 17mm, shortened bearing spacer for the inside to suit the bushes...I then made 17mm spacers to suit the rear wheel placement in the swingarm.   I'd probably go for alloy or steel for the sleeve in preference to CF. 6000 series is not bad, but 7000 would be better. I have my doubts that the 20.6mm CF would fit through the centre of the wheel anyway...plus stay away from machining CF as the dust is bad stuff! Do you plan to 'sleeve' the entire centre of the wheel (right through?) with the alloy/carbon tubing? That would work I guess, so long as you allowed a small amount of movement inside the bearings and around the axle...if it rusted/corroded there it may be hard for you to remove the axle...make sure to use plenty of waterproof grease. Not 100% sure how alloy would stand up over time...probably OK. The wheel to swingarm spacers could be made from anything suitable, steel, good alloy etc. Are you using rod back brake actuation? Good luck with it... SR  |
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sven
Full Member
Posts: 166
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Post by sven on Sept 8, 2008 10:59:52 GMT -5
Hi Bill! Aluminium is the correct material for your application. You don't need a "tube", just (axial) spacers with a little bit of tube that sits in the bearings (sorry for that english) Here's a picture of a front axle I turned for my XT:  See what I mean? Regards Sven |
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Post by Just Plain Bill on Sept 8, 2008 19:30:04 GMT -5
Thanks to you all for the great advice.
Stew Ross, what I'm doing is what you did and now that I've received some guidance, I'll be making aluminum "hat" bushes for the bearings and a spacer between them. I even have a hunk of round aluminum bar stock for the bushes -- though I'm not able to hold tolerances in the tenths of thousandths with my pre- WWII Logan 11" lathe.
I have parts from the foot pedal to brake drum arm from an XS650 to swap out for the disk brake set up. Haven't trial fitted it yet, except for the pivot in my frame. If necessary, I will use a cable for the rear brake as on Stew's black racer.
Bill
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