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Machining an axle - Melb

Discussion in 'Modifications and Projects' started by mattb, Mar 16, 2009.

  1. Hey all.

    I'm no fan of Yamamags!

    I want to go from this...


    ...to this...


    ...in one easy exercise. The front wheel is off the GR650, not that I'd steal the GR's, but another would be easy and cheap to get. Can anybody recommend a good place in Melbourne to get a new custom axle machined and a bracket fabricated (to move the caliper into position)? Preferably somewhere that doesn't charge an arm. Of course if its a private genius with the tools in his back shed who will give the time of day to boot, even better. Fortunatley, the GR wheel, which requires a shorter axle to fit my forks, requires a slightly thicker axle than the SR, so the custom axle would need thinner ends to fit the SR forks (if it were the other way around the task would be impossible with this wheel).

    Of course, this modification will also improve horsepower.




    Witness something like the final product - still a long way off; I'll be doing new bearings all round, painted frame, one third wiring ditched plus various switches ditched (with no battery, just a hidden on-off switch and bare essentials - indicators etc), chrome Royal Enfield tank (modified bacause of the oil-in-frame), flat and very rearward beach-cruiser-style (bicycle) handlebars, that Smith's chronometric speedometer I have sitting waiting...and a polished engine rebuilt for longevity - not performance, except for...a heavier flywheel! (either new aftermarket from Japan, or modifying the stock one)...And all of this, flywheel / engine aside, at quite a budget DIY price.

  2. You need a eccentric axle to get up to that fork. Could make the ride a bit bumpy.

    OK now for some help.

    can you do it by getting different size bearings? i.e same OD, but different ID.

    also make sure it's a better grade steel. 1040 or similar.

    edit: Bushes in the fork ends?
  3. I have a bloke westside of town who can do it but unfortunately he aint cheap but does an excellent job. if you want his number let me know.
  4. Good raw material for stuff like this can be had in the form of scrap car halfshafts/driveshafts. Cheap as, astonishingly tough and reasonably machinable as long as you avoid the (generally hardened) splined ends.

    Head studs from giant industrial diesel engines are also good, but rather less easy to obtain unless you know the right scrapyards.

    Worth remembering if you find an enthusiastic amateur to do the job and have to supply your own material.
  5. Thanks guys. I might get back re that phone number. In the meantime the bearing solution sounds like the easiest method if they're available.

    If not, I wonder if tubing would do the job as a sleeve over the SR's axle, one that fitted perfectly over it and was then machined down to the right thickness to take the standard GR wheel bearings...
  6. I'd suggest a cheap and simple sleeve like that would end up wearing and developing play if the tube started out as a slide-on fit. Maybe a machined sleeve very slightly undersize, heated and slipped over the axle, then finally machined to take the bearings.
    Different bearings is easy if they're available, or look for another wire wheel with matching axle size.
    A wheel off a trail bike might work (maybe an older drum brake model would look good) and then lace an 18" or 19" rim to it.
  7. When looking into bearing swaps, ths site may be of use as it lists all the common (and quite a few uncommon) ball races by ID, OD and width, allowing you to pick something that will fit both wheel and spindle (if available).

    SKF's website also has a very comprehensive catalogue listing on it, but I find it hard to navigate, slow and prone to crashing.

    +1 to using a shrink fit sleeve rather than a sliding fit. The idea has quite a bit of merit as you already know your current spindle is strong enough for the bike.
  8. Hey Pat, you didn't include the webiste address or link - I'd be very interested to look at it.

    I've managed to find this source of info for axle sizes http://www.postclassicracing.com.au/forum/viewtopic.php?f=9&t=3005

    The point about lacing up a 17mm dirtbike wheel is making a lot of sense too - especially as I could get one with a quality drum brake, which I'd prefer to disk provided I could get it sorted to work well (fortunately I engine brake a lot on the SR - on past bikes I've experienced both dangerous front drum fade, and rear drum mild seizure; currently the SR has disks front and back). Would also overcome the caliper-position issue, and would be fun to make up my own wheels. Of course, the disk doesn't look that bad...and it's mighty functional!

    A wreckers nearby is importing and wrecking used SR400s, and I could get a set of bolt-on spoked wheels with all components, including a big front drum. However it would cost me a grande, which is about six or seven hundred more than I want to spend!
  9. What would you do with the rear Matt? That'll be trickier...

    Also, you want my old SR400 shocks? Great condition but soft as buggery. I'll swap you for your short stiff ones. (Ahem)
  10. Sorry about that.

    Here it is


    They've recently change their site, making it harder to find stuff, but everything still seems to be there. Bearings in the typical bike wheel bearing sizes should run between $5-$10 a pop for sealed units. having bought some recently for one of MrsB's sculpture projects, I was pleasantly surprised to find that they were good quality Japanese kit too.
  11. I used XS650 wire wheels, which fit straight into the SR500 forks. If I recall correctly (it was a while ago) the SR disk went onto the XS wheel - which let me add twin-disk XS1100 brakes.

    I think you need an XS650 from after 1977.
  12. Are you serious about that?...if so, you've got an unequivocal deal! Even if you're in two minds and want to do a trial swap. I hate my friggin' shocks, but I'm sure they're great for a cafe racer; people comment on them as some upgrade, while I want to kick them in and raid an old Virago! They certainly do handle well, only offset by the fact that the swing arm wobbles about on screwed bearings and that I don't utilise the potentials of great handling enough to care.

    The one trouble with the XS is that every man and his dog (as opposed to just every man) is after the stuff, especially the wire wheels; but I continue keeping the ears out for them. I'll check out these bearings though, might be a nice easy fix, or open up other wheel possibilities - there's a million 15mm axled wheels out there, for instance. About the rear, I'll do it as I can, but am not too concerned with living with the mix in the meantime; somewhere on the web there's a guy's XV750 with a spoked front conversion and the mag rear which is covered over by cool homemade saddle bags...dodgy b*stard! I wouldn't do that! :wink:

    Thanks guys,
  13. Yeah, it's a deal mate. Trial them and see how you go. Your shocks look a bit knackered, but you'd be saving me $400 in getting some rear shocks. The SR400 ones I have are pretty trick looking.

    Drop me a line anytime you want to swing by and pick them up. I'd be interested to see how soft you find them. I've also got some soft as front fork springs if you want them?
  14. I suppose you could go for the dry lake racer look and hide the rear wheel spokes with ally discs. Beware crosswinds though :shock: .

    If you can get hold of a wheel/brake/cush-drive/sprocket carrier assembly that'll fit in your swing arm, half the job's done. Bearings can be swapped, sprockets can be spaced to line up properly, spacers can be made up to centre the wheel, custom sprockets can be had to match chain widths. IIRC the SR has a drum at the back, so I'd be looking at older dirt bikes and the like for a hub and brake assembly. Given a suitable hub, you can lace on pretty much any rim you like.
  15. That - the rear - is one area where it would be especially nice to find an XS wheel. The axle is bigger again but it's simply a matter of having the swing arm drilled to take it and everything else bolts and matches up, same with the XT, which is a much more likely candidate in terms of finsing a wheel and on eat a good price (and which of course is closer to the SR as most of you would know: the SR is essentially the XT and TT tarted up to look like a pommie road bike).

    Marlon, you just made my day!
  16. No worries mate.

    Oh, and did I mention I might need a hand getting the engine out of the frame? :grin:
  17. What you're looking at with 15x35x11 mm is a 6202. For bike wheel bearing service, I'd go with either this with rubber seals or this with metal shields. Of the two, I'd generally go with the rubber. Both are sealed for life so wheel bearing maintenance (though not regular condition checks)becomes a thing of the past until they wear out again, which should take quite a while.

    To fit a 17 mm axle, you'd need bearings with the same OD and width but, obviously, 17 mm ID. My pick would be this in the absence of any 11 mm wide bearings with suitable diameters. The slightly narrower width may or may not be a problem depending on how the bearings are fitted into the XR wheels.

    Provided that the narrower bearings are pressed fully home into the XR housings, the tubular spacer that fits between the inner races should still be the right length as the inner faces will remain the standard distance apart. As you will be needing spacers made up to fit between bearing inner races and the forks anyway (unless, by some automotive miracle, the SR and XR forks have identical inner face to inner face dimensions), these will just need dimensioning to suit.

    The most likely area to find problems is how the outer races are secured in the hub. They may simply be a press fit, in which case there is no cause for concern. If, however, they are held in place by a circlip, there will be a 1 mm gap between circlip and bearing race. I've seen gaps like this ignored without apparent ill effects, but it would be much better to address the issue properly.

    There are a number of options. Simplest would be to insert the bearing using bearing retainer to provide longitudinal location, using the circlip to act only as a retainer of last resort.

    A nice "engineering" solution would be to make up a spacer ring from 1 mm thick ally or steel (or copper or hard plastic or anything else really) to take up the slack. Quite a bit of tedious filing work involved without access to a lathe though, and if you make it even fractionally too thick, you'll never get the circlip in properly anyway. More work required to thin it down. Made in ally, a cheapo Bunnings holesaw kit run slowly in a drill would help.

    The real way to do it would find a circlip 1 mm thicker than standard, then stick the bare hub in a lathe (or the whole wheel given a big enough lathe) and carefully widen the circlip groove to suit. This is sledgehammer to crack a nut territory though.

    The larger internal diameter means that the balls will be smaller than in the 6202s. In theory this will generally mean the bearing will have a shorter life and will have a lower maximum load. However, in bike use, where most bearings will be working well within their load limits and where failure is generally a result of dirt ingress or lack of lubrication rather than bearing design, I wouldn't be concerned.

    As far as all the various other factors involved in picking bearings are concerned, for bike wheel bearings I wouldn't worry too much. Bike wheel bearing service is not mechanically arduous (rotational speeds are relatively low) and condition is readily checked by simple spin and wobble tests with the bike on its stand.

    You could go to the stainless steel units but I wouldn't regard it as necessary in Australia. I might consider it if I was running a bike in the UK again though :grin: .
  18. Thanks Pat, as usual mega-helpful!

    I've found a few source for rims and of course spokes are cheap, and I've found some instructions for lacing the whole thing up. The SR500 takes 19" rims, while QuaterWit's SR400 takes 18", so I'll have to hum and harr a bit about that...
  19. Well, 18s will give you a wider choice of modern rubber, or, at least, that's the impression I get when looking for 19" hoops for the Ural. I know you're more a cruiser than a racer, but it's always nice to have more grip in reserve.