woody Posted November 11, 2014 Report Share Posted November 11, 2014 Having a few issues with rear wheel alignment on my MK1 MAR Does anyone know the length of the original spacer between the sprocket and swingarm please - this is the original dished sprocket with the longish spacer I've now fitted a new dished sprocket on a newly built wheel in place of the old flat conversion but the spacer is long gone. Normally I'd just measure the gap and make the spacer but I've an added problem. The wheel that came out of the bike was the original MK1 with thinner brake shoes but it had some damage. The wheel I've rebuilt is a MK2 with the wider shoes and the MK1 brake plate won't fit (I'd forgotten there were differences and the brake plate for this wheel is broken) When the wheel is tightened the brake plate lip fouls the hub as the boss on the inside isn't long enough. It needs spacing to stop it fouling when tight, but when the wheel is then fitted it is 10mm too far to the right and I can't get the chainguard on. The wheel offset is correct so either the spacer I made isn't long enough and the swinarm may have closed up, or there is still some sort of issue with the brake plate that is pushing the wheel over. I could do with knowing the original spacer length so I'm at least starting with the correct measurement on the sprocket side, so if anyone can help it will be appreciated 1 Quote Link to comment Share on other sites More sharing options...
lbhbul Posted November 11, 2014 Report Share Posted November 11, 2014 Woody, With the thing 10mm off I take it the chain also wont line up. You may well have to machine the brake plate, as you say it is a slight miss match of parts. I know someone will know the original spacer length. Just making conversation. I have faith you will figure it out. Larry Quote Link to comment Share on other sites More sharing options...
dadof2 Posted November 11, 2014 Report Share Posted November 11, 2014 Why do away with the flat sprocket conversion which is superior to the dished sprocket arrangement? Quote Link to comment Share on other sites More sharing options...
woody Posted November 12, 2014 Author Report Share Posted November 12, 2014 Woody, With the thing 10mm off I take it the chain also wont line up. You may well have to machine the brake plate, as you say it is a slight miss match of parts. I know someone will know the original spacer length. Just making conversation. I have faith you will figure it out. Larry Well that's the strange thing as the chain seems to line up ok, I've also ridden the bike a couple of times with no chain issues. Although the wheel is noticeably set to the right it doesn't affect riding but I can't get the chainguard on and this weekend' s trials could be very muddy and to ride the Ossa, it will need a chainguard I need to have another look tomorrow and see if I'm missing something obvious. I've already had a go at machining the brake plate but things didn't go quite to plan... Why do away with the flat sprocket conversion which is superior to the dished sprocket arrangement? I absolutely hate loathe and detest that flat sprocket conversion. Original looks much nicer and I have a spindle a mate made me some time back from better material than the original, so no bending issues. I also have one of Keith Horsman's spacers with extra bearing that gave more support to the spindle to go with the dished sprocket but can't find it at the moment. Quote Link to comment Share on other sites More sharing options...
lbhbul Posted November 12, 2014 Report Share Posted November 12, 2014 Woody, If the chain lines up; few things left to do as you will have a hard time making up 10mm. By your description the tire must be very close to rubbing & certainly not pleasing to your eye. The only answer to me is to compensate the off set, I realize that is probably not what you want to hear, but this is long distance & you will probably find the elephant in the room as you stare. Good Luck Larry Quote Link to comment Share on other sites More sharing options...
woody Posted November 12, 2014 Author Report Share Posted November 12, 2014 I have the measurements I need now Thanks to John at Twinshockshop for scrabbling all over a MAR this morning with a tape measure Quote Link to comment Share on other sites More sharing options...
lbhbul Posted November 12, 2014 Report Share Posted November 12, 2014 Woody, Please let us know what the answer is as I for one had this on my mind and woke up early to check on you. Larry Quote Link to comment Share on other sites More sharing options...
woody Posted November 12, 2014 Author Report Share Posted November 12, 2014 Turned out it was the offset after all. The original wheel that came out of the bike has the MK1 hub, flanged rim and is fitted with a flat sprocket. The wheel I had built is a MK2 hub with a dished sprocket and non-flanged rim. In trying to compensate for the different measurements of the different components, I got something wrong, so when checking the offset of the new wheel against the old it looked correct but as it turned out, wasn't. Once I had had the measurements I needed from an original bike still fitted with dished sprocket, I dug out another original MK2 wheel and found an old dished sprocket to fit to it. Put this in the bike and checked the measurements against those I'd been given and they matched. Checked this wheel against my new wheel and the difference in offset was apparent. That's now been corrected, chainguard is fitted and ready to go, I hope, for the weekend. 1 Quote Link to comment Share on other sites More sharing options...
lbhbul Posted November 12, 2014 Report Share Posted November 12, 2014 Woody Thanks for the reply and glad it is sorted. Good luck for the trial. Larry Quote Link to comment Share on other sites More sharing options...
dadof2 Posted November 13, 2014 Report Share Posted November 13, 2014 I have had and seen a bit of fun with Ossa rear wheel spindles. First one kinked when bike was about 2 &1/2 months old, bearing collapsed at about 40 mph on the road, back wheel locked and I slid to an emergency stop sideways on and was damn near hit by following car. Next I bought a high tensile spindle that at worked fine for following 5 months. Then on 3rd gear hill climb out of a stream the spindle snapped just where threads start (possibly spindle over hardened and brittle). Then had to sit out the trial until a friend brought a spare spindle afterwards. Next bough a flat sprocket / extra bearing conversion. I think Bill and Mick Wilkinson eventually cut the back out of their swinging arms so the wheel could be removed even if spindle bent. Quote Link to comment Share on other sites More sharing options...
woody Posted November 13, 2014 Author Report Share Posted November 13, 2014 Yeah, I've had some fun with them too When I had my first MAR, at about 16, I was still very much 'learning' mechanics. The rear spindle had bent and I hadn't a clue how to deal with it. I had the bike on the stand in the garage, a lump hammer and a drift which I'd found in my grandfather's array of tools we'd inherited (he was a hightly trained electrical and mechanical engineer at GEC) It probably wan't a drift come to think about it, more likely some intricate tool for precision machining... Anyway, I was knocking hell out of this drift, trying to drift the spindle through and out of the sprocket side. It was seriously stubborn but it was moving eventually, bit by bit as it was bludgeoned through the spacer. All of a sudden it gave, without warning. All resistance to the drift disappeared resulting in the hammer meeting my hand and pulverising it between hammer and swingarm. The spindle left the bike like an exocet and travelled as true as you like into a large, vertical roll of cardboard on the other side of the garage. There seemed to be some sort of noise coming from the cardboard roll. I went to retrieve the spindle and as I pulled it out, some dust and small fragments fell out of the carboard. The spindle had neatly harpooned half a dozen or so of the old man's supply of spare flourescent tubes and reduced them to powder... Grandad was probably spinning in his grave at the mechanical butchery - and at the fate of his tools... 3 Quote Link to comment Share on other sites More sharing options...
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