OzVMX Forum
Clubroom => Tech Talk => Topic started by: PEZBerq on July 28, 2008, 09:54:19 pm
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Interested in peoples thoughts on this...... ???
How serious are cracked rims and what is the priority during a restoration to repair/replace a rim that has a crack? Does anyone have a tale of woe because of a cracked rear rim - rather than say loose or broken spokes? What happened...did the rim just flat spot :o :oor or did the wheel collapse :'( :'( Was there much pain involved :( :(
Is a cracked rim a scrutineering cause for rejection..assuming it is detected? Is a cracked front rim a bigger danger than a rear rim?
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I have just had a cracked rim TIG welded up last week ...went to all the trouble of removing the spokes ( thought I was doing the right thing ) had to take it back home put all the spokes back and tension up ???
Informs me the wheel will distort too much .
You can hardly tell it's been repaired - still runs true - no flat spots :) $25-00
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or a secondhand rim from the wreckers (if you can find them of course) $50 each for the last two I bought.
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hey oldfart where did you get it welded ? and does he do a good job.
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Hey that sounds good.
I have a great wheel but the rim is cracked and so I thought I'd have to throw it away.
Can anyone TIG weld it or is there some skill involved?
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Why try to fix it at all? Anyone ever hear of someone getting hurt or damaging their bike as a result of dirt riding using a cracked rim - knowingly or unknowlingly?
FYI I was told by a wheel respoking mob today in Albion that they will refuse to re-anodise any rims older than 7 years. They reckon they are too likely to crack.
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I've had a few bikes with cracked rims (stupid mid~late 1970s DIDs...). Always stress me out, and I always end up replacing/fixing them, but the cracks never seem to get worse from one ride to another.
Actually, one rim had a few cracks which I marked. Several events later, the original cracks hadn't grown, but several new cracks had developed...
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We get them welded all the time, clean them up, polish and some times anodise them. They look great and have never caused a problem.
Cheers,
K
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Slacks Creek - Hiley street - same side as Motorama Holden .
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PEZBerq, to answer your question in part..I have never witnessed a known cracked wheel collapse nor have I heard of anyone being injured from such. Someone would have during the course of history no doubt. It stands to reason that anyone with a cracked rim should not go jumping buses but I can't say I've had any wheel collapse cracked or uncracked. Self preservation says ride it 6 to 7 tenths since you know about it. There would be a whole heap of undetected cracked rims in use as we speak but rarely (personally ..never)do you hear of them killing someone on a dirtbike ;)
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Doc
That's what I figured would be the case too but wanted to get others experience. I'll just monitor the crack and see if it grows much. I reckon I'm not risking my neck and I certainly wont be jumping buses or doing 100km/hr + at Finke or anything! Vintage bikes and vintage bodies mean sensible speeds ;D ;D ;D Currently I'm getting the wheels respoked due to badly corroded spokes. If it needs welding one day I'll get it done with the wheel fully spoked to stop distortion.
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' Doc disclaimer' if the opportunity arrises I'd be inclined to say the sooner the better for the weld as the crack will get bigger maybe getting to a point where it may not longer be weldable. If the wheels are apart now wouldn't it be easier to find another rim and end the problem before it arrises? :-\
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You have to remember that there are an average of 36 spokes holding the rim together on the inside and a tyre on the outside. So long as the wheel is in good nic(ie spokes not lose) it should be ok.
I raced my sidecar for several seasons with a crackered rear rim and never had a problem.
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when i dismantled this rim from my MX250 front wheel it appeared to only have a slight crack at the weld seam.
this is how i found it a couple of weeks later.
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How Serious is a cracked RIM ?
How serious is your well being.
How much insurance would you like to keep you out of hospital, for me i don't trust them .
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yeah, can be like the proverbial iceberg - i noticed a small crack in my CR's front rim. eventually took front tyre off to change, and holy moly, the aluminium on the tube side of the rim was all bubbled and flaking off in layers halfway round it, and looked bloody shite. end result was the thickness was reduced by heaps. guess caused by water sitting in there for years somewhere along the way. i bought new excel rim and spokes, looks a beaut now.
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Will a modern rim spoke onto a vintage hub OK? Or do you need to buy a blank rim and get them drilled to suit the hub - in my case early 80's Husky?
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if the hub is the same width and not offset you have a good chance .
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My recent experience.......If you have a cracked rim dont despoke the wheel and leave it for months before fixing it. You might not be able to repair at all. Leave it spoked.
Replaced my cracked Nordisk rim at last and found the old cracked rim completely broken open after a few months sitting in the garage. Just like Vandys mudcatcher. There are large stresses in a rim from the manufacturing process it seems - enough to cause a crack to grow without any riding stresses. Makes you wonder what stresses there are when the wheel is being used and how much the spokes and tyre are contributing to reducing the stresses on the rim.
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seen that happen to a TT600 rim too, pulled apart right through the join. it was junk anyway though and didnt matter as it was already being replaced with an Excel.
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yup, never pull off a rim that's cracked unless you plan to toss the rim and fit another. If you're thinking of having a rim welded then just remove the tyre and tube only ;) gets very smelly otherwise ;D
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A 20 year old cracked rim is a damn sight easier to fix than a 40 year old broken bone
Dont ride on it.
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Most rims are fushion welded and rely on the spokes and hub to hold it true, hench the reason we have to check on spoke tension on a regular basis.
If you know a GOOD tig welder he should be able fix it.
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most rims crack on the join
you can weld them
some are harder to do than others
some have hollowed bead
which makes it difficult :'(
i have a crf450 front rim laced to my suzuki 500 1984
went on perfect and looks great ;D
also dont dismantle rim for welding (except tyre and tube) ;)
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i have a ktm 520 excel front rim on my yz250h :)
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eh I have a CR rim on my TM125. I also have a 34 hole yammie rim I'll give away to some lucky forum member. I sat down one night with a nice matching pair of rims and new spoke sets. Laced up the front, beauuuudiful, spent over an hour trying to lace up the rear before I realized I was trying to do the impossible :P Say no more! ::)
First person to ask gets the rim (free does not include free postage sorry). Me thinks it's about a 1.85 x 18, silver anodized, straight and in pretty good 'uncracked' condition ;D
Leith, no 18inch alloy suz rims spare sorry. Like decent seats they're always something in short supply around here :-\
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G`day we get them welded often tho depends on the inside if flaking toss it if only cracked weld it robin shoreline motorcycle services
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how do you go with re-annodising? i find the crack comes back once they have been re annodised and the annodising process re-acts with the weld and it comes back looking horrible
i have a rim that has some bad gouges. i was thinking of getting filled in with weld but from previous experiences this tells me its not a good idea as once its re - annodised it will just react with the welds and bring out all this black oxidation no mater how well i have cleaned/polished the weld. i would just be wasting time/money?
is there a particular welding rod that the annodizing process does not react with? they are welded from original and the factory annodizing doesnt react with the weld. At worst you the weld may look a little lighter in colour.
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Leith, ask them to flash dip it ( as this will not show up welds ) same process as used on Suzuki swing arms ;)
Note ....it will not have a gloss finish , more so a matt to satin apperarance
Use caustic solution to remove old Anodise .......hope this helps
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I AM WITH YOU, I DON`T TRUST THEM, THE FIRST NATIONAL MEETING AT BARRABOOL, A MAICO RIDERS FRONT WHEEL COLLAPESED WHILE GOING OVER A JUMP ON A DOWN HILL AND HE ENDED UP IN A BAD WAY, THE SPOKES COLLAPESED AND RIM WAS CRACKED. THINK ABOUT IT, BUY A NEW RIM.
CHEERS DA