OzVMX Forum
Clubroom => Tech Talk => Topic started by: caps 999 on August 14, 2007, 07:09:58 pm
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ive had a look through my stuff and i found 2 perfect rims for my dt1 but theve both cracked at the join (there off a rm500) does any one know if its worth re welding or should i just keep looking
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didnt you say perfect ?
alloy welding cost you nothing, just have a seam now.
Do you want a solution or a look ? thats the part only you can decide on.
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yup..whilst I once would have said ditch the rim I would have once said the same about a cracked crankcase too :o horses for courses..for myself welding can be utilized but the weld needed will have a fair overlap and won't ever look the prettiest. That's not to say a welded rim is no good and won't work as that's far from the truth. Unfortunately for the weld to be successfull it should not be smoothed or ground to shape but left as welded.
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agree, had a mudcatcher on mx250a, freaked, took it to chivos,
a weld is just as good as a seam.
the spokes keep it all together
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welll my dt1 started as a pile of bits a month ago an now is 80% cmplete missing carb easy fix it will just be a racer so the looks arnt all a problem
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I have two welded rear rims and I did buff the weld back and polish it (sorry Doc) Niether have given any trouble but the guy who welded them does aircraft stuff so is pretty good.
Brent
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Had one bike think it was a husky that had a welded rim . the weld was proud and didnt look the best but served the purpose. i kind of figured that originally they are welded and ground and polished back sooooo...
as Brent says if the guys knows his stuff there shouldnt be a problem getting it ground back again .
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I had a yz 250 d with a welded rear rim it lasted and worked fine, for a good look while you have them apart get the rim powder coated put in new spokes what a great look on a old bike I did them black satin my mate has since done his the same but red. cheap fix and looks good.
Cheers
fatboy
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ive had a crack in my 04 ktm3oo from jumping over water diverson mound that they put in up at the watagans state forest. i landed on a engine block that some one had put there and it has been great cost me 10 dollars from road and race ive left the weld as is
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ive had several rims re welded and then when they come back from annodizing they cracks have reappeared. dont know what it is but i will no longer waste money doing it and will just go for new rims in the future.
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So.... I've got a rim that has started to crack at the join. I priced a replacement today. After I picked myself up off the floor I decided that I'll get it welded. Anyone know of a good alloy welder in Brisbane area that can do this kind of work?
Regards
FatBoy
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Technically structural type alloys should be heat treated to give them strength, any heat from welding can cause this area to weaken, so a welded rim will be slightly weaker in this area, but it will still be stronger than a cracked rim. The anodizing may have made the weld more brittle perhaps?? did you run this problem past the anodizers?
I have welded a few rims but have always considered it a budget repair, if you are going to the trouble of relacing a wheel I would be more inclined to source a good rim. Unless it was some type of rare rim.
If the crack is 'Veed" out before welding then their is no reason why it can't be ground back smooth, but leaving the weld their will retain a bit more strength. I have always ground welds back on rims & comebacks are rare.
This sort of thing can never be guaranteed because their are so many variables such as spoke tightness, 70 foot triples etc.
Welding should be fine but simply keep an eye on it from time to time.
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fatboycrash, if you are on the Northside then give Bushell Engineering a go.
5 Jobson St Albion Ph. 32629044
http://www.bushellengineering.com.au/index.html (http://www.bushellengineering.com.au/index.html)
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this has happened to me at leat 2 or 3 times. as soon as they come back from the anodizers the crack has reapeared. i handnt even laced it up or anything. yes i ground out a 'V' before getting it welded. anyway im no longer going to waste hours of time preparing rims for restoration and $ on anodizing if they are cracked and need welding. we are helping a guy do a resto on a XT 500 and doing some work for him and his rims look pretty good on outside you dont know for sure what they are like until the tyre comes off as there can be cancer corrosion and cracks can appear after pulling the wheel apart. this happend with a set of PE rims i had. they looked brilliant until 2 or 3 cracks appeared >:(
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LW, I would check out heat treating the rims after welding if you really want to salvage a rim. It will add to the cost so all up with welding & anodising won't be that much short of a new rim price though.
It's a fair bet the alloy is 6061 but I'm not sure what temper for a rim. T6 (temper No 6) is the strongest but also the most brittle, while T0 (annealed) is the softest of which you can bend like it's butter, & different variations inbetween. T0 will bend before it breaks but T6 will break before it bends. Example, the extruded tube I use on my swingarms I take down to T0 to bend them, then after welding I take them back up to T6.
The only thing I'm not sure about is wether they take the alloy to T6 or maybe T4 or T5 to allow it a bit more flex which a rim may require, not sure where to research this one.
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like i said im not gonna stress over it now and in the future im just going to use new rims if i have a rim thats cracked.
a few months ago i got a rear rim on a 94 XR 600 welded up as it had a quite large split, but it wasnt going to be re annodized. we told the owner it would only be a temporary job till he has the dollars for a new rim, and it would probably crack again and the other he said actually had cracked again. also ive found that when ever ive had any alloy welding done on a part then got it annodized the process brings out all the chemicals/white or black stuff ( i dont know what it is) in the weld and tarnishes ths part.ive cleaned the area and polished it back and it looks fine but when it comes back from annodizing its basically ruined. the annodizing process reacts with the weld filler rod/flux or what ever.i dont think its a problem with the annodizer, its just the 2 different metals, eg the weld material is slightly different to the material of the rim. ive also had a PE swing arm annodized and there was no problems with the annodizing reacting with the original welds on that
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Thanks Doc, I'll give him a whirl.
FatBoyCrash
fatboycrash, if you are on the Northside then give Bushell Engineering a go.
5 Jobson St Albion Ph. 32629044
http://www.bushellengineering.com.au/index.html (http://www.bushellengineering.com.au/index.html)
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No, it's not the anodisers fault, different alloys will give different colours. You may be using the wrong filler rod on the rims, 5356 filler should work ok. I think it's the silicon that comes up black.
The trouble with repairs is that it's hard to know the alloy that was originally used. I have welded up chew marks in swingarms & they polish up fine but will show up as a discoloured patch after anodising.