OzVMX Forum
Clubroom => Tech Talk => Topic started by: YZ250H on April 30, 2014, 01:16:49 PM
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My 465 has a rusted (under powdercoating) and now cracked Gusset behind the head stem. Can anyone recommend someone in Brisbane to fix it for me please ?
At the very worst I can remove the old one and shape a new one, so even somone that can weld neatly might do the trick :-\
Cheers
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Someone with a Mig?
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Dave Kellett in Slacks Creek 3290 2811
He does frame repairs and straightening, I used him when I was road racing and he does good work
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Someone with a Mig?
Or a Tig ? My idea is to grind the whole thing off, shape a new piece and weld that on. It seems to me that's what's been done to it already. I will take some pictures and put them up (for interests sake as much as anything else)
Strangely enough these appeared after 2 stints at Echo Valley :o
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I can do that repair for you,i have mig tig and full machine shop,qualified fitter & turner,Logan Village area.
Rob 0438539654
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Thanks for all the offers guys. I am about as Northside as you can get without going out of Brisbane. A couple of people close to me have sent me PMs so I will have a chat to them.
Despite some of the shit that goes on with this forum it is still full of good people 8)
Thanks again
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This is what I need replacing :o :o
(http://i202.photobucket.com/albums/aa49/tbarsby/P1020657_zpsdeef85af.jpg)[/URL]
Until the Powdercoating cracked off it just looked like the bubble above the crack.
Nasty Aye ??
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This is why there are companies particularly in the UK making new frames. I would be taking a real close look at the frame, That rust has been there for a while. Your bike like mine is over thirty years old.
There are any number of parts on Vintage bikes that need to be replaced and if necessary up dated. My Maico now has a Billet Alloy double bolt front brake backing plate that is a lot better than standard (and safer) The standard magnesium backing plates break with age. Any magnesium parts become brittle with age.
Kevin
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I heard that is actually common for some YZ's as the gusset holds moisture which takes its toll over the years, be wary if you decide to chase a secondhand frame.
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I would also get the rest of the frame Sand blasted just in case...
but make sure you put a good rust sealer on the frame before you
paint it...
The stig
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Yep. will do thanks. The rest of the frame (as far as I can tell is good). I will be getting rid of the powder coating and just painting it once it is repaired.
Can you recommend any good rust sealer ? I've heard fish oil is pretty good :-\
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This is one reason why you use paint over powdercoating......p/coat does not seal from rust.
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I have had a stack of YZ250/465 G and H frames, all rust and then crack in the same area. Also check out the left side rear subframe strut where the chain has been sawing away for the last 30 years. I suspect IT's of the same vintage would suffer the same ailment as well.
The worst part of all, is that when you remove that gusset, you often find the frame down tube is rotten as well. This is a much bigger issue than the gusset itself.
Let me see if I have some pics of that area, I have some nice x rays of the frame gusset area around here too.
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Is there any improvements to make while I've got it hacked up rocketfrog ?
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I reckon you need to ease up on the triple jumps.
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The only triple jumps he would have been doing are the hop, skip & jump.
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What's the consensus about powder coating frames, is it all it's "cracked" up to be?
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The only triple jumps he would have been doing are the hop, skip & jump.
Hahahahahaha - Bang on Geoff ;D ;D ;D
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Ok, the fix is complicated and requires some specialty in the field of welding, heat treatment and machining.
First, you will want to buy some 4130 tube from performance metals in the Sydney. Tube should be heavy walled that can be machined to fit snugly up into the downtube from the bottom and extend past the damage to up around the head tube joint.
You will need to cut out the engine mount spacer tubes (cut them out with gas from the bottom and leave the upper and lower welded bosses in the frame - more to follow)
Mount the frame onto a large lathe saddle and run a boring bar down the length of the downtube to cut the seam weld excess off for said snug fitment of doubler tube.
A few 8-10mm holes are drilled into the existing outer tube to allow for stich welding of the inner tube after fitment of doubler (this serves to pin the inner repair section to the outer damaged tube, new engine mount spacer tubes are turned to inside diameter of 8mm same as stock and approx 2mm wall thickness.
Drill and ream the lower portion of the tube (oversize the existing bosses to accept the fabricated spacer inserts and continue to bore through the inner tube to make a new hole for the spacer inserts to slide through) the existing bosses are used as a guide or pilot for your drill and reamer.
Weld from the bottom to secure the spacers (upper spacer first so you dont obscure access by the lower spacer), the bushes should also have a 45 degree bevel cut on each end and the finished oversized hole should be cut with a 90 degree c/s to prepare the inner and outer spacers for a final weld in four places around the end of each and then file the bead flat to restore the original dimension.
Obviously you can trim out the rust damaged section of the original tube before the installing the repair section.
Now you need to bend a new gusset, use a section of 4130 tube to either brace the corner as a straight notched piece (unbent option) and then plate the sides in to close and add stiffness- or bend the 4130 to match the original contour and plate in the sides as said.
The original design is a die forged plate section which is going to be difficult to replicate although possible with sheet metal skills. I think the tube gusset left open would suffice and not become a moisture trap.
All welding should be carried out by competent persons and heat treating the entire frame after repair to normalise and stress relieve is highly recommended.
Since you are going to this length, consider a magnetic particle test over the entire frame to identify any cracks which should be repaired prior to heat treatment.
I consider this a good as new permanent repair, but it will cost you. I can mag particle test your frame at no charge, I think heat treatment for the frame runs at about $200 and the tube is around $50 plus freight. Machining and welding is per the hour and Niccom at Loganholme is very good and specialises in frame repairs, the fellow mentioned at slacks creek is also of good repute, but I have no experience with him.
Food for thought
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:o :o :o :o :o
Or find another frame. I'm not that attached to this one ::)
Care to have a guess at a cost for the repair works anyone :-\
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A good frame can be a tricky thing to find in Oz, have you had a repair quote from anyone yet?
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Not as yet. It's becoming bigger than I had imagined :o
Of course it has to be my favourite bike :'( :'(
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What did Rob have to say about the repair? It sounds like he has the gear to do the job.
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If you want my opinion now that i have seen the pic of the offending item,i would invest $50 or $60 in having it completely sand blasted,this will show up any other problems the frame may have,you can then decide whether or not to try and salvage it.Not a fan of putting powder coat anywhere near anything except maybe furniture!
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If you want my opinion now that i have seen the pic of the offending item,i would invest $50 or $60 in having it completely sand blasted,this will show up any other problems the frame may have,you can then decide whether or not to try and salvage it.Not a fan of putting powder coat anywhere near anything except maybe furniture!
Yep, that is my next step. Have to strip it first. It is behind a few others on the jobs list - the ones that have to replace it on the track.
To save a few bucks I will (carefully) cut the gusset off so I can get the down tube blasted as well.
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There are always guys who will barrack for paint or powder like they are barracking for a football team but the truth is neither is responsible for the problems here.
I have seen my fair share of bog under paint that hides shit as well.
The major problems like this often occur when moisture gets into a cavity and can’t get out, often mud will get into the cavity too which can hold moisture for a long time and eventually it will eat away until fatigue fractures appear because the material is so thin as it has been eaten away so much.
Common problems in a model mean chasing another frame doesn’t always solve the problem as you will most likely just be buying another with the same problem. Best to personally inspect a frame if you intend to buy another. Try and develop a keen eye for detail for when you inspect it.
I have had a few frames that when I cut the tubes water is then able to escape, it often comes out like black sludge and will stain the concrete floor for weeks.
Condensation will get sucked into the tubes on cold days but can’t escape on hot days so it stays there until the is a major break.
Rocketfrog is pretty much onto it, replace parts with cro-mo and heat treat after all welding is done.
His instructions seem to suggest keeping the downtube with reinforcement inside, I think I would most likely replace the whole tube and refit any engine mounts.
Your earlier photo shows the cracks okay but do you have a picture that shows more of the frame so I can judge how much would need to be replaced
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Thanks GMC. Some more photos for discussion/interest.
(http://i202.photobucket.com/albums/aa49/tbarsby/P1020668_zps0182330f.jpg)
(http://i202.photobucket.com/albums/aa49/tbarsby/P1020661_zps04ab12bd.jpg)
(http://i202.photobucket.com/albums/aa49/tbarsby/P1020660_zpsd1848995.jpg)
(http://i202.photobucket.com/albums/aa49/tbarsby/P1020658_zpsb295d59b.jpg)
(http://i202.photobucket.com/albums/aa49/tbarsby/P1020669_zpsa9ed255f.jpg)
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Photos added above. Hopefully they show a bit more detail