gensem
100 kW
Expert opinions needed.
Trash it or try to solder it? its aluminium...
Trash it or try to solder it? its aluminium...
Swing Arm (Broken)
- Thread starter gensem
- Start date
johnrobholmes
10 MW
Either remake it in steel or trash it. Aluminum braze or solder isn't a good load bearing material.
dogman dan
1 PW
Stick a fork in it, it's done. Excellent excuse to get one made in steel.
Normal use? Trail use? Crash?
I suppose you could still creep around on it, after a good size blob of PC7 or JB weld or something was applied. But it's done with curb hops or trails or high speed.
A braze or weld would destroy the heat treated frames strength, so that's out.
Normal use? Trail use? Crash?
I suppose you could still creep around on it, after a good size blob of PC7 or JB weld or something was applied. But it's done with curb hops or trails or high speed.
A braze or weld would destroy the heat treated frames strength, so that's out.
dogman dan
1 PW
Oh crap. I just saw on the other thread what this was going to be. Not a low power bike at all, that could get by with an epoxy repair.
Because the brazing done on the bike has changed the temper of the frame, you could have other weak spots in the structure. Normaly on an alloy frame, welding is done, then the entire frame goes through a very specific heat and cooling treatment. Somewhat like tempering a blade. Now you have changed that every spot that was heated.
You can weld all you want on steel though. Copy that frame in steel? Dang, the project just got a lot bigger.
Because the brazing done on the bike has changed the temper of the frame, you could have other weak spots in the structure. Normaly on an alloy frame, welding is done, then the entire frame goes through a very specific heat and cooling treatment. Somewhat like tempering a blade. Now you have changed that every spot that was heated.
You can weld all you want on steel though. Copy that frame in steel? Dang, the project just got a lot bigger.
gensem
100 kW
Frock it... didnt even had a chance to taste it... I ll try to get another swing arm from the factory, making a steel one is going to be too expensive... What pisses me most it that I have two cromotors and no working full sus bike to use the motors! =(
I hope that my battery box is safe being welded to the bicycle caster...
To be truth I also have a greyborg frame but the zippys ll not fit in the frame and I have no charging spot in my building garage.
I hope that my battery box is safe being welded to the bicycle caster...
To be truth I also have a greyborg frame but the zippys ll not fit in the frame and I have no charging spot in my building garage.
Gordo
100 kW
johnrobholmes said:
You have to remember that "solder" means welding in other languages. Does not matter much as without a molten salt bath, you can't get it back to T-6.
weld in Dutch is lassen, wellen
weld in French is soudez, soudons, soudure, soudent
weld in Italian is saldare
weld in Portuguese is solda
weld in Swedish is svetsa
JEB
100 W
I would do as most likely a temp-fix, remove arm, drill a hole through top, and bottom of the aluminum tube behind the weld (a through hole), maybe in the 1/4" range, use a hard wire (music) .032?~ number of wires to cover around the flat part of the broken arm, about 3/4 ~ of width. (the hole should be about the dia. that the number of wires of the picked size will fit in- 10 wires wide = .320~ wide) a *ring on the top to keep wires straight before spreading out to flat around ring. *(flattned ring), do a tight rap, epoxy, wedge to hold wire tight in hole, bend wire over, more epoxy.
gensem
100 kW
neptronix said:Sorry to hear this man.. you just got this frame not so long ago, didn't you?
Im yet to use the frame... frame was never used. ohweel the seller ll probably be able to send me another swing arm, the only bad thing about is waiting is 3-4 weeks in because of customs. .-
gensem
100 kW
Gordo said:
I was reading about aluminium welding (over 400 degree celcius) yesterday and its not like its going to be T-0, ll mostly likely get back to T-4 after a while, not good enough for to hold all the stress on the bearing, but should be more than to hold 10kg of batteries in the front.
gensem
100 kW
JEB said:
I tought of a simpler fix just for testing purposes until the the new swing arm arrives (roughly 1 month). Something like a 4mm C shaped aluminium piece welded just to hold the bike together.
MadRhino
100 GW
That frame won't make it, not with the power that you are building. Find a good DH frame to start with. A big, reinforced hydroformed DH racing frame, ideally with dual pivot suspension. Then, even with the best DH frame, never stretch the swingarm to fit a motor, and never solder anything to it.
If you can have a new swingarm for this one, build it low power or sell it.
If you can have a new swingarm for this one, build it low power or sell it.
dogman dan
1 PW
Sadly, it's a start over. But do you bounce well? Got good leathers? If so, Epoxy it with the strongest stuff you have localy, and go try to break it. Nothing better to do while you wait for a new swingarm, or new frame. Gotta find out if your torque arms cut someday anyway right?
Just don't do that if you are an old fart 50 year old with easy to break bones.
Just don't do that if you are an old fart 50 year old with easy to break bones.
kfong
100 kW
Any welding to an aluminum frame is usually a bad idea. It just weakens the area making prone to breaking. I know some ES members have done it, but they usually overbuild the area with more structure. Having a frame break on you while trail riding is not something you want to happen. I had a steel frame brake at the stem and was lucky not to get hurt.
gensem
100 kW
MadRhino said:
No one sells A-line to brazil MadRhino, I would build a bike based on the norko if it was in my reach. This was the the best option that could be shipped to brazil. To be truth I wouldnt be surprise if it fails, thats why Im looking at a greyborg frame while in replying your post. I was already expecting a failure, but not before giving it go.
gensem
100 kW
dogman said:
My elcheapo 10y old hard tail (aluminium) is holding a 9c at 3kw just fine, this XC frame with scandium should hold a 2x 9c (cromotor) with 6-7kw.
Im 30 and im used to crash
and do have leathers but brazil is hot as hell in this season.But I have a much better solution... I ll just do a 4mm ring that its just about the outer size of the broken bearing and ll use an hydralic puller.
MadRhino
100 GW
http://www.pinkbike.com/buysell/967535/
This frame is tough as nails for 200$, you don't need a new frame and this one will outlast any Norco
The guy doesn't ship to Brazil, but he had lowered the price twice since he first advertised it
You could easily have it re-shipped by a forum member in Colorado, if you can't negociate the seller
That one is only an example, many DH racing frames can be found for cheap on the west coast of US and Canada.
Even here on the east coast where there are no big mountains, we have a big DH community and the prices drop as much as snow this time of the year.
This frame is tough as nails for 200$, you don't need a new frame and this one will outlast any Norco
The guy doesn't ship to Brazil, but he had lowered the price twice since he first advertised it
You could easily have it re-shipped by a forum member in Colorado, if you can't negociate the seller
That one is only an example, many DH racing frames can be found for cheap on the west coast of US and Canada.
Even here on the east coast where there are no big mountains, we have a big DH community and the prices drop as much as snow this time of the year.
gensem
100 kW
kfong said:
I was dumb enough to think my welder would know that he should use cold welding. More things that I learn each and every week. I ll try to avoid aluminium alloy in the future, but its really hard to find a cromoly full sus frame that I could afford without selling an arm.
gensem
100 kW
MadRhino said:
I ll think about it, but I still wanna be proud breaking a frame.... I mean riding it until it brakes and not watching someone else overheating it with 600 celcius degree flame.
MadRhino
100 GW
I did that many times, and the feeling is is the same whether the frame was new or old.gensem said:
It feels much better to ride a frame that is not likely to break.
Kingfish
100 MW
gensem said:Expert opinions needed.
Trash it or try to solder it? its aluminium...
It looks new, that was damaged in some way. Maybe someone set a box on it and it got twisted and snapped. You are done; won't touch it ~ even if you gave it to me free. The one and only way to fix this, and not with my dime, would be to remove the bearing and tig-weld it back with full-penetration. Then re-machine the hole. The cold reality is that there isn't a lot of metal there to support the structure. Think positive: It could be your saving grace cos you've found out now where/how it fails before it could have in a critical moment.
Things like this scare me. Best to steer clear and find something else. :|
Kindred towards your loss, KF
gensem
100 kW
Kingfish said:
I ll just trash it... the manufacturer is going to send me new swing arm.
Would you trust the new swing arm to hold the cromotor @ 7-8kw?
dogman dan
1 PW
Not really, awful heavy motor which could be the real problem even more than the power of it.
Good news is you'll have a nice template avaliable to have a steel swing arm made once you can afford it. May as well ride what you have till it breaks. Hopefully it won't be a two ride bike though. Much depends of course, on how you ride it.
Maybe I'm just talking out my ass, since I don't have experience with a hubmotor that heavy. 5304 the biggest I've run. But one look at the cromotor and I was just thinking it goes beyond use on any "normal, mid price alloy bike frame" .
Looked to me like it needs a greyborg frame, or your own version of a stout steel frame. Steel mainy just because you can weld it yourself. At least, steel swingarm allows you to build the thick dropouts you'll need.
Good news is you'll have a nice template avaliable to have a steel swing arm made once you can afford it. May as well ride what you have till it breaks. Hopefully it won't be a two ride bike though. Much depends of course, on how you ride it.
Maybe I'm just talking out my ass, since I don't have experience with a hubmotor that heavy. 5304 the biggest I've run. But one look at the cromotor and I was just thinking it goes beyond use on any "normal, mid price alloy bike frame" .
Looked to me like it needs a greyborg frame, or your own version of a stout steel frame. Steel mainy just because you can weld it yourself. At least, steel swingarm allows you to build the thick dropouts you'll need.
MadRhino
100 GW
The Cro-motor weights about the same as an X5.dogman said:
The main difference is its construction quality, and the wider magnets that should let it take more power.
I'm building it in my large Santa Cruz V-10 frame, or maybe an Intense M9 that I will see tomorrow.
It will need a very stiff frame to ride the mountain with all its potential. I wouldn't trust any of the commercially available steel FS frame to be stiff enough, apart a 4000$ DH Race Link
It is the Clyte X54 that weights 30 pounds, I don't know yet what I'll build with this one, definitely not a dirt bike.
Thinkig about a custom FS tadpole trike...
Similar threads
