Wheels [JB] Welding some double wall aluminum rims??

[Skyliner70cc]

Would you use glue on a cracked rotor.

It's just a bad idea, no matter how much hot air you want to blow at it.
rc

JB weld is often used on wankel engines on the rotor housing to plug up ports when doing porting modifications. It holds up pretty well.

As for using it on a helicopter engine, while it was a pesky oil leak, please understand that the JB weld survived significant vibration inherent in helicopter operation and engine torque/twisting....the case is what secures the engine to the aircraft frame....it resists lots of twisting force.

 

[sparky]

Yes, 3950 psi is nothing to sneeze at.

(1) Make sure to get the two-part JB weld (and not the "qwik").
(2) Prepare bent rim properly (hammer, sand, stop drill, etc.).
(3) Make sure you mix the JB properly... too much of one or the other and it will end up like glue instead of a bonding metal.
(4) Try to get the JB weld "inside" the crack of the wall, even if you have to bend the crack ever so slightly. But this is likely not as important as just putting as much on the "inner-side" of the rim, itself, as possible.
(5) Let it dry for a whole day per layer, and put two or three layers (each time leaving enough "lip" for the bead to catch the rim).
(6) On my 20" rim, with a circumference of 62.8".... a quarter of the inside of the rim (just under 16"... & prolly closer to 12", because I think "20 inches" refers to the tire and not the rim) has a good layer, which extends FAR past the minor external crack and slightly past the hairline crack that extends 6" to 8" in each direction of the crack in my rim.

(***) Do NOT try this on a front rim!! (***)

I can understand why LBSs wouldn't want people to know about this and how they, of course, cannot recommend such action be taken by people. But it does work. About 35 or 40 miles in, now...

 

[rustycase]

Golly gee whiz!

I guess u fellas know more than I.
Best to yah with that...
rc

 

[retromike3]

the unloaded gun syndrome

the problem with using JB weld to fix a bike rim is that it was not designed for that use. there are incredible forces gong on all the time when you are just riding your wheel. The loading and unloading on every revolution and the force on each spoke, not to mention the side loading during the turns all adds up to a possible disaster. So why take the chance, just go out and get a new rim, there not that expensive. Kind of reminds me of how many people die every year with unloaded guns. Treat them all like they are going to kill you and you will live to be a old guy.


mike

 

[sparky]

That's a good statistic to know.

How many people DO die each year from unloaded guns?? I'd like to see a citation as well, thanks.

 

[Oddzball]

Its no joke man. It is the same reason you dont/cant bend a lot of those fancy car rims back in shape after a bad bend/dent. Bending metal makes it weak, just like if you bend a clothing hanger back and forth untill it breaks. You crack wont just reappear and give you time to stop, it will probably snap in half, lock up your rear whell and send you flying on your noggin. A new rim is not $150 bucks either. they are 15-30 bucks MAYBE.

 

[sparky]

Well over 60 miles or so, and you still want to say it can't be done???

At what point will you agree that it CAN be done?? 1,000 miles? 2,500 miles? 5,000 miles???

I know that it won't be $150 for a rim, but I'm not going to be the one lacing it, my friend.

I actually managed to find a spare 36-spoke front wheel that I can use the rim from... but I'm curious to see how many miles this JB welded rim can handle, honestly.

Anybody want to make some bets???

I'm willing to bet that I can get to 3,000 miles before it folds...

 

[Oddzball]

Im not saying it cant be done, im saying it "shouldnt be done".

Bent aluminum, even bent back to original shape, develop micro cracks that weaken the structure.

Ever try to take a aluminum car rim to a tire shop and ask them to bend it back? They wont do it because once aluminum has been bent from its original state, it looses structural strength.

It might work for 100 miles, or 10000 miles, but its just not a good idea.

 

[sparky]

Cool.

Don't think anybody was advocating riding on cracked rims.

But if you are in a pickle, it can be done. I would NEVER do it on a front rim, even in a pickle.

I have been wearing my gloves on ALL rides now, so I'm not worried about being flung. Thanks for the concern about me, but this is for science!!!

 

[impression]

Glue on a cracked case is plugging a pesky, leaky hole.
Strength of the casing was relayed to the remaining good metal.
Would you use glue on a cracked rotor?
Nevermind... Don't answer that.

A wheel rim is THE critical element of a bicycle.
Glue is NOT an effective repair. Never has been, never will.
I would be suspect of a weld. The effect upon the HAZ could not be determined without Xtreme test equipment.

It's just a bad idea, no matter how much hot air you want to blow at it.
rc

While i agree with you on the subject of jb-weld (glue) proper weldings would be alright if done correctly

Using the "butt Weld" method you can achieve 90% Ultimate Tensile Strength of the original material

May i ask what material the wheel is made from ? aluminum or steel grade ?

if it's steel then just use a mig/tig welder and do a nice clean job, you can also get away with an arc welder if you're good/careful and don't have the amps up too far

what i would do =>
we will do a combination of butt-weld and fillet lap-weld

1. take the wheel/tyre off and untension the spokes.

2. hold the rim within a vice nice and evenly

3. tack weld the outiside of the rim ( the inner part where the tube would go)

4. turn the bike over and butt weld the inner wall of the rim, remember to not go too fast as you want good even coverage. Note: you should have tack-welded the rim so none will slip/fall within the gap therefore you aren't increasing the circumferance of the rim

5. now but weld the outside of the rim ( where the inner tube lays )

6. sand/grind down the excess weld making sure it's not exposed or too sharp as to puncture the inner tube when inserted.

7. cut a piece of an old inner tube and place it over the weld, jb-weld that into place > thus an extra layer of rubber protecting the inner tube from puncture by the weld.

8. tighten spokes

9. put tyre/tube assembly back on.

10. go for a test ride.

Hope this helps. Remember, welding is like heat trating a portion of a machine. that part will have a higher UTS point ( hold more mass ), however will not be anywhere near as tough therefore will crack if placed under too much stress (energy load)