arc flywheel issue

[xspike77x]

So I was working on tuning the pz22 carb on my clone build and I went to fire it up last night after making a needle jet adjustment and the thing wouldn't fire. I check that it had spark and noted that it would not start on starting fluid so I immediately though, crap, I sheared my flywheel key (it was a 6 degree advance key). I have an arc billet flywheel on the engine which has probably seen only about an hour of run time and not only did the key shear, but the keyway on the flywheel did as well. I will attach a pic. It is not sheared flat like the keyway, but the wall on that side of the key is drastically reduced. I torqued it to 170 ft/lbs. which is what I thought it was supposed to be. I also had lapped the flywheel so I thought I was set. Anyway, I am wondering if this flywheel is shot or if I can still use it. I have heard of guys who torque down the flywheel real tight and do not even use a key. If I torque it a little extra do you think I can still use it, in order to keep in in place?

 

[korndog]

170 ft lbs?

 

[Bill Ellerby]

You might have an expert welder build up some material and then mill it back to orginial bore and dress up the keyway. If its made of aluminium it would be easier then steel or cast iron.

 

[xspike77x]

Whoops, typo, I meant 70 ft lbs.

 

[C9H13NO3]

i would contact ARC and see what he thinks you should do.

 

[vette66_00]

You should just go down to the auto parts store get lapping compound and Lap the crank to the flywheel. Put the key way half way between (see pic) and leave out the advance key. Half way is about 8 degs. Lapping basically seats the 2 together so they cant move. Put nut back on at 70 lbs torque. Been doing it this way for 18 years and not had any problems.

 

[minidragbike]

With the flywheel damaged like that you must now run it with NO key. Like they said, lap it onto the crank, clean the area good, set your timing, and TQ it on.

 

[Oldschool]

Welding flywheels to repair damage is one those things I was always told would get me in trouble.....

I never tested that rule and I would not try.

 

[vette66_00]

I totally agree. Welding on a flywheel will fatigue it.

 

[Bill Ellerby]

I strongly disagree. People everyday are welding up parts on very high performance car/motorcycle motors. Everyday people weld cracked blocks and heads. The amout of welding on the flywheel is not enough to fatique it anymore then the heat it is subjected to ever time the motor is run. A couple of well placed beads would allow for the key way to be reused. Along with lapping you got nothing to worry about. It's my opinion based on26 years in the Navy as a jet mechanic and Aircrewman on helos.

 

[vette66_00]

I strongly disagree. People everyday are welding up parts on very high performance car/motorcycle motors. Everyday people weld cracked blocks and heads. The amout of welding on the flywheel is not enough to fatique it anymore then the heat it is subjected to ever time the motor is run. A couple of well placed beads would allow for the key way to be reused. Along with lapping you got nothing to worry about. It's my opinion based on26 years in the Navy as a jet mechanic and Aircrewman on helos.

This would be the same Navy that throws perfectly good tools, planes, and whatever else they feel like off the back of a boat? ah yah I totally trust the crap they do. Go ahead and weld it but you will not be riding next to me when your leg gets WELL PLACED away from your body.

BTW Thank You for your service you have done for our county. That's not meant to be funny it sincere.

 

[Bill Ellerby]

Maybe in the old days, but not now. If you are caught doing that they have a cell with your name on it. No it goes to a place called DMRO where YOU can but it!

 

[Oldschool]

Once I had a flywheel for an Antique Outboard welded.

The welder was a fellow with some experience ( only guy I know who could weld over head, drink a coffee, have a smoke and talk to you at the same time ).

This fellow was not very comfortable with what I asked because he said it would creat internal stresses and aluminum has an unpredictable failure rate when stressed cracked and reapaird.

That motor was a shelf queen 1920 Evinrude and only ran for rallies.

Not much point in tryig to convince people what is or is not going to cause an accident but I would think ARC would be the expert on their flywheel.

 

[Bill Ellerby]

I agree with you that the manufacturer is the expert here, however let me point out the flywheel isn't/wasn't cracked. Rather a small piece of it was removed by the shearing key.Plus the key to welding aluminium is heating the area slightly prior to actual welding to relieve stresses. They once said you can't weld cast irom? Well that is a thing of the past! Also if you got the money for a new one use the old one for a paper weight.

 

[Cyanide]

I strongly disagree. People everyday are welding up parts on very high performance car/motorcycle motors. Everyday people weld cracked blocks and heads. The amout of welding on the flywheel is not enough to fatique it anymore then the heat it is subjected to ever time the motor is run. A couple of well placed beads would allow for the key way to be reused. Along with lapping you got nothing to worry about. It's my opinion based on26 years in the Navy as a jet mechanic and Aircrewman on helos.

umm welding creates 6 times the heat the motor makes if not more,

 

[Bill Ellerby]

You're missing the point, when you weld something like this you DONT just pull the trigger on your welder and go at it. You approach it in small tacts and the heat generate is very brief, why do must prople think welding is full bore balls to the wall. I've seen people who could weld two sheet of .010 thick stainless without warping the metal.

 

[Modding_out]

Hey spike, if ARC says "no go" I'll take your f'd up fly wheel off your hands

 

[metal man]

You're missing the point, when you weld something like this you DONT just pull the trigger on your welder and go at it. You approach it in small tacts and the heat generate is very brief, why do must prople think welding is full bore balls to the wall. I've seen people who could weld two sheet of .010 thick stainless without warping the metal.

not to sound like a ass but the reason is that is how most welding is done so we assume its all like that . yes you can just tack and tack till you have the base big enough to machine it back down , and remill the keyway . but if people are afraid to weld on a hit and miss flywheel that goes like 500 rpm, out of fear of it busting do ya really want to weld on something going alot faster like 8000 rpm? granted i have done some real stupid shit like welding the bushing in a snowcat clutch .it did hold for along time . but when it failed it was bad and i do mean BAD:scared::nuke: . there was chunks all over , some parts when a block from where i was sitting when it blew . i would not want to mess with a fubared flywheel . the force it sees when at speed is in the tons range . given how much damage that stupid little bushing did and it only weighted like 5 oz tops , i would not want to have a 8lb flywheel come unglued .
i would see what the company says about it and if they can fix it . they would have the proper tools to do it and the training .and can test to make sure its still safe .

 

[mini99]

I'd weld it. There's not enough damage in that bore to worry about.
It wouldn't take 5 min. to fix that. Problem is it's just gonna happen again. Billet alum. is not tough enough to do that job. You need an alum flywheel with a steel hub.

 

[olajoe808]

I can't imagine ARC would put themselves at risk and suggest to anyone they do not know to repair their product. A recommendation as others have put forward is to relapp and put more torque on it.