Author Topic: Flywheel (loose hub rivets)  (Read 91 times)

Offline croat1

Flywheel (loose hub rivets)
« on: May 19, 2020, 05:29:42 PM »
Being bored I was researching old R related topics and I found an interesting one about flywheels.  The topic was about welding the hub to prevent it getting loose on the rivets  Iím curious if anyone had done this as preventive maintenance?


Online Hawaiiysr

Re: Flywheel (loose hub rivets)
« Reply #1 on: May 19, 2020, 06:18:49 PM »
Would the flywheel need to be balanced after welding? I would assume so seeing that it spins at RPM.

Online The norm

Re: Flywheel (loose hub rivets)
« Reply #2 on: May 19, 2020, 09:25:13 PM »
If the tig machine used has a pulse setting you wouldn't need to add filler. You would just fuse the two parts together. So you have weld on the hub, but zero added weight. That is the method I have used to weld crank tins and pins.
« Last Edit: May 19, 2020, 09:28:23 PM by The norm »
1986 Trx250r-- Hybrid Engineering 391(Good bye super 310)
1986 Trx250r-- Hybrid Engineering  ported stock 86 cylinder
1986 Trx250r-- craigslist engine with unknown ported 89 cylinder.
1985 Atc250r-- Needs a lot of work (Super 310's new home)

Offline Jerry Hall

Re: Flywheel (loose hub rivets)
« Reply #3 on: May 20, 2020, 12:42:29 AM »
I have tig welded a lot of flywheels as a preventative measure.  If you wait until the rivets are loose enough to "rattle" you have waited too long.  It is next to impossible to get the flywheel shell and hub concentric before welding after the rivets get loose.  If the rivets are still tight and you see rust colored streaks on the flywheel shell that are originating at the hub and projecting radially outward, it is time to weld the hub to the shell.

I make 3 welds 1" long 120 degrees apart.  I have used filler rod on some, fused the hub to the flywheel without filler rod on others.  I have had both types balanced and could not feel any difference in the engine vibration between using filler rod and not using filler rod. If you are a competent tig welder, the weight of the welds will be really close to each other.  Each weld will be within 1 or 2 dabs of each other when using .035 or .045 filler rod.   I have welded some flywheels that the  rivets were rattling and they would vibrate a lot because they were not concentric.


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