Monark fork bearing cup shims

[SKPC]

^^^^^^ See above comment....1st things 1st. Look closely at your last pic of the head tube. The bearing cone is not parallel with the headset cup! Looks to be 1/8" higher in the front, which means the head tube is very damaged and out-of-true. This will cause even more damage if you run it like this.
For the frames' wellbeing and to solve the problem once and for all, get the top and bottom of the head tube professionally "shaved". A special tool is required to do this. Any bike shop should have one. Slapping a weld and hitting it with a grinder will not cut it. What does the bottom of the head tube look like?....

 

[mrg]

I hate to loose metal (shave) so was going to add materal (weld) to the back of the top bearing cup seat then grind flush and parallel with the bottom.

 

[Freqman1]

I agree with you Mark a shave on something like this is probably not a good idea. I’d see about adding the metal and get with a good machinist to make it right again. V/r Shawn

 

[buickmike]

I have yet to see a local bike shop that would be so well equipped. And willing to help a customer out. At least this customer. The original posters bike is pretty weathered
I would have difficulty locating new cups for the head tube as most of my stuff is Schwinn.

 

[SKPC]

I hate to loose metal (shave) so was going to add materal (weld) to the back of the top bearing cup seat then grind flush and parallel with the bottom.

That is the best option since the paint is shot, but it still will require some tool-age and maybe shims also. If you go that far, machine or "shave" it so the headset goes in tight, flush and parallel w/o shims..

 

[buickmike]

Anyway here is second attempt at THICKER shim for colson BB.Would be nice if people would let me pick thru the stores old inventory - but they dont- so I buy what they have which was generic bmx cups etc.
Final fit on non sprocket side was both aluminum + brass sham combo. AND whacked my fingertip 2

 

[Freqman1]

These came from the factory with shims. I have not seen a cup/bearing set that will work in this head tube. But hey what do I know about these bikes. V/r Shawn

 

[SKPC]

Maybe clear this problem up by keeping the shims out of the equation & put normal cups in it. Poor design imo.

 

[mrg]

They are normal cups ! , when Monark designed the Super frame (5 bar), Speedster (twinbar) and others (?) they were really different (revolutionary) including head tube stock and not wanting to make special hardware (fork bearing cups) that were usually purchased from hardware supplier, they just shimmed them to fit the frames. After years of ware (abuse) and probably disassembly many times the shims were either worn out or lost. the further use and or abuse caused top cup to move and ware the frame. when I got it the springer was not even assembled correctly and did not even function as a springer ( how many times did you take apart your bike when you were 10), so it's not a issue of finding right cups, its repairing the ware on the frame and finding OG shims or making them. I almost just made a shim with a lip o the back to level the cup but might as well do it right. with me it won't be machining/custom fab etc., just weld a bead over the worn spot to add material then grind/file and a use a square/ruler to make it even and parallel & back to OG and needing shims like when it left the factory. this ain't rocket science and don't think I'll be running Baja 1000 with it an I built cars for that without much more.

 

[SKPC]

Great idea mrg….nice frame to begin with and worth getting fixed up! Love that bike..skpc