Tomos crank too tight, PLZ HELP MEH

Braap Master Mope /

I've done two complete rebuilds on Tomos engines without an issue. Now I'm doing it for a third time and I've got a problem. When I put the crank case together and tighten the five bolts on the clutch side that tightens the case around the crankshaft, the crankshaft itself binds up and will not spin freely. When I loosen those five bolts a little, the crank spins just fine. so it seems like the case is tightening too much and squeezing the crank inside the case, preventing it from spinning freely.

I checked the thickness of my new gasket, thinking it may be too thin, which would allow the case to squeeze too tight, but it's the exact same thickness as the last one (deluxe A35 gaskets from treats).

When I first ran into this problem, I took the case apart and noticed one bearing had come out of place slightly. I'm guessing it came out of place when I first re-assembled it (I tighten the 5 clutch-side bolts in a star pattern to pull the case halves together around the crank, maybe i did this unevenly and it popped the bearing out of position?).

So I pressed the bearing back into position, then attempted reassembly again.

Same problem, crank won't spin easily. But now if I loosen the bolts slightly it spins fine, which makes me think the bearing is seated just fine but the case is too snug around the crankshaft.

On the exploded view, it seems there are two shims on either side of the crank inside of the crank case, mine only had one on the clutch side. I've looked through past threads on here, there isn't a solid consensus on these shims but most seem to use just one on the the clutch side (like mine). Maybe this shim is getting in the way?

What am I doing wrong?

Am I missing a shim?

Should I ditch that clutch-side shim?

Do you think the bearing is out of place again? Is this bearing damaged now that its been out popped and pressed in and out of position? (it spins fine, no evident damage)

I guess I could re-do the bearings. but that means splitting the case again, popping out the current set, freezing the new ones, heating the case halves, and then assembling it while the parts are hot/cold for an easy fit and without the risk of bearings popping out of place.

any advice/insight would be appreciated.* Moved to this forum by maize

Re: Tomos crank too tight, PLZ HELP MEH

yes the crank shim needs to be on the clutch side. u can put one on the other side but it isn't necessary. The crank will be tuff to turn by hand cause the cranks seals are new try putting it together and using the flywheel on the crank to turn the crank. the seals are going to be tight on the crank which is what u want so u don't have leaks.

Re: Tomos crank too tight, PLZ HELP MEH

If the crank spins once you loosen the case bolts then your bearings are binding due to side loads. They are not fully seated. Take a mallet and tap on the cases right at the bearing races. You can also thread a nut flush onto the crank to protect the threads and with light taps work the crank side to side to allow the bearings to center the balls within the races.

Re: Tomos crank too tight, PLZ HELP MEH

hit crankshaft briskly on either side alternately with a rubber mallet. it's not comfortably seated.

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