Crank play

[nicsar]

Hi all,

I´ve got a -73 primmy.

I recently installed polini130, cut crank, pipe, phbl24 and changed all bearings etc.

I had it running, all seemed well. After a couple of hours driving around I noticed the flywheel moving up and down.

I removed the flywheel and found a play of ca. 1mm on the crank and a busted oilseal.

Now I´m about to rebuild it again with new fly bearing+seal.

My problem is I haven´t found out what caused my problem. I had my crank checked, it´s ok.

Any thoughts on this ?

Nice forum by the way, been following for a while
ns

[Juan]

Presuming the crank is true as you stated I can think of only 2 possibilities,either the flywheel is very unbalaced which is doubtful or the bearing was a lemon.Was it a known,quality brand fitted?

[nicsar]

Yes, had the crank to local machine shop. SKF bearings.
That leaves the f.wheel.
I´ts original pv flywheel, so I presume its ok.
I´ll get some valve paste and match fwheel to cone, maybe that´ll do it.
Just wanted to make sure there isn´t anything I´m missing and end up with the same problems again,damn expensive those 2 piece bearings..

Cheers for the fast answer ,
ns

[MiNiKiN]

This bearing play seems to be normal with heavily worn SF roller bearings caused by high mileage or lack of lubrication.
Get your bearings cheaper at www.simplybearings.co.uk and ensure the oil bore to the outer bearing race is free especially after fitting outer bearing race and seal ring.

[nicsar]

Now I ghot a new flyside bearing installed, SKF roller bearing.

After mating the cases I notice that the crank still has a small play.

I can feel it moving, not see it with bare eye, very small.

Is this normal, is it because the metal gets bigger when hot?

Or should the crank feel like its welded to the engine, no movement at all?

ns

[hank]

i think theres always a little play. there was with mine after new bearing/oil seal.