Vintage Karting Forum

I have a Mc45 that has been rebuilt, but has a lot of crank end play. It seems to me that it needs shimmed. Has anyone done this?

Yea, no problem. The Mc45 has two different size ball bearings. You can get shims to fit behind either one.

Should the shims fit on the crank, between the bearing and crank, or between the bearing and the bore? I have been looking on mcmaster carr and not finding them.

Shims fit in the bearing pocket. Any large kart shop should have them. They are usually stainless or brass.

Philip;

I had this happen two years ago on a Mc91.  The bearing support on the side plate had cracked and was not holding the bearing as it should.  Found out that Locktite makes a bearing sleeve lock adhesive.  I found some and cleaning the bearing bore and bearing real good, I applied a couple of drops to the outer bearing surface and using a twisting motion pushed the bearing in until tight.  Do this without the rod and piston in and put it together with the crankcase.  This assured that crank was straight with out binding.  I let mine set overnight.  Put it together the next day and have been running it off and on for two years, still tight.  Hope this might help.

Bob Alexander

(04-04-2022, 09:07 PM)Bob Alexander Wrote: [ -> ]Philip;

I had this happen two years ago on a Mc91.  The bearing support on the side plate had cracked and was not holding the bearing as it should.  Found out that Locktite makes a bearing sleeve lock adhesive.  I found some and cleaning the bearing bore and bearing real good, I applied a couple of drops to the outer bearing surface and using a twisting motion pushed the bearing in until tight.  Do this without the rod and piston in and put it together with the crankcase.  This assured that crank was straight with out binding.  I let mine set overnight.  Put it together the next day and have been running it off and on for two years, still tight.  Hope this might help.

Bob Alexander

Listen to Bob, he's a smart cookie. My Pop used the early versions of the green Loctite back in his old saw/mower shop with good results. I see Loctite has a newer stick type bearing mount that rubs on. It still provides the same 3800 PSI shear strength of the liquid green compounds. It might be a help to you. The green stuff has saved many a block and side cover. Ted

I've had good luck shimming my 91's by pressing the PTO side bushing out and installing the shims behind the bushing, between the bushing and the block. I've done several of them and it works just fine.

Not supposed to be any end play on a 45, both bearings are supposed to be press fit on the shaft and in the bearing bore.

That being said, some guys like to have about 0.010" end play achieved by reducing the crank a few tenths where the inner race is normally pressed, this reduces the gyroscopic effect of the flywheel and is supposed to be easier on the crank and may increase performance a bit. This is done more on the 820 but I have done it on a few macs. It does shorten the life of the crank where there is slippage between the bearing inner race and the crank.

Bottom line is that McCulloch designed all it's engines to have zero end play. When things get too loose you end up with cracked and egg shaped bearing bores.

Just my two cents, the green high temp locktite retaining compound does work for awhile if the fits are not too loose.