420 Auto Rebuild - Case Splitting

All -

Apologies ahead of time, since I'm sure this topic has been covered here somewhere.

I'm bringing a neglected 420 Auto back to life and am splitting the case to replace all case bearings and seals. I purchased the Tusk Crankcase Splitter and successfully split the case. Upon using the splitter to remove the crank from the left case I got a lot of resistance - to the point where one of the arms of the splitter broke at the weld.

Am I doing something wrong here? Is there a trick to getting the crank out of the left case?

Any help you can give would be greatly appreciated!

Scott

The crank comes out of the bearings then the bearings are removed, I generally use an electric heat gun on the case to help get the bearings out. I can not comment on Tusk devices though. If I recall correctly the auto is just an aluminum case and has no steel insert for the crank bearings like the magnesium standard shift two cycle engines do. Upon further thinking I take off the left side half leaving the bearings in the case and the crank in the right side half but I suppose one could start by working from the ignition side. I would hope you took off the first gear clutch and then took out the big drum with the other clutches before splitting. I use manuals for most stuff but pretty much made up my own methods for these things.

Thanks Frank.

I think I can get the bearings out of the case with heat and other encouragement. But I'm having trouble getting the crank out of the left side case bearings. How do you do that?

Thanks again,
Scott

I have a disc that has holes for those tiny bolts or machine screws in that piece that stops the bearings from creeping outward. That disc is drilled and tapped for three 1/4 x20 tpi bolts that go to a three slot type puller, well pusher in this case. I have never damaged the cases or those tiny perhaps 4mm bolts or machine screws. I will look for a picture. http://www.frannyk.addr.com/cafehusky/engine.dissasembly.pix/P3040398.JPG not an auto but same special tool

Very helpful Frank.

I have one of those pullers I use for removing the 1st gear clutch in the auto. I'll give that a try.

Thanks again,
Scott

If it seems too hard perhaps at one time I used a tiny oxy acetylene flame on the inner race. Tiny means half an inch long total and less than a quarter inch on the inner cone. You are pushing the crank out of two 6205 bearings so at best it will only relieve half the load. The real battle on those automatics is when the taper for the first gear clutch becomes welded. Hard to believe it can get like a spot weld and not shear the key unless you have seen it. Torque that first gear clutch on at assembly and maybe at 5 minutes and then maybe at two hours, that I think is in some manual. There also is the shock factor of a blow to the puller/pusher main threaded piece.