Input Shaft Bearning Removal

[gregwils]

I bought a tired, old 160 engine seven or eight years ago for $100. The cylinder and piston are junk, but the case is fine and I purchased a separate head that is pretty good. I know it's a poor investment, but I enjoy projects like this and children are grown, mortgage is paid, retirement funded and I'm still working, so I don't care if I lose money. Plus, it will give me experience with the handful of 250 motors that I own.

I have all the bearings out except for the input shaft bearing on the oil pump side of the case. The issue is that the clearance between the bearing and the case is so limited that the two different bearing pullers that I tried are not able to get a grip on the inner bearing race.

Is there a top secret way of getting this bearing out? I have tried warming the bearing, but have not cranked up the temperature on the case. Any thoughts would be appreciated.

[ducwiz]

For me, heating up the bearing makes no sense. It will expand its diameter thermally, while the case bore dia. stays more or less constant, so the bearing cannot come loose. You might be successful by heating up the whole case half up to 150(180)°C, taking advantage of the much higher thermal expansion of aluminum, compared to that of the steel bearing. When the desired temperature is reached, impinge the case with the center gasket side downwards flat onto your workbench, so that the inertial force can drive the bearing out of its seat.
If this does not work, try to weld a kind of cross brace into the bearings bore , then drive or press it out from the exterior.

cheers Hans

[Jordan]

I've removed that bearing from widecase singles in two ways, that both employ a slide hammer.
First was to weld a long bolt (about 30cm, more the better) to the inner race.
Second was to use a blind bearing puller.

[themoudie]

Aye gregwils,

Hans' suggestion to put the cranckcase half into the oven; I would add, after thoroughly cleaning in the dishwasher (it's what they are for!) would be my preferred method, although I usually only take the oven to 100°C. Have a large piece of ¾ (18mm) plywood or OSB close by on the floor, so that when you remove the case, with the oven gloves, you can drop it squarely and with force onto the board and the bearing should pop out!

If the previous assembler has used a bearing glue (?) the heat should weaken this and allow the bearing to drop out.

Alternatively, two ⅜" (5mm) holes at 180° from each other can be drilled through from the outside of the bearing housing behind the sprocket, so that the bearing can be driven out using a parallel punch on the outer race! This method works when all else fails, or you don't wish to disturb other bearings in the case. The holes need to be sealed with a touch of silicone sealant, before installing the gearbox sprocket and filling the engine with oil. WARNING: This latter method is probably anathema to most engineers!

N.B. I have a sympathetic wife for the use of the dishwasher and oven for these purposes. Be aware that degreaser can leave a lingering smell for some weeks in a domestic oven, which is fine, if you enjoy barbecued food!

Best of luck and good health, Bill

[gregwils]

Thank you Hans, Jordan and Bill. I mis-typed my initial statement. I meant to say that I heated up the bearing area or a better description would be the area surrounding the bearing. I actually bought a small toaster oven at a garage sale for the dual purpose of baking case halves and staying in good standing with the kitchen boss. The case halves don't quite fit, but they go in far enough to get close to 200.

I like the idea of warming the case, then welding a bolt to the inner race. I have a couple of slide hammers. I will get it out. Thanks for the input.

[Geordie]

I used an expanding wall fixing. They come in various diameters. Edit: fitted from the outer side and tapped through iirc, plus heat.

Screenshot_20220502-094840_1.png

[blethermaskite]

I also use a rawlbolt type anchor bolt fixing expanded tightly into the inner bore of the bearing
,then heat and tap the bearing out.......has always worked for me.
Cheers,
George

[ducwiz]

More interesting and helpful ideas have been posted, i. e. use of a dishwasher which I also recommend, for keeping peace in the household.
I personally did not use an expansion anchor bolt to date, as it could produce radial force into the outer ball race, which does not ease the extraction at all - theoretically. But, I never made the experiment.
The bearing in question makes also problems in other motors, n/c and w/c. I had only 2 or 3 n/c's on the bench over the years, but roughly 10 times more w/c's. I remember having always trouble with this bearing to get it out. I also recognized, that often the bearing did not spin freely, but kind of "rough". Conclusion: the seat bore in the case seemed to be to small (bad tolerances), reducing the radial play of the balls to zero, or even set them under pressure, which results in additional radial force for the press fit of the outer race.
Sometimes I had to compensate the effect by installing a bearing with C4 class; C3 was always mandatory anyway.

cheers Hans

[gregwils]

"Conclusion: the seat bore in the case seemed to be to small (bad tolerances), reducing the radial play of the balls to zero, or even set them under pressure, which results in additional radial force for the press fit of the outer race."

Hans,

I think this is distinctly possible. I used a collet as Geordie suggested he used. My collet has a lip at the bottom to grab the inner bearing race. The lip broke before the bearing came out. Plus, my bearing feels 'kinda rough' which is why I wanted to remove it in the first place. I may try to slip a hone in case bore if the fit seems ridiculously tight.

[ducwiz]

Greg,

honing the bore slightly is basically a good idea, but it isn't easy to operate the honing mandrel in this kind of "blind bore". This is why I chose to fit a C4 bearing, which then spinned freely, without any "roughness". Anyway, when the case gets hot, the bore will expand more than the bearing's outer race, so in operation the situation for a C3 bearing gets possibly relaxed. I loosely remember having done this spin test while case and bearing were quite hot, just after forcing the bearing in.

cheers Hans