Removing Ball Bearings

[Braddock, VC]

Just a quick tip, I just renewed the bearings on an OS 91 Fx as it felt a bit graunchy.

The rear bearing was extremely corroded.

Any how I hear a lot of folks have problems with heating the crankcase to tap the bearings out so I gradually heated it up in my oven, 150C it didn't shift, 175C didn't shift, 200C two really hard taps on a solid wooden surface and it was out.

I bought SKF deep groove bearings standard clearance,cost less than the OE bearings, post free (2nd class) and they still arrived the next day.

At 200 C btw the paint on the crankcase plus all the burnt on gunge crackled off, so wrap the engine in alloy foil and let it soak in the heat for a good ten minutes before trying to knock the bearings out.

Engine is back together and sweet as a nut now.

[Keith Berriman]

Hello there I have just ordered replacement bearings for my Irvine 46 same problem rear bearing starting to go

I read the various threads on removal and actually got mine out by heating the crankcase with a hot air gun. So when I come to get them back in do I use the hot air gun again to warm the crankcase up and have the rear bearing on the crank to slide in or can I put the bearings in the freezer for an hour or so to drop in and wait for room temperature before the rebuild ??

[Martin Harris - Moderator]

Cooling will contract the bearing but you won't get more than 40 degrees or so difference, whereas with heating it's possible to increase by 150 to 200 degrees with relative ease. As expansion/contraction is essentially linear in these temperature regions you can see that heating offers much more benefit. Of course, you can (and I often do) combine both...

I prefer using the oven (wife out!) as the heating is more controllable and even.

Edited By Martin Harris on 24/05/2015 15:00:10