Bearing fitting help please...

[Farmer Giles]

Finally got the new rear bearing for my OS37 today so I need to fit it now. I know you have to heat up the crank case in the oven and it's also been said putting the bearings in the freezer helps too.

I just need to know what temperature in the oven, how long, do I need to cover it with foil or something, do you put it in the cold oven to let it heat through more slowly or can I just sling it in at full temperature ?

Basically any hints and tips greatly received as it's something I've never done before and I dont want to mess it up and damage the crank case in some way.

I will have the oven gloves ready and a block of wood ready to knock the old bearing out against.

Hope the missus understands why dinner is late

[Nick B]

i set mine to 120,once the light went off i turned oven off and put the engine in for 5 mins,tap tap on some wood and it popped out,new one straight in no problem

[Andy from Sandy]

150 - 180 degrees C for 15 minutes. Longer will not hurt. Alloy melting point is way way higher than this. If the oven is cold when you put it in just leave it for the few extra mins it takes for the oven to heat up. You don't need to cover it, just stand it on a baking tray.

Put the bearing on the crankshaft. When you remove the case from the oven and hold it up the crankshaft will literally fall in. If it doesn't you didn't leave it long enough. Do not be tempted to bash it in. Just put the lot in the oven to heat up again. The bearing will go in even when hot. It must do else you wouldn't of been able to take the old one out.

[Farmer Giles]

putting the oven on now...

[Andy from Sandy]

Check that the front bearing is still seated. It will fall out when the case is hot enough. I get two blocks of wood and place them apart so the crankshaft will fit between them. Hold the crankcase down on the blocks to hold the front bearing in place and then drop the crankshaft in.

[smokingtommy]

[ame=http://www.youtube.com/watch?v=TuzEco3EDUM]YouTube - How to change model airplane engine bearings (part 1 of 2)[/ame]

[ame=http://www.youtube.com/watch?v=OLSoXPLGzOI&feature=related]YouTube - How to change model airplane engine bearings (part 2 of 2)[/ame]

[Farmer Giles]

cheers guys, all done, no dramas.

Took about 12 mins at 130 deg C but the old bearing was shot to peices and really crusty.. hopefully a nice smooth OS37 now.

[POLAR BEAR]

I do mine with a hot air striper I hold the case near the front bearing with a rag then warm the case and WHAM (thats the technical term!!) it down on a peice of wood then put the new bearing on the crank shaft (before hand ) then while the case is still hot just shove in the new 1. If you use the crank to shove it in the bearing goes in squire\straight!
Kev.
PS im not aloud to use the oven!!

[waveydavey]

I do mine with a hot air striper I hold the case near the front bearing with a rag then warm the case and WHAM (thats the technical term!!) it down on a peice of wood then put the new bearing on the crank shaft (before hand ) then while the case is still hot just shove in the new 1. If you use the crank to shove it in the bearing goes in squire\straight!
Kev.
PS im not aloud to use the oven!!

Me an all! But I use a Whack instead

[Andy from Sandy]

I too use a paint "striper" but for someones first go the oven is more reliable and controlled. I have also found that when the engine reaches the right temperature and expanded enough no whack or wham is necessary, just a gentle tap to get the old bearing out.

[POLAR BEAR]

Me an all! But I use a Whack instead

I used a whack the 1st time but traped my fingers