removing bearings from aluminum case

[michaelwoodcoc]

ok I've tried several methods without the best tools and it seems the tools will be required. My experience has led to the development of several questions I'd like to discuss.

I tried hearing the case in an oven to 265 degrees with a papertowel filled with water inside the bearing to keep it cool, but the bearings did not fall out. After this, I tried applying ice water to the bearing with a paper towel, but this also did not work.

I am concerned with "galling" the aluminum upon bearing removal, and there being less aluminum for the bearings upon reassembly. Is this a concern? if so, I presume the best way is to use the proper tool after heating the case in the oven to 220 degrees?

will heats as low as 300 degrees affect aluminum strength?

I presume upon reassembly it's best practice to coat the bearing OD with antisieze, grease, or enging oil. This should help prevent galling or aluminum damage during future service, correct?

 

[benta]

Aluminium has a higher expansion rate than steel, so just heating the whole thing should release the bearing. But if you're out of luck, it's also been loctited.
You'll probably need to go up to around 200...250 deg C to get it loose. I wouldn't expect problems with the aluminium if it's cast. If it's machined dural it's more difficult.

 

[michaelwoodcoc]

^ Ok cool, I was told I should only heat to 275 F( 135 C) because you can "disrupt the grain structure" but I thought that only started to happen around 400 degrees F (204 C)
250C is 482F,

achievable in my oven, but I may get outgassing of the engine oil and upset others. There's one seal I didn't remove yet, which had enging oil bubbling around it, and bearings had some oil come out from behind or under them too. I don't know much about casting but I would think it's an investment or die casting.

I tried heating to 275 F with some paper towels with water inside the bearing to keep it cool. Others told me it would just fall out in the oven, but no such luck.

if those higher temps won't make the aluminum weaker after I'll heat it up and see if they fall out, and if no luck, I'll buy the special tools.

 

[berkshire]

If all else fails you can burn them out with nitric acid. But read up on that before you attempt it, Nitric is nasty stuff. You can buy a kit

http://www.chemical-supermarket.com/Tap-X-Broken-Tap-Removal-Kit-p574.html

This will enable you to dissolve the steel bearing in the aluminum housing.
B.E.

You are judged not by what you know, but by what you can do.

 

[benta]

"disrupt the grain structure"

That's why I mentioned Dural, where it's a problem. But cast should be OK.

 

[michaelwoodcoc]

Ok cool info guys, i hit it a lot with a heat gun amd just rented a slide hammer for this one.

Nitric acid, seems like it may bwork for brass mixture screws on aluminum carbs. That would be a dream, those frequently get stuck. I'm going to try that.

 

[Compositepro]

Many mechanical/engineering problems are solved by making the right tool to get the job done when one is not readily available.

 

[TugboatEng]

If the bearing is installed with typical interference galling shouldn't be an issue. Lots of interference changes the internal clearance or the bearing so it's not typically used.

https://www.summitracing.com/parts/...uOKg8Y11b3hdMQTS4uX5WKm_KCwNjf-kaApf-EALw_wcB