best way to change bearings

[anthony_marquart]

Let me know if there is anything wrong with this.

take apart the motor and clean thoroughly.

Freeze bearings over night

Warm case, hot to the touch but not blazing..

Push little bearing into place. Make sure it's all the way in and bottomed in the case.

Warm the center section of the case,..

put the big bearing on the crank,

insert the crank into the motor, push till the bearing is all the way in,..

let it cool,

check that the crank spins freely,.. put it back together.

Done

 

[FloridaScaleBoater]

Let me know if there is anything wrong with this.

take apart the motor and clean thoroughly.

Freeze bearings over night

Warm case, hot to the touch but not blazing..

Push little bearing into place. Make sure it's all the way in and bottomed in the case.

Warm the center section of the case,..

put the big bearing on the crank,

insert the crank into the motor, push till the bearing is all the way in,..

let it cool,

check that the crank spins freely,.. put it back together.

Done

Anthony;

This is how I heve done it for years

I'm assuming you have the old bearings out already?

Yes, clean case and crank with plenty of brake clean, and wipe out any black/discolored spots with rag.

slide big bearing onto crank, and freeze bearings & crank at least overnight (if you do not freeze the crank also, as soon as you slip the bearing onto a room temp. crank, it starts warming the bearing and you may not get it fully seated)

If you have a small counter top toaster oven, heat the case in it to 350* for about 20-30 minutes. (doing this heats the entire case evenly)

When ready use a leather glove, or welding glove, slip crank with large bearing into place, slide small bearing into place, put on tapered sleeve, flywheel and shaft collet, and just "snug it up" do not tighten as you would during final assembly.

Set off to the side & let it cool natuarally.

I'm sure there's other ways of doing it, but this has served me well for years.

Good luck,, and oh yeh,, when sliding it all together, you gotta be quick!!! not only to allow the heat & freeze to work properly,, But cuz that hot case will penetrate the best of welding gloves pretty dang quick

 

[RodneyPierce]

I use the oven set to 350. And use one of those glove oven mits. Otherwise just as stated above.

 

[anthony_marquart]

I think we're all on pretty much the same page.. I just won't go that high with the heat. Can't remember what the numbers are,.. but pretty sure at 350f you are in danger getting some property change in the aluminum. It's going to be pretty soft at that temp. I'll warm mine just enough to get the expansion that I need.

Mr Allen,,, we spoke about this a little. We talked about temp but I don't remember what temp you recommended,, please comment.

Thanks

 

[RodneyPierce]

Your hanging out with Jim Allen too much. His vast knowledge of metallurgy is wearing off.

I have been doing it this way for years, never had a single issue.

 

[anthony_marquart]

I just wish I had written down what he told me... just half of it.. Can't remember the temp we talked about.. Probably the 350 is just fine..

 

[Chris Wood]

lol ovens freezers lol.. i use a torch.. heat the case dump the old ones out pop the new ones in.. won alot of races with motors done that way.

each there own though

chris

 

[Jeff Barnhart]

I'd assume he meant 350C. I put my blocks in at 350F for about 5-7 minutes it's expanded just enough to get the bearings out. Everyone else seems to do the same with no problems.

 

[Ray Sametz]

lol ovens freezers lol.. i use a torch.. heat the case dump the old ones out pop the new ones in.. won alot of races with motors done that way.

each there own though

chris

KISS

 

[anthony_marquart]

That's funny.. I guess we do get carried away don't we... Talked to a friend with some metallurgic knowledge,.. Since we don't really know the exact makeup of the metal case,.. it's probably best not to go over 400 as a total temp,.. meaning you can put it a oven at 400,.. but don't leave it in there for an hours,..

I'm just going to do it like have before.. just wanted to make sure I wasn't missing something..

 

[David Bryant]

Thanks for your input here.

It would be nice to have some discrete parameters here-ie.

(A) what is target average case temperature for proper expansion (to allow removal/replacement of bearings)? 350 degrees F?

My method has been:

(A) Placing case (w/old bearings installed) into pre-heated oven (I believe approx 250 to 350 degrees F), heat for X number of minutes (I believe 10 to 20min)

( B) Slide new large inner bearing onto crankshaft

© Working swiftly Carefully remove case from oven (using mitt). I carefully tap on the outer case with safe object (I use wooden spoon), old bearings should fall out.

(D) Quickly slide crankshaft into position with large inner-bearing in place. Slide outer-bearing onto crankshaft front-end. Slide flywheel and collet onto crankshaft, hand-tighten cable collet nut. Bearings should self-position

 

[Ray Sametz]

lol ovens freezers lol.. i use a torch.. heat the case dump the old ones out pop the new ones in.. won alot of races with motors done that way.

each there own though

chris

KISS

In all honesty when I ran OPS and N/R 21's. I measured the crank and chucked up a piece of bar stock and made a mandrill to press on the outer race of the bearings to install them. Either way torch or oven, you have to be set up and work quick. B)

 

[Don Ferrette]

My method has been:

(A) Placing case (w/old bearings installed) into pre-heated oven (I believe approx 250 to 350 degrees F), heat for X number of minutes (I believe 10 to 20min)

( B) Slide new large inner bearing onto crankshaft

© Working swiftly Carefully remove case from oven (using mitt). I carefully tap on the outer case with safe object (I use wooden spoon), old bearings should fall out.

(D) Quickly slide crankshaft into position with large inner-bearing in place. Slide outer-bearing onto crankshaft front-end. Slide flywheel and collet onto crankshaft, hand-tighten cable collet nut. Bearings should self-position

This is the way I've been doing it for years.

 

[Shane Midkiff]

My method I the same as Don's exept I use wooden dowl to push the front bearing out and a hot plate set at 250-275 degrees F to heat the case up. I have found there is no reason to go above 275 degrees F, on any engine I have rebuilt. On some .81, .91 and 1.01 etc. 250 degrees is not enough heat but 275 degrees F is enough heat to replace the bearings. I have never done the freeze thing in the last 20 years but have seen people do it and personaly see no reason for it, just my two word's.

Shane

 

[anthony_marquart]

If you freeze the crank and bearings they drop in easilly.

 

[Shane Midkiff]

I understand the concept of the freezing them, I just have not had any trouble putting them in at room temp.

Shane

 

[Don Ferrette]

If you freeze the crank and bearings they drop in easilly.

The issue I have with freezing is heat naturally migrates to cold and with that much temp variation makes it happen very quickly............. :blink:
Room temp on the bearings and crank for me gang. B)

 

[Shane Midkiff]

Don, I agree it is better to let the case cool down slowly by itself rather than fast contraction coming off of a cold bearing.

Shane

 

[steve wood]

heat with propane or mapp gas till bearings fall out,keeping torch moving at all times.let case cool,then clean case.place bearing installation tool in vise,set large bearing on tool,then case,then small bearing.heat with torch till case falls on large bearing,push on small bearing if needed,till it seats.let cool.install crank and make sure both bearings are fully seated

 

[Jim Allen]

I think we're all on pretty much the same page.. I just won't go that high with the heat. Can't remember what the numbers are,.. but pretty sure at 350f you are in danger getting some property change in the aluminum. It's going to be pretty soft at that temp. I'll warm mine just enough to get the expansion that I need.

Mr Allen,,, we spoke about this a little. We talked about temp but I don't remember what temp you recommended,, please comment.

Thanks

Both A356 & A357 can be used as permanent mold casting & sand casting materials. Typical aging to the T-6 temper would be 315 deg F for A356 & 340 deg F for A357. Both materials need to be solution annealed before aging. Heating either material beyond 300 deg F could vastly change the ultimate tensile & yield strengths achieved during aging. Typical tensile strengths are 33,000 psi for A356 & 45,000 psi for A357. All the above information can be found on MatWeb.

Jim Allen