Freezing tri metal bearings with Liquid Nitrogen

[englertracing]

I've got some split tri metal main bearings that press into a motorcycle case here.
Have a mini Dewar of liquid nitrogen as well....
Have frozen them with dry ice before but it wasn't a big help.
I was sure about it at one point.
But now I'm having reservations.
These are also coated with calico coating.

[ProPower engines]

How Warn do you get the case they press into??
I have done some bearings with Nitrogen but not coated bearings.

I would contact Calico to confirm its OK to do. They coat the bearings they will know

[englertracing]

I'm afraid to go over 300

[peejay]

Wow! How much interference fit do they have that 250 isn't enough?

I admit that I haven't fought the particular demon you are fighting, but I've had aluminum housings that would stall a 20 ton press trying to force a race in, that ten minutes in a 250F oven would have a household freezer-cold race fall into place. And fall right back out again if you picked it up and flipped it over, as I found out.

[ProPower engines]

How much press fit are you fighting with??

[modok]

You will need to chamfer the extra edges, make a properly fitting solid driver, and possibly a ring of some kind to hold the two halves together against the driver, which is a little different.
In other respects it is NO different than installing a one piece plain bearing, like a camshaft bearing, which often have as much as .003" per inch interference fit. If it won't survive being installed then it was too weak to live anyway.

[englertracing]

I'm more concerned with damaging the case, it's sort of irreplaceable....

Case is nicely chamfered as are the bearings,
I have a delrin driver, nothing to hold them together though

[emsvitil]

Wouldn't they get brittle at liquid nitrogen temp?

[modok]

I'm more concerned with damaging the case, it's sort of irreplaceable....

Then don't jam them in there.
You think IF you can get the bearing in there then it will be ok, no.
Even if you use the star-trek transporter and have Scotty beam it in there, it will be still be damaged if the fit is not correct.
If it is too tight then Either the bearing will be crushed excessively or the hole will get bigger, or both.

[4sfed]

Case is nicely chamfered as are the bearings,
I have a delrin driver, nothing to hold them together though

A chamfer is not good enough. Break the sharp edges of the chamfers with some 320 grit wet-or-dry paper ... 0.005 in radius is enough ... and you won't have any shaving of the aluminum case.

[englertracing]

I'm more concerned with damaging the case, it's sort of irreplaceable....

Then don't jam them in there.
You think IF you can get the bearing in there then it will be ok, no.
Even if you use the star-trek transporter and have Scotty beam it in there, it will be still be damaged if the fit is not correct.
If it is too tight then Either the bearing will be crushed excessively or the hole will get bigger, or both.

Current problem is 0.0035" clearance on an 1.495" shaft.
New bearings should do 0.0018.
Thicker bearing and thicker coating.
Hoping the liquid nitrogen is equivalent to beaming it it.

I'll radius the edges and Chuck her in there.

[modok]

Ok, good luck!

if the press fit is on the high end of sanity, might do you good to use a lube such as..... standard silver anti-sieze, or coating the parts in soot, are the best lubes i know of for steel in aluminum press fits. But if it's beyond the high end of sane....don't do it!
There are things that can be done.
You can make a setup to measure the bearing OD, and take some material off the parting surfaces to change it.
Or bore a series of precision holes in a piece of steel and press the bearing through them to reduce the OD as needed.

Did they coat the outside of the bearing? Hmmm, didn't think of that, not sure. I've seen that work with copper plating.

[englertracing]

0.0045" interference

[Truckedup]

What kind of bike engine?

[englertracing]

What kind of bike engine?

Aprilia sxv550