R51/3 - rear crankshaft main bearing color change

Micha · Post by **Micha** » Tue Mar 10, 2020 12:38 pm

While installing a new rear crankshaft main bearing I warmed it up and maybe exaggerated a bit, however after pressing it to place, now I see that its outer race color is golden yellowish. I recall that extracting the old one was a pain in the you-know-what, and was accompanied by destruction of the oil slinger.
Should I be worried about this color change? Did I interrupted the heat treating procedure of the bearing? Must I go through the extracting procedure again?
I assume it was heated to about 200-400 Celsius. Its hard to tell.

jimcarrr100rs · Post by **jimcarrr100rs** » Wed Mar 11, 2020 12:04 am

I think you are OK. If it had turned blue you might have trouble.
How did you heat it?

Micha · Post by **Micha** » Wed Mar 11, 2020 4:19 am

Thanks.

I did it with an electric hot plate.

Twocams · Post by **Twocams** » Wed Mar 11, 2020 2:39 pm

You should be OK. Guess you haven't got a book yet? Some Items they suggest putting in the freezer to (shrink up some). You don't have to go that hot, as you found out. I have a used slinger, replaced mine with my rebuild. U pay shipping from Oregon you can have one of them for nothing.

Micha · Post by **Micha** » Wed Mar 11, 2020 4:05 pm

Thank you.
The freezer tip is well known over here :H

Captonzap · Post by **Captonzap** » Wed Mar 11, 2020 8:14 pm

Thank you.
The freezer tip is well known over here :H

That takes care of the cold, so next time you use the hotplate to heat a bearing, place a few drops of oil on the bearing, and when it starts to smoke, it is about 450 far,+/-. That is not hot enough to change the temper in the races.

CZ

Micha · Post by **Micha** » Thu Mar 12, 2020 1:01 am

Thank you!
That's a nice tip, I will remember it ;;)

Micha · Post by **Micha** » Thu Mar 12, 2020 1:03 am

You should be OK. Guess you haven't got a book yet? Some Items they suggest putting in the freezer to (shrink up some). You don't have to go that hot, as you found out. I have a used slinger, replaced mine with my rebuild. U pay shipping from Oregon you can have one of them for nothing.
You should be OK. Guess you haven't got a book yet? Some Items they suggest putting in the freezer to (shrink up some). You don't have to go that hot, as you found out. I have a used slinger, replaced mine with my rebuild. U pay shipping from Oregon you can have one of them for nothing.

Thank you! That is kind.
I already bought one over at Mark Huggett

Vintage BMW Motorcycle Owners

R51/3 - rear crankshaft main bearing color change

R51/3 - rear crankshaft main bearing color change

I think you are OK. If it had

Thanks. I did it with an

You should be OK. Guess you

Thank you. The freezer tip is

another trick

Thank you! That's a nice tip,

Good people over here