I need to remove the outer part of the bearing from the crankcase. Does anyone know what temperature is required to heat the case sufficient for the bearing to fall out? I understand that this bearing locates the crankshaft and therefore probably has a greater interference fit within the case. Any advice would be welcomed.
Stick the crank case in a cold oven and turn the oven to about 250. The case will expand faster than the bearing and will drop out at a lower temp and quicker than placing in a hot oven.
Assuming your replacing the bearing. The bearing number is NKIB-5907. I sourced mine from simply bearings.
Hello Allan,
Thanks for the temperature info, I didn't use the oven for fear of stinking the house out, but got the cases to the temperature you gave using an infrared temperature gun. The bearing wouldn't fall out at this temperature, so had to be persuaded. After cooling I noted that Devimead must have used Loctite as belt and braces along with
.0015 inch shrink fit that I have since measured.
Cheers,
James
Strange why they used bearing fit on the out race, it's far from needed. The inner sleeve is a different matter and if it stands any chance of coming off then I'd locktite
The hell out of it
Using the oven should be ok if the case was washed in detergent soap, galleries gone though with a pipe cleaner/brush etc. However it is prudent to send the wife out for the day. Sadly a trip to the shops doesn't cut it at the moment.
The advantage with using the oven is the whole casting gets heated uniformly, this doesn't happen with a blow lamp etc so it cools extremely quickly compared as the heat dissipates across the rest of the casting.
hello Allan
I noted the bearing number you gave nkib5907 was the same as the one i removed, but mine had a C3 internal clearance marking on the edge of the outer race .I have looked on-line but can only find bearings for sale with no clearance markings on them,which mean its a standard or CN fit. I measured the internal clearance to be .001 inch greater on the C3 bearing.Will fitting the standard bearing with tighter internal clearance cause any heat issues/preloading,or has it been used without any prblems whatsoever.
Would appreciate any views you have.
regards
James
I haven't had any issues using the cn bearing, I later switched to a RNA4907, this is the same bearing but without the thrust race so is a little narrower. The reason for that was I had fitted a outrigger bearing outboard the drive sprocket. The simply bearings NKIB5907 will work just fine. Just ensure that you have some endfloat before you tighten up the timing side worm gear otherwise this will cause an issue but otherwise you shouldn't have any problem. Certainly not with clearance.
I fit C class bearings, limit on diameter is tighter so wont hopefully spin.
I had a customers square 4 in to rebuild and he supplied cheap Chinese bearings from a well known supplier, they fell out when fitting!!
never scrimp on quality of bearings.
I had a Devimead Needle Roller conversion on my Thunderbolt and the inner race was loose on the crankshaft, in that you could pull it off with your hand. I used Loctite bearing lock and it lasted for years.