Sleeve gear bearing interference fit

Tried to install a new sleeve gear bearing in the gearbox using the heat the cases method. Gear box is off the bike. It didn't want to drop in and ended up getting cocked in the bore. Was able to get it back out. I'm thinking about taking it to my local machinist and have him have a look at it. Would it be better to have him press it it? Does anyone know what the interference fit is supposed to be on these?

RGM told me that originally they had been a dot 2 and at some point with the 850s the factory went over to dot 3 .. quite how that works with interference not sure but presumably a bearing supplier should know, When I replaced mine, it finished up cocked in the bore ,more than once somade up a jig which bolted on to shell and the new bearing was aligned by an old velo trunnion shaft , which passed through a hole in the jig.. the bearing itself being placed on the end of the shaft located by a jubilee clip .. Sounds crude but it worked and saved me having to pull the gearbox off the bike
Do make sure to use soap on the casing when it goes brown you are at the right heat..Good luck its a pig of a job

htown16 said:

Tried to install a new sleeve gear bearing in the gearbox using the heat the cases method. Gear box is off the bike. It didn't want to drop in and ended up getting cocked in the bore. Was able to get it back out. I'm thinking about taking it to my local machinist and have him have a look at it. Would it be better to have him press it it? Does anyone know what the interference fit is supposed to be on these?

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I Consider it to be a bad idea to press bearings into aluminum housings. Properly heated it should simply drop in - you probably were not hot enough. Of course, the bearing needs to be as straight as possible when you drop it which can be hard in that small space. Couple of tricks. Find a deep socket that is a easy slip fit in the bearing. Set the hot case on the bench and put the socket through the bearing. Lower the socket and bearing into the case with the socket sticking out so it touches the bench well before the bearing enters the hole. This will help keep the bearing straight. Alternatively, get a wooden dowel that can be sanded down to snugly fit the bearing center and use that to lower the bearing and keep it straight.

The internal clearances of a rolling element bearing have no relationship to the interference fit into the housing. However once the bearing is installed the internal clearance can be affected by the amount of interference fit as the bearing is compressed. Interference fit of steel into alloy of a main or large gearbox bearing is 1 to 2 thou, internal clearances are measured in 10's of microns.

You need more heat, for alignment I have used the sleeve gear with the mainshaft assembled into the bearing when fitting into a shell still on the bike. Sighting on the mainshaft shows you any misalignment.

Put mine in the oven (wife out shopping) for 45mins top temp, bearing in the freezer over night. Dropped straight in using long nose plyers to locate the bearing.