Main bearing retaining compound required?

[Dedubyah]

Just about to start reassembling my 850 engine and wondered if main bearing retaining compound is required when installing replacements? The old bearings were a pretty snug fit in the cases, which don't seem to show any wear.

 

[Triton Thrasher]

I don’t think Loctite works between the main bearing outer and the crankcase.

 

[dobba99]

Did you heat the cases up to remove the old bearings? Or did you just knock them out cold?

 

[marshg246]

Just about to start reassembling my 850 engine and wondered if main bearing retaining compound is required when installing replacements? The old bearings were a pretty snug fit in the cases, which don't seem to show any wear.

Assuming you had to heat the cases to get them out and you have to heat the cases to get the new in then nothing is required.

If you beat them out of the cases - bad move and I can't say.

 

[kommando]

Loctite does not work on main bearings to restore fit due to heat cycles, it will be gone within 1000 miles. If the interference fit is good then loctite will take away the internal clearance and wear the bearing out before the loctite fails.

 

[Dedubyah]

I had to heat them up for quite a while in the BBQ before they would come out, thanks. I see that there are specialty compounds for retaining roller/ball bearings in housings but I am loathe to purchase unnecessarily as it would probably be the only occasion I would use it

 

[marshg246]

I had to heat them up for quite a while in the BBQ before they would come out, thanks. I see that there are specialty compounds for retaining roller/ball bearings in housings but I am loathe to purchase unnecessarily as it would probably be the only occasion I would use it

You don't need any compound since they came out with heat. When you put them back, heating to 100C (212F) should let them drop in. Never hit them! It's fine if you have to go to 150C/300F to get them to drop in.

When bearings are loose, there are specialty "bearing set" compounds and they work. But they are formulated for different purposes such has heat, blindhole, press fit, etc.

Never use Red or Blue Locktite - not correct for the application!

 

[ashman]

When i do main bearings i always have the new bearing at the ready, i am lucky i have gas stove so i put the cases over the burner and just let the heat rise within a minute or 2 the old bearing drops then i flip the case over and drop the new bearing straight in then just let the case cool down while i do the other side case on the heat.
I have done this on every Norton rebuilds whether mine or rebuild my mates Norton motors as well a few paid rebuilds, once the cases have cooled down have never had outter bearings come lose doing it this way, over the stove burner it happens so quick so have to be ready for the clunk when the bearing drops.

Ashley

 

[acotrel]

My friend used to spit on the crankcases to see if they were hot enough, then turn the case over and use a wet rag to remove the bearing. I was never that flash - replacing the bearings was never a problem. I would not put bearing mount in there - it is an unknown, and new cases would not be cheap. I think heat unlocks Loctite, but I would not like to have that kind of problem, if it doesn't.
Relax and enjoy your life - you are the boss - not the motorcycle.

 

[robs ss]

My original cases for my 650ss have a looser than desirable fit for the mains so I have a cunning plan for them...
I was reading that a number of Porsche racing teams were extending the life of their alloy wheels or hubs by using blunted pipe-cutting rollers to press grooves in the bearing face, forcing metal upward between the grooves, thus restoring the fit. I can't remember the loctite they used. Its only job was to prevent the metal migrating back into the grooves.

I thought this to be quite clever and will be testing it!
Cheers

 

[Peteyoung75]

I have a domestic oven in the garage. I don’t know why it’s not more common. It works off a 13A plug and is incredibly handy with reasonably good temperature control. Cost me £13 from eBay

 

[franko]

Somewhere in this thread :https://www.britbike.com/forums/ubbthreads.php/topics/691207/1928-ariel-model-c#Post691207 Magnetoman describes how he use a Eastman DIY plating kit (I think) set up, to increase the outside diameter of one of his bearing races. Seamed simple enough as I read along as the adventure unfolded.

 

[concours]

Just about to start reassembling my 850 engine and wondered if main bearing retaining compound is required when installing replacements? The old bearings were a pretty snug fit in the cases, which don't seem to show any wear.

No.