Difference in main roller bearing?

[Dibble]

still pottering about with the bottom end on the hornet i noticed the new drive side bearing has a significant difference to its original. The new RHP mrj1.1/8j allows its cage to pass completely through where the elderly  Hoffman rm1/l v3 does not! I know when fitted into the casing it wouldnt ofcourse, but it gets you thinking! Do i go ahead with the new one? I notice its the same as SRM advertise on their web. The more i progress with this build,the more i realise idont know! Grateful for any advise. Dave

[Calum]

There was a discussion similar to this in the pre war section a few months ago. I chimed in as I had a similar experience with a cylindrical roller in an old gearbox - original had a lipped outer race but the new one was parallel and the rollers went right through.

Personally I think it will be fine - if the rollers actually touched the lip in the outer race they'd likely be wrecked in no time. There's not any lateral thrust from the big ends - look at shell or white metal bearings here, they don't touch on the sides. If the rollers are clear of the lip on the old bearing (which they should be) they are in fresh air and so no lip on the new bearing won't make any difference.
Just my thoughts on it.

[JulianS]

Be very very careful with a bearing without a lipped (flanged) outer race.

Presuming the engine has a bushed timing side earing rather than an SRM type end feed, the lip limits the amount of axial movement. No lip  the movement is not so limited and the crankshaft pinion may even bear against out edge of the main bush and chew it.

When the crank end float is being set it gives just a few thousands clearance between the rollers of the bearing and the outer lip. No outer lip how do you set the float?

[LightningAndStarfire]

Some cylindrical roller bearings do allow some axial load. Can be seen in the SKF handbook. Or at least, could be seen. Many years now since I did an application

[Dibble]

Thanks julian for that information it might just have saved my new motor! It gives rise to the question then, why do they advertise this type of bearing as suitable for this engine? They are all over ebay and as i said earlier SRM show what appears to be the identicle thing! Another call to the ever helpful guys down in Wales? Thanks to all for your thoughts keep 'em coming! Dave

[chaz]

I think its a case of whats available, I can get RHP double lipped cheaper than single lipped, as has been said, the single lip can be more accurately shimmed as for a non lipped there is always the possibility of the inner creeping along the shaft.
These special bearings are becoming less available due to production costs and quantity runs, some marque specialists are even selling Chinese made main bearings that are lesser tolerance and Ive had a case where the bearing has fallen out after it was fitted. the N3 closer tolerance fit ones tend to be dearer due to tighter production manufacture, which, as I work in engineering to close tolerances, I cant see why as working in machine shop , once the machines are set up its no difference in time or materials.
My main concern is buy the best you can afford, single lipped and shim correct and there will be no need to strip again later.

[JulianS]

This is the lipped type,

https://simplybearings.co.uk/shop/advanced_search_result.php?search_in_description=1&keywords=rm11l&;

[Calum]

Be very very careful with a bearing without a lipped (flanged) outer race.

Presuming the engine has a bushed timing side earing rather than an SRM type end feed, the lip limits the amount of axial movement. No lip  the movement is not so limited and the crankshaft pinion may even bear against out edge of the main bush and chew it.

When the crank end float is being set it gives just a few thousands clearance between the rollers of the bearing and the outer lip. No outer lip how do you set the float?

Interesting. How is the end float 'set' then? Is there not something to hold the crank in place other than the lipped bearing? Is it just a case of two opposing lipped bearings roughly keeping it in the middle? I've never been in said engine so can't really imagine what's going on.

[JulianS]

On many single cylinder BSA models the axial movement of the crank is locked by use of a ball race. The A series twins have no positive location of the crank that way, other than the SRM type end feed conversion which replaces the bush with a combined needle roller and ball thrust race.