Angular Contact Main Bearings

[double diamond]

Has anyone installed angular contact main bearings in a bevel single? If so, what were the results?

[Duccout]

Apparently Condors used them, but Nigel Lacey changes them for standard ball-races when he rebuilds those engines. I would doubt that the crank or crank cases are strong enough to take any sort of pre-load on the bearings.

Cheers,

Colin

[blethermaskite]

Never seen them used for that application.
Cheers,
George

[Bevel bob]

I have heard of this before, perhaps they were fitted to allow very close shimming of the crank maybe with a little pre -load and the bearings could resist that ?.

[Jordan]

A low resolution section drawing of a widecase engine is from a Massimo Clarke book.

alternator-detail-section.jpg

MassimoClarke book cover.jpg

[Bevel bob]

Perhaps the bearings cope better with slight missaligned mainshafts ?.

[Duccout]

I think that the worry may be that if there was not enough pre-load, when the engine was hot it would allow radial play in the crank, whereas with deep-groove ball-races if end-float develops then the crank can only move along the axis. How you would decide on the amount of pre-load I am not sure; maybe install the crank and then check by heating the cases in an oven?


Cheers,

Colin

[double diamond]

I’ve had my race engine tear up thin shims used for setting crankshaft end play. I thought it might be the helical primary gear forcing the crank to move axially and hammering the shim but a straight cut primary did not resolve this. Found the remains of a shim in the sump. Maybe the crankshaft bevel also causes the crank to move axially. Angular contact bearings are used on the Pantah engines; there is information on preloading those bearings that would be a starting point for singles. Still have to shim to set preload but the crank might not beat on the shims the way it does with deep groove ball bearings. The other alternative is to use a single thick spacer to shim the crank but that would involve having spacers ground to thickness in fine increments.

[DBDBrian]

This is a very interesting subject. Just a thought, the Pantah crank being one piece, would be less prone too flex than the pressed up type in a single.
Brian

[Duccout]

Brian, that is what Nigel Lacey has found apparently, that the Singles crank is too weak to take a pre-load, but the modern one piece cranks are a lot more rigid.



Cheers,

Colin