Odd noise

[Tony Press]

What do the lower dynamic ratings mean in the application please Tony?

A lower capacity bearing will give a lower calculated nominal design life in revolutions to fatigue failure on a ring or rolling element.

It is used to design any bearing application.

The basic dynamic capacity is the constant load under which the bearing will attain a nominal life of 1 million revolutions.   This is only a nominal life-  some may fall below it and 50 % will last over 5 times longer.

I quote the figures to indicate why Austin designers would have chosen the Angular Contact Ball front and Roller Bearing rear  for the crankshaft - the alternate bearings suggested would lead to a lower bearing life but if this is acceptable then it is alright to substitute.

If you may remember the pinion support bearing went from a roller bearing to a ball bearing and subsequently back to a roller bearing- I would think because of the unacceptable reduced life of the ball bearing.  

Tony.

[Ruairidh Dunford]

Thank you Tony, much appreciated.

[Austin in the Shed]

I don't understand why originally they took the thrust up on the front bearings,especially with the 1 1/8" crank,A design flaw?

[Charles P]

I don't understand why originally they took the thrust up on the front bearings,especially with the 1 1/8" crank,A design flaw?

Possibly Stanley Edge's youth?
Or maybe they didn't anticipate idiots still using the cars 90 years later and reving the nuts off them.

Charles

[Ruairidh Dunford]

Is this the same setup as you had in the previous engine Charles?

I have seen similar in an Ulster engine, many years ago.

[Zetomagneto]

Charles, I like the sound of that, particularly as it would save me having to repair the broken front lip.
A reservation with regards to future strip down, getting a ball bearing rear main does not sound easy.With the standard setup you obviously can get the the outer track out, then pull inner track.No so with a ball bearing, what are your experiences.
Best Wishes

[Charles P]

Yes, I've had this setup for a while now. I used it on the advice of Austin 7 men of repute and skill.
Didn't have any trouble removing the rear ball race .

Charles

[Tony Press]

I don't understand why originally they took the thrust up on the front bearings,especially with the 1 1/8" crank,A design flaw?

Trying to understand the reasons behind design of the Austin Seven engine is not easy.

If rolling bearings were to be used in the engine I think the accepted practice at the time would be to use roller bearings for the crankshaft.

If the rear roller was selected for design life and the thrust taken here by a similar sized ball bearing it may have been thought this would give too much overhang between the crank and flywheel .
 
Taking the thrust at the front would also ensure the cam gears were correctly aligned.

The end thrust is from the clutch which is only for a brief part of the running time.

The bearing shaft size is often dictated by the crankshaft size and calculating the bearing design life based on a very fluctuating load is not easy.

For each shaft size there is a light and a medium bearing available and in this case the medium bearing was selected.

Cheers, Tony.

[Ruairidh Dunford]

Yes, I've had this setup for a while now. I used it on the advice of Austin 7 men of repute and skill.


Charles

I agree, there are a lot of very clever people out there Charles. In my experience, almost all modifications have knock-on effects to other aspects of the design and key to success (or failure) is understanding the implication of those changes.

Good luck with it all.

[Charles P]

Quite.
There are both smart people and less smart people that give advice. The trick is to understand which one you're talking to.
In my case, both were hugely successful at speed and race events.

Charles