Odd noise

[Ruairidh Dunford]

In my case, both were hugely successful at speed and race events.

Charles

I don’t doubt that in any way Charles.

[Dave Wortley]

The ball bearing at the rear sounds a great idea. It would be nice to compare the dynamic ratings of 1920's ball and roller bearings as fitted originaly to similar of today. Bearing improvements in desiign and materials must be considerable. There will be thrust at the front from the single helical timing gears but I don't khow how that compares to magnified foot pressure on the clutch
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[Tony Press]

The ball bearing at the rear sounds a great idea. It would be nice to compare the dynamic ratings of 1920's ball and roller bearings as fitted originaly to similar of today. Bearing improvements in desiign and materials must be considerable. There will be thrust at the front from the single helical timing gears but I don't khow how that compares to magnified foot pressure on the clutch

[/quote]
I had forgotten about the timing gear thrust

The shaft fit will be critical if the thrust is to be taken on a rear ball bearing- possibly a tighter than normal shaft fit which would need a ball bearing with increased internal clearance - SKF C3. Trying to effectively trap the bearing inner ring between the flywheel and crank shoulder as well as getting the proper fit on the taper would be very difficult. 

The metallurgy improvements are significant - my initial discussion referred to the 1950's bearing specifications but checking current SKF bearing specifications-

Ball Bearing SKF RMS 10 is now quoted as dynamic capacity 7,464 lbs - approaching the 1950's Roller Bearing SKF CRM 10 at 8,000 lbs.  

New genuine inch series ball and roller bearings are hard to find now, so we source original old stock SKF or RHP bearings to avoid the too easily fallen into trap of buying new Chinese copies (which regularly mimic SKF in packaging and marking) made from inferior materials. 

My initial comment about relative bearing capacities was to illustrate the likely original design reasons for the Austin Seven engine bearing selection.

Can't help thinking this discussion should be under a different heading but that is often the way with the Friends Forum

Cheers, Tony.

[Dave Wortley]

Tony,
Locating the ball bearing at the back might not be too bad. With the crankshaft out of of the case you could fit the bearing inner race on the rear journal after first lapping the flywheel onto the taper, measuring the gap with feeler gauges and making shim washers to that size minus a thou or two.( I think that’s Charles P’s method). Alternatively you could use a Belleville washer(disc spring) to provide the necessary axial force. Then there’s loctite......
Cheers,
Dave.

[dickie65]

Hi Folks,
I used to run the Type 65 with a twin track self aligning ball race at the rear, with no issues, the crank is a 1 1/2" Allan which is very stiff. I used the front bearings for location as standard.
( I think its still in the garden shed, no sign of brinelling when removed )
I also have a very clever shell bearing conversion for the front and rear mains in the spares pile, I have not yet done a trial assembly on this as it would require some cunning in the oil feed dept.

[Charles P]

I used slip gauges to measure the gap and then ground a spacer to fit on the surface grinder.

[Tony Press]

Hi Folks,
I used to run the Type 65 with a twin track self aligning ball race at the rear, with no issues, the crank is a 1 1/2" Allan which is very stiff. I used the front bearings for location as standard.
( I think its still in the garden shed, no sign of brinelling when removed )
I also have a very clever shell bearing conversion for the front and rear mains in the spares pile, I have not yet done a trial assembly on this as it would require some cunning in the oil feed dept.

This would be an SKF RM 10 - with a much lower dynamic capacity than the equivalent roller bearing, lower than the ball bearing and not good at all for thrust loads - the outer ring would have to be a sliding fit in the housing. 

What was the reason for using a self aligning rear bearing with a stiff crankshaft and with the rigid front double bearing assembly (or did you mount these face to face?).

With the self aligning bearing the failure would be fatigue (flaking) on the track or balls rather than brinelling.   

Cheers, Tony.

[Bob Culver]

Alternative bearings seem to offer scope for less expense but that seems seldom a Seven consideration now. The load rating of bearings varied greatly between brands, and modern are rated very superior to older. Prior to strain gauges and computers many car components were sized from experience and intuition as the range and distribution of loads and effect difficult to predict or calculate. 
Large bore  motor cycle engines with high pressures survive with modest sized bearings.
 
 I have asked before, but are Seven mains in normal use and correct assembly ever found failed by traditional fatigue flaking? Corrosive wear used to be the main enemy. The tracks appear grey instead of chrome shine.
 
 I have an old Newnes which shows BSA 9hp engine as a Seven but ball at the flywheel end. Does not contact the flywheel but any spacer not clear. If anyone has worked on or has a more extensive manual would be of interest.

A collegaue purchased supposed SKF bearings from a major supplier. Failed promptly  and the supplier eventually identified as fake.