Engine Bearings

[Paulcars1]

Has anyone used an angular contact bearing at the rear of the crankshaft where thr roller bearing goes. This should stop the crank trying to go forward when operating the clutch and posibly making crankshaft flex. Evan 

[Greig Smith]

Not necessary, there are two angular contact bearings on the nose of the crank, fitted back to back, this takes car of the clutch 'push' as well as the crank end float. The rear only needs to be a roller bearing. It's a beefy roller as it has to deal with the rotational mass of the flywheel which loads & unloads during clutch operations.

Any original crank you use will flex, even the 1&1/2 sports ones if revved enough. Most who do "press-on" driving fit a Phoenix, If you are rebuilding a gentle driver then even the early bent wire cranks do a sterling job, but seeing as engine rebuilds are expensive, a modern Phoenix is a good preventative measure if your budget stretches to it.

For a non-flexing crank - see Tony Betts website for his superb counterbalanced Hadley Cranks !!

Aye
Greig

[Bob Culver]

The basic rule is that shafts are constrained at one end only. An ac bearing would only restrain in one direction; it could become either heavily loaded or so unloaded that it was loose.
Anchoring the crank at the flywheel seems more correct. Some other makes did.(And plain ball races are cheaper) However cranks in normal use usually fail from the inside radius outward so clutch loading presumably not a factor .
Some arrangement to positively locate on both crank and in housing necessary.
Anchoring at the front may benefit the timing gears.

[Chris KC]

I believe others have tried it Paul, but as Bob says you can't then use A/C's at the front.

The benefit is arguable but not compelling. Plenty of people get by OK on the standard bearing set-up.

[Ian Williams]

There are threads here with comments by highly respected racers such as Frank Hernandez and others who have used deep groove balls to locate the rear of the crank Evan, well worth reading. However unless you are racing hard like these guys I suggest completely unnecessary in normal use.

[dickie65]

I suspect the Austin bearing design was to hold the timing gears in the correct alignment.
There is a case for one end to float to allow for thermal expansion.
You should only be using the clutch for very short periods, the timing gears are always trying to drive the crankshaft and camshaft forwards or backwards all the time the engine is running.

[Tony Betts]

I have had 6 engines here over the years that have had fixed bearings at the rear 5 were by way of self aligning bearings.

All six engines pulled out the front flange.

It's your own risk to try it.

Tony.

[Bob Culver]

My thoughts about the timing gears are that the crank is constantly changing  length as it flexes with firing pulses etc and the plain ball or a.c at the front possibly dampens the impacts on timing gears. 
My father bought his car in 1940 and although the motor had just been reconditoned something seemed wrong so he repeated much of the exercise.. He could not obtain a new rear bearing so fitted a ball. He reckoned it was unsatisfactory for some reason and replaced a few hundred miles later when he managed to obtain a roller. Despite umpteen dismantlings over the decades the front lip remains. Careful amateurs often do better than "mechanics".