Flywheel taper

[jansens]

My engine building continues slowly, mainly due to lack of practical experience. I had a great visit with Mr Hainsworth who checked my cam gear meshing for me, something tricky to judge having never seen it before. Steve confirmed the cam gears are good.

He also spotted a mistake I had made where I had left off the dished oil thrower on the rear main bearing. He suggested replacing the old cover with one of the modern ones with an oil seal. Yesterday I speedi sleeved the flywheel boss and have the new rear cover plate arriving today hopefully.

I have lapped the flywheel onto the taper. This is where I am confused. The flywheel taper seems to have a section machined out of the centre so the taper doesn't touch at all in the middle. The red book doesn't seem to mention this but Austin 7 Club article does: http://www.austin7club.org/How%20To3.htm

So is that normal?

I just lapped enough to get even marking on the taper where it does touch. Definitely makes a difference, even with the nut finger tight the flywheel locks onto the taper and needs a tap with a rubber hammer to unstick it.

I measured the run-out at about 6 thou which I think should be OK. 

Another question is I am using Phoenix rods with modern shells. The rods have little notches where projections on the shells locate into. These are only on one side of the rod. Does it matter which way around the rods go in the crankcase? I suspect not as long as I have them all on the same side?

Simon

[Alan]

The taper is normal - some were like that, some weren’t. Both seem to work ok.
As far as the rods go- if they are horizontal split type, they can go in either way. If the 45 deg ones, they will only go in one way.

[jansens]

The taper is normal - some were like that, some weren’t. Both seem to work ok.
As far as the rods go- if they are horizontal split type, they can go in either way. If the 45 deg ones, they will only go in one way.

Thanks Alan, I'll make a note in my red book about that. Seems odd not to use the entire taper but I am sure there is some complicated engineering reason for it!

The rods look like this. You can see the notches that hold the shells in place.


Simon

[Bob Culver]

Relieved tapers seem to hold better. Many other make rear axles finished that way. Ford 10s give trouble with loose axle tapers; relieving is the standard cure. It is reckoned tapers often fail by fretting whcih starts at the big end. Releiving increases the pressure and reduces. The later Seven flywheel relief is apparent in some Austin section dwgs.

Ideally at last one shell should drive into the notches, rather than pull against the incline.

[Charles P]

The taper is normal - some were like that, some weren’t. Both seem to work ok.
As far as the rods go- if they are horizontal split type, they can go in either way. If the 45 deg ones, they will only go in one way.

Thanks Alan, I'll make a note in my red book about that. Seems odd not to use the entire taper but I am sure there is some complicated engineering reason for it!

The rods look like this. You can see the notches that hold the shells in place.

Simon

Bearing tangs/notches are for asssembly only. The shell is held by crush in a properly sized journal. Modern car bearings increasingly come without tangs/notches and big end/mains sail happily past 100k without issue.

Charles