ET: Engine (Twin) Broken Quill
- Thread starter bmetcalf
- Start date
have someone kick the engine over whilst you look at the crank end with a torch, you could observe the wobbling effect mentioned above.
Normally over the years the reason all/most of the quills are worn is precisely because discrepancies exist between cover and crank and this discrepancy was expected in use (hence the choice of material?)
The important thing here is that the quill hasn't worn (as intended?) but snapped off
This could be because of a poor component, a change of material or temper excessive movement of crank or a new way out of tolerance cover.
You should worry, back in the days of the wild west before we had good spares Ray Elgar had a quill that had a central hole not drilled right through (being Ray he checked it before fitting)
The important thing here is that the quill hasn't worn (as intended?) but snapped off
This could be because of a poor component, a change of material or temper excessive movement of crank or a new way out of tolerance cover.
You should worry, back in the days of the wild west before we had good spares Ray Elgar had a quill that had a central hole not drilled right through (being Ray he checked it before fitting)
It was relatively recently that Simon mentioned his being out due to a mismatched cover. IIRC he pulled the lower dowel pin and rotated the cover slightly. Didn’t take much movement to get the quill to line up better than it was. Obviously between the bolt that goes through to the oil filter cavity and the case screws there isn’t much wiggle room, but it might be worth investigating (assuming it doesn’t turn out to be what David suggested it might be). Simon made up a new lower dowel with an offset.
I’m tempted to make up an indicator to measure concentricity between the cover and oil gallery in the crank. Will have to give it some thought. Lots of mismatched covers around.
I’m tempted to make up an indicator to measure concentricity between the cover and oil gallery in the crank. Will have to give it some thought. Lots of mismatched covers around.
Maybe @Simon Dinsdale can share how the offset dimension was determined?
I installed the new quill and it didn't break during a 12 mile test ride. I added a second fiber washer to space the shoulder out a bit more and will get a proper 225 washer in the next parts order.
I installed the new quill and it didn't break during a 12 mile test ride. I added a second fiber washer to space the shoulder out a bit more and will get a proper 225 washer in the next parts order.
I first turned up a dummy quill using a lathe which was a slide fit down the centre of the crank and the larger diameter step was a slide fit in the threaded hole in the timing cover. The aim was to just check the alignment of the quill hole in the non matching cover and I discovered with the cover fitted to the engine the dummy quill wouldn’t go in. Then removed the lower dowel and refitted the cover using the upper dowel only so it could pivot on that dowel and found at one point the dummy quill would slide in and the timing cover screws would still fit. I then refitted the original lower dowel and refitted the cover to the cases and turned down the larger diameter on the dummy quill only by two thou at a time until it would slide in again and the amount removed off the larger diameter divided by 2 was the amount the cover needed to move to get perfect alignment. It was a few years ago and I cannot remember the exact offset I ended up with but it was less than 10 thou and think was 6 thou. The actual brand new quill that I finally used went in no problem using just fingers and not a spanner so could feel if it was tight and potentially catching or not on the crank and all felt ok. 2000 miles later and the new quill has only the slightest mark on it on one side which with a micrometer you cannot even measure. So it was a bit of hit and miss rather than accurate measurement but worked. Now if the quill hole had been out vertically then both dowels in the cover would need offset but that wasn’t the case with mine.
I had a similar method on my touring twin, non matching cover. The quill was so worn it was actually bent slightly. Panic !.
I made a solid steel quill, but with the required threads, not plain. The fit in the crank was made a perfect sliding fit, no slogger whatsover and lubed well with silicon spray so it could'nt jam. Then removed both dowels, fitted the cover with all the screws loose, false quill fitted tight, then tightened the cover screws.
The quill has got to be central. My son is running that bike now and the last look at the quill I fitted showed no marks at all.
( The false quill is in the tool tray, just in case.)
I will point out that the crankshaft had been re-done by Maughans, so guaranteed no eccentricity in that. Just a bad fit cover I should have checked with blue before assembly.
I made a solid steel quill, but with the required threads, not plain. The fit in the crank was made a perfect sliding fit, no slogger whatsover and lubed well with silicon spray so it could'nt jam. Then removed both dowels, fitted the cover with all the screws loose, false quill fitted tight, then tightened the cover screws.
The quill has got to be central. My son is running that bike now and the last look at the quill I fitted showed no marks at all.
( The false quill is in the tool tray, just in case.)
I will point out that the crankshaft had been re-done by Maughans, so guaranteed no eccentricity in that. Just a bad fit cover I should have checked with blue before assembly.