ES2 Crank issues

Hmmm... Have you checked the width of the main bearings compared to the ones on the old crankshaft?

If the lack of a thinner bearing is the problem, could the crank cases be machined out by the 1.15mm required?

Also, could the main crankshaft pins be machined back the amount required to fit the wider bearings?

I own a 1947 model 18 in bad conditions. Among the many wrong things, the mainshafts of the crankshaft were push fit into the wheels, so, I purchased through eBay-UK an used crankshaft, similar, but a bit wider in the wheel thickness, making a gap of about 2-3? mm. between crankcases.

What to do?

Because my lathe is too small, I send the wheels-with its mainshafts not removed- to a friend who has a larger lathe. He then turned off the outside of the wheels, the amount of the gap plus 0,5-1,0 mm. to allow the use of pen steel washers for the endplay.

I will soon load a photograph of the wheels and its thicknesses for accurate info.

Hope this help,

Hans in Chile.

I have a 1938 ES2 that I bought as a semi basket case. The engine was last used in 1975.

When I stripped the engine it was fitted with the double row self aligning bearings that were absolutely wrecked. I rebuild the engine with ball and roller bearings and found that the cases wouldn't go together by about 2mm. The centre of the con rod was in line with the crankcase joint with the crank fitted to the left casing. This indicated that the error was on the right crankcase or crank journal. Examining the old bearings it was clear that they had been heavily thrusting outward.

At the time Mike P was doing the head and I spoke to but he had not heard of this. I also drew a blank when speaking writhe the late great George Cohen.

In the end I machined the right flywheel to get the correct clearance.

I wonder if the 38-47 engines had a narrower right crank flywheel than the earlier engine. Is it coincidental that the timing gears are slightly wider than the earlier engines? I understand that there was a problem with cracked flywheel on my model so did someone fit an earlier (or 16H) crank in?

Anyway, the bike is together, runs well and goes well with my mod!

Colin

The complete crank and both left and right flywheels were given completely new numbers for 1938. The only part remaining unchanged was the crankpin. The 16H received new parts too so there may be something in terms of fit.

1935-'37 :-

Crankshaft complete - 9023

T/S half - 3014

D/S Half - 3017

Pin - 3020

1938-'39 :-

Crank complete - 8844

T/S Half - 8849

D/S Half - 8854

Pin - 3020

Even ignoring the incredibly numerous WD16H cast iron cranks, the 1938 500cc engine parts are likely to be less common as they were only made for two years pre-war and two afterwards.

As told above, thickness of timing- and drive side of both crankshafts varies from 29,4 to 29,7 mm. Gap between flywheels by assembled crankshaft is 21,4 mm.

The original flywheels had a step of 2,7 mm. between flywheel protrusion and mainshaft area.

The purchased flywheels were turned down to 2,4 mm. leaving a space of 0,5 to 1,0 mm. to each side to allow centering and suitable endplay.

The purchased cramkshaft came with a 8" conrod, instead of the 7" of the original one Nr. 4101 and 4099 respectively.

Curiously, both pairs of flywheels are 10262 cast in.

Attached a photograph showing the step.

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Another photograph showing the replaced flywheel.

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The only flywheels that I have here were removed from WD16H engines and they are all marked 10262.

I think there is a good chance that you have a WD16H crank there.

Check the spacer between the roller and the ball bearings at the drive side

GÃ?ran

I recall that the numbers on my flywheel did not tally with the part numbers in the books. I checked the gap between the two bearings on the left and this was correct. the books say that the crank should be shimmed so it is central to the crankcase mouth joint. the con rod was central when fitted to the left casing but not the right.

Part numbers may be different because of dimensional as well as material and balance factor changes.

In my case, modifying the right crank cured the problem and the timing gears lined up correctly afterwards.

I agree with Richard that it is probably a 16H assembly. It would be much harder to find the correct cfrank. The important thing is that it keeps the bike on the road.

Colin