Tight crank

[1608]

I meant the chamfer should be on the bulge NEAR the end cap, sorry.The con rod on the left ( as you look at the photo ) appears to have the chamfer facing the crank case correctly, but the one on the right appears to be in-board. Or is the glare on the photo misleading.

[trophy]

I meant the chamfer should be on the bulge NEAR the end cap, sorry.The con rod on the left ( as you look at the photo ) appears to have the chamfer facing the crank case correctly, but the one on the right appears to be in-board. Or is the glare on the photo misleading.

Yes, You are correct. The r/h con rod in the photo has it's chamfer on the inboard side. I will turn it round to face outboard on the rebuild. Thanks John for the confirmation.

[cf160]

In the same vein of Model 31 engine rebuilding, I experienced a related problem with my rebuild .. Just as it was getting too very cold (-10 with wind) to work outside any longer after puting the bottom end (cases bolted together) in the frame , I noticed a slight resistance on rotating the crank and rods at only one point in the rotation. Reluctant to tear it down again in the cold, I left it until Spring. The resistance is very slight , but clearly noticeable as though something was touching one of the cases as the crank and rods went around. You gentlemen seem to have a good deal more experience doing engine jobs on this bike. I wonder what you might think the problem is? It didn't seem to be a rod touching, although I couldn't swear to it now...
Dave(cf160) in Canada

[robcurrie]

Can anyone suggest o-ring part number and dimensions of the grove. Alternatively, I have a box of assorted o-rings that I could use but is there a formula for depth/ width of the grove?

Sorry for the delay in replying to this. I first had to find the spare o-ring I used, it measures ID 30 x 1.5 dia . The correct groove size for this will be ID 29.6 OD 33.4 depth 1.2 (giving you a 0.3 squash).

I borrowed a tool that was about 30 years old and quite blunt. I found a holesaw in a cheap set that I cut off and used to replace the original blade. The holesaw was a good interference fit on the spigot of the tool and I ground the outside of the saw to the correct diameter. The tool has a spigot which centres in the gallery hole and a step which stops the cutter at the correct depth. It can be used in a drill press.

Rob

[trophy]

Can anyone suggest o-ring part number and dimensions of the grove. Alternatively, I have a box of assorted o-rings that I could use but is there a formula for depth/ width of the grove?

Sorry for the delay in replying to this. I first had to find the spare o-ring I used, it measures ID 30 x 1.5 dia . The correct groove size for this will be ID 29.6 OD 33.4 depth 1.2 (giving you a 0.3 squash).

I borrowed a tool that was about 30 years old and quite blunt. I found a holesaw in a cheap set that I cut off and used to replace the original blade. The holesaw was a good interference fit on the spigot of the tool and I ground the outside of the saw to the correct diameter. The tool has a spigot which centres in the gallery hole and a step which stops the cutter at the correct depth. It can be used in a drill press.

Rob

Thanks for the info Rob. My friend with the milling machine is on hols at the moment but I will let you know how I get on. Thanks again.

[trophy]

On page one I said i hadn't checked the journals. I have now The centre bearing (std) and drive side big end (-0.060" under size) journals are fine the timing side big end journal (-0.060" under size) is 0.007" oval How the h*ll does that happen? Sludge traps were full too.
Are shells available for another re-grind? If not how expensive is metal spraying on that journal? I'm fed up. This restoration is getting to me and it's all to do with trying to keep spending down to a realistic level. Suggestions anyone.

[alanengineer]

you are playing with probably the most expensive bit.Full sludge traps dont help oil circulation. A new crank might be the cheaper option as for metal spraying, thats been discussed elswhere on these forums and someone else might offer guidance cos i cant remember the outcomes.
Keep plugging on, someone down your local branch might have a better one propping open a door you can have.

[robcurrie]

Could be oil starvation to that (oval) side. What did that bearing look like, and what do the rods look like in terms of ovality? What filter do you have? My '62 has the mesh covered with felt, probably marginally better than the plain mesh. Check oil holes are all clear if sludge traps are full. There was a post dealing with metal spraying recently - you can't do a cast iron crank. The club has commissioned a new manufactured crank which is in test phase at this moment.

Rob

[1608]

cf10 (Dave) the commonest cause of a tight crank following a re-build,I suggest, would be a misaligned centre web. I know its a real pain but, I think a strip down and re-alignment of the centre web is advisable.

Lol - I would suggest a s/h crank with a re-grind or two left in it is the answer. I recently bought two on e-bay, both still with plenty of life left in them for reasonable money too. Metal spraying, I believe anyway, is a last resort and expensive. It does not add any strength to the crank either, only allows for a regrind. It has been known for some cranks to go to -80th using BMC Mini shells. But for the price and peace of mind I would look for another crank. Try a wanted add on the club site. Your's is an alternator crank I believe.

[cf160]

In reply to John (1608) about my tight crank(cf160's) :
I thank you for the kind reply , but I just had the crank ground (rods .030" and main .010") and I tightened down the caps ever so carefully, so I can't understand how the centre main could be mis aligned as the rub only occurs at one point in the 360 degree rotation of the crank and rods. Perhaps I have deformed a case in tightning the bolts/studs so a high point on one of the flywheels is touching..,
Oh yes, now I see how the proper alignment of the crank could cause this , but surely not when the other two bearings (in the cases) are holding the crank in line...
I suppose I must tear it all down again... well that sets it all back a week or so at least. Well , thanks for the thoughts ,John.