Reassembly of crancase and crankshaft after regrind

[g80csp11]

well spotted , the photo is wrong and is in the process of being corrected
The new bearing shells look identical to the original

[Groily]

just to add, pic of centre main and b/end shells to compare. Big difference in width, shown in round metric numbers . . .

Twin shells.jpg

[ajscomboman]

The picture is wrong, those are the new big end shells. We do have the correct ones in stock and I'll get the picture changed to show the proper ones. Thanks for the heads up.

[clive]

So here comes a question from a singles man currently having to rebuild a twin engine after breaking the crank. As at least one conrod is mullered I have been looking at a number owned by fellow club members and one sold to me by a well know supplier. They all seem to be marked so that the cap fits wit the two depressions for the tabs on the Bearings are on the same side. Is this coincidence or how they should be? I just wondered if the centre web cap is round the wrong way causing the distortion. One of the centre webs has two marks to ensure they are correct o , the other I am looking at does not seem to . However when I turn the cap round there is clearly a right and wrong way round exhibited by a slight discontinuity in the thrust washer faces. Might this explain the problem David is having?

[Groily]

Here's a pic of a new rod Clive, showing where the notches are. It's how the rods in my 650 are oriented, and it's how my jig for chamfering the edges (which was sometimes necessary with new shells) is also configured . . . Haven't go a centre web that's not in an engine to look at though.

AMC rod.jpg

[g80csp11]

Groily/Bill's image is correct with the cap fitted and nipped up ( use old nuts) the split line should not be stepped . if it is then you either have mismatched cap/rod or the rod is knackered and spread .
The cap should be able to be fitted on the studs without force again another indicator of a knackered rod

Any of these problems with reduce clearance on the big end , and risk failure

In the old days when bearings were not available mini shells were often used but this required extra tab notches

Good rods are out there or you can but new ones i think from thunder engineering at about £200 a set

make sure you only use the cap nuts once as they are not reuseable ( or should not be reused)

All rods and caps are marked either with a line or dots on the joint

[ajscomboman]

Last price I saw of a Thunder Engineering rod was £226 each, all be it that was for a BSA. Scouring around the web Norton ones for Dommies seem to be around £290 plus VAT a pair

[Groily]

About right Rob. From memory, the 2 pairs I have were close to £400 each, a good while back now. Ouch.
The pic shows those new ones exactly as they came to me - haven't touched them. (Torque settings on them are VERY high compared to standard, but even not done up, the join is almost invisible.)
Nowt wrong with good 'checked-for-round' originals I don't think - that's what my 500 engines have in them. And there are rectified rods to be had I believe . . .

After a crank breakage I think rods ideally need thorough professional examination for peace of mind, given how much a rebuild costs these days - let alone two! T&L are great for this, but any good engineering company can measure better than we probably can, and address any ovality without noticeable effect on where the pistons sit relative to one another.

[g80csp11]

£299.50 +VAT a pair in April this year when i checked

[Groily]

Which is good value I reckon, given how things go these days.
Just more than the pair of tyres I had for my van this week, or 2 fills of diesel for same.

Maybe I wuz robbed (- but actually probably not by a whole lot, with the vat etc), or - more likely - mild brain fade . . .