A7 Crankshaft repair

[Rc30lover]

I have a '58 A7 small bearing crankshaft which is already -.040" and the big ends are worn, otherwise it's OK.
-.060" big end shells aren't available  and so the only options are to scrap it or expensively metal spray and regrind it.
There must be a load of cranks out there that have been scrapped for this reason.
Does anyone know of an economical way to repair it please ?
Can -040 shells have another coating put on them to make them fit -060 ?
Is there a source of 060 shells I don't know about ?
Has anyone got a spare crank with life left in it ?

[Mike Farmer]

 

This is very personal approach. If you cant get a replacement. and bear in mind any further grinding is putting your crank into a dangerously weakened situation. I dont see any inexpensive option.

I would Get it proffessionally measured to find out the minimum maching to a sound undersize condition. You could then get your big ends re-metalled and line-bored to crank size. Expensive.
Or simply have the crank re-metalled and ground to std size and new bearings. Maybe less expensive

Any used crank is likely to throw up the same problems. Unknown quantity therefore potentially expensive

I shall contact a friend in the biznis for cost of remetalling. 

Mike

[Rc30lover]

Thanks Mike, I take your point about weakening it.
Every option has a downside and an expense but it may have to be done, otherwise, eventually, there won't be many running A7s, all the cranks will be scrap, but I guess that goes for all classics.

[EDDIE SIMPSON]

replacing metal on worn journals with submerged arc process is fairly common. cars and motorcycles. but i would have thought a second hand a7 crank would work out cheaper.

[Mike Farmer]

 

I have now spoken to my friend and he is no longer doing it. Materials Too expensive. What he was doing: - Re grind crank with absolute minimum loss of metal and rebuild shells to fit. But it comes with the warning that the crank has been taken outside normal wear limits. Of course it will depend to a degree how the engine is used and or abused.

Mike

[TTJOHN]

I had an A10 small journal one done at Liddel & Bailey workshop near Faversham and what they do is weld it in rib form, then regrind to the original size, mind you it did cost me £300 but an excellent job they did of it.

TTJohn