20/21 • AUTOMOTIVE RESTORERS GUIDE
Crankshaft Straightening, Journal Repair and *Hardening
A note on crankshaft repairs If you have a damaged crankshaft where some, or all of the journals are scored beyond grinding, and it is impossible to locate a replacement one second-hand, then the journals can be built back up with either metal spraying or submerged arc welding. Damaged crankshafts are not uncommon, and often forms part of vintage or classic car restoration.
Metal spraying is a process where hot metal is sprayed onto a journal after it has been prepared. Submerged arc welding is when metal is welded onto a journal. In both cases, the repaired journals are ground back down to the correct tolerance for the bearings. Metal spraying can be carried out by the engineering listed further on under Engine Reconditioning Specialist, Engineering, Machining, *Welding, *Metal Spraying.
Metal spraying puts far less stress on a crankshaft compared to submerged arc welding. However, some views are that submerged arc welded journals are a superior job as the new metal is actually fused onto a journal by welding. Strictly speaking, a repaired crankshaft should be hardened to the same original factory original hardness.
Using hard chrome plating is often not successful for crankshaft journal repair. It is for this reason that I have not listed it.
The company below can often repair your crankshaft by submerged arc welding.
After repair work, the company below can send the crankshaft away to a specialist hardening company. When a crankshaft is re-hardened, the service is at your own risk.
The risk is that sometimes the hardening process on a repaired crankshaft can distort the crankshaft and render it useless, more so after submerged arc-welded repairs. It is for this reason that many people do not take the risk, and fit the crankshaft without surface hardening.