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crankshaft refurbishment and welding

What is crankshaft

crankshaft is a rotating shaft which (in conjunction with the connecting rods) converts reciprocating motion of the pistons into rotational motion. Crankshafts are commonly used in internal combustion engines and consist of a series of cranks and crankpins to which the connecting rods are attached.[1]

The crankshaft rotates within the engine block through use of main bearings, and the crankpins rotate within the connecting rods using rod bearings. Crankshafts are usually made from metal, with most modern crankshafts being constructed using forged steel

Can a crankshaft be repaired?

Fixing these parts may be less costly and faster than racers think, and companies that specialize in crankshaft supply and repair explain how to determine if the part is worth salvaging or whether it may be time to order a new one.

By John F. Katz

Even as the aftermarket industry develops crankshafts that are harder to break, racers get better and better at breaking them. “When we’re at the PRI Show,” said Dave Olsen of Mile High Crankshaft, Denver, Colorado, “about a third of the questions we get are about repairing cracked crankshafts: ‘Can you fix it, and how much will it cost?’”

The answer to “can you fix it” can be complicated, but a lot depends on the depth of the crack versus the journal diameter, “and how bold the crack looks in Magnaflux. If it’s extremely bright, that tells us it’s well-defined. We also look at the crack, and draw an imaginary line from point to point, to get a decent idea of how deep it is in the radius. And if we have to grind out or vee-out more than a quarter inch in depth, then we don’t feel good about attempting a repair,” explained Olsen.

The length of the crack is much less of a concern. “We get cranks with a crack that’s an inch long, and we’ve been very successful at repairing those. We’ve repaired cranks that have raced for another 10 years,” he added.

Mile High does custom work as well as repairs. And some racers combine the two. “Let’s say for an example a small block Chevy that has small-journal connecting rods. If the crank is damaged, they may have hurt one or two rods also, so they elect to convert to Honda-size journals. That’s become real common, where we grind a damaged journal down to a smaller diameter. And the racer might pick up some performance just due to the lighter weight.

Crankshaft repair cost

Crankshaft is one of the main mechanical parts of the engine. Sometimes, same drivers can see that motor is not efficiency as the first time operating. If you hear someone knocking inside engine, it could also indicate engine crankshaft problems.  It would be appropriate to say about these problems now, but I suggest to begin with the main questions which will see in this article:

  1. Engine Crankshaft Problems;
  2. The main repair methods of the crankshaft;
  3. What influences the crankshaft repair cost?
  4. Crankshaft Services & Pricing.

Engine Crankshaft Problems

We started be saying that crankshaft is very important part of internal combustion engine. This part converts chemical fuel energy into motion. The crankshaft provides a nexus between engine and gearbox. When it crashes is not possible to avoid costly repair.

Usually, the crankshaft can be crashed by two main reasons: engine oil not enough or excessive engine loading. Most modern cars are not afraid last reason crankshaft crash, because vehicle electric system controls all engine functions. The electric system turns off fuel supply, if engine begins to work with excessive loading.

Engine Crankshaft Problems

1 – Crankshaft flexing; 2 – wear of the outer surface of the crankshaft flange; 3 – run-out face plane of flange; 4 – wear of oil canals; 5 –  wear of  bearing  hole; 6 –  wear of flywheel bolts; 7 – connecting rod bearing and crankshaft bearing damage; 8 – wear of journals for  hub pulley and gear; 9 – wear of groove keyway; 10 – increasing the length of the front crankshaft journal; 11 – increasing the length of  crankshaft connecting rod journals.

The first reason is not enough of engine oil can be main reason of crankshaft problems. There is no oil between the parts which leads to dry friction. Effects of this problem can be connecting rod bearing damage, crankshaft bearing damage and the crash of crankshaft finally.

How to define that engine need crankshaft repair? It`s rule that problems of crankshaft have loud knocking.

The main repair methods of the crankshaft

Experience has shown that small sized crankshaft will be better for replace, but oversized crankshaft will be better to repair.  If this is the case will it be possible to achieve a comprehensive cost savings. Friction forces, vibrations, different loadings affects at the crankshaft in time engine operating.

This leads to crankshaft and connecting rod bearing journals wearing. So they have irregular wear: taper in length; ovality – in diameter; quality violation of bearing journals surface: notches, scratches or corrosion; mechanical damage: crankshaft cracks, thread defects; crankshaft deflection.  Exploration of someone crankshaft problems shown these are consequences fatigue of metals and internal stress inside.

In order to eliminate defects of crankshaft used repair technology bearing journals by repair size, grinding with the next polishing,   different kinds of surfacing and plasma spraying. Crankshaft flexing can be eliminated by the plastic deformation method.

What influences the crankshaft repair cost?

Unfortunately, the repair of a crankshaft is very difficult process that can do professional only. It needs to do grinding of bearing journals on the special equipment.   Let`s go explore the main possible works by crankshaft repair.

Main types of crankshaft repair:

  • Grinding;
  • Dressing;
  • Polishing;
  • Crankshaft pulley repair;
  • Canal cleaning;
  • Connecting rod bearing replacement;
  • Crankshaft Balancing.

Crankshaft repair is serious task, so it would have to be professional specialists and very expensive equipment. And you should not forget that dismantling the crankshaft also costs money. How much money does a crankshaft repair need?

Crankshaft Services & Pricing: Balancing, Repair & Grinding

If you want to get your car moving again, visit the Crankshaft Craftsmen. There are many service Centre, which specialize in grinding and repairing crankshafts for a variety of American-made vehicles, including Ford, Chrysler, Jeep, Buick, Chevy, Pontiac, and Oldsmobile.

Also check out the stairs page.

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