Crankshaft services

When you already have a crankshaft, but you would like to have it checked and / or repaired for further use, we can offer you several services

Testing for cracks

 

There are several reasons a crankshaft shows cracks, such as metal fatigue, bearing failure/damage, insufficient lubrication, excessive load.

Through the help of UV-light we conduct a magnetic examination of the crankshaft to verify whether the crankshaft shows cracks.

If the crankshaft shows cracks, there are 2 different possible outcomes. 
 
1.    If the test shows light cracks, it can be resolved by grinding or welding the crankshaft. After this process, the crankshaft can still be used.
2.    The other outcome is that the cracks are too severe, and that the crankshaft can’t be repaired, therefore it can no longer be used.

 

Grinding
A crankshaft needs grinding whenever it no longer meets the prescribed factory sizes, or when it has visible damage. Depending on the damage and / or available bearings, the crankshaft is grinded per 0,25 mm
(min. 0,25 – max. 1,5mm depending on the engine type). 
In the case of English / American cars, these intervals are 0,010”
(min. 0,010” – max. 0,060” depending on the engine type).
By then mounting a more thick bearing shell, the repaired crankshaft can be used again.
 
Welding
 
Depending on the damage of the crankshaft and / or availability of bearings, the crankshaft’s journal(s) can be welded. With this process, the journal is being brought back to its standard size, after which grinding to another oversize is still possible.
By executing the welding process, the stroke of a crankshaft can be made bigger or smaller. 

 
Polishing
If the crankshaft dimensions are still OK, we can polish it. This happens mechanically with a grain of 600, or more refined.
Crankshafts that have been ground, are polished as well.
With this process, we obtain an Ra-value of  0,1 µm.

 
 
 
Balancing
(flywheel and clutch assembly included)

The imbalance of a crankshaft can cause vibrations, which may result in (bearing) damage and general metal fatigue. This makes the parts wear faster, which is of course harmful.
Since the clutch and the flywheel are also attached to the crankshaft, they are also affected by the (im)balance of the crankshaft. With the improvement of the balance of the crankshaft, we will therefore also balance the clutch and the flywheel, each part independently.

Some crankshafts, like certain V-model crankshafts are balanced using bobweights. This simulates the weight of the conrods and pistons during the balancing process.
 

Flywheel
Whenever a clutch plate has caused wear on the flywheel, we can grind the flywheel.
Once a flywheel has been grinded, we advise to balance it again.
If wanted, we can also make the flywheel lighter, for example for racing purposes.
 
 
Hardening
We harden through nitriding.
This hardening process puts a very fine, yet strong layer on top of the crankshaft.
If an already nitrided crankshaft is grinded, it loses its strong top layer,
which has to be restored by going through the nitriding process again. 

 
 

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