The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Galvanic corrosion in aluminum driveshafts with steel u-joints

My company currently offers steel universal joints with an anti-corrosive coating on the surface of the bearing cups. I am involved in product management. We recommend these for use in vehicles equipped with Aluminum driveshafts to prevent Galvanic corrosion between the dissimilar metals. The coating is a registered trademark process that is used by some OEM automotive manufacturer's for this exact application. There seems to be no consistency in the automotive industry for the use of an additional barrier process to prevent the corrosion that would occur in these surface contact areas.

Is there a valid concern with the corrosion issue that would occur if an uncoated bearing cup is pressed into an aluminum driveshaft? Are there any technical papers or opinions addressing this concern in this application? If there is supporting documentation that unprotected surfaces will create longevity problems, why is there lack of apparent consensus at the OE manufacturer levels?

John Welsh
Driveshaft manufacturer - Pottstown, Pennsylvania, USA
2005

---

There is definitely a concern for galvanic corrosion aluminum in contact with steel. There is plenty of references to this in the metallurgical technical literature. I can show you some spectracular examples of aluminum corrosion from contanct with steel in automotive applications where the vehicles operate here in the land of ice and salt. I do not know why there would not be a consensus among the OEM.

Larry Hanke
Minneapolis, Minnesota
2005

Last week I replaced u-joints for a friend of mine with an aluminum driveshaft. It was on a 2001 vehicle but the u-joints were already reacting witht he aluminum and had to be pounded on much greater than to get the joints out of the steel yoke. I spent about an hour getting the first one out of the aluminum versus 5 minutes on the steel. I don't know if this answers your question or not but it certainly points out the need for the coating.

Clay Skarovsky
- Texas
2005