Are blue or black quad-rings better?

Answer: Totally equal, you should better pay attention to other things…

A customer recently decided to get his VC professionaly serviced at our workshop, after a failed self repair. He sent us also his already purchased spare parts for the VC along.

The X-Rings from the customer seemed strange to me, because of their blue color. (The VC of the T4-Syncro got also blue X-Rings). However, my expert in sealings assured me that the color is without any relevande and purely optical. The visible injection points means instead a poor quality, while good products have a smooth surface.

But it gets even better: After cleaning with kerosene the customer’s blue quad rings became partly black. The quad rings had just been painted blue, for optical reasons(!).

quad-rings in blue & partly blue

In the picture above you can see on the left an original quad ring from the T4-Syncro and the cheap and painted one on the right.


I also asked the importer of the cheap quad-ring about the basic rubber material:NBR = Nitrile Butadiene Rubber

NBR can’t be used as a sealing material in contact with silicon fluid in a VC for two reasons:

  • NBR shrinks in contact with silicon fluid and gets leaky
  • NBR has a maximum temperature of about 100°C – which is to less for a VC with a hump-temperature of 120-135°C
sealing materials in combinaton with silicon fluid

Both requirements are met by FKM (formerly FPM) which is better known under its brand name Viton®.

Conclusion: Better pay attention to other values than the color of quad-rings.