View Single Post
Old 09-08-2006, 10:34 PM   #33
Scooby Specialist
Member#: 81095
Join Date: Feb 2005
Chapter/Region: South East
Location: Left seat.
2005 WRX EJ205 weed-
whacker. OS self-tuned!


Man, I guess this is more complicated than just grease or no grease. It's probably not a good idea to use non-OEM fasteners to bolt down the calipers, since the following reference ( says that (emphasis mine):

From a strength and preload standpoint the ideal steel fastener would have a plain black finish, (sometimes called a light oil finish)...This finish would be unacceptable on a bike since it corrodes easily. The common solution is to apply a zinc or cadmium plating to prevent corrosion, and apply a conversion coating such as chromate to keep the finish looking nice...The torque-tension relationship is greatly affected by plating due to its effect on the friction coefficient. Cadmium plating reduces the friction by 25% and zinc plating increases the friction up to 40%. This requires a corresponding 25% reduction or 40% increase in required torque for the same tension. Stainless steel fasteners have a friction coefficient about two times the corresponding plain steel fastener. This does not mean that stainless fasteners require double the specified torque since they usually cannot achieve the strength of a steel fastener.
So it seems that whatever material the bolts are made out of, they had better have a similar surface treatment as the OEM bolts for the torque values given in the FSM to be relevant...

Still, that leaves the grease question open...
* Registered users of the site do not see these ads.
FromageTheDog is offline   Reply With Quote