>> I think that anyone with these type answers should be devoting
>>more time answering questions and improving the state of these lists
>>than cutting down the people that are trying
I wasn't trying to cut anybody down; I'm sorry if my comment were perceived
as such. I was really throwing out an observation for people to consider.
These lists have changed over the years. I don't think anybody really ever
anticipated that the time required to just read the messages would become
so overwhelming. I just wanted to point out that people have a fixed
amount of time they can devote to this list, so we all must consider
balance between volume of questions and volume of answers.
Anyway, the comment that I should be trying to improve the lists is right
on, so here goes...
>>
>> MY question (in all seriousness) is: Why did they make 'em out of brass?
>> would not a stronger metal have been better?
While it is true the trunnion is 'structural' component, it is also acting
as a sliding bearing surface. The material was selected for its friction
and wear properties. That it is weaker can be offset by beefing up the
size of the part.
>I heard somewhere that the trunions and other mechanical pieces that are
>highly subject to wear, are made out of some special allow, not just
>regular old brass. Apparently (if this is true) the properties of the
>alloy are that they are self-lubricating and don't require the normal
>lubrication that you would expect of ball joints, etc.
I'm not completely sure if it is used in the trunnions, but what you are
referring to is a family of materials called sinter metals. Typically they
are made by pressing a metal powder into shape and then heat treating it.
This results in a material which is (relatively) porous. This porosity
allows the metal to absorb and retain lubricants. BTW, this is why you
have to soak your pilot bearings overnight in oil before you install them
The Bosch Automotive Handbook states " Sintered iron bearings and sintered
steel bearings are ... preferable to sintered bronze bearings for use in
the motor vehicle. The advantages of sintered bronze bearings are greater
loadability, lower noise, and lower coefficients of friction. The
performance of sintered bearings over long periods of service is closely
related to the use of optimum lubricants."
Perhaps this gives some insight as to why the bronze is used in the front
suspension.
William Woodruff woodruff@fail.com
San Francisco, CA
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