"Richard Casady" wrote in message
...
On Mon, 4 Aug 2008 06:49:31 -0700 (PDT), wrote:
On Aug 1, 7:57 pm, "Calif Bill" wrote:
"Larry W" wrote in message
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Tim wrote:
On Aug 1, 10:59 am, wrote:
Stainless steel is not particularly stronger that ordinary steel.
It's just stainless. If you want stronger then you need grade 5 or
grade 7 bolts.
The v8/v6 starter mounting has had that bracket from the back of the
starter to the block for a long time. I'm surprised someone had to
figure it out again on the 4 banger.- Hide quoted text -
- Show quoted text -
Grade 7? I ahven't ehard of 7, but am familiar with grade 8.
I'm thinking that the reason that the brace was gone is probably
because somebody had changed out the starter before and deemed the
brace to be a PITA. and left it off with the thought of "We don't
need
that after all, all it is...is a bracket!"
It was the original starter that failed and didn't have the bracket.
I have since put my hands on some extra brackets to use on future
similar
jobs.
Larry
Problem with grade 8's etc. are they are too strong. They will loosen in
a
lot of applications as you can not get enough stretch to preload the
bolt.- Hide quoted text -
- Show quoted text -
My bad, I meant 8. You're right about the preload. You can get
preload on stronger bolts but it takes a whole lot of tightening.
Break out the torque wrench. But in a soft material like a cast block
with that bolt size you'll probably strip the hole before you get
enough. A grade 5 is usually appropriate for most cases where you
need a stronger bolt. I used grade 5 on my alternator mount where I
kept having bolts break. I have not found a source for stainless at
higher strengths but I haven't looked very hard. Since I boat in
fresh water it's not the end of the world if I use non-stainless
sometimes. Lowes has the grade 5s in most common american sizes.
I don't know why the stretch couldn't be in the hole rather than on
the bolt. Always get plated bolts, which in practice generally means
grade five. If you put a Helicoil in the hole you can safely tighten
it more.
Casady
You need the bolt to stretch more than the vibrations will move. You want
the bolt in the elastic range. If too loose, then when a vibration causes a
momentary no load condition on the bolt, the bolt can loosen. If you
tighten it too much, and the threads do not fail in the nut part, the bolt
can get into the plastic range and permanent stretch happens and you get
bolt failure. Do you can not take the stretch in the hole as the bolt
itself as to be stretched. Think of the bolt like a very strong spring.