Re: [DML] Modified Trailing Arms For 1/2" Bolts

["Jon Lockwood" <jn_lockwood@xxxxxxxxx>]

You are my kind of person. Touché!  Great story.  I worked on F-4's, F15's, 
A10's and many other aircraft.  I left that job and went to SATCOM..  Planes 
are really dirty.  That's not why I cross trained.  No future in it..  Today 
the only plane I would feel safe in is a C130..  My Fav!


----- Original Message ----- 
From: "Jon Lockwood" <jn_lockwood@xxxxxxxxx>
To: <dmcnews@xxxxxxxxxxxxxxx>
Sent: Wednesday, February 08, 2012 7:11 AM
Subject: Re: [DML] Modified Trailing Arms For 1/2" Bolts


> So we some metallurgy people on this site?  COOL!
>
>
> ----- Original Message ----- 
> From: "Martin Gutkowski" <martin@xxxxxxxxxxxxxx>
> To: <dmcnews@xxxxxxxxxxxxxxx>
> Sent: Wednesday, February 08, 2012 1:53 AM
> Subject: Re: [DML] Modified Trailing Arms For 1/2" Bolts
>
>
>> Actually while hard materials tend to be brittle, it's not the same 
>> thing. Soft is not the same as ductile - eg carbon fibre composite has a 
>> very high tensile strength and low ductility but is nowhere near as hard 
>> as even aluminium.
>>
>> Hardness is a surface property, brittleness (resistance to crack 
>> propagation) and tensile strength, modulus of elasticity and ductility 
>> are all structural properties.
>>
>> Martin
>> Sent from my BlackBerry®
>>
>> -----Original Message-----
>> From: "K.L. (KAYO) Ong" <klo@xxxxxxxxx>
>> Sender: dmcnews@xxxxxxxxxxxxxxx
>> Date: Tue, 07 Feb 2012 16:15:08
>> To: <dmcnews@xxxxxxxxxxxxxxx>
>> Reply-To: dmcnews@xxxxxxxxxxxxxxx
>> Subject: Re: [DML] Modified Trailing Arms For 1/2" Bolts
>>
>> Too much hardness (brittle) is just as bad as too soft (ductile)...
>> As for Toby's bolts.... So far, Toby's bolt has been serving my car
>> very well on the roads and streets of NYC. since his introduction
>> many years ago.   Before Toby's bolts, I had replace the trailing
>> arms bolt twice!  First time, they were both bolts were bent upon
>> inspection.  The right side bolt was more bent to the point a shim or
>> two fell out.  The second time the right side bolt had actually
>> snapped (sheared) off on a right turn!!!  I was luck to be one block
>> from home...  Anyway, my DeLorean was then towed to Rob to have the
>> replacement to have Toby's bolt installed...
>>
>> For what it is worth about softness and hardness about metals from
>> the aviation industry....
>>
>> Some years ago a helicopter had crashed.  Upon inspection, the
>> primary rotor blade's pivot securing bolt was at fault.  This bolt
>> was made in mainland China, where quality control was not a critical
>> issue.  To the manufacture, steel is steel... The problem was the
>> bolt produced was way too soft and did not meet the required Rockwell
>> hardness test as prescribed....  The bolt cost was $5.00 US.... It
>> was five dollars versus the $20.00 US approved bolt by the
>> F.A.A.!!!    From that failure there were major lawsuits and I
>> believe the Chinese manufacture got away with it, for one, it was
>> overseas and government affiliated and two, the company just closed
>> shop and change it's name... So, that is about soft metal.
>>
>> In the USA aviation industry/manufacturing, the rivets that are used
>> are sent frozen from the manufactures until they are ready for usage
>> upon assembly.  If the rivets are removed from the freezer and they
>> are not used and or they have been sitting around beyond a designated
>> time, they are automatically scrapped.  The reason is because the
>> room temperature with bring up the molecules movements which raise
>> their brittleness (work harden by temperature)... And also, the
>> assembler who is pneumatically hammering the rivets must know that
>> there are a prescribed amount of "hits" allow to the rivets.  This is
>> to not to over "work harden" the rivets upon compression which may
>> create a condition for premature failure!!!  Just several years ago,
>> we have seen planes in the news with the fuselage parts ripped off or
>> fallen off...  Rivet, rivet...  That is hardness in metals....
>>
>> Kayo Ong
>> #5508
>> Lic  9D NY
>>
>>
>>
>> On Feb 7, 2012, at 1:53 PM, Matthew wrote:
>>
>>> http://www.industrialchassisinc.com/Web-blog/?p=622
>>>
>>> --- In dmcnews@xxxxxxxxxxxxxxx, "Martin Gutkowski" <martin@...> wrote:
>>> >
>>> > Tensile strength is only part of the story, you have to be
>>> careful with ductility, aka "brittleness" and in general with steel
>>> the higher the tensile strength, the more brittle it becomes. A
>>> suspension component should have a degree of ductility, but not to
>>> the point of fatigue or elastic limit. The torque spec for the TABs
>>> is far lower than would normally be applied to such a bolt.
>>> >
>>> > Martin
>>> >
>>> >
>>>
>>>
>>
>>
>>
>> [Non-text portions of this message have been removed]
>>
>>
>>
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>>
>>
>>
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>>
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>>
>>
>>
> 



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