George Macdonald wrote:
> On Tue, 19 Apr 2005 06:14:00 -0700, jim beam <nospam@example.net> wrote:
>
>
>>George Macdonald wrote:
>>
>>>On Mon, 18 Apr 2005 05:56:59 -0700, jim beam <nospam@example.net> wrote:
>>>
>>>
>>>
>>>>George Macdonald wrote:
>>>>
>>>>
>>>>>On Sun, 17 Apr 2005 07:45:58 -0400, Imminent Vengeance <me@privacy.net>
>>>>>wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>George Macdonald wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>Depends where you live but that suspension system is prone to broken front
>>>>>>>springs in the frost belt - the spring breaks just where it enters the
>>>>>>>perch on the shock. Because of where the break is, you probably won't even
>>>>>>>notice any difference in ride/handling but you might hear a "doink" when
>>>>>>>you get out of the car on the side with the break; you'd definitely hear
>>>>>>>the "doink... doink" when you jack the front up. The break *can* put some
>>>>>>>side force on the shock which will wear it out quicker.
>>>>>>>
>>>>>>
>>>>>>The only time I broke a spring on my '93 Accord, it was at the other end of
>>>>>>the coil, at the top where it enters the strut mount. But I think this was
>>>>>>the result of that corner of the car jumping a huge curb while swerving to
>>>>>>avoid a bad driver.
>>>>>
>>>>>
>>>>>The break often happens on a violent bump but the root cause is usually
>>>>>weakening of the metal due to corrosion where water/salt gets through a
>>>>>hole in the epoxy coating of the spring. The upper spring seat has a
>>>>>rubber doughnut in it so there's no wear of the epoxy there. I've heard of
>>>>>the upper end going but AFAIK the lower is more common because of epoxy
>>>>>wearing away where it contacts the metal of the perch. If you live in a
>>>>>"corrosion area" it's worth checking springs for nicks in the epoxy...
>>>>>which *can* be caused by some of the (cruder) tools used to compress the
>>>>>spring, e.g. when swapping shocks.
>>>>>
>>>>
>>>>i've seen brand new springs with such nicks. bad [neglectful] handling
>>>>handling at the factory. as you say, corrosion pitting starts & that
>>>>causes a stress riser that initiates fatigue. it's the fatigue cracking
>>>>that kills the spring.
>>>
>>>
>>>Funny thing is I've always thought that spring metal can easily be made
>>>fairly corrosion resistant.
>>
>>sure, there's all kinds of non-ferrous springs, but they're fiercely
>>expensive. i know honda springs don't seem "cheap", but believe me,
>>they are compared to the alternatives. also bear in mind that steel is
>>relatively high modulus compared to other materials and silicon/carbon
>>steel typically used in auto springs has a very high yield point
>>compared to most fatigue resistant stainless steels. lastly, spring
>>wire has to be comparatively soft for the forming phase, then heat
>>treatable to become hard and resistant to yielding. stainless steels
>>exist that have these kinds of hardening reactions, but they're a big
>>step up in cost.
>
>
> I wasn't talking about stainless or non-ferrous - there are alloys of of
> "steel" which corrode much more slowly than others. This is a problem
> which, while not unique to Honda, is a rather glaring one...

well sure, there are /many/ aloys of steel, but the key one in this
application is the ability to heat treat to something with a very high
yield point, yet not be brittle

> not to mention
> that the epoxy coating seems like a bad idea, given the evidence.

that definitely could do with some work. honda don't actually make
springs - they buy them in. find out who the supplier is.

>
>
>>> If Honda thinks they can skip that because of
>>>the epoxy coating, somebody there is dreaming. The Lyle tool I used to
>>>replace my springs really did a number on the brand new spring coating -
>>>tried to patch with epoxy glue and hoping it'll hold for a bit.
>>>
>>
>>just rust resistant paint works fine. trouble is, once you have some
>>corrosion, you have pitting & therefore potential fatigue crack
>>initiation. strictly speaking, springs in that condition should be
>>replaced, but i can't say i'm a strict adherant to that rule. depends
>>on mileage & condition.
>
>
> Did you miss something here? This was a brand new spring which was marred
> by the tool - no question of corrosion having started.

!

>
>
>>interesting you mention the lisle tool. i was extremely unimpressed
>>with the principle of that device, for the reasons you're describing
>>happened. i therefore built my own - does not touch the spring at all!
>> i'll email a photo to tegger.
>
>
> I chose it because it *looks* safer than some others, since the loops
> cannot break loose from the spring coils under load. I found on use that
> the screws "machine" a "thread" into the collars, thus reducing their
> effective thickness - IOW safety may not be what it appears.
>
seems it's designed for operator safety at the time of service, not
subsequent fatigue damage safety.