[s-cars] Cracked Big Brake Brackets - ECS Stage 2

[Andrew Beckert]

I'm having deja vu....

Andrew

Eric Phillips wrote:
> Guys:
> 
> I think that it's a design flaw - due to *materials choice*.
> 
> Aluminum is the material from which this - and other - BBK brackets
> are made.  Aluminum has no fatigue limit, which is engineer-speak for
> being able to take ZERO stress without weakening the part made from
> aluminum.  Different alloys have different fatigue strength, which
> tells you how many cycles it takes to break that material.
> 
> http://www.sv.vt.edu/classes/MSE2094_NoteBook/97ClassProj/anal/kelly/fatigue.html
> 
> Steel has a fatigue limit, which means it can take an infinite number
> of stress cycles below the that limit, and will only begin to fatigue
> when the stresses happen above the limit.
> 
> This is the simplified version - but it is the basis for which I have
> decided to always recommend against BBKs with aluminum brackets.  Of
> whatever alloy.
> 
> Brake brackets get stress in two directions every brake cycle.  In
> addition, one has to be careful about the torque put on fasteners
> around aluminum.  Too much can create a stress riser that will lead to
> cracking.  So, if your torque wrench isn't calibrated properly, you
> could initiate a crack on the first install of a new BBK.
> 
> On any other automotive system, I don't think it'd be that big a deal.
>  But brakes are *the* primary mechanical safety system.
> 
> The next problem is corrosion.  The environment in the wheel well is
> pretty harsh.  Aluminum is more reactive than steel, by it's nature.
> Surface treatments and alloying mitigate this, but don't eliminate it.
>  Add to that galvanic corrosion from marriage to steel fasteners, and
> all of a sudden you have a potential problem.  And that's before any
> addition of road salt.
> 
> The reason to use aluminum in this application is price.  Cheaper to
> make stuff out of aluminum than steel.  Who wants to pay $600 for a
> pair fo steel brackets for a BBK?  That may be an exaggeration, but
> not by a large amount.
> 
> Maybe somebody could run an ECS, MoVit, StopTech, BIRA or other such
> aluminum bracket on their BBK forever without any worries - especially
> on a street-only daily commuter.  Maybe it would take over a million
> cycles to even approach the fatigue strength of the brackets.  I don't
> know.  But that's not something I'd like to find out by accident, pun
> intended.
> 
> So, now to the opinion part.
> 
> I wouldn't run aluminum brake brackets on my car.  Any of them.  And
> my car will never see the track.  Even the spirited driving I do is
> pretty mild.  During my research on BBKs, I came to the conclusion
> that the 993TT caliper, RS2 (steel) bracket and A8L D2 rotor was the
> way to go.  From a price and hassle standpoint, the ECS kit is the
> best choice.  But I just couldn't bring myself to put an aluminum part
> there.
> 
> With the RS2 bracket and the A8L rotors, some material has to be
> machined away from the bracket where it contacts the strut - about
> 1mm.  And the stock bolts (35mm) have to be cut down to 25mm, but that
> costs about $20 and takes all of two hours for any machine shop that
> can do it.
> 
> Rotors are available and relatively inexpensive, and you can get them
> plated and slotted from Apikol, if that's your thing.
> 
> Also, you can run Porsche 993TT rotors on custom hats.  Then you
> wouldn't have to machine the brackets at all.  And the rotors are
> wider, so you get more life out of the pads, and the rotors are MUCH
> lighter than the big A8 boat anchors.  Custom hats are in the
> neighborhood of $450 for the pair.
> 
> So, my opinion, FWIW, is to go 993TT calipers, RS2 brackets, and some
> flavor of rotors that suits your fancy.
> 
> You could change over for as little as $350 - $200 for the brackets,
> and $150 for the pair of rotors.  I would consider that cheap
> insurance, but again, that JMHO.
> 
> YMMV, does not include batteries, may contain nuts, etc, etc.
> 
> Eric
> 
> 
>>Date: Mon, 23 Oct 2006 08:30:21 -0700
>>From: "Alvin Labonite" <alabonite at gmail.com>
>>Subject: Re: [s-cars] Cracked Big Brake Brackets - ECS Stage 2
>>
>>I heard that chatter too and was very concernd. during that time, I had a
>>shop installed my RS2 turbo and EM and they brought up the crack brackets
>>too upon seeing them on the net. Mine turned out ok and they suspected that
>>over-torquing may have played a factor. but who know's it could also be poor
>>design.
>>On 10/23/06, manuelsanchez at starpower.net <manuelsanchez at starpower.net>
>>wrote:
>>
>>>S-heads,
>>>
>>>I was having my tech inspection for upcoming VIR school and found that
>>>both of my ECS Stage 2 caliper mounting brackets are cracked. Based on some
>>>recent internet posts on the subject, I made sure the tech checked
>>>carefully.
>>>
>>>I spoke with Gary at ECS, he was very nice and did some checking with the
>>>returns department. He told me he thougght this was an isolated incident. I
>>>mentioned that I was clued into this potential problem from chatter on the
>>>net, but he said he had never run across the issue and he handles 50% of the
>>>calls.
>>>
>>>I would be interested to know how many others have had this problem and
>>>what you did about it (contacted ECS?).
>>>
>>>I asked if the design had changed at all, and he said no. I suppose it
>>>could be an isolated manufacturing defect, but I wonder if it is a design
>>>issue. Obviiously I would prefer that this not happen again, and a design
>>>revision would probably make me sleep better.
>>>
>>>So check you caliper mounting brackets.
>>>
>>>Again, Gary was very nice and helpful, and ECS will warranty the brackets.
>>>I need to buy new brackets, returned the cracked ones, and then they will
>>>refund the cost of the replacement brackets.
>>>
>>>I'm wondering though what my other options would be for a 993TT Big Red
>>>brake kit. Any thoughts?
> 
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