Brakes sticking on after washing.

[vitesse]

The actual point I am making is that if these days they are steel ,then they will corrode far more easily particularly if left standing wet-as to why the inner face is worse-perhaps hosing down the wheels after cleaning with a fine highish pressure hose nozzle means the outer face dries better by evaporation leaving standing water(and shampoo possibly) on the inner.

 

[rob.kellock]

That's the engineer in you coming out.

Brembo the brake experts say of their product: "For greater versatility and to increase their ability to withstand extreme stress, Brembo Sport brake discs are made from high-carbon cast iron for improved thermal and mechanical resistance. "

The original discs on my 996 didn't last 40k miles but that car suffered the double whammy of not being used every day and being left outside.

 

[vitesse]

I just can't help it Rob-being also a physicist,musician,thespian etc-no wonder I get into dizzy spins-however to the point--have you not seen odd references to steel discs in Porsche Post & on posts on here,because I have & didn't want to query it because the references seem more likely to know than a mere mortal like me-always quoted in the context of enhanced performance,but all the metallurgy I've ever studied wouldn't put steel as a suitable material for contact with braking materials--same goes for flywheels/clutch plates although racing plates can have sintered facing materials.[8|]
Any discs I've had to replace on any car inc Porsches have been because of wear/grooving not rusting.

 

[BartyB]

It's my understanding that ever since asbestos was largely eliminated from disc pad compounds, to achieve similar levels of braking performance it has been necessary to use discs / rotors made of high carbon steels. This has necessarily resulted in increased disc wear rates. My car lives out of doors much of the time and it only needs a light shower of rain to cause the disc surfaces to oxidise and turn red. As it happens, I suspect that some of the sticking problem may be the result of moisture between the parking brake linings and drums. For this reason I avoid using the parking brake when the car is parked when its wet preferring instead to leave the car in gear and use a discreetly located chock.

 

[rob.kellock]

I completely agree.

 

[vitesse]

ORIGINAL: rob.kellock

That's the engineer in you coming out.

Brembo the brake experts say of their product: "For greater versatility and to increase their ability to withstand extreme stress, Brembo Sport brake discs are made from high-carbon cast iron for improved thermal and mechanical resistance. "

The original discs on my 996 didn't last 40k miles but that car suffered the double whammy of not being used every day and being left outside.

With what are you completely agreeing,given the quote you posted above?
High carbon Steel or parking methodology or both?

 

[rob.kellock]

Both.

Is steel not an alloy of iron and carbon?

My chemistry is a bit rusty, pardon the pun.

 

[tscaptain]

ORIGINAL: rob.kellock



Is steel not an alloy of iron and carbon?

And lots of other possible additions. Over 3500 different types of steel apparently!

http://www.chemguide.co.uk/inorganic/extraction/iron.html

Cast Iron has a carbon content greater than 2.1%

Amazing what we learn and all because someone has sticky brakes after washing their car..........[]

 

[lowndes]

ORIGINAL: tscaptain

Amazing what we learn and all because someone has sticky brakes after washing their car..........[]

Nice to see you over here Alan...tempted by something a bit more modern perhaps []

Nick

 

[jdpef356]

Many years ago at the NEC Classic I purchased a can of Anti 'what ever it was called' to stop this rust problem. It was made by Carcoon the indoor car cover people.

It worked! The problem is and still is. It was easy to use on the outer face but getting to the inner face was near impossible.

 

[tscaptain]

ORIGINAL: lowndes


Nice to see you over here Alan...tempted by something a bit more modern perhaps []

Nick

Add another 350 torques then maybe..........[]

 

[rob.kellock]

You don't need another 350 torques when you lose 600 kilos []

 

[tscaptain]

Oh I thought Nick was referring to a 981[] I do love driving the Boxster (her ladyship has one) and it's great around the twisty bits. But.....

 

[vitesse]

ORIGINAL: rob.kellock

Both.

Is steel not an alloy of iron and carbon?

My chemistry is a bit rusty, pardon the pun.

Then it might be sensible to drive your Chemistry after washing it to dry off the water-I think you could call it -distillation.[]

 

[rob.kellock]

I know, I know.

Spyder has proved a very enjoyable sparring partner with one of my very best pal's 997 turbo.

The back roads of France, Oulton Park, the Yorkshire moors, my little Boxster has held its own with remarkable effect. Just wish I could have both!

Edited to add, thanks Colin , cross posting! Must get distilling!

 

[tscaptain]

ORIGINAL: rob.kellock

Just wish I could have both!

Me too!

On the rusty brake front are cross drilled discs worse than grooved ones? Wondering if something like PF discs would be less prone to corrosion next time around? Such as..
http://www.gmpperformance.com/index.cfm?PG=detail&PID=205190

 

[rob.kellock]

I'm guessing its the composition of the alloy that makes the difference rather than the drilling?

Luckily my Spyder discs are good as new still so no worries for a while.

 

[Richard_Hamilton]

From a 996T Technical Bulletin:

 

[vitesse]

So on a 996Turbo,the brake discs are Alloyed Grey Cast Iron.
So they are are definately not steel."Grey"--means that the carbon is held in laminar form within the cast iron structure & so they are definately not Ductile or SG(spheroidal graphite) cast iron.
Alloyed--implys mixing the cast iron with other metals & frankly may only mean slight additions of Nickel/Chrome as innoculents at the ladle stage after bulk melting using either cupulas or electric furnaces.

These melting processes would normally be used by specialist foundries making brake discs & drums & flywheels because of the quantities invoved-generally they are melting the same metal specification everyday & the feedstock is generally pig iron,cast iron scrap,returns from the fettling shop including runners,risers,pouring basin blocks ,actual scrapped product & limestone.There might be the odd amount of steel scrap in the other scrap-final chemical spec is achieved by the mix of quantities,& by final innoculation mentioned above.

The carbon equivalent of the melt is checked & can be adjusted by addition of graphite & producers will endeavour to maintain the CE closely-the lower the figure,the stronger the iron & less corrosion resistance,conversely-the higher the figure you get weaker iron but more corrosion resistance.

There are other very minor but important constituents such as Manganese,Silicon,Phosphorous which do have a significant part to play together with the carbon content on the CE figure.

 

[Rodney Naghar]

Very interesting.
I read it is the reduced chrome content in the post 993 discs that's resulted in the prevalence of rusty discs (in an effort to reduce squeal). Could that be true?