Big Reds 993 brakes
- Thread starter garyalanlane
- Start date
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If they're non M030 type Hartech have loads in their stores. I was trying to find some M030 callipers when I came across a pile of about 20
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Just phoned them - aparently they are badly corroded, and they're not sure why they have kept them! Not just plate-lift, but around the piston seal, so I'm back to looking! Thanks anyway.
DivineE
New member
No worries. Sorry to waste your time, I didn't look too hard at them. I have an almost brand new set on my car that's there, they are immaculate but I'm still deciding what to do with that car at the moment. I don't really want to break it
I spent a lot getting it to where it is so want to keep it as a whole car and carry on building it slowly or sell it for someone else to finish really.
sawood12
New member
Anyone tried Boxster/Caymen brakes? Would they need the same conversion bracket? I found Big Reds to be a rip off with tatty pairs in need of refurbishing rarely going for under £700. My Big Black conversion which included brand new calipers, 928GTS disks, front and rear pads and the conversion brackets was $1500 back in the day where you got £2 for the $. In fact I priced up brand new Big Black calipers at £350 (which was the same as the turbo/S2 small blacks) each with brand new Big Reds being about £700 each when they are the same caliper apart from the colour.
Boxster / Caymen brakes will be lighter and are far more plentiful on ebay going for less money.
Boxster / Caymen brakes will be lighter and are far more plentiful on ebay going for less money.
Hilux
New member
They will do if the piston area is greater than standard as the hydraulic advantage is lessened.
This can be retored by increasing the mechanical advantage (pedal ratio) or the hydraulic advantage (master cylinder)
Agree entirely about them not necessarily being the answer.
Better discs and almost always better pads and fluid will make a huge difference and is only really needed if tracking the car regularly.
Driver tuition will also be a better bet as corners are taken faster and braking is less. The main reason people fade their brakes is braking too long on a track and not enough time between corners to cool. The other reasons are inadequate pads allowing a gaseous builod up between pad and disc due to resin burning/vapourising or poor fluid that gets too hot.
sawood12
New member
I'm not an advocate of the gas theory. Porsche were amongst the first manufacturers to play with drilled disks and the reason was for weight saving and nothing more. They found little advantage due to weight saving but did unexpectedly find improved stopping power. This is due to the abrasive effect of the holes - i.e. brakes work by friction forces tearing away small fragments of the pad and disc (i.e. brake dust). The force to tear these fragments away is the force that causes drag on your wheels and slows you down. Heat is a by-product of this process. Drilled disks increases the average size of the fragments meaning you get larger surface area of the fragments and more force required to tear the fragments away.
Brake pads do not contain resin or any other non-metalic compound - they are sintered i.e. metal powder compressed under very very high pressures until the particles fuse together. In order for this to work and give the pads the strength they need and for the pads not to be porous, the metal powder has to be very very sterile, so no moisture, solvents, glues, oils or greases, just pure metallic powder so i'm not sure what is supposed to be causing the gases. If gases form at the surface of the pads then they will form within voids in the pads causing them to explode. I don't believe that carbon metallic pads contain anything other than metal either. They just metal alloys with a high carbon content as high carbon content metal alloys have very high melting temps and what you are after with brake pads are metals that retain their mechanical properties at high temps and not go all soft and squidgy. Pure carbon wont work with sintered pads (it wont fuse with metal under pressure) and in any case pure carbon is used as a metal lubricant so not a great material for brake pads.
Agree that if your car is used for anything other than heavy track work then standard brakes are more than adequate even for the odd trackday. But because they are not needed it doesn't mean that you shouldn't do it! At the end of the day do we all really NEED 944's (perhaps a poor choice of analogy on this forum!)?
Brake pads do not contain resin or any other non-metalic compound - they are sintered i.e. metal powder compressed under very very high pressures until the particles fuse together. In order for this to work and give the pads the strength they need and for the pads not to be porous, the metal powder has to be very very sterile, so no moisture, solvents, glues, oils or greases, just pure metallic powder so i'm not sure what is supposed to be causing the gases. If gases form at the surface of the pads then they will form within voids in the pads causing them to explode. I don't believe that carbon metallic pads contain anything other than metal either. They just metal alloys with a high carbon content as high carbon content metal alloys have very high melting temps and what you are after with brake pads are metals that retain their mechanical properties at high temps and not go all soft and squidgy. Pure carbon wont work with sintered pads (it wont fuse with metal under pressure) and in any case pure carbon is used as a metal lubricant so not a great material for brake pads.
Agree that if your car is used for anything other than heavy track work then standard brakes are more than adequate even for the odd trackday. But because they are not needed it doesn't mean that you shouldn't do it! At the end of the day do we all really NEED 944's (perhaps a poor choice of analogy on this forum!)?
DivineE
New member
Excellent post. I've often heard about gasses building up so interesting to actually sit and think about it rather than just excepting it. I thought they were referring to the trapped air between the flat surface of the disk and the pad expending as it heated up and reducing the contact but I suppose if you think about it. When you trap water under your coaster on the desk and it floats you move the coaster and immediately the water is wiped away giving it grip against the table. I suppose because the disk is always turning as your applying pressure it should in theory remove the air in a similar fashion?
As for the difference between want and need[
] you've got me there. I still couldn't say no to a set of those sexy disks higher up the page. I just question if you'd ever really benefit from them.garyalanlane
New member
It's because I have the turbo mo30 brakes but each caliper is different (front) One is the older type one with the porsche logo in the casting and one is a replacement newer one with the printed porsche logo and I've managed to source a new set of Big reds for a very good price (£400)
DivineE
New member
Nice! Yes in your position I'd probably be doing the same. Just remember they really don't fit under many 16" wheels. I tested it with my turbo teledials and it doesn't happen! People say they are the same size but they definitely sit out further from the hub because standard M030 brakes do 'just' fit under those teledials.
Hilux
New member
All pads contain some organic elements (namely resins to bind the constituents together) The metallic elements carbonise (hence the dust) but the resins create gas and if too hot create sufficient for a boundary layer that reduces friction.
Grooves and holes are there primarily to break up this layer.
Lol, thanks Olli. I might just put that pic as my screensaver.
On the Gas or non Gas issue. Well I admit that if there is no build up of hot gasses between pad and disc then I'm guilty of repeating this theory Parrot fashion. All I can say from experience is that my brakes improved noticeably when shifting from stock non drilled/slotted rotors to the 964tt ones. Unfortunately they cracked very quickly so I searched for some slotted ones...to no avail. Which led me to have them made. Brakes have never been better. I don't think the holes or slots are merely acting as a friction inducer and this is why I had great improvement, but whatever the reason, if you go to the track I can't recommend changing to a vented disc more highly. Of course you need to get all your other 'Ducks in a row' so that they can work to their potential. Bleeding, proper fluid, new or upgraded lines, decent pads etc. Sometimes just leaving one of these items out of the equation can ruin the braking efficiency so don't skimp or short cut here. Very important.
On the Gas or non Gas issue. Well I admit that if there is no build up of hot gasses between pad and disc then I'm guilty of repeating this theory Parrot fashion. All I can say from experience is that my brakes improved noticeably when shifting from stock non drilled/slotted rotors to the 964tt ones. Unfortunately they cracked very quickly so I searched for some slotted ones...to no avail. Which led me to have them made. Brakes have never been better. I don't think the holes or slots are merely acting as a friction inducer and this is why I had great improvement, but whatever the reason, if you go to the track I can't recommend changing to a vented disc more highly. Of course you need to get all your other 'Ducks in a row' so that they can work to their potential. Bleeding, proper fluid, new or upgraded lines, decent pads etc. Sometimes just leaving one of these items out of the equation can ruin the braking efficiency so don't skimp or short cut here. Very important.
sawood12
New member
Nice theory but I don't buy it. I doubt any water will be clinging to the disk surface as it is rotating and therefore will be centrifuged off, coupled with the fact they are hot any water will instantly vaporise. Also the disk is inside the wheel so when you drive through a puddle the water is displaced by the wheel and away from the wheel and disk. Any water on the surface of the disk will be squeegee'd off as soon as you apply brake pressure. Also even when you are not on the brakes the pads are still in contact with the surface of the brake disk but no pressure is applied apart from the head of pressure due to the brake fluid reservoir being higher than the callipers. This is intended as you don't want any delay between hitting the brake pedal and getting some pressure on the brakes - therefore any moisture on the brake disk will be scraped off and around the pad rather than get under the pad.
Non-drilled or grooved disks work perfectly fine and there is no need to change them other than for aesthetic reasons (no problem with that as long as people are honest about it and don't try to justify it on the premise of some performance benefit) - unless you are racing or a real hard-core trackdayer. Furthermore they are more robust than drilled disks as they are not prone to cracking.
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