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as most of you already know I am a big fan of the small braking system, which is equipping the very naturally beautiful 993.
I like it for many reasons:
- the first one, because it is almost 15kg lighter than the big red kit
- the second one is because the front cilinders of brake calipers have the same exact dimensions of the big red, only the brake pads surface is a bit larger.
Having a larger surface helps spreading temperature, but also the braking force slightly spreads as well.
Materials have made big steps in the last 25 years and the Pagid yellow compound can help a lot against friction reduction under heavy heating, so I dont think this is anymore a crucial point.
Where the big reds are important, but a brembo system in that case would be much better, is when it comes to racing and especially endurance, and so having much larger brake rotors helps a lot rotors to cool down.
But on the other side, they are heavier.
But this car is not intended for racing, nor for endurance, it is intended to be as fast as possible.
I like the idea of enhancing the drive experience the most, and this comes through many aspects, one of which is for sure the weight reduction.
1, 2, 3 laps in a sequence, and then it is time to cool down the car, the brakes, etc. to reduce overall wear (engine, braking system, tires, etc.)
So I was wondering if there could be some of you with a spare set of standard braking system coming from a carrera, from a targa or from a carrera S.
I saw this advertisement on the Rennlist Marketplace, what do you think about it?
I have a spare set of calipers like you mentioned -I bought another NB (non big-red) 993 set and took my time to refinish them, stripping, powder coating, clear coating, and rebuilding the seals and boots- so the original calipers from my car, are for sale- I was going to take my time again and give them a full refinish and then sell them, but if you're interested, as they are, needing to be rebuilt PM me.. Here are some images of the process of rebuilding the new ones..
Purchased them and they arrived like this.. Hardware removed and Powder coated with the original seals in situ. Removing the old seals and gaskets- New seals and gaskets- Detail of the Stahlbus speed bleeder
Spoiler
Spoiler
Finished, these were a two powder coat process- first one is the base color and then there was a matte/milky clear hard coat.
Finished, these were a two powder coat process- first one is the base color and then there was a matte/milky clear hard coat.
Where are you coming up with the 15kg difference? Is that across 4 corners? The weight difference is primarily in the rotors. If you go RS rears you will shift the braking bias slightly to the back of the car by increasing the larger piston to 36/30mm vs 34/30mm. Although this will add weight to the rear using the larger 322 vs 299mm rotor and large rear caliper. I would think you might see 15kg difference with this setup but not the big brakes up front and stock 993 calipers and rotors in the rear which is essentially what the 94 turbo ran.
15kg = 33lbs. There is no way the Big Red calipers and rotors weigh that much more. I have both sets off my car and happy to weigh them for a comparison.
Purely for the fact that you are going to great lengths (and expense) to rebuild this car and make it very "RS-like", I wouldn't put the small brakes on there... The weight cant be 33lbs more; there are of course braking benefits; also no stock RS/C4S/Turbo ever suffered any detriment from larger brakes; nor did their owners downgrade them to reduce weight and get "faster".
15kg = 33lbs. There is no way the Big Red calipers and rotors weigh that much more. I have both sets off my car and happy to weigh them for a comparison.
Purely for the fact that you are going to great lengths (and expense) to rebuild this car and make it very "RS-like", I wouldn't put the small brakes on there... The weight cant be 33lbs more; there are of course braking benefits; also no stock RS/C4S/Turbo ever suffered any detriment from larger brakes; nor did their owners downgrade them to reduce weight and get "faster".
Big red RS/CUP braking system needs:
- bigger master cylinder
- boost pump
- reservoir
(I have them all)
- 322 mm rotors front and rear
- bigger calipers
- bigger pads
ORIGINAL BRAKING SYSTEM
(8,28 +3,5) x 2 front = 23,6 kg
(6,3 + 2,8) x 2 rear = 19kg
2,9 kg depression unit and support
Tot. 45,5kg
RS BRAKING SYSTEM
(9,7 + 3,7) x 2= 26,8 kg
(8,2 + 3,6) x 2 = 23,6 kg
1,7 kg master cylinder
2,6 kg hydraulic unit
1,3 pressure reservoir
Tot. 56kg
So yes, considering the larger brake pads there is more or less 11kg difference, not 15kg, for the same braking power front and rear.
Where the RS/CUP braking system plays a role is in racing and/or because of fancy/precious look.
But we are always talking about the lightest wheels and then we don't care about 8 more kg of unsprung weight?
This car is goint to be a sprint car, no way I put more mass on it, apart if there will be a further engine upgrade later on that will also request an improvement to diminish the cinetic energy with better efficiency.
I also think that a 1050kg light 993, which is 310 kg less than the homologated version (probably because they weighted the car with the DIN system) , will have a comaprable cinetic energie on the track, since arriving a bit faster in terms of speed at braking, but with 30% less mass to be stopped.
then maybe I'll be proven wrong by the facts, but I think its stock braking system will brake the car impressively.
Last edited by nothingbutgt3; 05-08-2022 at 12:30 PM.
If anyone is curious, my Sunday morning measurements.
OEM black calipers. Brake pads 50-75% remaining life and brand new rotors:
Front caliper: 10.1 lbs
Front rotor: 19.1 lbs
Rear caliper: 7.6 lbs
Rear rotor: 14.2 lbs
Total: 51 lbs x (2) = 102 lbs total
993RS "big reds". Brand new rotors and pads:
Front caliper: 10.7 lbs
Front rotor: 20.6 lbs
Rear caliper: 10.6 lbs
Rear rotor: 18.1 lbs
Total: 60 lbs x (2) = 120 lbs total
18 lbs total difference. (not adjusted for brake pad wear on the black calipers, so perhaps even 1lb less difference)
If anyone is curious, my Sunday morning measurements.
OEM black calipers. Brake pads 50-75% remaining life and brand new rotors:
Front caliper: 10.1 lbs
Front rotor: 19.1 lbs
Rear caliper: 7.6 lbs
Rear rotor: 14.2 lbs
Total: 51 lbs x (2) = 102 lbs total
993RS "big reds". Brand new rotors and pads:
Front caliper: 10.7 lbs
Front rotor: 20.6 lbs
Rear caliper: 10.6 lbs
Rear rotor: 18.1 lbs
Total: 60 lbs x (2) = 120 lbs total
18 lbs total difference. (not adjusted for brake pad wear on the black calipers, so perhaps even 1lb less difference)
I use the very usefull rosepassion spare parts website, where every article has the weight indicated, precise to .001 kg
they probably had to weight every part to determine the shipping costs, what I think is interesting is they let such a detail accessible.
I didn't consider the larger ergal pistons and pads in the back, since it is pointless to count half a kg to 1 kg difference, not to mention the oil weight inside the hydraulically assisted system.
The car will also be without hydraulically assisted steering: hopefully the engine will run better and the steering will not be that heavy in the parking situations.
to me 11 kg of unsprung weight are a lot, especially on a car weighing 1050kg: the suspension efficency is strictly connected to the ratio sprung/unsprung weight, so if one manages to reduce the sprung weight better if there is a way also reduce the unsprung weight as much as possiible, otherwise the overall suspension efficiency decreases.
If anyone is curious, my Sunday morning measurements.
OEM black calipers. Brake pads 50-75% remaining life and brand new rotors:
Front caliper: 10.1 lbs
Front rotor: 19.1 lbs
Rear caliper: 7.6 lbs
Rear rotor: 14.2 lbs
Total: 51 lbs x (2) = 102 lbs total
993RS "big reds". Brand new rotors and pads:
Front caliper: 10.7 lbs
Front rotor: 20.6 lbs
Rear caliper: 10.6 lbs
Rear rotor: 18.1 lbs
Total: 60 lbs x (2) = 120 lbs total
18 lbs total difference. (not adjusted for brake pad wear on the black calipers, so perhaps even 1lb less difference)
I use the very usefull rosepassion spare parts website, where every article has the weight indicated, precise to .001 kg
they probably had to weight every part to determine the shipping costs, what I think is interesting is they let such a detail accessible.
I didn't consider the larger ergal pistons and pads in the back, since it is pointless to count half a kg to 1 kg difference, not to mention the oil weight inside the hydraulically assisted system.
The car will also be without hydraulically assisted steering: hopefully the engine will run better and the steering will not be that heavy in the parking situations.
to me 11 kg of unsprung weight are a lot, especially on a car weighing 1050kg: the suspension efficency is strictly connected to the ratio sprung/unsprung weight, so if one manages to reduce the sprung weight better if there is a way also reduce the unsprung weight as much as possiible, otherwise the overall suspension efficiency decreases.
Very interesting weight differences. I'm also on the side that standard brakes are good enough. As mentioned earlier, definitely not a weak point. I ran my brakes on the track with never any problems. I painted mine red, so I get it all good! The only "bling" thing I did and would do it again in a heartbeat.
The standard 993 brakes are more than up to the task and if used on track with decent fluid and pads then again they are well up to the job there too. Big Red (Turbo) brakes probably won't make you stop any quicker but they will stay cooler for longer.
If you are going to get bigger brakes, and caveat - I have big reds, consider the RS brakes as an option for 2WD cars. The AWD system of the Turbo car adds a lot of rearward bias to the braking, so much so that the pistons on the Turbo rear calipers ARE SMALLER than the standard 993 calipers, giving LESS overall braking power at the rear. Conversely, the RS rear calipers have larger pistons than the std. calipers (30 + 36mm) and as such, keep the braking better balanced front to rear on a narrow body car.
The RS front caliper is the same as the 993 Turbo front caliper, the same part number. However the RS rear caliper is unique and different to the Turbo rear caliper and different to the standard 993 rear caliper.
It's not quite as simple as that though because the RS actually uses dual master cylinders, a PV valve and hydraulic assistance with the ABD system so RS braking is a whole lot more complicated. Simple and easy way to figure this out could be for you to run full RS calipers front and rear and then dial in a little front bias back into the system by using a stronger pad in the front.
Another reason to love the RS. Small things like this, to optimize the rear brakes just a bit more, for the ultimate car. Amazing. I didn't know this about RS brakes.
The standard 993 brakes are more than up to the task and if used on track with decent fluid and pads then again they are well up to the job there too. Big Red (Turbo) brakes probably won't make you stop any quicker but they will stay cooler for longer.
If you are going to get bigger brakes, and caveat - I have big reds, consider the RS brakes as an option for 2WD cars. The AWD system of the Turbo car adds a lot of rearward bias to the braking, so much so that the pistons on the Turbo rear calipers ARE SMALLER than the standard 993 calipers, giving LESS overall braking power at the rear. Conversely, the RS rear calipers have larger pistons than the std. calipers (30 + 36mm) and as such, keep the braking better balanced front to rear on a narrow body car.
The RS front caliper is the same as the 993 Turbo front caliper, the same part number. However the RS rear caliper is unique and different to the Turbo rear caliper and different to the standard 993 rear caliper.
It's not quite as simple as that though because the RS actually uses dual master cylinders, a PV valve and hydraulic assistance with the ABD system so RS braking is a whole lot more complicated. Simple and easy way to figure this out could be for you to run full RS calipers front and rear and then dial in a little front bias back into the system by using a stronger pad in the front.
Exactly, I completely agree with you.
In the front there will be the air conveyors placed on the lower A-arm and in addition two nicely large air ducts coming from the front bumper, as well as pagid yellow braking pads + Motul RBF 700.
I don't think braking will be a problem.
At the rear, on the other hand, as I already do on the polar silver 993, I use textar pads, because they have an immediate grip and allow the ABS/ABD to work in the best way.
In various time attack experiences on the track I have noticed how the discs at the rear never ever exhibit cracks of any kind, meaning that the temperatures reached at the rear are not a critical aspect as in the front.
A significant point is that at very low ride height the front squat, i.e. the load transfer is completely different: the car remain much more flat and so the rear brakes become more important. Bigger RS Pistons in the rear for bigger rotors, I think this is the main + of the RS braking system, but only if the car is in the 993 CUP and below RS ride height I assume there can be a noticeable improvement.
It wpuld be super cool having on-board the exact braking system of the Guntherwerks creature, but unless someone send it as a gift, I don't think I will ever have such a pleasure of braking power combined with super lightness.
05-07-2022, 10:32 AM
