Saturday, November 26, 2005 - 04:41 pm, by: David Vaughan(Davidv)
Your comment ["If ABS is enabled..."] was true of many of the earlier systems Jeff but it is no longer.
Also, you will not stop only a little faster with F1 rotors and disks. It is unlikely your brakes are currently the limiting factor in the brake/tyre equation, so all the F1 disks will do for you is dump heat faster even within a single stop, and probably provide more initial bite. After that, tyres and control (avoiding lockup) are the problems. If you really want to stop in a hurry, fit F1 tyres.
Saturday, November 26, 2005 - 06:33 pm, by: Dan McColl(Hoon)
ABS lets you stop quicker as you can have all the wheels right at the point of optimal braking, (which I read is about 4% slip, right on the verge of lockup) whereas without you are limited to the wheel that locks up first.
As David said, If the ABS can activate, or you can lock a wheel, then bigger brakes won't help you stop faster. What they will do is allow you to stop more often before fading, such as a racetrack situation.
Thats what I've been led to believe, by reading and asking. I am always keen to learn if someone has differing, sustantiated info.
Saturday, November 26, 2005 - 09:38 pm, by: Emanuel Spinola(Manny)
UZZ32 weighs a little more than a UZZ30 UZZ32's anti-dive on braking presumably consumes a considerable proportion of the available braking force UZZ32 sucks with bugger all pedal feel imho
Saturday, November 26, 2005 - 09:40 pm, by: Jeff Harper(Jeffh)
So, using your theory, as I can stop my car in an emergency braking and not have my ABS come on, or any skidding, I stop almost as quick as an F1 car if that car weighed the same as mine? Nope.
The HP equivilent of my brakes are nothing compared to an F1 setup.
I noticed no superior stopping using my semi slicks.
Also, we prooved ABS on a Soarer consumes greater distance at our driver training, so sorry, but you are wrong as I have seen it and measured the difference.
Sunday, November 27, 2005 - 08:48 am, by: David Vaughan(Davidv)
Jeff, your first three paragraphs are each of them nonsensical, variously missing the point or carrying wrong assumptions. In the fourth you hypothesise that the Soarer ABS is crap. Could be true, although I doubt it. I will leave your proofs to you, so long as you do not waste any young lives by giving them bad advice.
Sunday, November 27, 2005 - 11:21 am, by: Dan McColl(Hoon)
If the F1 car weighed the same, had the aerodynamic aids removed and had the same tyres fitted then they should stop in the same distance.
The major factor in stopping is tyre grip. If you can lock a wheel then how can bigger brakes help???
The amount of horsepower your brakes supply is relatively meaningless. It's like saying that because you have a 5000 horsepower engine you can still run a 5 second quarter mile on space saver tyres.
It's one thing to have the horsepower, but it's another to be able to put it to the ground effectively.
Sunday, November 27, 2005 - 11:28 am, by: Peter Nitschke(Pen)
How well you can stop depends on the weakest link.
Factors that contribute are:
Tyres, pads, rotors, callipers, brake lines, brake fluid and the booster.
As ABS only kicks in when the tyres are losing traction, it can be used as a guide to what can be improved.
If your ABS kicks in easily on a dry road that is in good condition, get better tyres.
If your ABS doesn't kick in easily on a good road, then you can start improving your brakes.
On the track, I have found that brake fade is more a factor of pads. eg, with nothing else changed, OEM pads faded on the 4th lap at Mallala. Lucas pads didn't give up, but got a bit softer when really hot. Ferodo DS2500's just keep on working no matter what.
Different brake pads also have different amounts of bite, meaning that some can apply more stopping force. Brake pads are not just pure friction, there is also how they stick or grip the rotors when in use. For that reason, we don't use steel brake pads. In my experience, until limits are reached, most people will benefit from better brake pads more than any other brake upgrade.
If I upgraded my tyres to full race slicks, I would probably find it hard or impossible to get the ABS to kick in, so I would then start looking at eg Supra or Celsior 4 pot brakes to be able to apply more braking force to the rotors, and for the bigger rotors to have a bit more leverage.
Find the weakest link, upgrade it, then look for the next weakest link.
Sunday, November 27, 2005 - 06:57 pm, by: David Vaughan(Davidv)
Jeff, I apologise for any personal affront in my post but I had a lot to do today and it appeared I would have to write at length, for which I did not have the time. Dan and Peter have explained things, probably more concisely than I would have done and with the advantage of Peter's track experience.
Sunday, November 27, 2005 - 07:24 pm, by: Peter Nitschke(Pen)
Emanuel Spinola wrote on Saturday, November 26, 2005 - 09:38 pm:
UZZ32's anti-dive on braking presumably consumes a considerable proportion of the available braking force
Manny, the anti-dive on a 32 would be powered by the pump, I don't see how it would consume any of the available braking force. Possibly it may allow increased braking effort from the rears as there may be less weight transfer to the fronts, but I am not convinced of that either.
Sunday, November 27, 2005 - 07:56 pm, by: Emanuel Spinola(Manny)
Peter Getting technical now and probably not best explained by me... but a car with softer suspension takes less braking force to stop it than an equivalent car with ultra stiff suspension. The 32's anti-dive in effect makes it a car with ultra stiff suspension under braking. The lack of weight transfer from the "stiff" suspension accentuates forward momentum rather than downward momentum from soft suspension under heavy braking. Kind of the reverse anti-squat in heavy acceleration from a standstill - a stiffly sprung car will have less traction than a softly sprung equivalent car... ie drag cars with 90/10 suspension for the front to lift and rear to drop quickly/readily and transfer the car's weight downward for more traction.
Back onto the brake upgrades... many people like myself go for a braking package upgrade to promote repeatability in braking in varying conditions. It's all well and good to pull up nicely on single/twin pots with small rotors the first couple of times, but they will heat soak and fade a lot more readily than calipers with more pots and larger rotors. Fitting the larger braking hardware alows you to avoid fade readily and with repeatability. I personally prefer not to sacrifice the initial excellent cold bite of oem pads - in my experience, fitting higher temp rated aftermarket pads will be less prone to fade but at the expense of poor initial bite until warmed up. I used to regularly fade my factory TT brakes with oem and TRD pads on the street and the track. Fitting the Supra 4 pot front/2 pot rear with 320+mm rotors was the best braking move I ever made which allowed me to retain excellent all round braking on the street and the track with no more fade, no dust and no poor initial bite.
Sunday, November 27, 2005 - 08:23 pm, by: Jeff Harper(Jeffh)
I'm not being difficult here; I'm trying to put the whole 4 pot thing into perspective. And I'm not fazed either; I just drive cars to my maximum capacity and never question or study the physics of it.
Peter's comments make common sense to me. My ABS hardly ever comes on now, but my tyres cost me more than most cars I have owned.
I make money out of selling brake upgrades to people and I want to make sure people are fully aware of what they are buying.
So, in a 1 off crash braking incident 3 similar Soarers, same tyres same bit of road and same speed, 1 with F1 system, 1 with 2 pot and 1 with 4 pot the 2 pot owner will only stop slower if his brakes fade quicker? Amazing.
Of course if the road is fast and there is lots of braking sections the better systems will be cooler quicker, I understand that.
Sunday, November 27, 2005 - 08:58 pm, by: David Vaughan(Davidv)
Assuming other things (e.g. pads, aerodynamics) are also equal, and that the 2 pot brakes are capable of driving the ABS to its limit, then that is so, give or take a little in-braking fade. If the stop were from racing speed rather than street speed, then the F1 brakes would show a big advantage over steel brakes because even within a single stop there is a lot of heat to dump.
As discussed on another occasion, the brakes were the limiting factor on my V8, so I switched to TT brakes which have not proved limiting in street driving on good 225 tyres. I would need more tyre width to improve one-off stops.
The reason I keep mentioning aerodynamics on F1 cars is that they get free braking from their very high drag -- an F1 car at 300Km/h "brakes" at 1G merely by lifting off the throttle, no tyre/brake friction involved. Better, the downforce increases traction so they stop at multiple G's when they do brake.