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Discussion Starter #1
Or HOW to challenge a Lamborghini for 100 -0!
Or Beat the super cars not on 0-100 but on 100-0 !

The photos are from my car. These are the calipers that Lambo is using on both Murcielago and Gallardo. They are very hi-tech, made by Brembo. They are huge but they have some unique specs.

About 2.9 kilo each from special aluminum-magnesium materials.
They use 4 small pads for every caliper and not 2 big like 4 or 6 pot calipers. That make them more accurate and easy to respond even
on small brake pedal movements.
But since we have 4 pads driven by 2 piston each- one small and one big- when you push the pedal more the bigger pistons take action and give very firm braking power.
And this happens plus 4 times for the 4 pads plus 2 times for the 2 calipers. So you can have a very progressive braking and also very
powerful when you needed. Thats called depth on braking.

Braking is not only if you can stop or not for that distance, Or how
to make it shorter. Is more . Is also how deep can you brake in a big
turn. How late can you brake? And in which position can you place
the car before start to accelerate?





 

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Yes beautiful indeed - very impressive. Looks like a very tight fit, even behind those 18" wheels.

I would hate to think of the cost but if you have the power then big brakes are essential
 

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Pacs,
An easier fit than you can imagine, using the correct rim offset that is. I drove the car, the braking performance is fantastic & very confidence inspiring. I managed to carry some very high speeds into long sweepers on the main Attika highway. Me GTAFAN & 2 passengers, cruised through there between 210-240km/h, continuous.

Some tasty mods to his car, nice coil overs, strut braces,brakes,18" rims, Q2 LSD & yes the by now infamous Monster TB,BMC CAI kit, Supersprint decated exhaust & remap. His car is great but next time I drive it he will have my old stage 4 Glenwood Motors 3.7L V6 in it, now then it should really be exciting.
Should be able to give a Lambo a run in the 0-100km/h dash then instead of the 100-0?????
Monstro3.7
 
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Very interesting topic.
Sounds like the calipers are not that heavy, but how about the discs ?
 

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Have you fitted a brake bias proportioning valve ?

Your front to rear balance should be changed fairly radically by that mod.
Have you taken any measures to keep an optimal balance?

Cheers,
TB
 

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TB, he has big Brembos on the rear too :cool:
 

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Gents,

There is no brake proportioning valve in the car as per some competition type set ups that I've run.

GTAFAN can ellaborate on the details but the tech that did the work in Greece is 1st class.
Changes within the system MUST exist, I never got into that. I drove the car at some pretty high speeds, we spoke technical until my wife, who was with us got a little board with our persistent shop talk. You know how it is????

What made the system impressive was the progressive brake feel & balance, far better than what I've experienced with the MOV'IT system.

So I would like to know some details & I plan to have the car fitted out with the same kit when I move it to Greece in 08'. It's that impressive!!!!!

So lets hear what GTAFAN has to say.
Monstro3.7
 
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Have you fitted a brake bias proportioning valve ?

Your front to rear balance should be changed fairly radically by that mod.
Have you taken any measures to keep an optimal balance?

Cheers,
TB

Yes, it would be interesting to hear about the changes made to the system.. I can not understand why the brake bias is not adjustable..It must mean they either pre-balanced the system, or just slapped on some Bling Hardware..

Particularly intersted if the ABS software was modulated, and how(scan tool)..Is the Master brake cylinder running on standard sized pistions? Has the brake lines ben upgraded? What are the total surface area of the 4 small pads mentioned, and was the 8 piston calipers originally made for 365mm disc?

What about the car itself.. is it optimized for this type of extreme braking system? What tires are used.. Is it corner weighed, and to what values front to back? How was the suspension set up to optimize the brakes?
 

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Peter,
I will be interested to hear more details as well from my friend GTAFAN. I can tell you what I have observed, from checking it out, obviously as much as is possible without getting the car on a lift. The balancing of the brakes is definitely in the system. Details we can get from GTAFAN, although I suspect that the brake tech will be the one who knowns all the details.

The calipers are engineered for 365mm discs as per fitment to the Lamborghini. The discs & bells on the car were made up by AP Racing.

It's definitely NOT a bling system & I drove the car 65km on the main Attika highway at seriously high speeds.....no fade..fantastic balance.
I've had some serious brakes on my cars, especially the forced induction M3's. This has been the best system that I've experienced on the road ever.
Monstro
 

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Sorry Peter,
GTAFAN's car has Intrax adjustable coil overs which look I must say identical to the Autodelta Sport Corse adjustable coil overs fitted to my 147GTA.
These are adjustable but again he will have to tell us how it's set-up. The present set-up is definitely a good road track compromise. He has strut braces & then an interesting rear re-inforcement engineered for the rear.This was custom, done by the Greek techs who set the car up. It does work though.
Tyres at present fitted to the 8.5X18 BBS CH rims are Yokohama Parada 2's but his tried various brands from Pirelli's to Michellins. I don't think he gets much more than 10000km's from tyres, not at the speeds he is driving.
It's one of the first GTA's produced & he has had it for many years, it's covered 132000km but it's a very clean car, well maintained. When I first saw the car & I'm really fussy, it looked like a car that's covered around 35-40000km.It's that clean.
GTAFAN has had alot of experience with the GTA, over a long distance.His had a couple of suspension set-ups, tyres, wheels etc.Good feedback for other members in this regard.

Like us his an enthusiast, he has had his share of being robbed by some tuners & the like.
I just wish there were not such vast distances seperating us all as it would be great to get together with our cars. So I look forward to The Ring in 2008.
Regards,
Monstro
 

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Discussion Starter #12
Like my friend Monstro said there is no proportioning valve in the car .
Our ABS reads automatically the Difference and cuts out the rear system every time to keep balance.

But I should start from the beginning my brake story, because I have
done many changes that most of the people wouldn't imagine that could be done.

With the GTA I first started with sport pads and metal hoses, just to
give a better feeling. But that was not enough. The GTA is very heavy
front car and 240km is very easy to have. So I was looking for something Better.
Just about that time I met a very enthusiastic brake technician. I was crazy to see some photos from his work. That was
improving brakes on Ferrari's, Porsche's,evo's, sti's and a lot of racing stuff. So I asked If we can do something in to my car.
He explain to me that even the 330mm alfa upgrade was not so big improvement, because : The bigger caliper is not so big finally. Why?
is using the same piston diameter 38-42 as the small one. just have
a bigger body to be able to take the 330mm disk. The only improvement is the bigger pads, and the bigger disks that has 32mm space between instead of 28mm the old 305mm. BUT this gain is not
so big, because 330mm disks are heavier(10,5 kilos) and much heavier than 305mm(5,5 kilos). So the same size pistons have to stop a double weight disks.
So I had to find a lighter disks , and decided to go for 2 piece with aluminum bells. But said to me that he could place an even bigger
4piston caliper from a Ferrari Maranelo 575 !!! Is that possible? Yes.
And I got my first Ferrari braking system in my Alfa. These calipers
are from the biggest 4 piston. They use 38-46mm pistons with special ceramic hats. And are a bit lighter than Alfa's 330 calipers! We placed 2 piece disks 330mm with alu bells- 5,5 kilos each!
So that was an improvement !!!
Much more progressive, much more powerful and at the same time much more lighter than the OEM.

I have some photos from that to see before we speak more about braking...


 

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GTAFAN,
Even I'm suprised, never knew about the Ferrari set-up. You have done with brakes what I have done with big bore Alfa V6's it seems? Tried all sorts of set ups.
Monstro
 

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I do agree the 330mm is heavy. I still remember when I picked the parcel (2 calipers and discs). I almost dropped the box and it needs to be handled by 2 people.
 
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TB, he has big Brembos on the rear too :cool:
Sadly that doesnt even out the score..not even close..The 147/156 GTA is very nose heavy with centre of gravity far out front. While the longer wheelbase of the 156 is a destinct advantage, you are always fighting the physics during hard braking. In the end brakes dont stop the car, Tires do.. so you really need those rear tires in play if you want ultimate brake performance.

My own 3.2 is a good example of what happens when you got too beefy brakes. The original system can't cope with the bias ratio, too much is allocated to the front, physics act, and the rear goes light.....:rolleyes: So you are sometimes left with the limit of adhesion of basically two tires and not four..Brakes still bite like a Motherf....and everyone that rode Pax with me commented on them.. but it's mostly held together by the sticky tires, and brakw torque is still nothing compared to properly biased brakes on a properly track oriented car. Trailbrakers car is a good example..156 Challenge Race cars on stock 285mm system with Adjustable brake bias are another.. you can brake shorter and more precise. You really need to experience different 156's braking at maximum before you can compare Apples to Oranges.

In my case I am going three ways to solve the brake bias problem. First i must get a brake porporioning valve or perhaps adjustable brake bias system. Secondly will have to upgrade the coilovers to KW III or similar and get it cornerweighed..Making it possible to adjust the compression should hopefully weed out some of the issues. Thirdly I may have to see if it's at all possible to fit the GTA master brakecylinder to the system. From Eper it doesnt look promising..but anything is possible i guess..Just worried the ABS software will get even more confused, and hardly anyone knows how to access and revise ABS software.. All this is done to in an effort get the proper brake Bias. Proper brake bias and proper suspension balance means more Rubber has contact with the surface More rubber in contact with the surface means you can stop the car quicker.. In the end the tires are the single most important factor on a high performance car.

Unless the guys who fitted that impresive looking Lambo system did some drastic moves to optimize balance, not only of the brake bias, but balance of the whole car, then I am willing to bet the pink slip of my GTA that overall brake torque is drastically reduced compared to a well proportioned stock 330mm system like TB's.

In any case, knowing that the 330mm system easily outperforms the limit of adhesion for any street tire with just upgraded pads and brake lines, it all seems a bit pointless to me to sticking on those huge exotic brake caliper and discs.. It looks great, but apart from weight saving which is always great, and improved pedal feel, which is also great, it's pretty much Bling unless you really really went to town on the engineering and track testing side of things... Money is imo better spent on upgrading the stock system, fine tuning suspension/balance of the car, and practising your driving & braking technique on track.

If those 330mm Cabon discs didn't cost silly money, i'd say there was a significant overall performance gain waiting.... Especially if you add lightweight 17" wheels and high end Semi Slicks like Pirelli Corsa's..:cool:
 
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Just saw a lot of post was made since i started writing the above last one.. Am working right now to was sort of typing 10 min on 20 min off, and wasn't looking for new posts meanwhile..... looks like a lot of information was posted, so cheers for that.. I'll look it over later tonight when i have more time.:)
 
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Like my friend Monstro said there is no proportioning valve in the car .
Our ABS reads automatically the Difference and cuts out the rear system every time to keep balance.

He explain to me that even the 330mm alfa upgrade was not so big improvement, because : The bigger caliper is not so big finally. Why?
is using the same piston diameter 38-42 as the small one. just have
a bigger body to be able to take the 330mm disk. The only improvement is the bigger pads, and the bigger disks that has 32mm space between instead of 28mm the old 305mm. BUT this gain is not
so big, because 330mm disks are heavier(10,5 kilos) and much heavier than 305mm(5,5 kilos). So the same size pistons have to stop a double weight disks.
So I had to find a lighter disks , and decided to go for 2 piece with aluminum bells. But said to me that he could place an even bigger
4piston caliper from a Ferrari Maranelo 575 !!! Is that possible? Yes.
And I got my first Ferrari braking system in my Alfa. These calipers
are from the biggest 4 piston. They use 38-46mm pistons with special ceramic hats.

Just a quick note to give you something to respond to then..:)

There is a fundamental flaw in what your tech guy told you..

When a bigger front disc is installed there is a simultaneous need to decrease the effective clamping force of the caliper. Smaller pistons is the easiest method to match the increased torque created by larger rotor's effective radius

Exactly because of this, the 330mm calipers is a HUGE step forward compared to the 305. It also means that they are directly interchangeable for all GTA's..If the Pistons on the 330's was bigger, the ABS software and brake system hardware would not be compatible. This is the very reason i have Bias problems on my custom built 2.5.

**Edit*** The 305mm discs does not weigh 5.5kgs. btw! I'll get the weight later on this week. Have both 305's, 330's and 342's on the shelfs..
 

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Discussion Starter #18
Yes Peter your questions are very reasonable.
I started with the same questions my self. But for the last 3 years
I tried all the suggestions of my friend Master brake technician and
we came to some impressive results.

First of all if you dont use the GTA master brake cylinder you should
place it. It has more Psi pressure than from 2.5 V6 and even more
Psi than normal 156, 147. I think something like 24 if I remember.

Second to improve braking to our cars we have to understand our
Abs system.
We have (only the GTA's ) one of the best ABS system,
without many electronic bull**** like the most new cars.
The Abs controls the balance. And it works very well.
When you press the brake pedal the system send pressure to the rear calipers first. By the time the rear calipers comes just before to the
end, the ABS unit cut the rear Chanel (diagonal) and send all the pressure to the front calipers. That can be from 10%-20% rear to 80%-90% front. That depends on the surface, suspension, wheels and more.. So is not easy to take off ABS system and place a valve to make all that balance because for every braking is different number.

Peter is correct, to say that if you place a bigger or stronger brakes in front the car becomes lighter at the rear. That happens if you have small rear calipers. They have small limits. They have no Depth. From the time start pressing the disks to the time they are fully firm pressed there is no distance . Thats the reason the ABS cuts the rear so soon. And you feel all the weight of the car to come on your front side.
To bring back the balance we had to do some work on the rear side.
First a good adjustable suspension. I use corso-intrax and 60 kilos rear springs and give 20% stiffer the rear shocks than front.

And bigger rear calipers. I placed 4 piston Rear calipers from Porsche GT3 with 305 mm disks. That's another project. I don't have the time
to explain now. On another post.
 

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Interesting info GTAFan.

As far as I understand the EBD brake proportioning system on the GTA I don't think the ABS/EBD processing interferes much until wheel slippage occurs as detected by the wheelspeed sensors.

Until that point, as I understand it, the brake proportioning is essentially mechanically controlled by the physical characterisics of the parts involved (pad friction, disk, piston size etc) plus the default proportioning hardwired into the system (possibly changing for various speeds).
I think of this as the default brake bias, i.e. before active intervention.

My point is that until slippage occurs the default effective brake torque bias with a radically modified setup may be very different from optimal.
Okay wheels aren;t slipping but the actual balance of the car could be different than intended..

That of course isn't to say that a very experienced technician may be able to ensure that the overall mechanical brake bias is still sensible.

I can root out a very detailed excell spreadsheet which will calculate your brake bias for you if you input various measurements in it if you are interested.


I do agree though that a strong rear braking effort will eb controlled by the EBD / ABS once wheel slippage occurs, however excessive mechanical rear bias would, I think, cause the rear EBD/ABS channels to be working overtime and the tyres would be totally on the limit of adhesion making the car very nervous.

A very front biased car with huge front brakes would have hugely stable braking, but perhaps not turn-in on the brakes (i.e. trailbrake) as keenly as an optimally balanced one.

All this is quite tricky, since the more powerful the front brakes, the lighter the rear gets, and effectively the less braking you can actually do on the rear anyway.
As David_C pointed out on here the rear brakes on WTCC Alfas are teeny weeny, any more braking effort to the rear and they would just spin out (they have so little weight in the back anyway).

Even though the 330mm can outbrake road tyres easily enough on slow speed tracks, I have to say that on type-R tyres from very high speeds you certainly would get good value out of huge brakes.
The Ring is certainly one such place, Donnington park another.

Cheers,
TB
 
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Don't forget TB, that the more G's you brake with, the more weight you shift forward..R-tires will amplify any bias problems and confuse the ABS system even more..

On some sections on the ring where surface yeilds more grip, my car gets incredibly light at the rear.. If you know the corner weight and front/rear axle weight, then it's simple to calculate how much weight shifts by using braking g force as a variable..I've dont that loosly.. Where it get's complicated if when you try to put it into real life compensating for off camber or inclines.

The best example i have on the blue pill is Eschbach just before Brünchen. It's truly hairy.. exiting Wipperman you are going through a high G right hander up hill, setting up for the off camber down hill left hander.... Braking for the left hander which is both off camber and down hill.. I think the rear wheels are almost in the air! the least amount of steering lock sends the car fish tailing.

Not that it is of relevance to 156 GTA, but how would VDC react to altered brake bias?

Did WTCC racers have adjustable brake bias?

@TB as you felt of the safety course, the ABS was completely gone on my car.. What will be interesting is to see if the ABS "Returns" once the season is over, and i change back to stock pads, stock discs and street tires..In fact i might even put on the old 305 mm system i have as a spare.. I did some parts comparrison on Eper and was surprised just how different the brake systems are between 156 models 1997-2001 and models 2002 onwards (GTA included) If I am not mistaken, then there is probably a difference in the Mechanical Pedal Ratio, which combined with altered caliper pistion size and numbers is what is messing things up..Add R-tires and agressive pads/discs/brakelines to the mix, and you get seriously muddied waters.
 
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