Big Brakes - Who's done 'em.

[moridin2004]

Personally, I'm not a fan of any of the Wilwood calipers short of the newest ones. Reason being is the lack of dust seals for a street vehicle. Only now are they starting to do this.

For those who are doing the custom Wilwood setups, aren't you worried about ABS functionallity with the new calipers? ABS computers are designed with the stock clamping forces and can effectively lengthen stopping distances if the ABS comes on with the bigger brakes. I know the Cobra R's and the Stoptechs are designed to work within the constraints of the factory ABS, but what aobut the Wilwoods, Baer 6 piston (Alcon or AP Racing if I recall), etc...?

 

[ShelbyGuy]

dust seals are way overrated.

my car sees chicago winters without dust boots.

only issue i ever had with dust boots was corner workers complaining i was having brake fires as i was burning them off.

the abs servo is a non-issue. you get equal pressure on both ends in a closed hydraulic system. the pistons merely spread it out over a greater area.

 

[moridin2004]

dust seals are way overrated.

my car sees chicago winters without dust boots.

only issue i ever had with dust boots was corner workers complaining i was having brake fires as i was burning them off.

the abs servo is a non-issue. you get equal pressure on both ends in a closed hydraulic system. the pistons merely spread it out over a greater area.

I've had my Wilwoods on my Honda freeze up in California. Maybe its a matter of leaving a car sit, as my Honda was sitting for quite some time before I tried to use the calipers again.

I'm not worried about the pressures and how its divided up mechanically, but rather how the ABS computer reacts to the different calipers and supposed higher braking torque from them. The computer has an accepted deceleration rate under braking. Excede that and the ABS computer steps seeing a lock up. You are no longer using the maximum braking force of the brakes or tires. I'm not even taking into account that the system is probably far more complex and has different ramp up/down rates that it operates under. Go outside of the deceleration rates understood by the computer and your brakes are no longer nearly as effective.

 

[ShelbyGuy]

the brake torque isnt generated by the caliper but by the rotor. the caliper only sees hydraulic pressure and heat from the friction of pinching the brake pads against the rotor.

not sure what you mean by the computer having an accepted deceleration rate under braking. thats not how abs works. it merely reads the hall effect from the sensors (square wave magnetic) and if it notices a wheel thats stuck it releases pressure to that caliper.

remember, this is a 30 year old platform. nothing on it is very complicated.

 

[aaronl]

I don't have ABS, I have a Fox with an '03 Cobra IRS.

 

[moridin2004]

the brake torque isnt generated by the caliper but by the rotor. the caliper only sees hydraulic pressure and heat from the friction of pinching the brake pads against the rotor.

not sure what you mean by the computer having an accepted deceleration rate under braking. thats not how abs works. it merely reads the hall effect from the sensors (square wave magnetic) and if it notices a wheel thats stuck it releases pressure to that caliper.

remember, this is a 30 year old platform. nothing on it is very complicated.

Sorry, got a bit mixed up on the brake torque.

How often does the hall effect sensor take a reading...everytime one of protruding pieces of metal passes it, right? Or you could say the opposite of the detents...Anyway, the point is that the sensor does not know its exact position, correct? All it knows if it sees a signal or not based on the ABS ring. The computer than converts that to the speed of the individual wheel based on tire diameter. There is an acceptable deceleration rate that is programmed by some engineer. The wheel may stop turning at lockup, but its not going to be instaneous, and the whole point of a very effective ABS system is to keep that tire on the verge of lockup without actually starting. The computer senses what would be an out of range deceleration rate by seeing the abrubt change in wheel speed and releases pressure. Works as planned, right? Unfortunately modern ABS is not so simple. I would try to interpret more, but I'll just post this link:

http://www.stoptech.com/tech_info/wp_abs_bigbrakekits.shtml

 

[ShelbyGuy]

but again, its simpler than that. its merely comparing it to the other wheels.

the whole point of a very effective abs system? this is a mustang not a mercedes. everything on the car is RUDIMENTARY. there's NOTHING complicated on this 30 year old platform.

stop tech is trying to sell you something. i am not.

i pull the abs fuse when im on the track anyway. like most abs systems, it increases your stopping distance. abs is just an idiot proofer. its not a performance enhancer.

the abs servo is also a non-issue because you arent changing the master cylinder. its moving the same amount of fluid at the same pressure. i dont know why you're so hung up on the abs servo. all it does is modulate.

 

[LargeOrangeFont]

Sorry, got a bit mixed up on the brake torque.

How often does the hall effect sensor take a reading...everytime one of protruding pieces of metal passes it, right? Or you could say the opposite of the detents...Anyway, the point is that the sensor does not know its exact position, correct? All it knows if it sees a signal or not based on the ABS ring. The computer than converts that to the speed of the individual wheel based on tire diameter. There is an acceptable deceleration rate that is programmed by some engineer. The wheel may stop turning at lockup, but its not going to be instaneous, and the whole point of a very effective ABS system is to keep that tire on the verge of lockup without actually starting. The computer senses what would be an out of range deceleration rate by seeing the abrubt change in wheel speed and releases pressure. Works as planned, right? Unfortunately modern ABS is not so simple. I would try to interpret more, but I'll just post this link:

http://www.stoptech.com/tech_info/wp_abs_bigbrakekits.shtml

When I do a really hard stop on the street, my tires chirp, then abs kicks in. This tells me that this is a passive ABS system. I have Cobra R calipers and Kumho MX tires. The stopping power is much greater than the stock setup. While I understand your point, I dont think the Mustang ABS system is that complicated. It sees lock and says OH SHIT!!! I must unlock that wheel!! It only releases force at a predertermined rate. Anything you can do to improve grip (better tires) will raise your lock point and you will gain better performance.

 

[LargeOrangeFont]

the whole point of a very effective abs system? this is a mustang not a mercedes. everything on the car is RUDIMENTARY. there's NOTHING complicated on this 30 year old platform.

Agreed.

Unfortunately, this is all you are really driving.

 

[Todd03Blown]

awesome thread!!! Great information!!

 

[moridin2004]

but again, its simpler than that. its merely comparing it to the other wheels.

the whole point of a very effective abs system? this is a mustang not a mercedes. everything on the car is RUDIMENTARY. there's NOTHING complicated on this 30 year old platform.

stop tech is trying to sell you something. i am not.

i pull the abs fuse when im on the track anyway. like most abs systems, it increases your stopping distance. abs is just an idihttp://www.svtperformance.com/forums/svt-black_images/editor/createlink.gif
Insert Linkot proofer. its not a performance enhancer.

the abs servo is also a non-issue because you arent changing the master cylinder. its moving the same amount of fluid at the same pressure. i dont know why you're so hung up on the abs servo. all it does is modulate.

I agree that the platform is very old and not very complicated. Fortunately, thats not the truth with the ABS unit. Its a Bosch 5.3 unit that's also used in various other cars, such as the 99-01 Saab 9-3, 99-03 Saab 9-5, 98 Saab 900, 96-01 Audi A4 and A6, and of course, the 03/04 Cobra. I just found this link about the unit:
http://www.babcox.com/editorial/bf/bf20136.htm

What was said on Stoptech's site has been reiterated elsewhere too. Not all of it, but the general workings: http://auto.howstuffworks.com/anti-lock-brake.htm

From what I understand it has the ability to change pressure too. That would be extrememly important to know if its expecting a result when it does something and it doesn't happen.

Also, ABS does not increase stopping distances in most situations. It actually reduces them. Why has it been outlawed in a lot of different motorsports arenas? I know that the PTG M3's in the GT2 category of the ALMS are allowed to use ABS as a performance enhancer to level the playing field with the Porsches, Panoz', and Ferraris. It seems to be working too. Now, I know the unit in the Cobra isn't the same as those in the BMWs, but in a straight line, I would venture to say that stopping distances are greatly reduced with it on. If I had the right equipment, and space, I would go do some 60-0 stops with the ABS on and off to compare.

Typical ABS programming can cause some funky things to happen when trail braking and on split mu surfaces. So, your lap times may drop because of more corner speed (with the ABS off), but your effective braking in a straight line is less.

I'm hung up on this ABS thing, because I know its not as simple as it seems. There are far more variables involved when a computer comes into the mix that can't be changed to account for new components. When changing braking systems on the newer ABS cars, one must be careful about more than simply getting mounted up properly, which is not quite the sentiment of what's being said in this thread.

EDIT: FIA GT championship car Maserati MC12 uses a Bosch 5.3 ABS unit and Porsche 996 Carrera 4

 

[ShelbyGuy]

oh ok you're one of those. when you're done reading web sites and magazines and marketing drivel, go to the racetrack and talk to people actually running cars on the track.

abs in the dry increases your stopping distance. abs in the wet decreases it. this has been covered ad nauseum in other places. google is your friend.

 

[moridin2004]

oh ok you're one of those. when you're done reading web sites and magazines and marketing drivel, go to the racetrack and talk to people actually running cars on the track.

abs in the dry increases your stopping distance. abs in the wet decreases it. this has been covered ad nauseum in other places. google is your friend.

I just crewed another race for a GT2 ALMS team...so I do talk to the people at the track. Miller Motorsports Park is quite nice. Too bad I couldn't go to Portland. I'm supposed to work the Road America race and Mosport, as long as school doesn't interfere.

I post links, because what I'm supposed to do...say I said so.

I can post pics if you need me prove it.

I'm not in here to start a pissing match though. Just to learn and provide a bit of tech were I think I have the knowledge.

 

[ShelbyGuy]

point taken.

but again i say, since you havent changed the volume or pressure of the fluid through the abs servo, there arent any problems adding any of the available calipers.

maybe when one of us finds a problem with the abs we'll post about it. the only one who may have come close is cheyne.

http://www.daggettracing.com/graphics/photos/2005/cleveland/index.html


99% of the people with an upgrade are running something off-the-shelf. pulling numbers out of my butt, i'd say that 90% run the 00R kit, 8% run the wilwood kit, and the rest run stop tech and the rest. I havent learned about yet.

those companies have done the homework in order to keep the volume of fluid needed from the master cylinder and the pressure required from the brake pedal within the range of normal oem master cylinders. even if you peruse the racing catalogs, you're still only going to find two or three different sized master cylinder pistons. piston travel is dependant upon pedal ratio, which is basically how close to the pivot point you have the master cylinder pushrod on the brake pedal.

is there something special that you want to do that would cause some sort of abs problem?

 

[jking32]

I picked up a set of Roush Alcon 4 piston, B type calipers and stainless steel lines off of ebay. I got them cheap because at the time no one knew what they were from. I sent pictures to Roushperf and they said they were obviously made for Roush but were not the same as the production models used on the stage 3 mustangs. I finally called Alcon USA and talked to a very helpful gentleman who looked at the pictures and told me they were one of the original 10 prototype models built for Roush when they were trying to make the deal. The only difference was the size of the name Roush machined into the side, which apparently Roush want the logo to be smaller. Anyway, they did not come with brackets. Roush wanted over $500 for a set of brackets not to mention the rotors. Baer was just as bad. I finally took the spindles and stock 13" cobra rotors and designed a bracket out of wood until they fit perfectly. I then took the entire setup to a race shop in KC who machined me two brackets for just under $300. All total with pads and bolts I spent $750. They work great.

 

[moridin2004]

point taken.

but again i say, since you havent changed the volume or pressure of the fluid through the abs servo, there arent any problems adding any of the available calipers.

maybe when one of us finds a problem with the abs we'll post about it. the only one who may have come close is cheyne.

http://www.daggettracing.com/graphics/photos/2005/cleveland/index.html


99% of the people with an upgrade are running something off-the-shelf. pulling numbers out of my butt, i'd say that 90% run the 00R kit, 8% run the wilwood kit, and the rest run stop tech and the rest. I havent learned about yet.

those companies have done the homework in order to keep the volume of fluid needed from the master cylinder and the pressure required from the brake pedal within the range of normal oem master cylinders. even if you peruse the racing catalogs, you're still only going to find two or three different sized master cylinder pistons. piston travel is dependant upon pedal ratio, which is basically how close to the pivot point you have the master cylinder pushrod on the brake pedal.

is there something special that you want to do that would cause some sort of abs problem?

If I had the money...6 piston AP's up front and 4 pistons out back with other corresponding upgrades to actually use them. Those would require a dual master cylinder setup. Wouldn't mind the new Tilton or AP pedal box and a hydraulic TOB too. Those are pipe dreams, and I'd probably just buy an actual track car if I could do that.

I was just trying to provide a bit of warning to those thinking about custom setups that aren't sized properly. It will mess with more than your pedal feel (assuming you keep the stock MC and pedal ratio), meaning the ABS. You may not even notice the reduced stopping distances, because you're enjoying the infinitely better pedal feel than the stock setup. Then again, those that do generally don't use the ABS anyway. I just wish there was some way to get a hold of the Bosch programming to customize the unit. I also found out that the Bosch unit can adjust bias too, which means you may not even need the dual MC if you could work something out. That may be more difficult than its worth. I know Lotus programmed their ABS system with performance/track in mind now with many sportscar racing groups (when allowed).

 

[ShelbyGuy]

im coming to the conclusion that ford used the abs servo they did becuase it was already on the shelf. it apparently does lots more than the computer driving it can do. eecV is still pretty primitive.

if you dont mind losing the hydro-boost, then a dual master cylinder isnt that hard. im working on something like this in another thread in this subforum.

 

[moridin2004]

I think I asked what model MC it was. Are you changing the pedal ratio to reduce pedal effort?

 

[ShelbyGuy]

yeah it would require drilling the brake pedal arm to move the pushrod closer to the pivot point of the pedal. on the early models we just get a manual brake car brake pedal


the brembo kits, the wilwood kits, and the alcon kit all ASSume the stock rear caliper is retained. dont underestimate that little varga single piston. its vvery good at what we ask it to do.

the brembo kit uses the factory rotor, but has more piston area than the lame stock pbr two pot, so it feels like a brick.

the wilwood kit uses greater piston area, but a slightly smaller diameter rotor to keep the brake bias within reason.

i have no experience, nor have i seen anyone running, the alcon kit for grand-am cup cars.

ive found some people who are well-versed in the abs strategy on these cars. they're already onto the differences on the s197 chassis. i guess the shelby gets a completely different abs servo with a different strategy, but when you pull the fuse is defaults to the v6 parameters....:/

any help you can give me forming intelligent questions to ask them is appreciated

 

[moridin2004]

yeah it would require drilling the brake pedal arm to move the pushrod closer to the pivot point of the pedal. on the early models we just get a manual brake car brake pedal


the brembo kits, the wilwood kits, and the alcon kit all ASSume the stock rear caliper is retained. dont underestimate that little varga single piston. its vvery good at what we ask it to do.

the brembo kit uses the factory rotor, but has more piston area than the lame stock pbr two pot, so it feels like a brick.

the wilwood kit uses greater piston area, but a slightly smaller diameter rotor to keep the brake bias within reason.

i have no experience, nor have i seen anyone running, the alcon kit for grand-am cup cars.

ive found some people who are well-versed in the abs strategy on these cars. they're already onto the differences on the s197 chassis. i guess the shelby gets a completely different abs servo with a different strategy, but when you pull the fuse is defaults to the v6 parameters....:/

any help you can give me forming intelligent questions to ask them is appreciated

You are much better at finding people to talk to than I am. Hmmm...questions. I'm going to have to think about that a bit.

I guess the big ones are the deceleration rate that throws up the flag (1.5g's, 2.0g's, etc...) for the ABS to get ready and how much for it to activate. Can the unit be reprogrammed? Is it available to be reprogrammed? How much can bias be changed around in the unit itself? What would one have to do to get the unit reprogrammed and what kind of info would be needed to do it (in terms of how and what parameters need to be set).

What about pressure? Won't different combos provide different braking torque (less pad area, more aggressive pad, etc...)? If the unit has the ability to regulate pressure to each caliper, I guess you would need to know/calculate it to reprogram the unit itself. Would any of the people that you know, know how to figure out those things in such a way as to be interpretted by the ABS computer? I guess I should get out my physics book and start calculating.

I'm sure more things will come to my head soon. I wonder if Roush, Saleen, or Steeda had the ABS reprogrammed for their brake stuff. Does the Cobra R have ABS and if so, is the strategy different than the 03/04 Cobra.