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post #1 of 24 Old 08-10-2009, 09:11 PM Thread Starter
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Ford ABS and Traction Control - How effective for performance - AutoX/OT

I am curious as to how the Ford TC system actually works. I've seen various things on the internet that say it cuts fuel, cuts spark, applies brakes. It could be a combination of all these but I'm not sure and I've never seen anything definite. I'm ready where people attributed a blown motor to a reduction of fuel causing a lean burn (mentioned in one of the Sean Hyland Books) triggered by TC.This was in a FI application as well, so I've thought that if it was actually true it could have been caused by the computer removing what it thought was enough full to prevent any type of detonation but since it was an custom tune, the computer couldn't compensate. Of course, I've also thought that it might just be flat wrong.

Also, how good is the stock ABS? I've heard people, mostly in autocross, comment how good an ABS system is but I don't know what makes a ABS good or not.

It would be nice if it were possible to reprogram the stock TC but I don't believe that has been explored and probably isn't worth it for what would be a very niche audience. As an alternative, a race logic system would be the shiznit. The expense is high, but wouldn't it be possible to move the unit from one car to another if one were sold etc. Also, worth noting is that the race logic system also offers flat shift, two step capability, and custom adjustment, I think. Any thoughts? I'm just a little curious because I'm dealing with the ABS system now trying to run down a worn sensor.


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post #2 of 24 Old 08-11-2009, 07:53 AM
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FWIW the only thing I've ever heard is that it applies brakes. Think about it. If it detects that a particular wheel is slipping, how is cutting fuel or spark gonna help it "tune" that one wheel?

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post #3 of 24 Old 08-11-2009, 10:58 AM Thread Starter
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I believe the system differs between pre 05 and 05+.

I'm sure that it cuts spark in some manner, I've smelt the unburnt fuel with TC kicks in after charging hard into a corner. I've also felt the hesistation caused by the lack of combustion.

It ma also appl the brakes. FWIW, I've head the brakes are only applied under a certain speed which seems to make sense. I'm not sure the system trying to correct a high speed loss of traction would work well with driver inputs.

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post #4 of 24 Old 08-11-2009, 11:20 AM
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The systems do differ from pre and post '05. '05 was the introduction of drive by wire, thereby they can control the throttle plate to cut back on air along with fuel. Pre '05 the car had a throttle cable and the computer was unable to control the throttle (no they didn't use the speed control servo for that). There's essentially three types of traction/abs control. ABS, TC, and Stability Control.

ABS, obviously stops the wheels from locking up, simply removing hydraulic pressure from a wheel determined to have locked through wheel speed sensors.

TC, cuts power and applies the rear brakes. Apparently the timing is retarded to reduce engine torque and the ABS pump is activated to apply the rear brakes.

Stability Control combines both TC and ABS. It has an active brake booster that can be charged and activated to apply brakes to individual wheels under the right conditions. They also have two accellerometers, a gyroscope, and a steering wheel angle sensor to determine the forces acting on the vehicle and what the driver is doing. Additionally, the system will cut power to aid in slowing the vehicle to get it back under control.

When someone talks about good and bad ABS, maybe they mean the difference between standard ABS and Stability Control, or maybe they're talking about the level of sensitivity, these systems are calibrated by engineers and each one will have different feel and activation points, I imagine under the car's limits those small differences can be felt where they weren't under normal driving conditions.

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post #5 of 24 Old 08-12-2009, 02:50 PM Thread Starter
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Based on what you said the pre 05 systems do not apply the brakes. They may cut fuel or spark or both. I know for a fact that I've smelt lots of unburnt fuel when the TC activates so I would take a wild guess that either the fuel cut is not 100% or that the spark is also cut.

I've heard that the Cobra TC adds a additional variable over the GT TC. Not sure if that is yaw or what.

Does anyone with working TC actually use it in spirited driving such as autox or lapping days, etc. When mine was working I found it very intrusive on tight autox courses.

Of course it rains down here more than in Seattle, so having TC is a nice thing on the street and possblly even on rainy autox days. Now I am just trying to decide if it is worth fixing since my ABS module is not working.

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post #6 of 24 Old 08-12-2009, 04:28 PM
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I'm going to edit my earlier statement, they don't cut fuel or spark on the pre-05s, they retard timing to limit engine torque. They also do run the ABS pump to actuate the rear brakes. Sorry for the confusion.

I've driven my car with no ABS on track and I'd definately pay the price of an ABS module to get ABS back, I've locked up several times and ruined two right front tires.
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post #7 of 24 Old 08-13-2009, 12:38 PM
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My ABS module went bad last year and I flatspotted both front tires doing time trials. I finally got used to threshold braking somewhat but probably left about 1 second on the table without ABS. I opted to pay to replace the ABS module.

Some people say that if you can threshold brake properly, then its better than ABS. But unless you can apply braking to all 4 wheels independently to increase braking to those tires with traction, then I dont buy it.

FWIW Ford Racing makes an ABS module for racing. I think it is for the FR500 cars. I got the impression that it has a revised algorithm to account for the increased traction of race tires.

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post #8 of 24 Old 08-13-2009, 01:20 PM
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If your ABS is broken, get it fixed. My car does not have it and I wish that it did. I have flat spotted many a tire, and it gets expensive quick. I have had to resort to tweaking the suspension and using different brake pads to minimize the problem. Save yourself the hassle if you can.

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post #9 of 24 Old 08-14-2009, 08:20 AM
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Learning to threshold brake is good if you don't have ABS, but your brain ain't faster than an ABS module. Well, maybe it's faster than the one in a Chevy Cavalier.
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post #10 of 24 Old 08-14-2009, 10:26 AM
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To the point of what makes a "good" ABS or "bad" ABS is how much slip it allows, and under what conditions. I've driven far too many cars lately that get into "ice" mode way too often. That's when the ABS assumes you're on ice or very low traction surface thanks to very fast wheel deceleration and just ####in' won't give you brakes no matter how hard you press the pedal. Lotus Elise drivers have complained of this on the track, and I just recently had a pucker moment in a rental Altima. I was braking moderately hard, no where near lockup, but I was on some washboard pavement that I guess caused momentary wheel deceleration that told the ABS computer I was on ice, and my stopping distance was easily 10 feet longer than if it would have let me have the brakes or simply not had ABS at all. My old Contour used to do the same thing. It's maddening, and IMHO, flat-out dangerous.

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post #11 of 24 Old 08-14-2009, 11:17 AM
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To the point of what makes a "good" ABS or "bad" ABS is how much slip it allows, and under what conditions. I've driven far too many cars lately that get into "ice" mode way too often. That's when the ABS assumes you're on ice or very low traction surface thanks to very fast wheel deceleration and just ####in' won't give you brakes no matter how hard you press the pedal. Lotus Elise drivers have complained of this on the track, and I just recently had a pucker moment in a rental Altima. I was braking moderately hard, no where near lockup, but I was on some washboard pavement that I guess caused momentary wheel deceleration that told the ABS computer I was on ice, and my stopping distance was easily 10 feet longer than if it would have let me have the brakes or simply not had ABS at all. My old Contour used to do the same thing. It's maddening, and IMHO, flat-out dangerous.
Alot of '98-'02 F-body owners complain of the "ice" mode, one guy I run with says he lost all brakes and ended up crashing his car while on track in his Camaro. He is positive this caused it. I haven't heard any Mustang guys complain though.
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post #12 of 24 Old 08-14-2009, 11:21 AM
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What makes the car go into ICE mode is when one wheel is unloaded to the point that the wheel is stopping much faster than the others. The most common occurrence of this happening on track is a wheel is being lifted off the ground when the brakes are applied. I have autocrossed and been on track with cars with ABS, and I only had it happen to me once. It was on an autocross exiting a hard fast sweeper that quickly ended in a hard braking zone. The front inside tire must have been just slightly off the ground as I applied brakes and the car kept on coasting.

The Elise will experience it more than most cars because it is mid engine and the weight is towards the back. Cars like the Elise, 911, and MR2 are notorious for picking up the inside front wheel. Under the right conditions, they will easily see ICE mode. The problem is less likely to happen on track since transitions are a bit slower than autocross, and the driver should always be aware of their technique so that they are not unloading any tire right before braking. If it does happen just pump your brakes one more time and the brakes will work.
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post #13 of 24 Old 08-14-2009, 11:54 AM
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Originally Posted by MJ91GT View Post
I've driven my car with no ABS on track and I'd definately pay the price of an ABS module to get ABS back, I've locked up several times and ruined two right front tires.
Slight tangent here...

I do NOT like ABS on track cars. They're an unecessary crutch, and a poorly-tuned system (like found in many inexpensive cars,) can actually INCREASE your stopping distance since they activate LONG before lock-up.

A good driver should be able to beat almost any ABS-equipped car using good threshold braking technique. By relying on ABS to keep the fronts from locking up on the track, the driver never really gets to practice threshold braking and if/when the ABS fails, he's out in the weeds.

Plus, the ABS system adds weight and complexity.

Keep in mind, I'm talking about TRACK cars here. ABS is a Good Thing on the street (and on ice, snow, etc...)

For beginning drivers, ABS can also prevent a flat-spotted tire, which is also a Good Thing, but at some point the training wheels have to come off and you've got to learn how to threshold brake.

My feelings are similar for traction control. On the street and for beginning drivers, it's very nice to have. (It saved my ass open-tracking a Touareg -- I got a little over ambitious and slid 3 wheels off in an 80mph sweeper,) but at some point it just gets in the way, especially if it cuts the throttle to modulate torque (Are you listening Mercedes? Your TC SUCKS!)

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post #14 of 24 Old 08-14-2009, 11:57 AM
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Some people say that if you can threshold brake properly, then its better than ABS. But unless you can apply braking to all 4 wheels independently to increase braking to those tires with traction, then I dont buy it.
Keep in mind, you don't need to control all 4 wheels, just the fronts, unless you'r brake balance is too far rearward.

The Porsche Club I used to open track with used to have threshold braking exercises, that I loved. I regularly out-braked 911's with ABS, even with my punny 10.8" brakes.

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post #15 of 24 Old 08-14-2009, 01:25 PM
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Slight tangent here...

I do NOT like ABS on track cars. They're an unecessary crutch, and a poorly-tuned system (like found in many inexpensive cars,) can actually INCREASE your stopping distance since they activate LONG before lock-up.

A good driver should be able to beat almost any ABS-equipped car using good threshold braking technique. By relying on ABS to keep the fronts from locking up on the track, the driver never really gets to practice threshold braking and if/when the ABS fails, he's out in the weeds.

Plus, the ABS system adds weight and complexity.

Keep in mind, I'm talking about TRACK cars here. ABS is a Good Thing on the street (and on ice, snow, etc...)

For beginning drivers, ABS can also prevent a flat-spotted tire, which is also a Good Thing, but at some point the training wheels have to come off and you've got to learn how to threshold brake.
The problem is that some modern cars need ABS because it is an integral piece to their braking system. The example I can think of is the Corvette. GM has designed their cars around the ABS module and is a key piece to controlling brake proportioning. The factory brake system needs the ABS and will not work properly without it. The system is so over boosted that it is hard to modulate the brakes. Corvettes that lose ABS are practically guaranteed to flat spot their tires.

The Corvettes that race in ST1, ST2, T1, etc, are all using ABS because they can't disable it. They would need to completely re-engineer their brake system to run without ABS. And honestly the rewards wouldn't be that great because I can't think of too many cars that can out stop a Corvette. But in all honesty, racing isn't just about speed. Consistency is as important if not more so.

In a Mustang, ABS isn't necessary. But if you are threshold braking, it shouldn't be kicking in anyhow. But if you exceed that threshold, then the system will at least save your tires some wear and tear. And if you are running in the rain, I would bet the ABS will be worth its weight then.

An interesting bit of observation I have seen over time is the braking distance of the Viper. The cars were initially released with out any nannies like ABS. In all the media tests that were performed, they could never get the car to stop like some of the other cars with ABS. As soon as the Viper was introduced with ABS, their stopping distances were finally comparable to other cars in their performance bracket.
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post #16 of 24 Old 08-14-2009, 01:38 PM
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I've noticed on the street the mustang will go into "ice mode" when trying to turn going downhill. I'm not sure what causes it, but just the lightest touch on the brakes causes abs to kick on. I noticed this most when trying to leave my old apt complex where I had to go one way across the parking lot then there was a short hill down followed by a left turn onto the road. When I would turn the wheels on that short hill, the brakes would quit working.

Also, those times I was going under 20mph.

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post #17 of 24 Old 08-14-2009, 02:00 PM
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The problem is that some modern cars need ABS because it is an integral piece to their braking system. The example I can think of is the Corvette. GM has designed their cars around the ABS module and is a key piece to controlling brake proportioning.
Technically correct, but you make it sound moreessential than it is. If you want to remove ABS, it's no harder than removing the compon3ents, re-plumbing the hard lines , installing a proportioning valve and PERHAPS adjusting the pad compounds front-to-rear to geta F/R bias split that you like. You end up doing that on any race car any way.

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The factory brake system needs the ABS and will not work properly without it. The system is so over boosted that it is hard to modulate the brakes. Corvettes that lose ABS are practically guaranteed to flat spot their tires.
I've driven C5 and Corvettes with disabled ABS. It wasn't difficult at all to threshold brake.


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I can't think of too many cars that can out stop a Corvette. But in all honesty, racing isn't just about speed. Consistency is as important if not more so.
Do you race, or run open track? The vast majority of passes are made under braking. You HAVE to get the maximum out of your brake system under those circumstances to out-brake the other guy.

You can lap within 0.001 seconds of your best lap time, but if you can't out-brake the guy in front of you, you'll have a much harder time passing him.


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In a Mustang, ABS isn't necessary. But if you are threshold braking, it shouldn't be kicking in anyhow.
Depends on the tuning of the system. Most ABS systems (including the Bosch units, which are considered some of the best in the industry,) are pretty conservatively tuned, probably for liability reasons. Threshold braking often will be defeated by an over-egar ABS system kicking in before the tires really have locked up.

It you're threshold braking and not kicking in ABS, then you're being too conservative, or your ABS setup is DAMNED good (which I doubt.)

Quote:
But if you exceed that threshold, then the system will at least save your tires some wear and tear. And if you are running in the rain, I would bet the ABS will be worth its weight then.
It is nice in the rain, but not as critical, since speeds are so much reduced. Threshold braking in the rain isn't all that hard, so the need for ABS is reduced, plus the fact that it's almost impossible to flat-spot a tire on a wet track.


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An interesting bit of observation I have seen over time is the braking distance of the Viper. The cars were initially released with out any nannies like ABS. In all the media tests that were performed, they could never get the car to stop like some of the other cars with ABS. As soon as the Viper was introduced with ABS, their stopping distances were finally comparable to other cars in their performance bracket.
MEDIA tests? Please. Early Vipers had a whole raft of tuning problems in the suspension and the brakes, which most media writers either didn't know about, understand, or write about for fear of confusing their readers.

I'm going on personal observations I've made in a variety of cars on the track as an instructor. Generally speaking, I can threshold brake better than most ABS modeules will let me. Cheap GM and Volkswagen systems seem to be the worst. The Corvette's ABS is pretty decent. The Porsche ABS is tuned very, very well, but they all interfere when turned on.

ABS encourages bad habits and rewards a lack of control and finesse at the brake pedal. Simply stand on the pedal and let ABS to the controlling.

No thanks.

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post #18 of 24 Old 08-14-2009, 05:01 PM
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I just want to start by saying I am not trying to start an argument, and I respect your thoughts. Things typically get a bit out of hand when one's post is broken down like above. We are both sharing facts, but also liberal doses of opinions.

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Technically correct, but you make it sound moreessential than it is. If you want to remove ABS, it's no harder than removing the compon3ents, re-plumbing the hard lines , installing a proportioning valve and PERHAPS adjusting the pad compounds front-to-rear to geta F/R bias split that you like. You end up doing that on any race car any way.
I don't think it's essential, but I think even you are admitting there are ABS systems that perform extremely well. I don't think it is necessary, but I wouldn't mind using a well engineered ABS solution. The key to any brake system is making sure it can be easily modulated so that you aren't easily locking tires up.

The above work is just part of a lot that needs to be done to rework the brakes. I don't know many Corvette guys that would go through that amount of work for their cars. But I agree with enough work and track testing it can be tuned with good results. But the question is, is the amount of work worth the return (for their already well engineered ABS system)?

My GT has no ABS, and my car has always had a problem with locking the front passenger tire. It seems to be a common issue with Mustangs. I discovered that the driver side of the car is considerably heavier than the passenger side without the driver. It is not perfect, but I have been able to get it more under control playing with my corner weights. Threshold braking is actually very easy to perform, but any inherent problems in the suspension will still cause lockups. ABS would have saved me on the several tires I flatspotted or ruined because of this chassis deficiency.

Quote:
I've driven C5 and Corvettes with disabled ABS. It wasn't difficult at all to threshold brake.
The F/R bias though is not being adjusted through the ABS. Performance should have suffered since the front brakes will have much more bias. My Z06's brakes are very boosted and slows down very quickly with light application. If the ABS were to fail, I know I would have to be really sensitive with application. I know other owners (and good drivers at that) with ABS issues had problems with locking up their tires.

Quote:
Do you race, or run open track? The vast majority of passes are made under braking. You HAVE to get the maximum out of your brake system under those circumstances to out-brake the other guy.

You can lap within 0.001 seconds of your best lap time, but if you can't out-brake the guy in front of you, you'll have a much harder time passing him.
I agree here. But you are talking about modified race setups. Tires, suspension, brake pads, and balls (the bigger the better) are also a part of how quickly a car comes to a stop. I was just saying that an ABS system has the capacity of being more consistent, and can clean up one's mistakes. I have no experience with the Mustang ABS, but I wouldn't doubt that you or anyone could out perfom it. No ABS obviously takes more skill, but with the progression of technology in the car industry, it is becoming hard to ignore the benefits of all the system being engineered.


Quote:

ABS encourages bad habits and rewards a lack of control and finesse at the brake pedal. Simply stand on the pedal and let ABS to the controlling.

No thanks.
Technology is moving quick. I think eventually ABS will be necessary in racing to even keep up.
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post #19 of 24 Old 08-14-2009, 05:46 PM
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I don't think it's essential, but I think even you are admitting there are ABS systems that perform extremely well.
Correct. There are some VERY good ABS systems out there that delay actuation until very close to lockup. There also some drivers out ther that are very good at trailbraking. In many (most?) cases, the driver can get closer to lockup than an ABS system can. I can in most of the cars I've driven.

That's not a knock against ALL ABS systems, though. Some are merely tuned worse than others.

Quote:
The above work is just part of a lot that needs to be done to rework the brakes. I don't know many Corvette guys that would go through that amount of work for their cars. But I agree with enough work and track testing it can be tuned with good results. But the question is, is the amount of work worth the return (for their already well engineered ABS system)?
Well, keep in mind that I'm talking about a purpose-built race car, not a street car used for open-tracking. In a purpose-built race car, you're unlikely to keep the OEM brake system totally unmolested anyway.


My GT has no ABS, and my car has always had a problem with locking the front passenger tire. It seems to be a common issue with Mustangs. I discovered that the driver side of the car is considerably heavier than the passenger side without the driver. It is not perfect, but I have been able to get it more under control playing with my corner weights. Threshold braking is actually very easy to perform, but any inherent problems in the suspension will still cause lockups. ABS would have saved me on the several tires I flatspotted or ruined because of this chassis deficiency.[/quote]I wouldn't call it a deficiency, necessarily. It's the nature of the beast. The under-loaded tire will lock first. That may be because of uneven STATIC weight distribution, or it may be caused by uneven DYNAMIC load distribution. Trail-brake deep into a tight corner and the inside tire will lock first, regardless of the car's static weight distribution. (that is assuming you don't spin first!)

It'd be nice to get both tires to lock simultaneously, but that's not going to happen much of the time, and ABS won't help much, either. Most systems will cut braking to both front brakes when one locks up.

Quote:
Technology is moving quick. I think eventually ABS will be necessary in racing to even keep up.
We'll see. Many series have outlawed ABS. Some have not, mainly because the cars already have the systems.

I still maintain that while it has advantages, ABS will get in the way of trailbraking to some extent. How much is determined by the skill of the driver and the tuning of the ABS unit.

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post #20 of 24 Old 08-14-2009, 06:24 PM Thread Starter
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I've noticed my front passenger wheel locking up a good bit, guess it is from the weight distribution like you said.

My car is primarilly a street car so I think I will try to fix the ABS, if it becomes to expensive then I am going to remove the system. ABS/TC would be beneficial in the rain on the street and ABS would help for autox. I'm thinking that TC could help for wet autox days as well.

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post #21 of 24 Old 08-14-2009, 09:20 PM
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I think what Diesel is referring to is Electronic Brake Force Distribution (EBD) (in Ford speak at least). Cars with this, don't have a hydraulic proportioning valve at all. They use the ABS hardware to dynamically adjust the brake balance. If you have a car with EBD and you disable the ABS, the braking is going to absolutely suck for two reasons. One, the front to rear balance is going to be very far off, especially when stopping hard. Two, everything about the suspension tuning is designed to rely on the car having functioning ABS to brake well.

Once dynamic stability control is added to the system, you now also have lateral/diagonal as well as front to rear EBD. This has the potential to improve braking performance even more.

ABS tunings are just like engine control tunings. For a given car model, there may be four or six different tunings in a ten year product period. Some of them may suck, some may be great. I think it is too difficult to generalize for a given car model.

I can confirm that the pre 05 Mustangs retard spark first to control wheel spin and then if that doesn't work, start applying rear brakes. It depends on the slip rate of the rear tires.

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post #22 of 24 Old 08-16-2009, 04:18 PM
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Can our Mustang ABS be (easily) temporarily disabled without compromising the way the brake system functions?
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post #23 of 24 Old 08-16-2009, 04:24 PM Thread Starter
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Originally Posted by Jack Hidley View Post

I can confirm that the pre 05 Mustangs retard spark first to control wheel spin and then if that doesn't work, start applying rear brakes. It depends on the slip rate of the rear tires.
Jack, is there a certain speed at which the TC won't engage the breaks and only controls engine power?

2001 Mustang Bullitt #01992
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post #24 of 24 Old 08-16-2009, 11:09 PM
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I don't believe that any of the SN95 Mustangs have EBD, so you can just pull the ABS fuse to disable it and not affect any other functions of the brake system. EBD wasn't used until 2005 in the Mustang.

The choice of spark or brakes for traction control isn't a function of vehicle speed. It is a function of wheel slip. If the slip is low, the EEC will attempt to control the high slip through spark. If that doesn't work and the slip gets high, then the EEC will start to deactivate cylinders in the engine and apply the brake on the wheel that has high slip.

Slip is a measure of the relative speeds of the wheels. If three of the wheels all have the same rpm, but one of them is at an rpm that is 5% higher, than that wheel is at 5% slip. Slip is used an an input parameter for both TC and ABS operation.

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