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Discussion Starter #1
Two disclaimers to bear in mind about this post:

I have to replace an ABS sensor.

My brake pads are Wagner ThermoQuiets.

Now that we've gotten that out of the way, after last weeks track event, I'm bitterly aware of the deficiency of my braking system.

Before I go further, let me describe what I have:
Stock 1995 GT ABS/MC/PB
MM/Stoptech Braided lines in front
Stock lines in back
1994-98 Cobra calipers (one side is a baer casting, but same 38mm pistons)
13" cryo-frozen slotted rotors up front
11.65" ford rotors out back, with FRPP caliper bracket kit
500* DOT4 fluid, system recently bled (bled out 3 bottles worth).

My complaints are:
Pedal is initially soft, not really mushy, but its not firm like I would like it.
The brakes really don't react till later in the pedal (my little brother's civic has nicer feeling modulation).
The system just doesn't cut it hot. slid off the road course in Gainesville when I had them heated up.


My considerations are either to rebleed the whole system and get hawk hps+ pads (after resurfacing the front rotors, which have nill wear, besides glazing)

or

save up for the brembo 4 pot stang calipers. Most likely the FRPP kit.


The car exhibits little brake dive, however, which is nice. What do you guys think?
 

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What kind of tires do you run at the track? Street or R-compounds? Can you engage the ABS with them which is the equivalent of locking them up?

It looks to me like your upgraded system should be up for the job. Personally, I'd get away from the slotted rotors and go with plain Brembo replacements and follow the proper bedding procedure for new pads.

I have a Cobra with the stock braking system other than steel-braided lines up front. I can engage the ABS all day long running Falken tires and can brake deep and late when necessary. The only thing I know of that would improve the brakes on my car right now are brake ducts and R-compounds. I had pedal fade issues until I started using Motul RBF 600 racing brake fluid with a DBP of 594*. Then I had pad fade issues until I started using Hawk HP+ pads. I haven't gotten around to adding brake ducts but that's a project for this winter. Maybe try some Motul fluid and add brake ducts before spending a lot of money on 4-piston calipers.
 

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Buying Brembos at this stage would be a waste of money. For what the Brembo conversion would cost you can do many things that would make the car work much better on track. I would invest in an extra set of wheels and tires before anything else, that is if you plan to continue doing track events or autocross.

Going to a set of Hawk HPS pads would be a good upgrade that you could live with on a street car. The HP+ are very dusty and squeal badly in a daily driver. As you and many others found out Sunday, stock replacement pads just don't cut it for performance driving. :shakehead

Make a plan for where you want your car to be when you are done, then map out the stages for geting there. Still, you have to remember that the more track worthy you make the car the more uncomfortable it will become on the street, so plan accordingly.
 

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My guess is you have some air in the lines. I have successfully gravity bled my system as long as I didn't replace any parts. If you remove the front hoses you need someone to pump the pedal and hold it down to get the air out.

I had a little air trapped in mine after replacing the front lines and it felt similar to your description. The pedal was hard as a rock when I did the cobra caliper change on all fours even with stock hoses so I knew I left air in it but didn't get around to flushing and bleeding again till recently.

There are no street pads that will not fade at track temps so try something different there but start with assisted bleeding.
 

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the best brake mod I did to my car was a motive pressure bleeder :)
 

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huesmann said:
Speed bleeders will make your life so much easier. :)
You will get my agreement on that! Speed bleeders will be the best low cost modification (~$30) you can do to your brakes. Makes it an easy 1 man operation and prevents any air from getting back into the lines. I did all 4 of my brakes last week in about 15 minutes.

Also Chris, I forgot to add in my first reply that you really shouldn't run the DOT 4 in your system. I'm not sure if the Bosch ABS is compatible for DOT 4, just get a good high quality DOT 3 approved fluid. With what the ABS costs to repair/replace I would not wnat to take a chance on any unapproved fluids. The DOT 3 does a much better job of keeping the system dry than the DOT 4. Just bleed it well before any high speed track events and once every 6 months to a year otherwise.
 

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Upgrade your pads! Stock pads will not "bite" like a performance pad so you feel that you have to press harder to get the response you want. I had the same issue with my brakes after an upgrade until I swapped out to the Hawk pads and it completely changed the feel. I had much better inital bite (even when the brakes were cold) and zero fade.
 

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Do you have ducting to the front brakes? This is essential on a heavy car like the Mustang.

Dump the DOT 4 and get Ford Heavy Duty or Motul 600 and change it after each event. IIRC, the DOT 4 stuff is silicone based and that causes a mushy pedal feel even when fresh.

I've had good luck with HP+ pads for street and auto-cross. They are dusty and do squeal sometimes, but the squealling seems to abate after a couple of hard brake pedal applications. The have good initial grip, which true race pads do not, so they are good for the street.

Putting a street car on the track requires compromise. Only you can decide which way to bias your car. My personal theory is that it's not possible to have brakes that are too good. And so, I would suggest the biggest rotors you can fit, ducting to the center of the rotor and full race pads for the track and other pads for the street. That's the minimum for a street/track car IMO.

Even then, you can expect some fade near the end of a track session.

You might also have an instructor ride with you and observe whether you abusing the brakes.

Good luck.
 

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Chris, do you have ABS? If so it probably was'nt bled properly. The easiest way to cycle the ABS is to find a dirt/gravel road, get up to speed and lock the brakes up several times. This will cycle the ABS and should firm up the feel.
Good luck,

Bruce
 

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Discussion Starter #11
Ok, well, for this year then, here's my plan:

-Hawk HPS pads, stat.
-Resurface rotors (I have a friend who doesn't mind subjecting his lathe to the work, I am going to get them just enough to break the glazing)
-Replace the rear left ABS sensor.
-While at ford, pick up lots of that heavy duty fluid (how much is a good amount for a complete flush of the system?)

What's the best way to flush/bleed the system since it has abs? I have speedbleeders on the front, havent gotten any on the rears (the ones I bought didn't fit, I just used a reaalllly long hose last time), however, I've also considered getting a shop to powerbleed them, but I don't know if you have to use their fluid or not.
 

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Get 5-6 bottles of fluid. It's cheap enough and you'll be pretty irritated if you run out before you are finished. I'm guessing MOST of your problem is the pads . . . stock pads are rarely adequate for even a few laps around a track at speed, and aftermarket stock-stlye pads like you have are probably even worse. Also, make sure you bleed the master cylinder when you bleed your brakes.
 

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Discussion Starter #14
J98GT said:
Get 5-6 bottles of fluid. It's cheap enough and you'll be pretty irritated if you run out before you are finished. I'm guessing MOST of your problem is the pads . . . stock pads are rarely adequate for even a few laps around a track at speed, and aftermarket stock-stlye pads like you have are probably even worse. Also, make sure you bleed the master cylinder when you bleed your brakes.

how do you bleed the M/C?

Also, you're right, after my first low speed lap, my brakes were done.
 

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- Don't turn your rotors. It's a waste of rotor material, time, and money (although I guess your friend will do it for free). Just use some sandpaper to scuff up the pad wear surface - that's all I ever do, and I've never had any problems swapping from one set of pads to another. And I know it works, because the one time I didn't scuff up the surface when shifting from track pads back to street pads the initial bite was noticeably worse.

- DOT3 and DOT4 are essentially the same thing, and I see no reason to be worried about your ABS system using DOT4. A lot of brake fluids are even marketed as DOT3/4. DOT5 is the bad silicone-based stuff. DOT5.1 is fine with DOT3/4.
 

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Patrick Olsen said:
- Don't turn your rotors. It's a waste of rotor material, time, and money.

- DOT5 is the bad silicone-based stuff.
Agreed as to turning rotors, though do mike them.

Thanks for the DOT 5 correction, it's been 20+ years since I made the mistake of putting that crap in a motorcycle brake system.

I will repeat, if you have fade problems, duct, duct, duct.
 

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the motive pressure bleeder system is only $50 and it takes me about 10 mins to bleed my brakes alone, and I dont have speed bleeders.

it also made "bench bleeding" a thing of the past for me for m/c's.

used it on a friends car that we took completely apart, redid everything. it was a `94 BMW 318is, he bought a `95 BMW M3 wrecked donor. It took us 20 mins to bleed the M3 m/c, all 4 brakes, and the clutch slave cylinder with the pressure bleeder.

no air was left in that system, pedal feel was perfect :)
 

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Discussion Starter #19
this has been put on hold for the time being. Tonight in fog I had the fortune of catching a guardrail with some snap oversteer. Damage is minimal, but the core support likely s cheaper to replace than repair. Only bodywork is replacing a fender and headlight. Airbags went, suprisingly, so those too. Coming out of pocket, no less.

Don't drive on inferior parts. Period.

Once I've paid the repairs, I'll revisit this, although I'd really like to know more about bleeding the MC. Also any considerations like what was mentioned above about the abs would help too.

With some luck, I'll have her back together and feel confident about any sort of performance driving by Sebring. I'm just bummed right now because the accident wasn't really related to performance driving, but just poor engineering, and bad decisions on my part.
 
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