Brakes FOX BRAKES ISSUES

[Mustang5L5]

Usually I like to educate folks so they can make their own decisions….

But I’ve done this exact setup as you with the GT mc and then went 1” and it was a much better braking feel.

So yes, my opinion is you should make the change to the 1” MC

 

[PonyGTrider]

94-95 Cobra (with vacuum assist brakes) used the 15/16” bore MC, but also had smaller caliper pistons up front. Those units had 38mm pistons.

99-04 cobra calipers are 40.5mm pistons, which is why I personally recommend the 1” bore MC with this setup. The 1/16” larger bore matches the increase in piston surface area.


Also, I fudged up earlier when I said a 94-95 GT 1 1/16” on that setup would make the pedal soft. Opposite actually. It would be firmer. Purely subjective if it’s too firm. Once you get the system up and running and find waaay too much leg effort to stop, then you can make the change.

So what master cylinder should I get? I followed some instructions online about the brakes upgrade where they suggested the 94-95 GT master cylinder.

Should I get the 93 cobra 1” bore?

Thank you

Usually I like to educate folks so they can make their own decisions….

But I’ve done this exact setup as you with the GT mc and then went 1” and it was a much better braking feel.

So yes, my opinion is you should make the change to the 1” MC

Sounds good, thank you.
I’llI follow your advice

 

[AeroCoupe]

Did you modify the stock ebrake handle for the rear disc brakes? If you did that and have the adjustable cable the ceramic should hold it unless you just have some really ty pads.

 

[PonyGTrider]

Did you modify the stock ebrake handle for the rear disc brakes? If you did that and have the adjustable cable the ceramic should hold it unless you just have some really ty pads. V dninde gt is

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Did you modify the stock ebrake handle for the rear disc brakes? If you did that and have the adjustable cable the ceramic should hold it unless you just have some really ty pads.

Did you modify the stock ebrake handle for the rear disc brakes? If you did that and have the adjustable cable the ceramic should hold it unless you just have some really ty pads.

Yes I did the proper modification and yes everything is pointing to the ceramic brake pads to be the issue

 

[GOvert]

Has anyone mentioned to check the condition of the metal (body) line going to the rear brakes? If it were pinched, it would result in reduced braking on/at the rear brakes. Just a thought.
Thanks, guys, for all of hands-on information. There is a lot to think about as I upgrade my '85 to 5 lugs on the front, maybe using the 5 lug (stud) SVO rotors and not too sure what to do on the rear for a disc conversion? I have a '97 Mustang rollover vehicle with rear disc if any parts would be usable.
I'll search here and the I-net before I start a thread and ask any questions!

 

[Willybill32]

Has anyone mentioned to check the condition of the metal (body) line going to the rear brakes? If it were pinched, it would result in reduced braking on/at the rear brakes. Just a thought.
Thanks, guys, for all of hands-on information. There is a lot to think about as I upgrade my '85 to 5 lugs on the front, maybe using the 5 lug (stud) SVO rotors and not too sure what to do on the rear for a disc conversion? I have a '97 Mustang rollover vehicle with rear disc if any parts would be usable.
I'll search here and the I-net before I start a thread and ask any questions!

I used a rear disc conversion kit from SSBC on my ‘86. They’re now operating as SSBC-USA. Summit is one reseller: https://www.summitracing.com/search...&fr=part-type&ptr=disc-brake-kits&ptr_oos=260

 

[nickyb]

To the op, how have you adjusted the bias?
I only ask because the only mention in this thread is you opened it all the way to bleed the brakes.

 

[AeroCoupe]

@GOvert - start a build thread and we can address any specific questions you have. You can use everything off of a 94-98 GT or V6 car on the rear end on the Fox housing. This means axles and axle brackets out. If you want to get more specific start a thread and we can walk you though it there.

 

[PonyGTrider]

Has anyone mentioned to check the condition of the metal (body) line going to the rear brakes? If it were pinched, it would result in reduced braking on/at the rear brakes. Just a thought.
Thanks, guys, for all of hands-on information. There is a lot to think about as I upgrade my '85 to 5 lugs on the front, maybe using the 5 lug (stud) SVO rotors and not too sure what to do on the rear for a disc conversion? I have a '97 Mustang rollover vehicle with rear disc if any parts would be usable.
I'll search here and the I-net before I start a thread and ask any questions!

There are no sharp bents nor kinks on any of the hard brake lines.
I used the 94-95 front spindles and as you can see I used all new parts on the stock rear axle.
I’m not sure if you can use some parts from your ‘97 donor

 

[PonyGTrider]

To the op, how have you adjusted the bias?
I only ask because the only mention in this thread is you opened it all the way to bleed the brakes.

I followed all the Willwood instructions to do that.

 

[AeroCoupe]

What I did was start with the least amount of pressure on the rear brakes (proportioning valve screwed all the way out), run it in four turns (was told this was a good starting point by multiple people), and take the car out and panic brake it. You want to get it where the rears lock up just before the fronts so in a panic situation the car stops straight. I had to turn the ABS off on the car the last time I adjusted it and then turn the ABS back on. Car stops violently on dry pavement.

 

[Qtrhrse23]

Hi all,

A question to all of you.
On my ‘90 GT I have the five lug/brake conversion upgrade from a 2001 bullitt but have been dealing with not too effective braking issues. I have the 95 booster and master cylinder installed for this upgrade. For all of this project I gutted the stock proportioning valve and installed the WIlwood adjustable proportioning valve by the driver’s side strut tower.

The problem like I said is not having a strong braking and I noticed my rear brake pads are almost new while the front ones have just a quarter of the pad material left. This is telling me that the rear is not braking hardly anything.

The wilwood adjustable proportioning valve has ten turns from all closed (Counter clockwise) to full open (Clockwise). I adjusted it eight turns clockwise and still not having good rear brake pressure bias. what should I do? Should I completely delete the stock proportioning valve??? My rear brakes are not working properly even adjusting the adjustable proportioning valve eight out of ten turns clockwise?
Any help will be greatly appreciated!

Front pads usually last 1/2 of the rears, sometimes less.

 

[PonyGTrider]

Front pads usually last 1/2 of the rears, sometimes less.

100% agree on that however it seems like some of my problems lay on the pad material because it seems I don’t have that “Outstanding” braking feeling others have described and one noticeable thing así mentioned somewhere in this discussion is that when I apply the parking brake the car still sliding down no matter how hard I pull the handle so that must be that cheap ceramic pad material. I will run it like this until I finish those pads and install something better and see how it behaves.

 

[Mustang5L5]

For my bias, I initially set it to full reduction to the rears. Then while driving around over time I’d add a little bit more rear braking. Not much though.

TBH, I don’t really need the brakes dialed in for every little bit of brake reduction. On a non-ABS car I’d rather err on the side of less pressure on the rear in case I panic stop when some idiot cuts me off. The car stops fantastic as it is and I’m just too used to driving cars with good brakes and ABS. My SN95 has cobra brakes and ABS, my Explorer ST has 14.5” brakes, ABS and good 275 tires and will throw you through the windshield. 99.9% of my driving is in a car that you just plant the pedal to the floor and steer. My fox has hydroboost and 235 tires up front. I typically only drive on warm sunny days when traction is great, but I know I can get myself in trouble quick if I get too rowdy on the stop pedal