Removing Hydroboost Brakes Only

[Chandler]

Hey all,

I have a question regarding the hydroboost setup, specifically deleting just the brake portion. I have a 2000 GT that’s been converted to a road race car. I installed the ATS front rotors and tried the Taurus calipers on the rear but could never get a good pedal so I went back to the stock GT calipers as race time was approaching. The race went well, but I can tell there is too much front bias as the fronts are prone to locking up, so I’d like to delete the hydroboost setup and go with manual brakes and a bias adjuster. Does anyone have an recommendations on MC bore size? 1.125 seems to be the biggest bore that works with the Maximum pedal kit, which I think is what I’m going to go with. All the info I can find regarding deleting the hydroboost is also focused on deleting the power steering, which I don’t want to do since this is a road course car. What are my options? Can the lines going to the booster be blocked off? Do I need to change the rack and power steering pump to something off another car that doesn’t have HB? Any help would be appreciated. Lots of info on deleting the brake side on the drag forums but I couldn’t find anything where anyone wanted to keep the power steering. Thanks in advance for any help.

-Mark

 

[TMSBOSS]

If you have more front brake than tires, you fronts lock easily. Have you considered a better front tire/wheel combo? What tires are you running?

 

[Chandler]

@TMSBOSS I am restricted on the tires due to the series we run with, Lucky Dog Racing League. We’re running the Hankook Ventus RS-4, 275/35-18. So far they’ve been great tires.

 

[TMSBOSS]

And then there is that. Lol.
if you could possibly do a build thread. There are a few experts on the site who could possibly give you advice.
I would imagine adjusting brake pads, or even a proportioning valve might help before diving into a major change.

 

[RinerAuto]

While I have not worked on a hydroboost setup, my understanding is it's just using power steering pressure to assist the brakes. If you reroute the power steering pressure to be like on a non-hydroboost setup it should work just fine. The power steering is just a pump it doesn't care what it is pressurizing.

As far as your lockup the issue is the rear calipers. Your front to rear bias is way off. Going to manual brakes isn't going to solve your problem. I don't have a recommendation on MC size but I will be doing this same setup on my car later this year. Try searching the "79-04 Mustangs Road Race-HPDE-AutoX" Facebook group, this has been asked about multiple times.

What brake pads are you using? Could you change braking feeling by putting more aggressive pads in the rear or reducing the fronts?

 

[Chandler]

Thanks for the replies all. @RinerAuto, I'm more looking at removing the HB to reduce failure points and so that I can run a bias adjuster. I've read that bias adjusters don't work well with the power brake setups. That's a good idea, going with a less-aggressive pad compound up front - @TMSBOSS mentioned the tires and I'm restricted there but the rules don't have limits on what pads I can run. I will look into that as well.

 

[RinerAuto]

I'm not familiar with a bias adjuster is it another name for proportional valve? Or are you installing a balance bar?

Either way remove the hydroboost assembly, reroute the power steering lines to steering rack (may need new lines for this), and install manual brake setup. This would be the same as on an early SN95 or Fox.

 

[Chandler]

@RinerAuto it's an adjustable proportioning valve, basically what you installed in your YouTube video. I've always called them bias adjusters. I have a call in to the Maximum techs to talk about this and their pedal assembly, I will keep you guys updated on what comes of that. They called yesterday but I didn't get back to the tech in time before they'd left for the day.

 

[blacksheep-1]

About page 6, I used all the parts from a pre hydroboost GT
.This would be a good article for you to look over.
You'll need to plumb one of these in line, next to your seat where you can adjust it
Forget the bias adjuster unless you want to go full pedal box and twin master cylinders, as long as you stay close to stock, use the adjustable prop valve and ditch the factory prop valve, just plumb the brakes straight with the adjustable valve in the raar line.

JEGS 63020: Adjustable Proportioning Valve - JEGS

prop block

www.jegs.com

Junkyard Dog Build

So.. a quick look at the FAST rule book says this....M0 (Open Modified) Rules The Open Modified class (M0) is for exotic cars, and cars that exceed any of the above limits, but are otherwise street legal and on street tires. Cars that bump up from M1 also go to M0. For safety, doors, hood and...

trackmustangsonline.com

 

[Chandler]

@blacksheep-1 , thanks for linking your build thread, it has been a good read and I've learned a lot. We actually did the upper rear control arm delete to help with binding and it made a huge difference in the way the car feels under braking. I do have a couple of questions for you:

1. Was this car originally an ABS car? If so, did you delete that and go with the 94-95 booster or did you go full manual and leave a booster installed?
2. If you did keep the power brakes, how did the proportioning valve work alongside them? Any funkiness?
3. My car is an ABS car that's been deleted, but it still has the brake pressure switch (this is what Ford calls it, I'm assuming it's just a complicated proportioning valve). Would the MM blockoff kit work with this valve so I can remove the spring and piston from it?
4. If the answer to #3 is yes, would I come off that valve with a new line routed into the car, put the new proportioning valve inline in the car, then route back to the rear of the car? I can't recall and I'm not at home to look, but does this car have one rear line that runs the length of the car to a distribution block or do the rear brake lines run separately the length of the car?
5. If they run separately, do I need to combine them into one line and add a distribution block or how do I do that?

Thanks for your help. I'm used to circle track cars with no booster and single brake lines running to distro blocks so this setup is a little new to me and I want to get it right.

-Mark

 

[blacksheep-1]

@blacksheep-1 , thanks for linking your build thread, it has been a good read and I've learned a lot. We actually did the upper rear control arm delete to help with binding and it made a huge difference in the way the car feels under braking. I do have a couple of questions for you:

1. Was this car originally an ABS car? If so, did you delete that and go with the 94-95 booster or did you go full manual and leave a booster installed?
2. If you did keep the power brakes, how did the proportioning valve work alongside them? Any funkiness?
3. My car is an ABS car that's been deleted, but it still has the brake pressure switch (this is what Ford calls it, I'm assuming it's just a complicated proportioning valve). Would the MM blockoff kit work with this valve so I can remove the spring and piston from it?
4. If the answer to #3 is yes, would I come off that valve with a new line routed into the car, put the new proportioning valve inline in the car, then route back to the rear of the car? I can't recall and I'm not at home to look, but does this car have one rear line that runs the length of the car to a distribution block or do the rear brake lines run separately the length of the car?
5. If they run separately, do I need to combine them into one line and add a distribution block or how do I do that?

Thanks for your help. I'm used to circle track cars with no booster and single brake lines running to distro blocks so this setup is a little new to me and I want to get it right.

-Mark

The car ended up with the 94 brake booster and master cylinder along with the pedal box. That right there save you a lot of engineering on pushrod lengths and whatever. The portion of the master cylinder ( I think it was the front half) went to a distribution block and to the front brakes. The rear went to the adjustable prop valve, then the distribution block, and the rear brakes. Front brakes were not modulated except by your foot. The rears were modulated by the prop valve. .. easy peasy simple. I've done several fox body sn 95s this way.

 

[Chandler]

Awesome, thanks for the info. My car still has the 4.6 2V so I'm not sure how a 94-95 booster will fit, but I definitely think I can make the prop valve work with our system. I appreciate the help and responses.

 

[PatientZero]

I'm still running hydroboost and I actually like it. I'm running a massive power steering fluid cooler but otherwise I've never had an issue. I deleted the ABS and put a Wilwood proportioning valve on the rear brake line. I was also going to suggest some less aggressive pads on the front.