Ported heads/big cams affecting braking?

[Greg Hazlett]

You can see in my sig the setup I am running; at idle/cold start I am drawing 11 vac, is this not enough vaccum to allow my braking system to work properly? I have seen brake boosters for about $50 but not sure if I need one or not.

I have upgraded the brakes to Hawk pads and SS lines on all 4 corners.

 

[JeremyH]

Your car already has a brake booster.

Check this out Greg.

http://forums.vintage-mustang.com/v...-big-cam-low-vacuum-goodbye-power-brakes.html

 

[Greg Hazlett]

Hmmm...in reading that there did not seem to be a conclusive answer.

 

[JeremyH]

No, but it seems to be the exact problem, he had 10vac as well. And issues rolling to a stop, and couldnt fully stall the convertor.

The answers from my research are vac canister may help some but most reccomend vac pumps.

As i doubt its the brake booster itself with your car being so new.

 

[GB10]

See if your tuner can add more timing at idle, because that will raise your vacuum some. I did this on another vehicle with a decent cam and it went from 10"/hg of vacuum to about 14"/hg. Just a thought.

 

[white05gt]

If you search you will find what you need, several people on here have been through this.

 

[cobra mike]

I thought these cars where hydro boost brakes

 

[JeremyH]

Nope, just a standard vacuum operated brake booster.

 

[Department Of Boost]

You can see in my sig the setup I am running; at idle/cold start I am drawing 11 vac, is this not enough vaccum to allow my braking system to work properly? I have seen brake boosters for about $50 but not sure if I need one or not.

I have upgraded the brakes to Hawk pads and SS lines on all 4 corners.

I have between 8-9 in of vac and have not had any "soft" brake issues.

 

[JeremyH]

I have between 8-9 in of vac and have not had any "soft" brake issues.

You wont have "soft" brake issues, having too low vacuum means the pedal is going to be stiff or harder than normal since the brake booster isnt doing its job so you have to really use your foot, and initial braking force is greatly reduced especial at low speeds, start/stop traffic.

 

[Department Of Boost]

You wont have "soft" brake issues, having too low vacuum means the pedal is going to stiff or harder than normal since the brake booster isnt doing is job so you have to really use your foot.

Sorry, just getting started on my first cup of "Joe". Wrong therm. You are correct, I have not seen any increased pedal effort.

 

[Greg Hazlett]

I was unaware of this until Jeremy drove my car and said he thought the brakes were not stopping the car as well as they should, esp with the upgraded pads/lines on it.

 

[JeremyH]

Sorry, just getting started on my first cup of "Joe". Wrong therm. You are correct, I have not seen any increased pedal effort.

The problem is everybody gets "used" to their cars so they dont realize it or notice it, its becomes normal to them. Your foot becomes calibrated to the extra force you have to apply to get the car to stop. Go drive a stang with 18-20 in/hg vac at idle and see what ya think.

I drove Gregs car just on some side streets at like 15-20mph cruising and went to stop at a stop sign and thought I was going to roll out into the street and i had to push really hard on the pedal to get the car to finally stop.

Really low vac like this isnt a issue on your first stop like on the highway since under load when you let off the throttle and the tb closes it creates more vac and will jump to 20-22 vac for a sec so when you jump off the pedal on to the brake for the first time everythings good. But repeative braking especialy at lower speeds is where it can become a problem.

I guess if you use to it or it doesnt bother you its no big deal. But it scared me, didnt like the feeling at all.

 

[Department Of Boost]

The problem is everybody gets "used" to their cars so they dont realize it or notice it, its becomes normal to them.Your foot becomes calibrated to the extra force you have to apply to get the car to stop.

Agreed.

Go drive a stang with 18-20 in/hg vac at idle and see what ya think.

I do it a couple of times a week. I have a 2010 GT Vert Premium also. There may be a very slight difference between the two cars but its hard to tell exactly because the 2007 has GT500 brakes. In addition to that I think the 2010's brakes are a bit too over-boosted.

I wouldn't complain about slightly more "boosting" out of my 2007 but it doesn't bother me. I think going with some Hawk pads will put it right in its sweet spot.

Now that I have said that I imagine the stock GT brakes with 8-9in of vac would be a little wimpy. Like you stated its how your mind is calibrated. Well I'm calibrated for 14" rotors and 4 piston calipers. Not a great comparison. Doh!

 

[Greg Hazlett]

Little help in what you mean by the 2010's are overboosted?

 

[JeremyH]

Im normaly calibrated for baer 14" rotors and 6p calipers as well , I know what ya mean. But I haven't really driven my car in a couple months so right now im calibrated to driving the corolla lol and even it stops way better especialy being a smaller/lighter car in all.

But yes I am use to the brakes being consistent and efortless. So for me it was a shock.

I mean you can deal with it and learn to drive accordingly its not a super big deal.

Guess the bigger deal would be line lock not holding well and brakes not holding to stall the convertor at the tack and rolling out too much.

 

[JeremyH]

Little help in what you mean by the 2010's are overboosted?

He means from the factory, the 2010 brake booster works really well with the stock -22 vac. Also the newer the car, better condition its in and the seals are in, so the booster will work better anyway.

 

[Department Of Boost]

Little help in what you mean by the 2010's are overboosted?

I think all Fords are over-boosted (touchy pedals) anyway but my 2010 is borderline snatchy. Which reduces its “feel”. I’m a nit picky bitch when it comes to that stuff though. I roadraced for 15 years. I’m very sensitive to the controls, their placement and their feel. The 2010 brakes (all stock) require that you drive very, very smooth if you want to trail brake it deep into a corner for example. They could do with a less abrupt initial “bite” which tends to unsettle the chassis a little. The abrupt transition from brake on to brake off makes both actions very hard to do smoothly when pushing the car into a corner hard. And in its place provide more stopping power once the brakes are applied.

Like I said, I’m a bit of a bitch when it comes to this stuff.

 

[Miracle]

Isn't this the same reason a lot of track only cars run vacuum pumps anyways?

Not saying that he needs one, but it's been done before, I'm sure. For this, and to run PCV systems as well.

 

[GI Joe]

I had this issue too and chased it everywhere and canister did not help then I was given some advice. Remove the vacuum line to blow off and plug it and see what happens. My problem was a leak bad spring there. I ended up needing a light spring there to let it stay closed at idle