Brake woes

[aray327]

I originally posted brakes stay locked up, where I was experiencing my brakes locking up after driving for a while.

I have disc all the way around on my 69 camaro 13" front 12" rear. I set up the brakes with a CCP package and ran them as a manual unit until just recently adding a booster. Under manual the brakes were fine, not great but not bad. I didn't like the peddle effort so I added a booster. The first booster provided great peddle feel and great braking. The problem was when you apply the peddle it would click as if the rod was caught on something, and after driving a while the brakes were locking up. I decided to just replace the booster.

The new booster now has a hard peddle and terrible braking distance. I measured the boost and it is 10-12" at idle. CCP says i need at least 18" at idle to run the booster. When measuring the rod/master/distance... I caused the center bore on the master to come out. I pushed it back in and reinstalled the C-clip, CCP doesn't think it would have been damaged.

My question/problem; the master leaked from the top the moment I installed it, now I am not 100% sure if there is a leak from the top or from the center bore and I hate the breaks. Am I running enough vacuum to use the booster? Is there a better or newer style master that I can use? I like the plastic reservoir style which seems to seal better.

Tobin/Kore I have read a few of your replies to similar issues and would appreciate your input. You suggested a master from an 98-02 camaro/TA for someone else; would this be a good option for my set up? Anyone with a suggestion is welcomed to reply.

[oestek]

I've been there, man, and it sucks. My recipe for killer brakes is get a early 70's Corvette master... get one from Rock Auto cheap. Rebuilt Cardones for 1971 are $20 after core return. Then get yourself a hydroboost unit and you'll stop like crazy forever. We also get the $25 brake line kit from YearOne... it comes with 25 feet of 3/16 steel line and a variety of fittings to fit any master you can think of for that price. I think it includes like 10 fittings. For another $25 you can get a 1/4" kit for the rear. You'll have all the line and fittings you'll ever need, new fittings with no leaks, and great stopping hardware with out the need for 18" of vacuum. Does any car actually make that much?

[Apogee]

Am I correct to assume that you have a CPP (Classic Performance Products), not a CCP kit?

To recap, the first booster feels and works great, aside from the issue of brake lock-up already mentioned. You replace it in hopes of fixing the brake lock-up issue, pressumably with the same type/style booster(?), and now you've got poor feel and even poorer performance...but it did fix the lock-up issue I take it? The only thing that changed was the booster, correct? Apparently there's no pleasing you...just kidding.

Even though 10"-12" Hg vacuum is really sub-par for a vacuum booster, you say that it worked great before you swapped boosters, so it's tough to lay the blame on the vacuum levels without knowing why the second booster performs so poorly. I typically like to see around 14"-18" Hg for any vacuum boosted application and consider anything in the 12-14" Hg range tends to be marginal at best. You could add add an auxilliary electric vacuum pump to serve as a fairly effective band-aid to the actual problem, but they're not particularly cheap and "your results may vary", meaning that they seem to be the golden bullet for some people and very expensive paper weight for others. There have been a few threads recently either here or at lateral-g.net with respect to specific pumps and members feedback about them...could be worth a search.

While I like the 98-02 LS1 MC for C5/C6 vacuum boosted applications, it really doesn't have enough volume for the CPP kit. In speaking with Jim Ries at CPP a while back, his big-brake kits are really designed around the GM standard 1-1/8" bore master cylinder with a functioning vacuum booster. They did that in no small part to reduce the overall cost of swapping to "big-brakes" because most GM cars with power brakes are good to go as they are...assuming the engine makes vacuum at idle. For those who aren't familiar with CPP's kits, they use PBR front calipers from a truck/SUV application with twin 52mm pistons. For comparison sake, the C5/C6 calipers have twin 40.5mm pistons, or roughly 78% of the effective piston area.

You mentioned your MC is leaking from the top since the time that you installed it. That isn't normal. Did you swap MC's? It almost sounds like you're bypassing fluid, which could explain the terrible pedal feel and possibly the poor performance as well.

Tobin
KORE3

[aray327]

Correct on the Classic Performance. Your point on the original working great is also correct, why would it work great and the other booster not work? Did I mention I purchased a 3rd booster to see if the second wasn't working. Since the result was the same with the 3rd booster it is going back tonight.

I replaced the booster originally because of the bump in peddle as you apply the brakes. I figured if there was a bump it may have something to do with the lock up.

The MC did (hopefully) leak a small amount, last night i put cork in between the rubber and the metal cover to take up space and make sure there was a good seal. I wanted to be sure the leak isn't comming from the center bore, and to stop the leak from the bowls.

I am planning to swap the motor later this summer. I have an LQ9 waiting. I was thinking of swaping the cam before I install it, now I guess I need to think about the vaccum levels if I do the swap.

So is there an easy answer, do I need to just live with manual brakes for now? Hydro is a nice idea but a $700 booster isn't cheap. If I could get the peddle feel and stopping power from the first booster I would be happy and have an extra $550 to spend on something else.

[6'9"Witha69]

Let me go back to the manual brakes. What MC were you running? Are you open to Manual if the effort goes down, stopping is better and you can deal with a non plastic reservoir MC. I suggest the 7/8" Wilwood MC. Perfect.

[Apogee]

Let me go back to the manual brakes. What MC were you running? Are you open to Manual if the effort goes down, stopping is better and you can deal with a non plastic reservoir MC. I suggest the 7/8" Wilwood MC. Perfect.

Nick, do you know of anybody running a 7/8" bore MC combined with the effective piston area that the CPP kits have? The twin 52mm piston calipers equate to what is essentially a single 73.5mm [2.90"] diameter piston...essentially the same piston area as a GM metric cast iron caliper with 2-15/16" pistons. I can't imagine that would work with most of the pedal ratios out there...you'd run out of real estate and be pushing on the floor boards before you started generating any significant pressure, don't you think?

I know I said that the 1" bore would be on the small side of things for a boosted application, but it pencils out pretty well for a manual setup with the calipers that you're running. Like Oestek said previously, you can pick up a 67-76 Corvette manual 4-wheel disc MC with a 1" bore and deep pushrod hole for dirt cheap and it might let you get back to driving your car instead of beating your head against it.
:6gears:
Something not yet mentioned would be to look at using a stepped bore, quick take-up master cylinder like the ones used on the 80's S-trucks amonst others. That's a slick solution to the volume versus pressure debate as you apparently can have your cake and eat it too. That MC is not without it's cons, but just a thought.

Tobin
KORE3

[Tito]

...recently adding a booster ...... when you apply the peddle it would click as if the rod was caught on something, and after driving a while the brakes were locking up. ...

Just to be sure -- when you added the booster, you moved the brake pushrod from the upper hole in the pedal to the lower hole, right? Running a booster with the pushrod in the upper hole would put the pushrod at a weird angle which "might" cause a click-type noise.

Just thought I'd throw that out there...

[aray327]

I did move the rod down to the lower hole. The clicking sound continued even when I removed the booster. You could push the rod in by hand and cause the clicking even out of the car.

To set the record straight, I don't beat my head. I pound my fist, curse, and talk to my dog, she always understands.

If I can't figure out this booster issue I will run the brakes as a manual unit. The MC is from CCP and came with the brakes as a unit. CCP told me I could run the brakes as a manual unit until I decided to go hydro or vacuum. I used it as a manual brake originally, wasn't satisfied but at least I could drive.

[silver69camaro]

...you'd run out of real estate and be pushing on the floor boards before you started generating any significant pressure, don't you think?


I would imagine so. I've run a 1" and 15/16" with stock brakes and they worked very well for manual applications.

I suggest try running manual brakes for a while. Make sure you have a good set of pads in the calipers. I don't suggest hydroboost because the feedback tends to be non-existant (either stock or modified). Vacuum boosters are better, but it looks like your engine vacuum is low anyway.

Run a properly sized MC and drive it for a while. You may end up liking it (I sure do!). To me, manual brakes vs. power brakes is like comparing manual transmissions to autos. Manual brakes and trans really connect you to the car and bring the feeling of control.

[aray327]

When I originally installed the brakes I ran just the MC with no booster. the brakes worked but the peddle feel is not that great. I don't understand why some like running manual brakes. I would suggest the comparison is not like a manual vs auto trans but a 3 speed vs overdrive. Why drive old technology when new technology is readily available? The stopping distance and effort is greatly reduced which translates into a safer car. Plus (not that she will drive much but) my girl didn't like the manual feel either.

So to recap, my vacuum may be too low?? But that doesn't explain why the first booster seemed to provide good peddle feel.

If want to try a new MC look at the 70's vette MC? It looks like I would have to choose manual or power application which would suggest I have to get a manual now and a power when I swap the motor? Is that right or can I run the same MC power and/or manual? CCP said the one they game me would be fine either way.

Vacuum or Hydro? The cost is high on hydro and is it really a cure all? I read on other post the pressure is too high for some applications.

I thank you guys for your input. I think I am well versed but I don't know anything compared to what you guys offer.

[6'9"Witha69]

When I originally installed the brakes I ran just the MC with no booster. the brakes worked but the peddle feel is not that great. I don't understand why some like running manual brakes.Let me get this right, you used a power MC with probably a 1.25" or so bore as a manual setup and decided you don't like Manual brakes? That is not right. Kinda like putting a10-71 blower on a Goodwrench base crate engine and wondering why it don't work too good.

Do not let that impression fool you about manual brakes as you were deceived my a mismatched setup.

If I got it wrong let me know and I'll change my tune.

[silver69camaro]

When I originally installed the brakes I ran just the MC with no booster. the brakes worked but the peddle feel is not that great. I don't understand why some like running manual brakes. I would suggest the comparison is not like a manual vs auto trans but a 3 speed vs overdrive. Why drive old technology when new technology is readily available? The stopping distance and effort is greatly reduced which translates into a safer car. Plus (not that she will drive much but) my girl didn't like the manual feel either.



Manual brakes should have somewhat high effort (figure 50-75lbs of foot force) but is rediculously stiff if too large of a master is used, which appears to be in your case.

Drive a car at its limit and perform threshold braking with a manual system, then you'll understand. Definetely not old technology, and stopping distance is NOT reduced with power brakes.

[aray327]

Opps, I didn't mean to be offensive. I have to conceit to your knowledge and experience. I didn't look at who was making the suggestion. I am merely a banker, I believe your engineering background trumpts.

So do you think the CCP MC is best for boosted application and for manual I should consider a different MC?

[6'9"Witha69]

So do you think the CCP MC is best for boosted application and for manual I should consider a different MC?Yes.

[silver69camaro]

Opps, I didn't mean to be offensive.

No worries, offense not taken!

[Apogee]

CPP appears to offer a 1" bore MC as well as a 1.125" bore MC (CP31500 versus CP31501)...if you were using the 1.125" in a manual configuration then you more than likely would've had fairly high pedal effort. Matt hit the nail on the head with 50-75 pounds of force at the pedal being ideal for lock-up on a well set up manual system. Any higher and you'd better be driving to the gym. Any lower and threshold braking becomes more difficult, since smaller force changes at the pedal translate into proportionally larger pressure changes at the calipers.

Tobin
KORE3

[whytry]

So for this setup would you suggest going to the early 70's vette MC? I am looking to get the front CPP setup as well, front's only for now. I will be running a manual setup since my F1R procharger filter currently hits the manual mc right now, so not looking to go into Hydro or Power. Manual is the way to go for me, but I want to know what mc to get as well before I dive into this and run into the same problems you have right now. I am not a brake guru, so the size of the mc I will probably go with what most say on here.....