iWon

iTrader: (13)

My 93 z28 has been sitting for the last 2 years after the motor was built, so naturally some rust built up on the rotors. Ever since the new motor, the brakes are very weak.. I've tried some high speed braking to burn the crud off, but it doesn't seem to help any.

When making a soft or gradual stop, it feels like the rotors are almost warped very slightly.... the brakes will grab, slip, grab, slip, until I kind of pulse to a stop. They're also squeaking when almost nearly to a stop, or when braking at slow speeds.

So could sitting for 2 years have done this? They felt fine before I parked the car and did the motor... I'm also wondering if the build may have something to do with it? It's a 383 stroker with a CC306 cam now.. I've heard some guys say after cam swaps their brakes feel weaker, but idk.

Any thoughts?

t/a98

iTrader: (6)

Is it automatic? I'm in the same boat, big cam=less vacuum which means less braking. If its an auto you need a bigger stall, Im told that helps stopping.

Your problem sounds different, but the cam definitely makes it worse..

jimmyblue

iTrader: (11)

You may want to pull and lube the slider pins, these are known to get
crusty over time and may be keeping the calipers from following mild
rotor warp. Wouldn't hurt to bleed the system either though I gather
some ABS systems make this more of a chore; dunno about your case.

Low vacuum may weaken braking power but this would go away as an
issue at RPM over, say, 2000. More of an idle-vacuum deal. My 224,
116 LSA cam affected braking none. High overlap would be worse.

Racin'Z28

iTrader: (7)

In addition to what the OP's have said, the brake fluid in the lines needs to be flushed out and changed. 2 years is a long time for the fluid to absorb moisture, (it still does it even when it's a closed system and just sitting). Any moisture or water will only add to your problems. I agree the cam and the lack of vacuum could possibly be the culprit. But I would be pulling the calipers off and greasing up the slider pins (after you brush/grind any built up crud off) and maybe a freshening up of rotors with a light turning (yeah to the others who will say something, I know it's better to not always turn rotors) and bleeding the lines with all new fluid and get all the old stuff out is where to start.
After you get the brakes up to speed, then if it still does it, you may need to look at a vacuum reservoir to maintain the vacuum you need for power brakes. Or you could always go to manual brakes....

Good luck

iWon

iTrader: (13)

Thanks for the good info guys, I think I'll start by cleaning / greasing the calipers, turning the rotors lightly, and getting a set of fresh pads on them. I'll also bleed all the old fluid out.

I'll probably get some Hawk HPS pads for the fronts, and just turn the rotors. Is it ok to use new pads on turned rotors?

99FormulaM6r

iTrader: (2)

^^^^ Yes, you can use new pads on turned rotors.

iWon

iTrader: (13)

Alright I'm starting to think it has much more to do with the cam than the brakes actually being bad. I took it out today, and I am braking just enough to roll forward very slowly in drive, the car pulses forward, almost along with the chop of the cam.

What should I look at to remedy this? Racin Z28 mentioned a vacuum resevior, can you eleborate on that a little bit?

Grimes

iTrader: (3)

Before you do that, make sure the vaccum line to the brake booster is not damaged or kinked.

t/a98

iTrader: (6)

Vacuum reservoir helps maintain vacuum for vacuum operated Systems like our a/c switches, brakes, etc. But it only helps at low rpm, going up hills, or when pressing the gas.

It may help with the low rpm part. Have a vacuum gauge? You can use it to diagnose alot of problems, even tells you if your lean or rich, pretty neat tool...

iWon

iTrader: (13)

Yep the brake booster line is all good, and the brakes feel fine it's just the pulsing sensation.

I don't have a vacuum gauge, but I know I could rent one no problem... how would I use it in this scenario?

iWon

iTrader: (13)

Bump.. hoping to get this fixed soon

Marinez28

iTrader: (1)

What stall do you have?

iWon

iTrader: (13)

The trans was built by the previous owner, but he told me it was the stock stall redone to flash 2600.

BigD383lt1

I have a 383 with the cc306 and the car sat for a couple of years as well. I had major problems with the breaks and vacuum. I installed a vacuum can and did a tune and it cleared up most of my issues. Has your car been tuned since the new motor it helped a lot even after installing the can.

Marinez28

iTrader: (1)

Thats probably your problem, stall is not big enough, If its pulsing like you say. Probably need at least a 3600 or so.

joe77

can you explain why a stall would make a difference I dont understand the concept.

t/a98

iTrader: (6)

I'll let the blind lead the blind. I have a big cam and stock converter (waiting on a 4l80 swap) but stock is so tight it transfers low rpm power more "stiff" feeling. The looser converter would absorb the pulse and what not.. I've been told a torque converter would fix my brakes.

Not to mention a big ole stall like 4k is just nasty on the street and strip. Stock is like 1800 so only going to 2600 is like nothing. Plus there is alot more to it like str.

iWon

iTrader: (13)

Yeah it's pretty interesting stuff... I suppose maybe I'll hold out on messing with the brakes until I get a 3600 stall, I was planning on getting one anyway this summer For now I'll just throw some new pads on and freshen up teh rotors / calipers.

The car is kind of half-tuned right now, I'm doing the cable loan tune with Solomon but had to hold off due to some crazy medical emergencies and a ton of snow here in WI lol.

Marinez28

iTrader: (1)

t/a98 is spot on although it gets pretty technical. Do a search on here and there are people that can explain it alot better. One of the first things I learned is never do a cam, especially a big one, without the stall first. Check out Yank, Vig, Circle D. There all sponsers on here and I am sure would be more than willing to set you up with the right one
Good luck!

iWon

iTrader: (13)

Probably going to go with a RevMax converter unless I can some how justify 800$ on a torque converter to my girl.... lol