wrd1972

iTrader: (12)

Aslso if this helps.
Engine running when you push the brake pedal, you can hear a whooosh sound coming from the booster firewall area.
Is this normal?
Is this a smoking gun saying my booster is junk?

Kevin97ss

The woosh sound is normal unless its really loud. Sounds to me like crap pads, I've used customer supplied crap that were so bad I could litterally stand on the brake pedal and the car would barely slow down, after three of these stops the pads would be smoking. If your considering changing the pads anyways...try it as the next step in diag.

Lt1Porsche

iTrader: (6)

How much manifold vacuum do you have? hook up a gauge and read it. Dont use a sensor as a gauge. sounds to me you cam is causing low vacuum at idle and low speeds causing your booster to perform at an inefficient level causing a hard pedal.

speed_demon24

iTrader: (6)

My MAP reads 20 at idle and I have no problem kicking on the abs with a ton of reserve on the pedal. Then again I have C5 brakes with hps pads.

~BuMps AloT~

iTrader: (5)

The first thing that came to mind while i was reading your thread was the cam causing a low vacuum situation. When i pulled the bone stock lt1 out and put the 383 with the le 236/242 i thought the brakes really sucked also. I found that if i were to ease into the brakes it seemed as if they would slowly grad, but if i were to push a littler quicker and harder it would stop pretty good (Have Brembo eridaspeed front brakes on it). I talked to a few of my older rot rod buddies about what i was experiencing and they said that with that large of a cam it was more then likely causing a low vac problem, and that they use to just ditch the power brakes in favor of manual brakes to shed some weight.

wrd1972

iTrader: (12)

Weight savings is of no concern to me. Its not a race car.

My plan is to get a Hawk pads and a vacuum pump from Summit and try it out to see if there is an improvement. Its definitely a vacuum problem because the difference in braking between AC on and off is noticable. That extra loss of 2 points with the AC is obvious.

brucer

might try running a vacuum canister.

wrd1972

iTrader: (12)

I did. It did very very little to reduce the problem.

jaycenk

iTrader: (1)

sounds like bad pads. Have you swapped the pads yet? I find that Napa says everything of thiers is made by some name brand company but thier stuff isn't worth a **** compaired to the actual stuff. I run a Raybestos HD pad but it is squeeky as hell. It will do the job though. Stops real good. If you have not changed pads try a fresh grind on the rotor if you can and new pads and burn them in slow. I have better long term preformance when I burn the pads in real slow. They mate better and there is no high speed glaze at all on the pads or the rotors.

wrd1972

iTrader: (12)

Yeah ithat makes sense. I am going to get some Hawk HPS pads on before the vac pump.

bills02raptor

iTrader: (4)

Did you get this figured out? I am having the same issue on my 95 LS1 Camaro, all the brakes are LS1 as well and the just don't feel as good as my 96 TA. If you hit them hard its stops okay but if you let up and hit them again right away its like there is nothing there. I wonder if its cam/vacuum related in my case.

wrd1972

iTrader: (12)

Vaccum issue due to the cam.

If I hard brake without pushing the clutch (engine makes ~20" vacuum), it brakes hard and the ABS easily kicks in.

If I brake while pushing the clutch (engine makes ~10" vacuum), it does not stop as well.

I am going to install a vacuum pump this winter.

speed_demon24

iTrader: (6)

I still think it's something else. I have the same vacuum as you and my brakes work fine under all conditions.

bills02raptor

iTrader: (4)

I just tested my vacuum and it was 9", hmmm maybe a leak?

wrd1972

iTrader: (12)

Its the vacuum. I have ruled everything else out.

Also a buddy of mine has a Miata with a Ford 331 (fast MF'r BTW) and it has a 224/230 cam just like mine and his vacuum readings are nearly the same as mine. He was complaining about his brakes too. One day were out driving around and I tell him to panic stop and the brakes would not even lock up with race pads and of course he clutched.

I then told him to panic stop and NOT to push the clutch and he laid stripes all the way down the road.

Same exact symptoms and remedy as mine.

bills02raptor

iTrader: (4)

Just an idea but I removed my intake tonight to verify there are no leaks or anything unusual. When I took it off I found the little rubber coupler that connects the HVAC hose to the intake had cracked on both ends and was leaking. I had noticed the vents taking a long time to go from floor to face and this must have been why. Just an idea, I will know more tomorrow when I hook it back up as this is also right where the booster gets its air from so that leak would have reduced that as well.

Paul Bell

iTrader: (9)

First, the master cylinder is different between the LS1 brakes and the LT1 brakes. As the LT1 rears have pad retraction springs to let the parking brake system function, it’s master cylinder has a residual pressure valve to hold some PSI to them. The LS1 brake system does not need this hence the different master cylinder. I HAD great brakes until I swapped the LS1 rears to LT1 to clear some drag rims I have. I had to install the LT1 master cylinder to have great brakes again. The LS1 master cylinder is a bolt in EXCEPT for one fitting that’s a different thread. You’ll need to get an adapter.

Second, as I’ve been fooling with brakes longer than most around here have been alive, I’ll advise you to find a reputable brake shop that can do a pressure bleed for you. This will also eliminate any issues you might have from the ABS or by not bench bleeding the master cylinder.

You could buy a pressure bleeder on eekbay, they’re like a hundred bucks and a great way to really do the job right. It’s pretty cool: You pressurize the system with a tank of fresh fluid. Then you crack the bleeders with a hose on the bleeder into a clear jar. The tube is in fluid in the jar and you can see when the fresh fluid is flowing and the bubbles stop. Always start at the furthest corner and work your way to the towards the master cylinder. Repeat-if you really wanna be sure, like me.

Wicked94Z

iTrader: (26)

looks like I'm pulling ~5 inHg at idle... it is a stiffer pedal, but i had no trouble locking up the skinnies the other day. No engine braking with this trans either, so i'm probably not pulling more than 8 or 9" ever.

wrd1972

iTrader: (12)

Did you mean you had to install the LS1 MC?

I have a LS1 and a LT1 MC and I disassembled them for analysis. Internally they are identical however one of the two outputs is the next size larger. I cant recall offhand if this was the front or the rear. If its the rear, maybe that larger line has something to do with it. It was the difference in the fitting that resulted in my not installing the LS1 MC.

Can anyone with a real LS1 car tell me if the main brake line to the rear is the smaller or larger size?

As far as bleeding them. I had a professional bleed them out so I am very confident they are done correctly. I have noticed in the past that anytime they were not bled right, the pedal was spongy and I got a dash light.

Paul Bell

iTrader: (9)

I have a LS1 car. I went to LT1 rear brakes. To get them to work properly, I had to install the LT1 master cylinder. It made a difference.

Prior to the master cylinder change, using the LT1 rear brakes with the LS1 master cylinder wasn’t great. Upon stepping on the pedal, it would first pass what I would call a "free zone" as the pressure went to the rear brakes to move the pads pulled back by the springs. After this initial free movement of the brake pedal, it would "catch" and the brakes worked normally.

It’s the front line that has a different thread fitting. The line size is the same but the fitting on the LS1 master cylinder has a corse thread. The lines, fittings and threads going into the ABS module are the same through the years.