I'd like to get some opinions from people who have upgraded to 1LE brakes or better as far as brake 'feel'. So far, the car has this for a brake system:
(1987 IROC)

-1LE front calipers/discs/brake lines (new)
-1LE proportioning valve as indicated for a 1987 car in all of the guides.(new)
-standard master cylinder disc/drum(new)
-rear 93-97 camaro brakes (equivalent to 89-up 3rd gen brakes) used, low mileage.
-low mileage booster (less than 11K miles), swapped to try and diagnose this issue.

so the bottom line is that the system works well, and the car stops rather quickly when above 20mph or so.....but when it gets closer to low speeds, the 'feel' is very hard. very hard, in fact, I cannot get the brakes to lock up at all. It almost feels like I lost vacuum to the booster, if you know what that feels like.

I basically think its one of two things: the prop valve is just not right. its 'right' as far as the car is concerned, but these cars just never had a 'good' valve.

the master cylinder is just the regular one, and due to the bore size, it just can't generate enough system pressure.

I see people hinting at this kind of 'feel' (I think), and I've never seen a decisive solution.

anyone got any ideas or know how to improve this?

 

The prop valve shouldn't affect your fronts locking up. Are you sure you got all the air out of the system? Does your engine have adequate vacuum at idle to operate the booster?

 

yep, the brakes aren't spongy at all, I'm sure there is no air. The engine is a rebuilt 350, with a zz4 cam. Can't say I measured the engine vaccuum lately, but it seems to have enough. Especially since when you are braking, the engine should be in decel and have good vaccuum against the closed throttle blades. I could be wrong however.....

 

I thought it was a possiblitly, what about a vacuum leak, or a clogged filter?

I think I have a similar brake setup, C4 vs 1LE front, you should be able to lock that thing up at any time.

 

I've verified I don't have any vacuum leaks, but what filter are you talking about? If you mean the engine air filter, they are brand new elements.

thanks for the help so far, BTW.....it helps to just get thinking maybe a differnt direction to figure out what's going on....

 

I'm refering to the filter inline with the vacuum line to the booster. Its a black plastic can. See if thats clogged or not.

 

that is an excellent suggestion! I have to see if that filter is still on there.....

 

what kind of pads are you useing when i 1st upgraded to the c4 brakes almost the same as 1le i used the cheap pads they seem to hook much better at overall but they turn the wheels black in about 3 days of driveing
but the ceramic pads dont dust much but seem to lack the low speed grab everyone is used to

but i have also noticed i cant lock up the brakes as easily with the ceramic pad then with the semi-metallic

if your pedel feels a little hard ive noticed thats normal with this setup
the vacume canister "orb of power" has nothing to do with the brake booster its directly connected to the manifold

the canister is ment for heater vents and other things

it seems everyone that dose a brake upgrade has some minor issue after but then again even with all the issues ive had i still stop better then with the stock brakes

as for wheel locking my car stock would lock the fronts with ease

my fathers iroc will lock its rear drums before locking the fronts but only has 27k miles on it

my car with the c4 fronts and drum rear would lock the fronts with a double pump

my car with c4 fronts and pbr rears stops evenly very hard to lock up but stops on a dime

a double pump unleashes a fury of wheel locking grip from all 4 corners lol

but also it will lock the fronts if i do a hard fast stop from above 60 but only locks the last 10 feet

but im useing the stock master cly and prop valve

 

anytime I have ever had a car with an overly stiff brake pedal, it was the brake booster dying on me.........

 

well, as I suspected, I do not have a filter on that vacuum hose, its a direct line through the 90' check valve to the manifold.

I have changed the booster already, to a very low mileage unit. I'm hoping I don't have to swap to yet another one.

As always, thanks for all your help so far.......

I would love to hear anyone else that might have a similar feel to their brakes!

 

I have a 1989 GTA with upgraded SSBC 1LE front kit. I installed it about 2 years ago, and from the day they went on the pedal has always been VERY hard. I can not lock the fronts up on demand (At high speed or at low speed) unless I stand on the pedal, which has caused several "near miss" incidences. Its about time I did something and I am glad to hear I am not alone.

Here is my current situation, I am looking for thoughts/suggestions.

1. The vacuum pressure from intake to booster has been measured with and is good.
2. The fronts have been upgraded to 1LE kit but the rears are stock
3. It has a stock setup master cylinder and booster
4. Fluid is new and lines bled thoroughly
5. Upgraded steel braided lines all around

a few things:
1. There is apparently a master cylinder that is compatible with a 1LE setup, and another part number that is not. Since my stock brakes were not 1LE, could I have the wrong master cylinder part number? Anyone heard of this before?
2. The booster and cylinder are old, but I have gone through the standard tests to ensure that they are operating properly and both "seem" good. Should I just replace the whole thing with a new ac delco system and cross my fingers that that is the issue?
3. Could there be an issue with having the 1LE upgrade on the front and not the rear?
4. Would I need to add a proportioning valve?

Im not sure what the next best move is...

 

The 1LE system by design is very high effort. See chart below. People swapping to the 1LE system and thinking they are going to get less pedal effort are mistaken.

As mentioned the prop valve is on the rear circuit, so that should not be affecting you, unless you have goofed the installation. Please confirm that the lines are not swapped somehow.

If you want to decrease pedal effort and everything else is working ok, you need to either go to:

calipers with larger piston area (will increase pedal travel and decrease effort)
master cylinder with smaller piston area (will increase pedal travel and decrease effort)
go to a larger rotor (will decrease pedal travel and decrease effort

John

Right click - view image for larger

 

That chart will def give some pause before upgrading your front brakes.

Good stuff, thanks...............

 

I've had poor braking / hard pedal on both my cars and here were my solutions:

Car 1 - 89 TTA with high stall and 210/215 cam, stock 1LE brakes with Hawks pads
Pedal felt dead and stiff, not much feedback. Was very hard to lock up wheels especially at low speed. I replaced the ENTIRE brake system and no improvement. When I added a $20 vacuum reservoir can, it will lock up the brakes at will anytime.
SOLUTION - VACUUM RESERVOIR

Car 2 - 89 GTA 350TPI with mild cam, Baer 13" front brakes with unknown pads, 1LE rears with unknown pads
Pedal felt OK, but the brakes just didn't have much "bite" at any speed. I flushed the entire system with 1 quart of DOT4, then filled with DOT 5.1. I replaced all pads with EBC yellowstuff. I took the car out and immediately did 10 moderate stops from 60MPH to 10MPH. The brakes are now INSANE. Feels like my friend's 350Z.
SOLUTION - FRESH FLUID AND HIGH QUALITY PADS

 

89GTA22 - what pads do you have and were they properly "bedded"?

 

Get this figured out yet ?

 

?