vipervetteguy

I bought a nice 66 L79 about 3-4 years ago. I immediately decided the manual brakes were sub-par. (I can mash them and not a hint of lock-up) I drove many 60s cars that would skid 1,2 3 or 4 tires when stomping on the brakes. My car has no initial "bite" at all. Each year I convince myself that for the type of driving we do, it's adequate, but I worry about what's over every hill I crest.
1. The previous owner replaced all calipers, rotors and pads.
2. I bled the brakes over and over and do have a hard pedal.
3. I replaced his pads with an aggressive Hawk 5.0 street pad that requires no heat to work. That made zero difference, so it's not a pad issue.
4. I replaced the single line MC with a dual line MC for safety reasons and hoping that might make a difference. Zero difference.
5. The rear calipers had a small leak so I replaced them instead of rebuilding them hoping for an improvement. Zero difference.
6. The MC rod is connected to the correct hole on the brake pedal.
7. The rotors were properly cleaned and the pads were bedded as per instructions.

I am reasonably mechanically inclined (I built a FactoryFive Cobra and have been doing brakes, etc. since the 60s)
This spring I want to have brakes I can trust in an emergency without going to a power brake conversion that I don't need to do. I don't want to give up again and say the brakes are good enough.
I've done my forum searches over the years, but wanted to start out with some fresh views now that I've listed 1-7 above.
I know that 60s brakes won't feel like a new ZO6, but I also know my friends' 60s cars will completely out-stop my Vette!!
Any suggestions as to where to go from here?
What am I missing here?

69z28&ss396

Soft lines are the number one culprit of soft brakes, after every thing you’ve said.

I’d also look at re lining the car too. (New brake lines)

vipervetteguy

I wouldn't think the hoses could make that much difference, but , at this point, I'll follow any advice. New hoses ordered today. Thanks.

davekp78

Try the cheapest organic pads from autozone or advance auto.

Frankie the Fink

In item #2 he said he had a hard pedal...

Hoses won't hurt but it sounds like the brakes aren't spongy, more like hard foot pressure doesn't result in commensurate braking..

My questions are:

1. Does the car brake in a straight line, just not with enough conviction ?

2. Is the problem that the initial application of the brake pedal doesn't immediately start some slowing effect until you really push it towards the toeboard (a common 63/64 problem) ?

Seems to be a disparity between the driver's application of force and what happens at the wheels...

Wrong bore size M/C ? Wrong bad distribution block, proportioning valve, residual valve ? Calipers wrong or bum rebuild ? Etc. ?

I'm thinking there are some mismatched items in the stew...

Tampa Jerry

Do you have the rod that connects the MC to brake petal adjusted correctly? A small adjustment can make a big difference. Is it possible that you have installed the wrong bore MC. They are different for power vs. non power brakes. Jerry

Robert61

If you sure certain positive that the brakes are bled correctly I would go buy a brake pressure gage. They're relatively cheap and you can measure the pressure at each wheel.

Nowhere Man

Did you check roter run out?

biggd

My question is, why don't you want power assist? It's not that expensive and it makes all the difference in the world!

Avispa

Yeah, that. If you have a power brake MC (larger diameter piston) the pedal effort for any amount of brake force will be noticeably higher than for a non-power MC, everything else being equal.

Nowhere Man

That’s all well and good but won’t fix his problem. Unless he has the M/C for power

biggd

Well we don't know if that's his problem, do we?
Anyway, I've never seen a car with manual brakes that was easy to lock up. I've worked on some cars with power brakes that are not easy to lock up.

Pop Chevy

Like others have said, I think you got the wrong size MC.

Nowhere Man

I can lock up all three of my dads 67’s with manual brakes

biggd

I guess I just don't have cement feet.

Nowhere Man

Either do I. Either Dad and I put the car/brakes together wrong or that is just how it’s supposed to work. I never really drove anyone else’s cars

jimh_1962

yesterday, I had to lock mine up due to an idiot driver. I had both feet on the brakes and one arm holding my son back to his seat on the passenger side even though he had a seat belt. The arm thing must just been an instinct from the old days.

It stopped but slightly sliding to a stop. I am running dual manual MC with front disk brakes. Also I added residual valves to the mix.

I wonder if the OP really did get all of the air out of the lines? I would take the top cover of the MC and check that there is no air in the system then bleed the brakes once more...

Would different using DOT-3 versus whatever else is out there with fluids cause an issue? The other thing is the calipers on correctly? Because that would definitely cause a problem too.

Also, how are the rear brakes adjusted? I had a pickup once where the rear brakes were not adjusted correctly causing the front brakes to heat up from being overworked and feel spongy. Just some things to look at...

biggd

I have power brakes in my 67 Coupe, everything is brand new, I bought the power booster with the master attached and I really have to stomp on them to lock them up. But I do have some big meaty tires on the car.

emccomas

I am also leaning towards wrong size master cylinder piston diameter.

Can you tell us what master cylinder exactly you have on the car now?

Part number?
Piston diameter?
Original application for this master cylinder?

63Corvette

Even drum brakes will lock up ALL wheels....ONCE!
Please note that the stock Delco disc brakes are used by ALL C2 Vintage race Corvettes...and they work VERY well. They are certainly able to lock up all wheels with no problem. I would find a "race" shop, not necessarily a brake shop and have them look at your brakes, because (as others have observed) there is something wrong (parts mismatch) with your brake system.