vipervetteguy

The brakes on my 66 327 are poor. I am a cyclist with strong legs and I cannot even start to lock up a wheel. Due to some leaking, I replaced all of the calipers. We did a good bleed and have a very hard pedal. I am running Hawk's new 5.0 street pads which are their most aggressive and need no heat to perform well. The car has what looks like an original single master cylinder. The correct hole on the pedal arm is being used. I've read that a non-power brake car like mine will stop very well. I don't see where a dual mc conversion will help out. I'm thinking I just need a new mc for some reason. Any opinions???

Bluestripe67

Are you panic slamming the brakes, and they won't lock up, i.e, slide the tires? Dennis

JohnZ

Nothing is going to change until you pull the Hawk pads and replace them with OEM-type organic pads, or install power brakes. The Hawk pads will eat your rotors, which commonly last well over 100,000 miles with the OEM organic pads.

vipervetteguy

Doesn't matter if I stab the pedal or just press VERY hard........car just stops poorly at best.

vipervetteguy

I had new OEM organic pads before the Hawks and the brakes were even worse. Being a low mileage car, rotor life is no concern to me. Safe brakes are my goal.

toddalin

Did you turn the rotors? Maybe they are glazed.

JohnZ

When I got my manual-brake '67 many years ago, the PO had installed some hot-dog semi-metallic pads, and the pedal effort to get normal braking force was beyond unacceptable. I pulled them and installed some standard Raybestos organic pads ($20 per axle set), and that was the cure - normal pedal effort, progressive brake response like you'd expect.

If your car was worse with organic pads than it is now with Hawk pads, you have some other brake problem. Is your pedal pushrod clevis in the top hole where it belongs?

vipervetteguy

I thoroughly sanded all the rotors with red garnet sandpaper (that type leaves no adverse material on the rotors) after sanding, I wiped them down with Brakleen. The brakes just have no bite.

toddalin

When I put disks on front of the '64, they had semi-metallic pads. The pedal effort was very hard (I'd often use both feet), but the stopping was terrible; especially that last bit just before the car actually settles to a stop. (Sound familiar?)

I replaced the pads with the Andy Porterfeld Street compound and the brakes are now great with much less pedal effort. I was even able to bias more pressure to the rear before panic lock-up which means that the front stopping power was improved

While you say that the Hawk's are better than what was on there, unless you put them on new, how do you know that what was on there wasn't contamintated with brake fluid so wan't doing it's job to begin with? Maybe anything would have been a step up.

kellsdad

If your brakes worked OK before you changed the calipers, and they don't work afterwards, the problem might be ........ the new calipers. Are they the stock replacements? Same size as before?

jim lockwood

The brake behavior you are describing is consistent with the master cyl. bore being larger than stock. It's also consistent with other causes, but you've pretty well ruled them out.

I'd pull the master cylinder apart and check the diameter of the bore.

Jim

vipervetteguy

Yes......that was the first thing I checked.

vipervetteguy

I might not have been clear in my explanation. New calipers didn't change brakes at all, just stopped the minor seapage.

vipervetteguy

What bore would be correct for a non-assisted car?

kellsdad

If they were bad before and they're bad after the new calipers, pads and cleaned rotor, then I agree with Jim Lockwood. Something is not stock, quite possibly the master cylinder. If the master cylinder bore is too big, the force of your leg is being spread over a larger area reducing the PSI in the fluid going to the wheel cylinders. Result: too little pressure pushing the pads to the disc.

ghostrider20

My notes for my 65 say 7/8"

MikeM

The '65 master cylinder should look like/similar this:

http://www.cssbinc.com/1965-1966-cor...er-brakes.aspx

1" cylinder bore.

7/8" bore cylinder was used on drum brakes.

vipervetteguy

That's exactly what the one in the car looks like. I wonder if somehow it doesn't have the 1" bore.

Canuck62

I'm with Jim,,, i think you have a master cylinder problem
if you pedal is firm,,, almost hard i would guess the cylinder is not releasing completely after applying brakes
I had this problem on my 62,, i know different master,, but it was pointed out to me by a forum member that the cylinder could be locking up... he told me how to check and he was right
I dont know how to check yours,,, but it might be worth looking at

MikeM

FWIW, I've never seen a MC like that used for anything other than '65-'66 Corvette with manual brakes and they're all 1" bore. I'd SPECULATE that even if the bore was 1 1/8" you should still be able to slide the tires on a stop with heavy pressure and OEM type linings.


If it were me, I'd head to Auto Zone or other local parts store and buy the cheapest lined organic pads they had and put them on the car and figure on that fixing the problem.



Grasping at straws, make sure someone hasn't installed a pressure regulator in the lines somewhere before the first junction in the lines.

Another long shot, make sure the pedal will go all the way to the floor without hitting something under the dash.