bleeding brakes.

[Gunther]

Hi
I bled my 68 Vette brakes and at the same time replaced the fluid.
I only used the caliper bleed ports and it seemed to have worked out fine ( I hope ).
What are the master cylinder bleed ports for ( 2 each ) ?
By the way, no power brakes on this config.
Thanks Gunther

 

[jsimpson]

There are no master cylinder bleed ports. You bleed the master cylinder at the brake line connections when you first install it.

 

[Scott81]

Hi
I bled my 68 Vette brakes and at the same time replaced the fluid.
I only used the caliper bleed ports and it seemed to have worked out fine ( I hope ).
What are the master cylinder bleed ports for ( 2 each ) ?
By the way, no power brakes on this config.
Thanks Gunther

Gunther,

You should be fine using the bleeders on the calipers. Some older Vettes came with master cylinders that had bleeder screws on them, not sure why though. I've been told by several people who work for companies that make calipers or deal with brake systems the best way to bleed the system is by gravity. What I did with mine was to put the car on jack stands to get all 4 wheels off the ground, take the tires off then attach some rubber hose to the bleeders. Once I had the hose attached I used old milk jugs to catch fluid and opened the bleeders, keep an eye on the fluid level in the master cylinder making sure not to let it run dry. After no more bubbles come out of the bleeders tighten them up, make sure you have plenty of fluid in the MC and put the cover on. Then test the brakes, see if they feel firm. If you want to also do the pump method that won't hurt anything. BTW, this is also a good way to flush your lines out.

I bought clear rubber tubing at a pet supply store, used for fish tanks, it's cheap and no mess to clean up in the garage.

 

[jsimpson]

Gravity bleeding didn't work for me and is not recommended by any Vette shops down here. I pressure bled mine, trued the rotors, and solved my braking problems.

 

[Gunther]

Hi Jsimpson,
Believe me, my car's MC has 2 bleed ports, they are not grease nipples.

Hi Scott81
I used the pedal pumping method and it worked out fine.
Had lots of air in the back calipers, both of them ?
Also the aft fluid was very dark.
The front had no air and the fluid was clear.
I first emptied the MC by sucking out the fluid. Refilled it with new fluid and than flushed and bled all calipers till new fluid appeared.
Hope it's ok now. Pedal feels much more firm now.

By the way, this are non PB .
Thanks Gunther

 

[jsimpson]

If you keep getting air in the back calipers, check the rotors for runout with a dial caliper. Anything mre than 8 thousandths will cause air pumping. You can sometimes get them within tolerance by rotating them one lug at a time and rechecking. If not, buy a shim kit and shim them.

 

[ChuckG]

SUPPOSEDLY...master cylinders with the 2 bleeders were used for power brake cars. Master cylinders used with non PB cars did not have the bleeders. Why? Don't know. I gravity bleed mine, and when I'm happy, I go back and use the old "pump the brake and hold" method. Chuck

 

[Gunther]

Hi ChuckG

Do you think that my MC is a power brake unit.
The car has no power brakes. I even think never had.
What's the difference between both MC's ?
Don't you need special MC for power brakes and wiceversa ?
Thanks Gunther

 

[Glassman]

I have some pictures of my cheep power bleeder. Any one can make it and is simple to use. Just email me for them. I have been using this one for about ten years at least.
In case you are inclined to try to shim the run out in the rear rotors be aware that they must first have the half shaft removed so it doesn't influences the reading.

 

[jsimpson]

I didn't remove the half shafts, and mine are fine now. However, a rear wheel bearing job is due in the futrure. They aren't noisy, but have a lot of play; and that's rough on rear tires!

 

[ChuckG]

I truly don't think there are any differences in non PB and PB master cylinders other than the bleeders. I think that they are the same ID/OD, etc. I honestly don't know why one uses bleeders and the other doesn't. Chuck

 

[wolf_walker]

Generally a power and non MS will have different size pistons, similer to how a non power stearing box will be geared different.

Or I could be full of crap after about three hours sleep...

 

[Glassman]

There is no way you can get a true reading of end play or run out without disconnecting the half shafts.

 

[jsimpson]

neither my 78 power, nor my 70 non-power has bleeders. Don't know why you would need them anyway.

 

[BobbyBJr]

neither my 78 power, nor my 70 non-power has bleeders. Don't know why you would need them anyway.

Hello,
My 75 has the bleeder ports on the master cylinder, although I have never opened them for any reason. I plan to place an order for a complete brake kit to Vette Products in the next day or so and they have asked if I have power or nonpower brakes. I thought I had powered brakes, but now am questioning that. How can I be sure?

Bobby

 

[jsimpson]

Do you have a big vacuum can between the master cylinder and the firewall? If no can, then you have non-power brakes!

 

[BobbyBJr]

Do you have a big vacuum can between the master cylinder and the firewall? If no can, then you have non-power brakes!

Okay, that is what I thought, and yes, I have the can. Needless to say, I don't call myself a mechanic by any means. The Vette is just a hobby for the wife and I to play around with.

thanks,
Bobby

 

[jsimpson]

Interestingly enough, the non-power brakes on my 70 have a lot better feel, and are a lot less trouble, than the power brakes on my 78!

 

[ChuckG]

Gunther: Did some checking in the NCRS JG. Both PB and non PB original master cylinders had the bleeders. Some replacement ones....both types...did not have the bleeders. So...I was incorrect about that one. Sorry. I would think that there would be a different ID to the piston for the 2 different styles, but I do not know what that difference is. Chuck

 

[wolf_walker]

"Interestingly enough, the non-power brakes on my 70 have a lot better feel, and are a lot less trouble, than the power brakes on my 78!"


Nature of a good non-power system, been my preference for years. I dont like touchy brakes on a performance car.
I absolutly love, love, love a well setup manual four wheel disk setup...