Braking it down...

phazersonstun · Nov 19, 2007

I have a new problem...

First of all, thanks to all who have contributed to my past threads. You guys have helped me out a great deal and I appreciate it!

Down to business. My '67 Coupe has factory disc brakes. And the master cylinder was replaced a few years ago with a Bendix unit. The system is fully stock. I had to remove the master cylinder to detail the engine bay and ease the installation of the new motor. The problem is with the rear brakes. I am not getting any fluid to them. They are not working at all. I have bled them several times and still nothing. I adjusted the star wheel and am not getting anything. I cleared the line of all fluid from the the master cylinder to the junction at the rear. For some reason I can't get fluid through to the drums.

What can I do?

gsxrken · Nov 19, 2007

Sounds like you need to bench bleed your master cylinder again. It can lose its "prime" and you'll have trouble pushing fluid until you bench bleed it again.

phazersonstun · Nov 19, 2007

How do I do that?

Grabber70Mach · Nov 19, 2007

This should answer most of your questions.

http://www.superchevy.com/technical/chassis/brakes/0509sc_bench/index.html

phazersonstun · Nov 19, 2007

Sweet! Thanks for the link!

Is there anything else I should consider or look at?

Tim65GT · Nov 19, 2007

If you have a combination valve, it's possible the piston inside shifted and is blocking the rear output. It can be reset by pushing the pin back in so it's at the neutral position.

I don't know if '67s had them though.

Rusty67 · Nov 20, 2007

Tim65GT said:
If you have a combination valve, it's possible the piston inside shifted and is blocking the rear output. It can be reset by pushing the pin back in so it's at the neutral position.

I don't know if '67s had them though.

Tim, yes 67s have them and good call.

This is most likely the problem. These things are nothing but trouble and I'm surprized anyone besides me mentioned it. Take that POS out of there and replace it with a brass T block for the front and a straight through coupler for the rear. The only thing you loose when you do this is the brake warning light. If you can't feel the problem in the pedal that the brake warning light would indicate you shouldn't be driving a car.

Tim65GT · Nov 20, 2007

Rusty67
The only thing you loose when you do this is the brake warning light.

If it's a combination valve, doesn't it include the residual valve, proportioning valve, warning light switch and moving piston?

If you can't feel the problem in the pedal that the brake warning light would indicate you shouldn't be driving a car.

There's a lot of people that shouldn't be driving!

phazersonstun · Nov 20, 2007

I Have a pretty good idea of what you guys are talking about. Do you happen to have any photos of the new parts you are talking about and where I could find them?

Rusty67 · Nov 20, 2007

Any of the major parts houses should have a drawer full of brass fittings. Be prepared because I can gaurente you that they will be disorganized.

If you go to a typical parts house be prepaired for the moron parts jockey behind the counter to feel the need to assist you in finding what you are looking for. This is a BAD idea and they should know better. I have yet to have anyone working at a major parts house be anything but a hinderance when looking for brass items... I'm not saying everyone who works at chain autoparts stores are comepletely retarded, just the 90% of the ones I've delt with so far. Try a Napa auto parts, usually the people working there are above average intelligence.

For reference here are the brass T's
http://www.tperformance.com/street_rod_store/brake_fittings/brass_tee_fittings/

and the union/coupler:
http://shop.easternmarine.com/index.cfm?fuseaction=catalog.prodInfo&productID=5660&categoryID=156

Tim65GT · Nov 20, 2007

If your stock system was working fine, I don't see any reason to start replacing parts.

Look for a pin about 1/8" in diameter sticking out the end of the combination valve. Look on both ends. It may have a rubber cap over it. Push it back in.

The purpose of it is in case a leak developes in the rear, the pintle moves inside blocking the fluid to the rear, thus still having front brake operation. If the leak is in the front, visa versa (hold on, 'cause the back brakes only will give you a ride.)

Here is a picture of a combination valve.

bnickel · Nov 21, 2007

Rusty67 said:
Any of the major parts houses should have a drawer full of brass fittings. Be prepared because I can gaurente you that they will be disorganized.

If you go to a typical parts house be prepaired for the moron parts jockey behind the counter to feel the need to assist you in finding what you are looking for. This is a BAD idea and they should know better. I have yet to have anyone working at a major parts house be anything but a hinderance when looking for brass items... I'm not saying everyone who works at chain autoparts stores are comepletely retarded, just the 90% of the ones I've delt with so far. Try a Napa auto parts, usually the people working there are above average intelligence.

For reference here are the brass T's
http://www.tperformance.com/street_rod_store/brake_fittings/brass_tee_fittings/

and the union/coupler:
http://shop.easternmarine.com/index.cfm?fuseaction=catalog.prodInfo&productID=5660&categoryID=156

ouch, now that hurts, having spent most of my life working auto parts.

bnickel · Nov 21, 2007

Tim65GT said:
If your stock system was working fine, I don't see any reason to start replacing parts.

Look for a pin about 1/8" in diameter sticking out the end of the combination valve. Look on both ends. It may have a rubber cap over it. Push it back in.

The purpose of it is in case a leak developes in the rear, the pintle moves inside blocking the fluid to the rear, thus still having front brake operation. If the leak is in the front, visa versa (hold on, 'cause the back brakes only will give you a ride.)

Here is a picture of a combination valve.

oh, Tim not all combo valves have the pintle accessible like that. for instance the pintle on my 69 isn't accessible like that. there is a procedure in the 69 shop manual explaining how to re-center the pintle should this happen and it's kind of a pain to do, requiring a helper to do so.

Rusty67 · Nov 21, 2007

bnickel said:
ouch, now that hurts, having spent most of my life working auto parts.

No offense to you bnickel. I'm sure if you helped me out at a parts counter I would be very happy with my experience. Thats why I like going to Napa, usually the parts guys there know what they are talking about.

But around here, Autozone/Kragen/Pepboys just highers the most idiotic people around to sell parts. I've had people tell me that a part doesn't exist or that the store never carried it and then given them a part number and low and behold its siting on the shelf. I don't want to turn this into a "my local chain autoparts blah blah" thread but when you give a parts guy a part number and he doesn't know how to find it, there is a problem.

/end off topic

bnickel · Nov 21, 2007

Rusty67 said:
No offense to you bnickel. I'm sure if you helped me out at a parts counter I would be very happy with my experience. Thats why I like going to Napa, usually the parts guys there know what they are talking about.

But around here, Autozone/Kragen/Pepboys just highers the most idiotic people around to sell parts. I've had people tell me that a part doesn't exist or that the store never carried it and then given them a part number and low and behold its siting on the shelf. I don't want to turn this into a "my local chain autoparts blah blah" thread but when you give a parts guy a part number and he doesn't know how to find it, there is a problem.

/end off topic

i agree about the big name chain stores, i never worked at one of those, it was always local stores that had people who actually knew what they were doing. the idiots got to stock, pull and deliver parts. ok, my off topic bit is done as well. BTW, no offense was taken, i forgot my smiley.

Tim65GT · Nov 21, 2007

bnickel
oh, Tim not all combo valves have the pintle accessible like that. for instance the pintle on my 69 isn't accessible like that. there is a procedure in the 69 shop manual explaining how to re-center the pintle should this happen and it's kind of a pain to do, requiring a helper to do so.

I realize that, but I was just trying to help the guy out and cover another possibility. Maybe you could mention a couple of the steps to re-center a non-accessable pintle type combo valve.

BarnStang · Nov 21, 2007

Just read this in a 64 Galaxie shop manual. THis car had this problem. The "proceedure" by the book to reset the pin after it has shifted. Fix the leak that caused the loss of pressure in the brake circuit. Then, open the line that was ok. Press the pedal to pressurize the failed circuit, the good circuit will now have no opposition so the pin will slide back to center. You use the brake light to know when the pin shifts enough. Meaning the light will go out. If it goes out and comes back on, the pin shifted to the other side and you will have to reverse the process. Make sense? Barely.
Alternativly, you can contort yourself sideways and upside down in the engne compartment and take the little plug off the back of the combo valve, dropping your 3/8 wrench on the floor 52 times...saying "darn it, I dropped my wrench again!, and pushing the pin manually back into the centered position.
Or, just take it apart, take the combo valve out of he car, reset the pin, put it back in.
As long as the presssure is equal front and back, the pin stays centered and the light off.
My parts store bit. I had the MANAGER tell me they don't carry Autolite plugs..right. Too funney.

bnickel · Nov 21, 2007

you can also crack all the lines on the valve one at a time and have the helper stomp the pedal to help re-center the pintle and do it to each line one at a time until the light goes out. if that doesn't work repeat the procedure but lightly tap the valve with a hammer while the helper stomps the pedal, been there done that, one of my old bosses taught me this trick on an old LTD we worked on.

BarnStang · Nov 21, 2007

I would imagine that you would have to stomp the pedel pretty hard to get the pin to move back. I've never tried it that way. It should move with the line off the working side and you stomp hard enough.

Rusty67 · Nov 22, 2007

Mine is perminently stuck which is why that POS has been perminately removed from my car.

Braking it down...

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