I came to the realization that my cam was too big for the vacuum booster. Poor vacuum = poor/dangerous brakes. Didn't want to go the electric vacuum pump option, so I converted to manual brakes. here is my setup...

Wilwood 4-caliper front discs
stock rear drums
Wilwood 7/8" bore MC for manual brakes
Factory "hold off" valve plumbed to the front
10 psi RPV on the rear port
brake pedal pin in the top hole now.

OK, I can finally lock up the wheels, but the pedal feel is not what I had expected. I understand that with the pin in the top hole and a small 7/8" MC, it will need more travel to stop the car, but it feels like the first 4" of pedal travel do hardly anything. I have to stand on it pretty good to stop the car and even then it feels rubbery/spongy. I bench bled the MC and power bled the entire system. Ran over 2 quarts through the Motive Power Bleeder through the system. Get a good clean stream of fluid at all 4 corners. I never had a manual brakle car before. Is that what the pedal is suppoed to feel like? Spongy and travel 3/4 the way to the floor before the car can stop well? It is the first time in years though that I have been able to lock up the wheels. Just not sure everything is right. Opinions, experiences to share? The pedal feel now is not very assuring.

Here is what piratejack.net (http://www.piratejack.net/Tech-Support/FAQs-Proportioning-Valves.html) have to say about bad RPV:

What are the symptoms of a bad residual valve?

The brakes will be very spongy and you will need to pump the pedal to get good brakes.

The fact that you have a smaller M/C must not help on the pedal travel if the valve is defective.

I've just finished writing this post (http://www.chevelles.com/forums/showpost.php?p=2747243&postcount=2), which might be related to your problem.

Jack.
RPV is brand new. Red anodized version that I actually bought from Pirate Jack. The brakes donl't ge any better if I pump them either. No change from the first push to the floor compared to several pumps of the pedal and then push to the floor. I think that tells me the RPV is good. Not real sure what a manual disc/drum pedal feel is considered normal??:confused:

sorry to hear its still not working out well, mine has the same master to the factory combo valve and that is it. The first 3/4" or so of mine does nothing but by half pedal the brakes are fully locked up

Hi Jim. Just some observations and suggestions. 1 Are the rear brakes adjusted correctly?. 2 What is the condition of the brake hoses, front and rear? Are they "ballooning" when you hit the pedal ? You can also lengthen the rod between the pedal and MC , but not too much or the brakes will drag. Been there done that. Also those multi piston calipers with more than one bleeder can be a royal PITA to bleed.

I'd adjust the rear brakes out as far as possible. Manual brakes are really touchy and tricky. I have a 7/8 bore on mine and I can get a high hard pedal. I don't have drums though.

Manual pedal travel is by default going to be longer than a power setup.
at what point in the pedal travel is decently firm?

sorry to hear its still not working out well, mine has the same master to the factory combo valve and that is it. The first 3/4" or so of mine does nothing but by half pedal the brakes are fully locked up
The first 3/4"?? I wish I had that. Mine is the first 3"" of basically nothing. You have the Wilwood 7/8" and rear drums?

Hi Jim. Just some observations and suggestions. 1 Are the rear brakes adjusted correctly?. 2 What is the condition of the brake hoses, front and rear? Are they "ballooning" when you hit the pedal ? You can also lengthen the rod between the pedal and MC , but not too much or the brakes will drag. Been there done that. Also those multi piston calipers with more than one bleeder can be a royal PITA to bleed.
I have the rear brakes adjusted so that the drum is a bit snug to get on, there there is a slight hint of drag when spinning it. Break hoses are new and braided stuff. No rubber hoses. Bled the inboard and outboard bleeders on the front calipers, no air seen.

I'd adjust the rear brakes out as far as possible. Manual brakes are really touchy and tricky. I have a 7/8 bore on mine and I can get a high hard pedal. I don't have drums though.
I am pretty sure I have the rear shoes adjusted out as far as I can and still be able to get the drums on/off. I turned the star adjuster until I could not get the drum back on, then went about 3 clicks back the other way. Drum is a snug fit.

Manual pedal travel is by default going to be longer than a power setup.
at what point in the pedal travel is decently firm?
Never feels decently firm. Still feels a bit soft even when the wheels are locked. But that is just about at the floor.
I don't know,...maybe my bench bleed was not sufficient on the MC?? It did seem difficult and time consuming to get all of the air bubbles out of it. I was expecting about 2 minutes or 10-15 strokes, but it took about 10 minutes.

no I have a $20 napa master from a 78 malibu, I have heard sometimes the willwood masters do put up a good fight, but I have not used one

no I have a $20 napa master from a 78 malibu, I have heard sometimes the willwood masters do put up a good fight, but I have not used one

Was this a direct bolt in, I'd like to change to something lighter in mine.

... I have heard sometimes the willwood masters do put up a good fight.

As far as what??

Is yours the one with a plastic reservoir or does it look like a regular cast iron MC?

i have read some things on here that people are getting bad wilwood MC's. the seals dry up in them, and they are impossible to bleed
i dont have one, its just something i read.

good luck man.

aaron

I'm going to pull the MC again and re-bench bleed the thing. It did take quite a bit of time to do it yesterday. Maybe it wans't quite done. I would push the rod in about 20 times and see no air bubbles, then on the 21st time, I'd get some bubbles. So I kept going unto I saw none. Maybe I should have given it another 50 pumps to be sure.:sad:

yep, its all iron and a direct bolt on, and like Aaron said sometimes the wilwood masters seem to have some odd problems from time to time where they just dont work. On the upside though they are one of the few that offer a rebuild kit for their masters.

That's a good idea Jim. Are you bleeding the brakes starting with RR,LR,RF,LF starting with the outboard bleeder? I've found the Wilwood calipers to be a pain to bleed compared to a factory caliper or wheel cylinder. I like to vaccum bleed them and then let them gravity bleed for a little while. I take a flash light and look for air bubbles.

One other thing may be a miss matched master cylinder. With drum brakes, you may require a 1 inch piston. I don't know, there are formulas or just call Wilwood. The larger bore with decrease pedal travel but will require more leg force. The Wilwood masters only have a stroke of 1.1 inches. If you have room, you could always drill a higher hole you just need to make sure you have enough stroke. It doesn't take much. An inch will cut pedal effort in about a 1/3rd.

Yes, bleeding the back drums first RR, then LR. Then I go to the front and do the RF, outboarb/inboard, then LF outboard/inboard. Then I went and repeated the cycle all over again.
....just to complicate things more, I posted this. http://www.chevelles.com/forums/showthread.php?t=309028
Hope I did not dig myself into a hole with this one.:(

Bench bled again, had a good amount of air. So I kept going until it all cleaned up. Looked good for a while, I let it sit and then plunged it a few more times....bubbles. Pulled the boot off of the rear and I see brake fluid leaking out of the bore.:mad:
Gotta call Wilwood tomorrow and see what they say. Probably going to recommend a rebuild although I don't know why it would need one, it is brand new!

hooray, at least you got it figured out

hooray, at least you got it figured out

Yea, hopefully. My luck,......... I'll rebuild it or replace a seal, it will bench bleed good then I will have the same spongy pedal after i put it back in. :sad:

My first Wilwood had a blown seal right off the shelf. Or, as the tech explained to me, 'some of the big online retailers have inventory that sits for a while. If the seals dry out and duct could accumulate in the bore, the very first press of the plunger could damage the seals.'
I bought my M/C from Jegs, they let me print out a return tag and they shipped me a new one once they recieved the defective one.

Yea, hopefully. My luck,......... I'll rebuild it or replace a seal, it will bench bleed good then I will have the same spongy pedal after i put it back in. :sad:

I know the feeling bro, we have all been there.

well, whats the deal now ??? any word from wilwood ???

well, whats the deal now ??? any word from wilwood ???

I have been out of town all week for work. I am in Vermont, so I have not been able to touch the car since last weekend. I did call Wilwood on Monday. He told me:
1) That MC can be a bitch to bleed because of the ports on both sides. I'll have to bench bleed it at various angles in my vise and do some slight taps with a mallet to get the trapped air bubbles loose in various locations.
2) If it had sat at a retailer (I didn't buy it directly from Wilwood) for quite some time, the seals may have dried out. He wants me to clean the bore, lube the seals with fresh brake fluid and bench bleed again. If it continues to give me problems, send it back for an exchange. I'll try it again on Saturday.

Im using a 68 camaro 1 inch bore manual master in my 69 chevelle,and it will put ya thru the windshield if you aint strapped in,lol.Got it from NAPA for 40 bucks,plumbed it into existing lines,bled the system,and away I went.I cant tell the difference in pedal pressure from power to manual at all.Definetely one of the best changes Ive made to this car.Manual disc for a street car with a RADICAL cam is the only way I will ever go.The motor compartment looks so much cleaner and zero issues with drivers side valve cover interference.

Im using a 68 camaro 1 inch bore manual master in my 69 chevelle,

Well, if I can't get this Wilwood to work, I may go that route or the 77/78 Malibu 15/16" MC.

FENCO M1751 Reman from Autozone...$16.99
Ask for a "1970 Camaro Manual Disk"...15/16" bore I think.
One of the best changes I ever made to my '69...Got rid of that big, ugly valve-cover-binding, clutch-linkage blocking, "is it vacuum leaking" clunker of a booster. Wish I'd done it 25 years ago.
I have a 274 grind cam BB. Takes all to worry out of hard stops. I'm thinking the pedal goes down 2-3" before really solid. That's normal when using more leverage at the top hole.

Got rid of that big, ugly valve-cover-binding, clutch-linkage blocking, "is it vacuum leaking" clunker of a booster.

Now that's funny.:D
Thanks for the info. Gives me more options.

Just because things cost more does not mean they are. I use stock replacement items and have great brakes. I am thinking of changing the rears to the Parise Dyno setup. Does anyone know where to get 11" back plates for the rear. The company that supplied GM and others went bankrupt.

good deal hope it all works out, mine are a huge improvement over the stockers