Adding Power Brakes to 66 can't get bleed or any pedal

[buildinga55]

I bought a kit that included the booster, master cylinder, brackets etc. for a 66 chevy pickup. I split the brake line at the T on the passenger side and ran a new one to the new MC, I have done this a few times worked well. I cannot seem to get the brakes bleed. I even went and bought another master cylinder thinking the one in the kit was bad. I have bench bled it 3 times, checked all fittings, fluid will gravity flow out of the bleeders, but pedal goes to the floor and will barely even stop the truck at 5 miles an hour. I am at the point I dont know what to do. I have never had this issue bleeding brakes, I have probably bled brakes on 50 cars in my life and never had this trouble. I bought a booster for Drum Drum brakes since that is what I have on the truck. Any ideas?

[Big Fenders]

Got me too..do you need a proportioning valve on a drum/drum system?
Another thought...push rod too short?
Bob

[buildinga55]

The kit actually came with the little spacer that goes in the MC and brings the contact point up to about the surface of the MC where it goes on the booster. However, when you bolt the booster to the MC it actually preloads the MC which is not good, so I shortened the spacer to normal specs. After all the trouble I put an original spacer back in and still have issues with not a firm pedal and goes to the floor basically.

[geezer#99]

Did you drill a hole 1 1/2 inches lower on your brake pedal for the rod.

[luvbowties]

Originally Posted by buildinga55

I bought a kit that included the booster, master cylinder, brackets etc. for a 66 chevy pickup. I split the brake line at the T on the passenger side and ran a new one to the new MC, I have done this a few times worked well. I cannot seem to get the brakes bleed. I even went and bought another master cylinder thinking the one in the kit was bad. I have bench bled it 3 times, checked all fittings, fluid will gravity flow out of the bleeders, but pedal goes to the floor and will barely even stop the truck at 5 miles an hour. I am at the point I dont know what to do. I have never had this issue bleeding brakes, I have probably bled brakes on 50 cars in my life and never had this trouble. I bought a booster for Drum Drum brakes since that is what I have on the truck. Any ideas?

First, re-think your fluid-line setup/design and be sure it makes sense, as it's easy to err in its design. Linkages must be correct--including pedal to booster, AND booster-to-master. If you have mis-matched mc-and-booster, a *plug-spacer* may need to be slipped into the rear of the mc piston; else, the booster-shaft may enter too deeply into the mc piston, ending up with a too-short booster-shaft. *This plug-spacer can be easily made from the shoulder of a bolt, once you see just what is needed--using only a hacksaw and a bench grinder [and if you're quite picky, you may wanna use a big drill bit to slightly indent the booster-end of this plug-spacer].

Next BIG thing touted so much on our forum is the necessity of pressure-bleeding the system. Many have found no joy until they pressure-bled their system. This utilizes a pressure source to apply pressure to system thru top of master cylinder. Google will show you how to build such a 'tool'. Also, you may find an affordable one to buy at Harbor Freight. You may find the most economical way, for maybe a one-time application, is to take it to a shop that has their own pressure-bleeding system.

If you wish to know ALL the ramifications, do a search on here: you should find just about all the ideas, all the workable solutions, and all the failing solutions that one could want. Good reading, by the way, and lotsa replies to such threads.

Maybe start reading here, seeing a write-up and pics I replied to earlier:my replies at #3 and #5.
>> http://67-72chevytrucks.com/vboard/s...d.php?t=566217 <<

#5 shows 2 mc's--left one with no hollow in mc-piston, NOT needing a spacer-plug (regardless of booster), and requiring a booster with the short shaft. Right one shows a mc with the deep-hollowed-piston, which MAY need a spacer-plug (DOES require it IF the booster has the SHORT shaft going to mc--does NOT require spacer IF booster has the LONG shaft going to mc).

HTH,
Sam

[buildinga55]

No, it did not mention that was needed. That might be something to consider, however, the pedal feels like it is bottoming out. Is the hole standard to make this change? I know on my 55 chevy seems like I had to make a new hole.

[buildinga55]

The kit came with the spacer and if you use it in its shipped form, it is preloading the MC about 3/8", meaning the plunger on the MC is pushed in 3/8" with no pedal pressure. I have never heard of that, I have always read you should have just a slight amount of play at that point. I have tried the spacer at its normal length and cut down, still no brakes. I have bench bled the MC, used the gravity bled method, used the vacuum method and still cant get a decent pedal that will stop the truck.

The new hole in the brake pedal does sound reasonable as i have had to do that before, but this kit really came with no instructions. Just the booster brackets and MC

[buildinga55]

I did just find some instructions on line about the new hole that needs to be drilled, I will try that in the morning.

[luvbowties]

Originally Posted by buildinga55

The kit came with the spacer and if you use it in its shipped form, it is preloading the MC about 3/8", meaning the plunger on the MC is pushed in 3/8" with no pedal pressure. I have never heard of that, I have always read you should have just a slight amount of play at that point. I have tried the spacer at its normal length and cut down, still no brakes. I have bench bled the MC, used the gravity bled method, used the vacuum method and still cant get a decent pedal that will stop the truck.

The new hole in the brake pedal does sound reasonable as i have had to do that before, but this kit really came with no instructions. Just the booster brackets and MC

After all the above, I believe pressure-bleeding will cure the problem completely.

Re: drilling a new hole: As I see it, drilling that hole does more for pedal-feel than anything else. All else equal, its geometry makes the eventual push on the mc more difficult; this difficulty is offset by the booster; w/o the new hole, braking is really 'too easy'; with the new hole, the feel is more natural. But my experience, when adding power brakes, has shown NO better braking either with or without the new hole.

Please let us know--esp. since I've never had to resort(just lucky, I guess) to that technique. Should yours work, as have several before you, I will be even more-nearly convinced. Might invest in a pressure-bleeding system. Seems like it could even make the job easier for a one-man operation.
sam



Sam

[hopped up]

Make sure the bleeder screw is on the top side of the calipers. If they're on the bottom you'll never get the air outta them
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[buildinga55]

This is a drum drum setup, original brakes

[slepysal]

A little off the wall, but are the brake shoes addjusted right?.

[buildinga55]

I checked all the brake shoes tonight and tightened them up against the drums. Drilled the hole in the brake pedal, that brought the bottoming out up from the floor but still bottoming out. This is the second MC I have put on this, both doing the same thing, cannot seem to build any pressure. I have used the traditional gravity flow method, the pump and hold while squirting out fluid and tonight I used the pumping into a bottle at each corner and probably ran 2 bottles of fluid through the system and still, no pedal. Just bottoms out and if you put the car in a gear, the brakes will not even hold the truck still, that is how bad they are. The brakes are all new and were done prior to me wanting to put power brakes and dual reservour. This is driving me crazy I am ready to either get rid of the truck or get rid of the father in law!

[jayoldschool]

Did you bench bleed the master before install? Are you bleeding correctly? Helper pump/pump/hold, you open bleeder, close bleeder, helper releases?

[geezer#99]

Do you have residual check valves in the master or have some plumbed into the lines. Requires 10# ones for drum brakes. If not then air can be drawn back into the wheel cylinders each time you pump them.
I have 2 m/c here and checked and neither have check valves. Here's a link for what you need.
http://www.ebay.com/itm/Wilwood-10-l...0e9767&vxp=mtr

[jayoldschool]

Aren't check valves only needed with low mount masters?

[geezer#99]

Nope. Before discs became common the masters (whether single or dual) had check valves in them for 4 wheel drum set ups.

[buildinga55]

yes bench bled, no to external valves, from all I read, the 67 Camaro style drum drum MC I bought should have them installed internally. I am reading every possible thing about this, I am now to if the lid should be on or off of the MC during bleeding. You can get both answers, so maybe it does not matter. I have bled a lot of cars in my life and never had this trouble.

[geezer#99]

An original 67 camaro master would of had valves but any newly or rebuilt one might not.
Easy to check. Pull the line off and see if you can push a toothpick all the way inside. If there's a valve you'll feel it.
I have a dual master here that's listed for a corvette or camaro ( same number) with drums and it has no valves.

[buildinga55]

I will check that

[geezer#99]

When I bleed brakes I put the cap on the m/c loose just limit the mess. I have my helper pump up the brakes slowly. Down slowly to elimate any splash. Especially up slowly to limit any air ingress. HOld till I open the bleed. I close the bleed then up slowly.
Chack the master after two sets, refill if needed.
Slow and steady wins the race.
Just the way I do it. Others may differ.

[jayoldschool]

Originally Posted by geezer#99

Nope. Before discs became common the masters (whether single or dual) had check valves in them for 4 wheel drum set ups.

I understand. I thought you were talking about external check valves, not the ones built into the master.

[awbrown]

can you pump the pedal and get brakes??? if you cant then the <MC is not bleed or it is really air bound...make your own power bleeder by drilling a hole in the cover and hitting it with a few pounds of air pressure with the left rear bleeder open get a friend to help so you can see if it works , but I have done it by my self and you need to make sure you dont run the MC out of fluid....