First off I did a search but could not find a cure to my problem. 56 Chevy truck 70 Camaro front disks rear drums 7" booster under floor. I have never been happy with the brakes could never lock them up. I changed the pedal ratio to 7-1 brakes got a little better but still no lock. This weekend I changed the 1-1/8" master to a 1 " and added 2# check to the front 10# to the back. Without the motor running brakes feel good. Good pressure no leaks pedal returns to top of stroke. With the motor running and vacuum booster the pedal goes down a little farther which is expected but will not return to top of stroke. It will eventually creep back up. I have someone interested in buying the truck and told him I would look into repairing the brakes. So if anyone has any ideas i'm all ears. Or eyes in this case. Thanks Sent from my iPhone using The H.A.M.B. mobile app
Brakes are really a personal thing. 1st point.... Since you have never been happy with them, maybe the whole system needs to be evaluated. Since the truck has a buyer......figure the cost and effort for you to possibly re-do it and deduct that from your asking price. Let the new owner deal with it. What you do not want to do is pass on a problem that you and the new owner think is fixed but it is not. 2nd point.... Withdraw the vehicle from the market and do not sell it until the system is truly fixed and confirmed by putting a few miles on it. I would let the new owner fight this battle.
#1 I did evaluate the system that's why I replaced the master added check valves and increased pedal ratio. # 2 I don't pass my problems onto someone else. I did remove it for sale 3 weeks ago because I wanted to make a new bed floor replace ball joints and give it a complete inspection. I'm not happy with a sale until I know the new owner is completely happy with his purchase. Sent from my iPhone using The H.A.M.B. mobile app
6:1 is correct pedal ratio for power brakes. The 1 1/8" bore MC is also correct for a disc/drum system. Problem lies elsewhere. All components must move freely. Start at each corner and examine movement when brakes are applied and then released. Something may be hanging up. Disconnect pedal from booster pushrod and make sure pedal moves freely both ways. I've seen pivot bushings that were egg-shaped and caused this problem--seriously. Booster could also be defective in that it is not returning properly. What type of brake fluid is in the system?
One problem is the 7" single booster which is very marginal. Much better to use a dual 8". Second problem is no pedal return spring. You really need one. Normal power brake pedal ratios are around 3:1, while manual are 6-7 :1.
Ok thanks pedal ,pushrod, booster is all free moving no bind. Even if I pull the pedal up by hand the master and booster is slow to return. The pedal had no problem returning with the old master and no check valves it also has no problem returning with the engine off . I do have a metering valve in the system after the master and before the check valves. Remember my master is below the floor. I think I'm going to start with removing the check valves or put the 1-1/8 master back on. Sent from my iPhone using H.A.M.B.
Maybe not so much lockup but stop a hell of a lot better than they do now. Sent from my iPhone using H.A.M.B.
Well for one thing, a non-ABS system should lock something up, it's up to the driver to not lock them up. If a hydraulic system was put in and doesn't lock the tires up, then something is not right. Yes I know that skidding is not best fo braking, but the system should still have the ability to do it. A poorly setup non-abs system that does not lock up the tires, is just trouble. Think of a 5-10 MPH roll into a parking lot, kid runs out in front of you, and you hammer on the brakes, sat that speed you won't skid, but stop fast enough to toss you forward in your seat...now if it creeps to a stop, you're digging a kid out from under your ride.
I see no mention of a pedal return spring or that the adjustment between the master and booster is correct. Chris
I agree on the 7 inch booster not being enough. In the past year I have had a 35 Ford and a 64 Merc full size car with brake conversion and neither were confidence inspiring as far as brakes. Changed to an 8 inch booster and much better brakes. In face the Merc pulls a vintage airstream on long trips now without worrying.
Distance between booster and master is .010. I had no spring return on the pedal with the 1-1/8 master and it returned fine just not enough pressure. The check valve is only allowing air to flow one way. Tomorrow I'm going to remove the check valves. If I still have issues I'll put the old master back on and start from scratch. Sent from my iPhone using H.A.M.B.
Still been fighting with these brakes. Went back to the 1-1/8 master and have good pedal with and without the booster and pedal returns to top of stroke. I don't know why the 1" mc won't return. I think that if my brakes still army better I'm going with a dual 7 " booster. Sent from my iPhone using H.A.M.B.
Could the 1" m/c possibly have some sort of built-in residual or check valve? Are you sure the front and rear brake lines are oriented correctly at the master cylinder? This kind of stuff can drive you nuts...
Mabey its Me but I don't understand some People, they Decide to Change there Brake system over to Disk When I was Racing my 64 Chevelle had 4 wheel Drum Brakes! the Car had a BBC putting out over 800 HP & doing 9's in the Quarter mile & you know what The Car Stopped Great. That was in the 70's Just my 3.5 cents Live Learn & Die a Fool
I'm running a 70 Camaro clip on a 56 Chevy truck. It came with disc. Clay mart ,no check in the master and the lines are right. I pulled the back drums off and found they were only hitting on a 1/3 of the shoe. Had drums turned today and got new shoes. Check the arch of the shoe to the drum, looks to be good. Sent from my iPhone using H.A.M.B.
Master cylinders, like everything else these days, seem to be hit or miss. I had to put 3 on my newer pickup before I got one that worked. The worst part was that the original one worked fine except the rear seal leaked.
Dot 3. I have a good hard pedal I can stand on the pedal but still won't stop right. I think most of my problem is with the size of the rear wheels 20x10. That a lot of wheel to stop. I'm thinking of putting disk on the back. Sent from my iPhone using H.A.M.B.
And then you will have compounded your problem. Have you thought of eliminating the booster and seeing how well it stops?
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