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I've been having brake issues for a few months now. I ended up buying a brand new brake booster with a dual master cylinder. I figured splitting up the front and rear brakes would help make it safer. The booster works great. I can hear the reservoir filling up after I turn the car off, the vacuum reservoir? Anyway, I figured it was time to replace all brake shoes and inspect, since it's been at least 5 years, maybe more on the fronts.
I replaced all 4 sets of shoes, only to find that as I drove the car and it warmed up, the pedal travel would get less and less. The brake pedal would become stiffer and you BARELY had to put any pressure on the pedal to get it to halt. I would smell the brakes warming up. When I parked in the garage, I felt the rims and both fronts were HOT. You could smell them too.
I decided to swap out the wheel cylinders and install brand new ones. I cleaned the backing plates, I replaced hardware, and inspected the shoes. Shoes looked good. I thought replacing the wheel cylinders was the issue, since they both looked rotten and were leaky. I figured they were keeping the shoes against the drums, causing them to overheat and never to return, which would explain the harder and harder, less and less traveling pedal as I drove the car, along with the brake smell.
Turns out, it STILL did not fix this issue. I decided to check the rears out and simply replace those wheel cylinders as well. Just did that today. Bled everything really well, checked brake fluid. Upon starting up, the pedal felt great; a good amount of travel and then it felt like the brakes adjusted properly. Those did not feel warm after driving the car for a while and testing the brakes. The fronts were the HOT ones!
After driving until it was warm at different speeds and stopping and testing the brakes, same thing; the brake pedal would travel less and less until you barely had to tap it before they would grab and heat up.
All fours star adjusters are backed all the way off. Brand new wheel cylinders all the way around. Have I got something wrong?
Any input? Suggestions? Ideas? I just want the pedal to travel as it does upon a cold start up, and to keep that travel distance even after the vehicle gets warm and I've been using the brakes.
Any input is greatly appreciated. If you need more details, just please let me know!
If you didn't change the hoses that would be the next thing I would do. That would be both front ones and the one on the rear.
Good idea! I actually did change the front ones, but, I did notice they were a smaller diameter. Would that afffect things? The ones that were on there seem thicker and heavier duty compared to the new OEM ones I picked up at O-Reilly....
There is a chance that a brake line is starting to delaminate on the inside and not allowing the fluid to release after braking, kinda like a flapper valve. I'm just trying to get my head around why it would do it on both front brakes, usually only affects one side at a time.
You might try backing off the bleeder valve after the brakes have been pumped up and foot off the pedal and see if it is still holding a lot of pressure, it should drop off upon peddle release. Just a thought...Tedd
Do you have a 1961 Oldsmobile Shop Manual?
If not, get one. It explains the proper method of adjustment of the brakes.
It sounds as though you may have the adjustment too tight.
I also agree with Glenn, the hoses may be suspect . Unless they look fairly new, I would replace them.
Do you have a 1961 Oldsmobile Shop Manual?
If not, get one. It explains the proper method of adjustment of the brakes.
It sounds as though you may have the adjustment too tight.
I also agree with Glenn, the hoses may be suspect . Unless they look fairly new, I would replace them.
I do have the shop manual. What I did was back off the fronts ALL the way off. They spin freely when jacked up on the front. I figured if I backed them off, and this still happened (which it is), something else is going on.
I will probably replace the brake hoses all the way around and eliminate that possibility.
Do you have a drum brake master cylinder or one for a disc brake car? There are differences, notably some disc m/c have a check valve to keep some residual pressure on the front brakes. Idea is the check valve keeps the brake pads in light contact with the rotors so the brake calipers don't have to pump up to make contact.
If you have a correct drum master cylinder make sure the pushrod length is set correctly. It may be causing the M/C piston to not retract enough to uncover the return port, thereby keeping hydraulic pressure on the front brakes.
Get a master cylinder for 65-66 Cadillac and it should work well. There was a factory-offered dual master cylinder conversion kit listed in the parts books at least as late as 1974.
Do you have a drum brake master cylinder or one for a disc brake car? There are differences, notably some disc m/c have a check valve to keep some residual pressure on the front brakes.
Actually, Glenn, it's the other way around, Drum brake systems use the residual pressure valve in the outlet ports, disc brake M/Cs do not. I have a dual circuit disc brake M/C in my four wheel drum 1962 F85. No issues whatsoever. The residual pressure valve is not really needed in cars where the M/C is above the brakes. Many rebuilt M/Cs for drum brake cars don't even have the valves in the ports anymore.
Crack a bleeder open when the wheels are binding. If fluid squirts out and the brakes release it is a hydraulic problem. If not it is a mechanical and/or adjustment problem.
The master cylinder / booster are a direct replacement for the original booster and single master cylinder it had from the factory, so I was told.
I took the old gal out earlier today for a drive and here are the results:
After warming it up and driving it for a good 20 minutes, I got back to the garage and checked the temp with an IR gun on both fronts; the passenger front was about 160 degrees and the driver front about 120 degrees. After driving it for a while, it would pull to the right and that pedal travel got less and less. Once I parked the vehicle in the garage, I jacked up the passenger side (which had the higher temp and brake smell) and the wheel would barely spin freely, even though I had the star adjuster backed ALL the way off. I cracked that wheel cylinder and there was lots of pressure. As soon as that pressure was relieved, the wheel spun free, even with the touch of a finger.
What is causing this hydraulic issue? Any ideas guys?
You could do the same test upstream at the MC to see if that is by chance retaining pressure but again hoses usually cause this.
Good luck!!!
Is it possible that the I.D. of the brake hose could affect things like this? The older hoses on the front were both thicker than these brand new ones I slapped on last week.
Also, could the front passenger wheel cylinder be bad again?
I won't say impossible but I don't see how the ID of the hose could make it retain pressure. Also I don't see anyway the WC could either. Try cracking lines upstream, to locate the one way restriction. The master generates the pressure, open lines working upstream until no pressure is found. This test would require rebuilding the pressure each time it is released.
The master cylinder / booster are a direct replacement for the original booster and single master cylinder it had from the factory, so I was told.
Told by who? The people selling that aftermarket brake setup? Since these cars never came from the factory with dual circuit brakes, there is no "direct replacement" dual circuit system.
How did you plumb the dual circuit brakes? Did you use a 1967-up style distribution block, or did you run the front brakes to a tee fitting and from there to the M/C port? What other non-stock elements are in the brake system?
Assuming there are no wayward and unneeded valves or distribution blocks in the brake circuit, there are only two ways for the front brakes to retain pressure. Either you have a bad rubber hose where the inner lining has separated and formed a check valve, or you have an improperly adjusted master cylinder or booster pushrod that is preventing the M/C piston from reaching the fully retracted position when you release the brakes. I guess if the new M/C has a malfunctioning residual pressure valve, that could also cause a problem.
Well, the manufacturer said it would bolt right up as the original one, and it did. That's what I meant.
As far as the piston goes, I did not adjust that. Could that be out of adjustment? The piston on the booster that sticks into the MC?
I will get pics of the setup so you all can see how its plumbed.
Told by who? The people selling that aftermarket brake setup? Since these cars never came from the factory with dual circuit brakes, there is no "direct replacement" dual circuit system.
How did you plumb the dual circuit brakes? Did you use a 1967-up style distribution block, or did you run the front brakes to a tee fitting and from there to the M/C port? What other non-stock elements are in the brake system?
Assuming there are no wayward and unneeded valves or distribution blocks in the brake circuit, there are only two ways for the front brakes to retain pressure. Either you have a bad rubber hose where the inner lining has separated and formed a check valve, or you have an improperly adjusted master cylinder or booster pushrod that is preventing the M/C piston from reaching the fully retracted position when you release the brakes. I guess if the new M/C has a malfunctioning residual pressure valve, that could also cause a problem.
So the front reservoir of the MC has a line that goes right down below it to a small junction block. This block is a small brass looking block which feeds the front wheel cylinders. I plugged off the remaining port, which used to feed the rear brakes as well. The 2nd reservoir of the MC feeds that line that used to thread into the now plugged port of the junction block. I coupled that line to the MC line coming out of the 2nd reservoir.
It may help if you could take a picture of the brake item you're referring to as a "junction block" - it may help since the car's brakes were upgraded, it's difficult to know what you're referring to by "junction block" (which most likely is not what the part is called or its function).
It may have been upgraded to a combination valve? It may be a distribution block (which is not a combination valve). It could (possibly) be a metering valve. A picture of the device would help so others can assist you in the proper routing.
So the front reservoir of the MC has a line that goes right down below it to a small junction block. This block is a small brass looking block which feeds the front wheel cylinders. I plugged off the remaining port, which used to feed the rear brakes as well. The 2nd reservoir of the MC feeds that line that used to thread into the now plugged port of the junction block. I coupled that line to the MC line coming out of the 2nd reservoir.
This should work fine correct?
Yes, that will work fine. That's exactly how I plumbed the dual circuit brakes in my 62 F85. The fact that the booster and M/C bolt up does not mean that they are adjusted correctly for the pedal position and throw in your car.
Yes, that will work fine. That's exactly how I plumbed the dual circuit brakes in my 62 F85. The fact that the booster and M/C bolt up does not mean that they are adjusted correctly for the pedal position and throw in your car.
Just curious. What is the 'junction block' being referred to?
Just curious. What is the 'junction block' being referred to?
The stock single circuit brake system had a simple brass junction block. One line in from the M/C, three lines out (one to the rear and one to each front wheel). The OP simply plugged the port that previously fed the rear brakes and ran that into the other side of the M/C. That's the easy way to make this swap. This is the similar junction block for the 64-65 A-body cars, and yes there's one more port on the far side.
Alright guys, I think I may have figured it out.
I did take the MC off the booster and i adjust the push rod IN so that there was more travel. I assumed it was set up properly when I had it shipped to me. Didn't even bother to adjust it. I just turned it in several threads and tightened the small nut against it so it wouldn't come out of adjustment.
I drove the car for a while, stopping and testing the brakes at all sorts of speeds.
I think I have it dialed in. No more overheating fronts, no more brake smell, no more hard, tiny travel-pedal. The feel on the pedal is much more 'modern'. It never got to the point where there was no brake pedal travel. It felt pretty darn good! Stops great too!
That was the issue there.
Since I believe that is taken care of, when I back up, and apply the brakes, I can hear and feel creaking, as if something is very loose on the shoes, either fronts or rears. It kind of 'jolts' when I apply the brake and am going in reverse to slow down. Any ideas?
Could my star adjusters still be off? Does the e-brake have anything to do with that feeling? Right now the ebrake is pretty loose, and it travels pretty far before it engages the rear shoes.
Any advice or suggestions on THIS issue would be awesome guys.
It may help if you could take a picture of the brake item you're referring to as a "junction block" - it may help since the car's brakes were upgraded, it's difficult to know what you're referring to by "junction block" (which most likely is not what the part is called or its function).
It may have been upgraded to a combination valve? It may be a distribution block (which is not a combination valve). It could (possibly) be a metering valve. A picture of the device would help so others can assist you in the proper routing.
Here are a few pics of the setup, and the junction block. Brakes seem to working well right now. These are pics from an overhead view just above the MC.
I believe your 61 does not have self adjusters, so if the brakes are not correctly adjusted, there will be noise like that.
I have been trying to adjust the rear brakes one side at a time by putting the car in neutral, blocking the tires, and feeling the drag that way. Is there a proper way to adjust the rears with the star adjuster?
With the drum off the car, put the prongs in the drum at its widest diameter. Tighten the thumbscrew, then put the device on the brake shoes and use the star wheel to expand the shoes to the diameter of the drum.
With the drum off the car, put the prongs in the drum at its widest diameter. Tighten the thumbscrew, then put the device on the brake shoes and use the star wheel to expand the shoes to the diameter of the drum.
One of the best tools I ever bought.
I just ordered one up. It should be here today! Excited to get the rear shoes dialed in properly. Thank you!
Thanks for the images. Different orientation than Joe’s image (as expected) same orifices - one input, two outputs to front brakes, one to rear (which is blocked now). Got it.
One final comment. While adjusting the pushrod between the booster and M/C has solved the problem, be sure the actual cause isn't a mis-adjusted pushrod between the pedal and booster. That's the one you should adjust first, to ensure you have full travel in the system. Simply remove the pin holding the clevis to the pedal and verify that there is no preload with the pedal all the way up. If that's the case now, you're done and don't need to do anything (well, other than put the pin back in... ). If there is a preload one way or the other, adjust the clevis accordingly then go back and readjust the pushrod between the booster and M/C to ensure you have full travel from the pedal to the M/C. This may not be an issue now with everything brand new, but once the shoes wear and the drums are at the limits of machining, this might become an issue.
For the clunking, completely empty the trunk and retest. Move/shake the exhaust system to try to reproduce the noise. Stand outside and alongside of the car while someone else backs it up and applies the brakes and watch for excessive fore/aft wheel movement, you may find a worn control arm bushing(s).
I don't know what the clunking noise is or whether the parking brake might produce a noise, but earlier you stated the parking (e-brake) was loose & the pedal had to travel a great length before it engages. The top inner metal plate for the parking brake should be taut - as in some modest slight tension so when you apply the parking brake that metal plate should immediately begin to move laterally. There's two inner parking brake (metal plate) arms, IIRC - one behind (side of) the axle and one on top of the axle. The inner arm behind (side of) the axle moves (pivots) the arm on top of the axle allowing the top arm to move outward (laterally) applying pressure so the shoes compress outwards when applying the parking brake. I might be incorrect about this, but without self-adjusters I believe you must first adjust the parking brake before you make adjustments to the drum brakes via the slot to reach the star wheel or however you access the star wheel on your assembly. Could this be the issue? I'd ensure both rear brakes have operational inner parking brake metal plates and adjust your parking brake cable appropriately before making adjustments to the star wheel. There should be an equalizer under the floor board of the car where a single cable from the parking brake meets two cables - one to each rear brake assembly. Ensure all cables meet and are securely attached to the equalizer.
I don't know what the clunking noise is or whether the parking brake might produce a noise, but earlier you stated the parking (e-brake) was loose & the pedal had to travel a great length before it engages. The top inner metal plate for the parking brake should be taut - as in some modest slight tension so when you apply the parking brake that metal plate should immediately begin to move laterally. There's two inner parking brake (metal plate) arms, IIRC - one behind (side of) the axle and one on top of the axle. The inner arm behind (side of) the axle moves (pivots) the arm on top of the axle allowing the top arm to move outward (laterally) applying pressure so the shoes compress outwards when applying the parking brake. I might be incorrect about this, but without self-adjusters I believe you must first adjust the parking brake before you make adjustments to the drum brakes via the slot to reach the star wheel or however you access the star wheel on your assembly. Could this be the issue? I'd ensure both rear brakes have operational inner parking brake metal plates and adjust your parking brake cable appropriately before making adjustments to the star wheel. There should be an equalizer under the floor board of the car where a single cable from the parking brake meets two cables - one to each rear brake assembly. Ensure all cables meet and are securely attached to the equalizer.
I have adjusted the ebrake, made sure the cables are secure. I will have to play with the adjustment. I think I’ll have to check the rear drums and make sure every single piece associated with the ebrake is proper and not backwards. There’s an arm with two slots on either end with a spring; need to make sure it’s orientated properly on both rear brakes.
I noticed the driver side rear was about 290° after a cruise tonight! The pedal play became smaller and smaller again…thought I had nipped this issue in the bud! I may back the pushrod from booster to MC in a bit more.
What would make that rear driver’s side brake that hot?! I adjusted both rears with the drum gauge tool until the drum fits JUST over the shoes. I had to pressure it on and use a little muscle. Too tight of a fit?
Wondering if you guys think this looks proper. Passenger rear. I want to know if the ebrake arm with the spring is oriented correct. Hard to tell in my manual which way it goes in. Spring goes towards the front is all I can really tell but I need to know if flipping the lever makes a difference?? See the pics. Thanks guys.
Look at the top center pin where the return springs attach, the shoe to the right is seated against the pin. The shoe to the left isn't. If the shoe to the left is the shoe that the E-brake cable attaches to the E-brake cable may not be fully releasing.
July 26th, 2022, 05:53 PM
). If there is a preload one way or the other, adjust the clevis accordingly then go back and readjust the pushrod between the booster and M/C to ensure you have full travel from the pedal to the M/C. This may not be an issue now with everything brand new, but once the shoes wear and the drums are at the limits of machining, this might become an issue.
