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1966 Mustang: Squishy Brakes

5842 Views 18 Replies 10 Participants Last post by  StevenCobra8494
I recently bought a 1966 Mustang Convertible, 200 six banger with an automatic. I've been driving the heck out of it and loving every minute of it. The only issue lies in the four wheel drum brakes. The previous owner has replaced EVERYTHING. New master cylinder, lines, wheel cylinders, drums, pads, fluid, bled them multiple times. Yet the pedal is still as squishy as ever. I have to put my foot almost completely to the floor, pull off and shove it back in again to get her to stop. It's a little scary at times. I really need to figure out a solution here. If there truly still is air in the brakes I'm thinking about just having a professional bleed them and save myself the time and pain. I just want to safely drive my baby! Any help would be greatly appreciated.

Thank you,
-Steven
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yeah, you get used to pumping the brakes to stop one of those old relics...I'd look into some stainless brake lines, better yet a disc brake conversion...Stainless Steel Brake company has the nice setup
Aloha
I recently bought a 1966 Mustang Convertible, 200 six banger with an automatic. I've been driving the heck out of it and loving every minute of it. The only issue lies in the four wheel drum brakes. The previous owner has replaced EVERYTHING. New master cylinder, lines, wheel cylinders, drums, pads, fluid, bled them multiple times. Yet the pedal is still as squishy as ever. I have to put my foot almost completely to the floor, pull off and shove it back in again to get her to stop. It's a little scary at times. I really need to figure out a solution here. If there truly still is air in the brakes I'm thinking about just having a professional bleed them and save myself the time and pain. I just want to safely drive my baby! Any help would be greatly appreciated.

Thank you,
-Steven
Drums are difficult to get "right", but it sounds like they still need to be adjusted. Jack it up and adjust one wheel at a time using a brake adjusting tool, or a wide flat screwdriver, just until you detect a slight drag while spinning the wheel by hand.
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Cracker289 is right, I would start by what he says about adjusting the brakes, then if you still have squishy pedal, I would rebleed the brakes, many times if all the parts or most of the parts have been replaced getting all the air out is hard, I've seen some that you bleed the brakes, then you have to rebleed them a couple of days later to get the rest of the air out. Also check the fluid in the MC it should be within 1/4" of the top. In addition, if the PO didn't replace the single reservoir MC with a dual reservoir MC, which makes a good upgrade to consider, because if you get a leak with the single reservoir type and lose all the brake fluid, the only way to get it stopped without damage, hopefully, is the parking brake. Good Luck.
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I agree with Rex1965 and I also agree with 2Manystangs.
I recently bought a 1966 Mustang Convertible, 200 six banger with an automatic. I've been driving the heck out of it and loving every minute of it. The only issue lies in the four wheel drum brakes. The previous owner has replaced EVERYTHING. New master cylinder, lines, wheel cylinders, drums, pads, fluid, bled them multiple times. Yet the pedal is still as squishy as ever. I have to put my foot almost completely to the floor, pull off and shove it back in again to get her to stop. It's a little scary at times. I really need to figure out a solution here. If there truly still is air in the brakes I'm thinking about just having a professional bleed them and save myself the time and pain. I just want to safely drive my baby! Any help would be greatly appreciated.

Thank you,
-Steven
Can you tell us how you're bleeding them to make sure there's not something you're doing wrong there?
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Hello. :) I would definitely adjust them like Cracker289 suggested. When it comes time to bleed the brakes, you might want to consider making one of these. :)
The Care and Feeding of Ponies: Bleeding the brakes 1965 1966 Mustang
The original drum brakes are not going to win any awards for greatness but you should not have to pump the pedal on a drum brake car.

You said the PO used a 'new' master cylinder. Was that really new or just new rubber seals installed? Taper in the MC bore can make it impossible to rebuild just with new seals. Those require re-sleeving which is likely not worthwhile if new MCs are available.
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I appreciate all the feedback this has gotten, I know that drum brakes a pain to deal with at times. I myself haven't bled the brakes yet, the previous owner has done it all the other times. It is in fact a totally brand new master cylinder, the old one is in the trunk. When I get the chance I'll try to adjust the brakes and re-bleed them. If I'm in light traffic the pumping isn't an issue, but I'm really concerned when I go downhill and in moments when I need to brake suddenly. Someday when I have a spare $1500 I'll get the five lug disc brake setup, but until then, I'll work with what I have. I'll be sure to look into those stainless brake lines someday too.
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Oh, I get it. Whatever the previous owner has 'done,' assume hasn't been done at all. So you probably have a lot of air in the lines. Second, you probably need to adjust the shoes. Pick a tire, jack it up and tighten the adjuster (rotating the wheel teeth down if you are going in through the slot on the backing plate) until you can no longer freely turn the tire by hand. Then back off 3 teeth. Next, apply the brakes several times while operating the car in reverse to finalize the adjustment.
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Hi again. :) I've been driving with 4 wheel drums on my car, and driving it daily, since the 90s and have never had any trouble with them. True, the required stopping distance is a little bit more than that of a disc brake car, but, it isn't as much more as some might lead you to believe. With everything functioning correctly, they work well enough if you pay attention to what you are doing. The car is not automatically a death trap simply because of the drum brakes. The trick is to get everything functioning correctly. :)
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Oh, I get it. Whatever the previous owner has 'done,' assume hasn't been done at all. So you probably have a lot of air in the lines. Second, you probably need to adjust the shoes. Pick a tire, jack it up and tighten the adjuster (rotating the wheel teeth down if you are going in through the slot on the backing plate) until you can no longer freely turn the tire by hand. Then back off 3 teeth. Next, apply the brakes several times while operating the car in reverse to finalize the adjustment.
That's pretty much how I'm looking at it at this point. Either he didn't do it or he did ir very poorly. If I want something done right, I'll be happy to do it myself.
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just for the sake of clarification, the adjustment is done to all the brakes. When I said 'pick a tire' I was meaning 'pick a starting tire' but it sounded like 'only adjust a single brake.'
just for the sake of clarification, the adjustment is done to all the brakes. When I said 'pick a tire' I was meaning 'pick a starting tire' but it sounded like 'only adjust a single brake.'
Thanks for the clarification, I assumed that's what you meant. Do you perhaps have a picture or video of the process?
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This is the anatomy of a drum brake. The start wheel in the bottom center is the adjuster. If it is rotated one way it tightens the shoes against the drum and the other way it loosens the shoes. Don't quote me on this because it's been a few years since I've done it, but if you were to rotate the wheel up from the front (down from the back) it tightens, and the opposite direction loosens. You have to do the actual adjustment through a slot in the backing plate right behind the adjuster because the drum has to be on. You can see the slot in the picture. There are adjuster tools but I use two flathead screw drivers...one to push the locking tab (you can see it on the left) off the adjuster wheel, and the second flathead to actually turn the star wheel.

I would first bleed. You should probably do a visual inspection of all the brakes too, to make sure all your springs are in place and nothing looks obviously broken. I would not be driving the car in its current condition if you have to pull the pedal back to stop.

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This is the anatomy of a drum brake. The start wheel in the bottom center is the adjuster. If it is rotated one way it tightens the shoes against the drum and the other way it loosens the shoes. Don't quote me on this because it's been a few years since I've done it, but if you were to rotate the wheel up from the front (down from the back) it tightens, and the opposite direction loosens. You have to do the actual adjustment through a slot in the backing plate right behind the adjuster because the drum has to be on. You can see the slot in the picture. There are adjuster tools but I use two flathead screw drivers...one to push the locking tab (you can see it on the left) off the adjuster wheel, and the second flathead to actually turn the star wheel.

I would first bleed. You should probably do a visual inspection of all the brakes too, to make sure all your springs are in place and nothing looks obviously broken. I would not be driving the car in its current condition if you have to pull the pedal back to stop.
I agree on the point, turning the star wheel from bottom to top tightens it, therefore turning from top to bottom loosens, however the thingamajig keeps it from being loosened, therefore you need to stick a screwdriver in there to hold it from catching and that will allow you to turn the wheel downward. Clear as mud?
:p
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My brakes were squishy and I bled them and it helped a lot. I might do the adjustment that everyone else is mentioning too.
I have a ,66 convertable with the same problem.I have replaced every part on the system,with no improvement.The only thing I haven't tried is metallic linings.If I switch,and it helps,I'll let you know.Good luck
Alright guys we have a new development in the Spongebob Squishybrakes saga. The previous owner was driving her to the harbor today to be shipped to me and the back right drum went out completely, puked brake fluid everywhere. He had just bled the brakes and the pedal wasn't doing the sponge action anymore. He managed to fix the issue but he is bringing the car in to a brake shop at his expense to be checked and repaired before he gives it to me in good conscience. Although it'll delay the shipment of the car by a few weeks, if he's willing to spend the money to get it safe before I get it into my hands, then I sure won't argue.
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