Brake pedal travel

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RedBird64
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Post by RedBird64 »

That's a great shot of what we're looking for, thx Steve.
I guess I'm going to have to bleed my brakes again. I did it about 9 months ago but for some reason the fluid is already cloudy enough that I can't clearly see into that little hole.
1964 Coupe Wimbledon white/Rangoon Red w/black int. Owned for 42 years. It was my folks car before that (second owners). VTCI # 12013.
Dainbramaged
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Post by Dainbramaged »

If you want less brake pedal travel you could look into an adjustable shaft to go from the brake pedal to the booster. They're available from most "Hotrod" vendors. It'll take some measuring and prob'ly a couple of phone calls to get the correct one. Maybe someone at your local auto parts house could help.
tbird
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Post by tbird »

The original plunger for the master cylinder is adjustable and I believe the OP has already adjusted it if you follow the thread through.
Jim Mills
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Jaylan_Bates
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1966 brake booster too big for valve covers

Post by Jaylan_Bates »

Hello guys i have a 66 tbird and i have edelbrock valve covers and the brake booster is too big , and the bendix is very rare for this year so i wanted to know if it is possible to convert this car to hydro boost concerning the windshield wipers and if not tuff stuff has a brake booster for. A 67 mustang and part #2225NB and i wanted to know if that would be a possible solution , its 9 inches in diameter but it is not as thick as the original , and if you guys wouldn't think those don't work what possible solutions would you guys suggest besides getting different valve covers because these are a must. Sorry if this is not jn the right subject im still learning to navigate this site thanks...
tbird
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Post by tbird »

Jaylan

If you move a little further down the headings on the main page of the forum you will find a modified area to post your own thread on the subject, that would be your best place to post a question on modification.
Jim Mills
VTCI # 8071
VTCI 1964-66 Technical Editor
2002 Thunderbird
1965 Convertible
1962 Convertible (in progress)
1959 Ford Retractable HT
Many parts cars
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sseebart
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Post by sseebart »

I got this assembly back together and in the car as part of my dashboard project. Even though I didn't adjust the master much (and extended the screw as well) the brake pedal is still extremely low.

I've bench bled the master a couple three times--the last couple of times it didn't blow any bubbles at all. I've also bled all around 3 times, the last being today. Found a little air in the right front line in the last go-around and no leaks in the system.

With the car off, the pedal firms up about half way down (or a little more)--gets pretty hard at that point, in fact. With the car running though, the brakes don't engage until the pedal is nearly at the carpet and the feel is spongy all the way down.

In an empty parking lot today, I tried to get the brakes locked up, but they refused. Stopping distances are fairly long--too long to consider going faster than 30-40 mph.

The master cylinder was new about 2 years ago, and the booster was rebuilt by someone local (don't know who--a mechanic I will never use again [long story] sent it out to a jobber). I replaced all the wheel cylinders in the last year or two, as well as all the lines, steel and rubber.

So, the question is, where to go from here? I've got new drums on order and will install new shoes as well when they arrive. I checked the adjustment all around and the shoes have a tiny amount of rub with the brakes off. They appear to be adjusted correctly, so the new drums & shoes won't help (unless a drum is cracked, I suppose).

I could run this adjuster out further, but that seems like a bad idea.

Image

Is it possible the booster is bad? The master cylinder defective? If so, is there a modern, bolt-on replacement for either? (I know there are better booster rebuilders out there, but it cost over $500 last time and I hate to think of spending that again to rebuild an old, but extremely critical, part.)

Here's a short video of the brake pedal in action:

Image

~Steve
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sseebart
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Post by sseebart »

So, I pulled the MC today after purchasing a new (not rebuilt) replacement--the assumption was that the MC had to be bad, everything else looks ok.

It may be hard to tell in this photo, but there was some fluid back in the booster. I took the old MC apart and there was some corrosion at the back, towards the rear seal.

I doubt that the leak has been there long--it probably developed while I was bleeding the brakes over the last few weeks. I've run the car, but only a few miles for testing. I would rather not buy a booster--second one for this car--but if it will inevitably fail, better to do it now rather than wait and do all this over again.

Is there any chance I can clean up the fluid I can see inside the booster, put a new master on and expect a reliable system?

~Steve

Image
edpol
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Post by edpol »

Hello guys i have a 66 tbird and i have edelbrock valve covers and the brake booster is too big , and the bendix is very rare for this year so i wanted to know if it is possible to convert this car to hydro boost...
Was done on a '62, should be very similar for Flairbirds:

http://www.vintagethunderbirdclub.net/p ... php?t=9117


Is there any chance I can clean up the fluid I can see inside the booster, put a new master on and expect a reliable system?
I had the same problem a while back with a Chevy. I wiped the fluid out and didn't have any problems later. If possible, open the booster to check for any excessive fluid.
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sseebart
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SOLVED

Post by sseebart »

I decided to take a chance on the old booster. Installed a new (not rebuilt) MC after extensive bench bleeding. I adjusted the pushrod--nearly had to run it all the way out, in fact.

Bled the system once again and made sure all the shoes were adjusted correctly.

Problem solved!

Pedal is firm, and while not as high as I would like, higher than it was. I suspect the MC I had in there has always been bad.

~Steve
Midniterider1959
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Re: Brake pedal travel

Post by Midniterider1959 »

I converted my 1964 Thunderbird to front disc brakes and I’m having trouble I think with the rod adjustment that goes between the booster and the master cylinder. My kit came with another adjuster that was longer than the one in the booster but I didn’t change it and whenever I put everything together I could see movement in the fluid as soon as I started pushing the pedal but I’m almost convinced now that I need to disassemble the master cylinder from the booster and put the longer rod in there but I don’t know what the final dimension for the adjustment should be if any one could please help me I would certainly appreciate it. Carl
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RedBird64
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Re: Brake pedal travel

Post by RedBird64 »

Basically the piston in the MC should not move as you bolt it to the booster.
If your eyes are better than mine, you can see the hole in the bottom of the MC and use that to know when you have it adjusted perfectly. Having no slop in the rod is the ultimate adjustment but in short, you should be able to measure how deep the piston is in the MC and set the rod to take up that distance without pushing on the piston.
1964 Coupe Wimbledon white/Rangoon Red w/black int. Owned for 42 years. It was my folks car before that (second owners). VTCI # 12013.
Peddller
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Re: Brake pedal travel

Post by Peddller »

You can not go by the specs in the shop manual for the adjustment of the push rod in the booster! That was only correct for the Ford Factory replacement parts at the time. The new MCs have varying depths to the bore in the plunger so careful measurements need to be made and the length of the rod may be way off from the factory specs. As was noted you want the rod as long as possible without moving the plunger when tightened to the booster.
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RedBird64
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Re: Brake pedal travel

Post by RedBird64 »

You can't trust rebuilt booster either. I had mine redone by Booster Dewey and they messed with the rod length. I figured they knew what they were doing and left it. Have to tell you, with the rod adjusted too long you have tremendous brake feel.
Of course, they don't retract and eventually over heat.
1964 Coupe Wimbledon white/Rangoon Red w/black int. Owned for 42 years. It was my folks car before that (second owners). VTCI # 12013.
Terry64HT
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Re: Brake pedal travel

Post by Terry64HT »

Getting the rod length correct isn't too difficult. Begin by measuring the distance the piston is from the flange on the master. All you need is a caliper (I cribbed this image of a digital one from eBay) and a piece of fiberboard or Masonite about 1/4 or 1/8" thick, 3 inches square or so will work. Drill a hole it the center of the board just big enough for the rod (make sure there is no burr around the hole). Measure the thickness of the board. Sit the board flat on the collar with one edge lined up with the side of the collar. Place the end of the caliper blade on the board and extend the measuring rod until it touches the flange. This gives the distance from the top of the board to the flange of the master. Subtract the board thickness for the distance the master goes into the booster. Then center the board on the collar of the master and place the caliper with the end of the blade across the hole. Open the caliper so the depth bar goes into the hole and touches the piston. Subtract the board thickness. Now subtract the distance the master goes into the booster and you have the distance from the flange to the piston.
To get the rod length, put the board on the booster with the rod sticking through the hole. With the end of the blade on top of the rod, open the caliper until the depth bar touches the fiberboard. Add the thickness of the board , and you have the length of the rod.
This is the length the rod should extend from the booster flange, but there should be 1/16 to 1/8" of play.
Sorry for the wordy post, but hopefully my explanation is of some use.

Terry
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