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Author Topic:   Brake problem
Gary
Gearhead

Posts: 725
From: Sarasota, Fla. USA
Registered: Jun 99

posted 11-29-2001 04:47 PM     Click Here to See the Profile for Gary   Click Here to Email Gary     Edit/Delete Message   Reply w/Quote
On my 69 mach PB car im having brake problems. Iv'e replaced everything related to brakes,lines ect. and just now installed a new booster and master. Im bleeding the brakes but there's no resistance in the pedal, Iv'e cracked open the two lines on the master as to bench bleed the master. Iv'e bled all four corners 4 times and have only fuild coming out no air bubbles. At this point im stumped??? If there is no air in the lines why then is the pedal going almost to the floor? I pump the pedal 4-8 times and hold down the pedal while a freind cracks the line, Im using clear tubing to see any air coming through but all is fuild. What could cause this problem??? I have no leaks anywhere either.
Whats the deal??

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SteveLaRiviere
Administrator

Posts: 33988
From: Saco, Maine
Registered: May 99

posted 11-29-2001 04:58 PM     Click Here to See the Profile for SteveLaRiviere   Click Here to Email SteveLaRiviere     Edit/Delete Message   Reply w/Quote
Do you have drum brakes in the rear? How are they adjusted?

What about the rod between the booster and the master cylinder? Is it original? Is it adjustable?

------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC
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SteveLaRiviere
Administrator

Posts: 33988
From: Saco, Maine
Registered: May 99

posted 11-29-2001 05:00 PM     Click Here to See the Profile for SteveLaRiviere   Click Here to Email SteveLaRiviere     Edit/Delete Message   Reply w/Quote
Does the pedal feel as hard as a rock, or is it spongy?

------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC
My Photo Page
Christmas shopping? Why not use the Mustangsandmore.com Bookstore?

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Gary
Gearhead

Posts: 725
From: Sarasota, Fla. USA
Registered: Jun 99

posted 11-29-2001 05:55 PM     Click Here to See the Profile for Gary   Click Here to Email Gary     Edit/Delete Message   Reply w/Quote
I have disc in front drum rear. I just installed a completely re-built power brake booster and it came with a master cyl. as one unit. Before I had brakes but no power asist, the pedal was hard as rock then. Now after replacing the bad booster with a re-built one and master the pedal feels spongy and will go to the floor with no resistence as if no hyd pressure is being built up in the system. Now this has got me thinking, I had some brakes before with my other master which was new, maybe I should change out the new one that came with the booster and try the one I just took off that seemed to work.
My luck I got a bad new master cyl. At this point I don't know what else to try.
All during this build I have purchased not one but many new parts that were bad. When someone like you or me is trying to do their best or want the best this stuff can drive you crazy. Im sick of back tracking to find parts I bought new are worse than the old parts One would not think suspect of new parts and would else where to find a problem. Guess you just have to get lucky you get new parts that are in fact new and work like new......Back to the shop to swap out the master again..CYa!

[This message has been edited by Gary (edited 11-29-2001).]

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SteveLaRiviere
Administrator

Posts: 33988
From: Saco, Maine
Registered: May 99

posted 11-29-2001 06:05 PM     Click Here to See the Profile for SteveLaRiviere   Click Here to Email SteveLaRiviere     Edit/Delete Message   Reply w/Quote
I doubt your new master is bad. It's not leaking out of the back of the master, is it?

I believe you still have air in the lines somewhere. An air bubble can be a real pain to get out. You're bleeding the wheel cylinders in sequence, right? Starting from the furthest from the master forward? {RR, LR, RF, LF}

------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC
My Photo Page
Christmas shopping? Why not use the Mustangsandmore.com Bookstore?

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Gary
Gearhead

Posts: 725
From: Sarasota, Fla. USA
Registered: Jun 99

posted 11-29-2001 06:36 PM     Click Here to See the Profile for Gary   Click Here to Email Gary     Edit/Delete Message   Reply w/Quote
Yes to bleeding them from the rear to the front starting at the RR. This is driving me crazy, I finished everything else on the car two weeks ago.....still I have no brakes and dyeing to drive the car!!! All iv'e been able to do is drive around the block..bummer!! The last problem I found was a fualty Vac. canister for the PB, It was brand new but had a leak in the can, then they sent another replacement only to find that one had a leak too. I finally got pissed and welded up the area that was leaking myself because Im sick of set-backs, now the can works fine and keeps at least 15 inches in the can now that the can and new booster has been installed. My luck has not been the best lately.....figures the car is done and this crap keeps persisting. That is why I purchased all new parts for the brakes, I figured that should fix the problem and wanted new anyway.
GRRR

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SteveLaRiviere
Administrator

Posts: 33988
From: Saco, Maine
Registered: May 99

posted 11-29-2001 07:29 PM     Click Here to See the Profile for SteveLaRiviere   Click Here to Email SteveLaRiviere     Edit/Delete Message   Reply w/Quote
If push comes to shove, you can pressure bleed the air out of the system.

1. Get a metal tire valve and a spare master cylinder cover.

2. Drill a hole in the cover, and weld the valve to the cover.

3. Install cover on full master cylinder, and pressurize to 10 psi or so.

4. Bleed in sequence. Make sure you don't run low on brake fluid, if you do, start over.

------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC
My Photo Page
Christmas shopping? Why not use the Mustangsandmore.com Bookstore?

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460-67Stang
Gearhead

Posts: 195
From: Southern Ohio, USA
Registered: Feb 2001

posted 11-29-2001 09:35 PM     Click Here to See the Profile for 460-67Stang   Click Here to Email 460-67Stang     Edit/Delete Message   Reply w/Quote
Gary - Here's some thoughts. Some are basic, but they may help you.

1) When I rec'd my remanufactured Booster it did NOT come with the pushrod that goes into the MC. Don't know if it was supposed to, but I used a pushrod I had laying around. Also, it's important that you have the correct clearance between the end of that pushrod and the M/C mating surface. It the pushrod is too long you'll already have pushed in on the M/C before the pedal even moves. Too short and the M/C won;t travel fully in it's bore....or at all if the rod is really short.

2) I don't know, but didn't all '69 Stangs come with front disc as standard? If they didn't, then perhaps you got a 4 wheel drum M/C. As you know, I installed 4 wheel disc in my '67 and learned from research that the bore and stroke of a M/C is critical and changes according to disc or drum, power or manual.

3) Are your front calipers and rear slave cylinders free and able to move?

4) That proportioning valve you mention (in your other post) is critical. It adjusts pressure between the disc and drum system. It allows the front brakes to have more stopping power so you get better braking actoin and control. Yes, it can be installed backwards and it would have a bad affect (not sure what affect though). Do you have a '69 Ford manual? It shows the correct installation and explains how it works. I'll look in my '69 manual if you don't have one, just let me know.

5) Did you change fluid types? I went from Dot 4 to Silicone (Dot 5 I believe). Since my entire brake system was new I was OK. But if you're changing from one to the other I believe you have to thouroughly rinse the old fluid out with alcohol (Jack Daniels would work fine!) , otherwise the ruber can deteriorate....which would allow fluid to leak everywhere at your wheels.

6) Are you running a line lock (also called roll control)? If so the solinoid must be installed in the proper direction. Doubt this would cause your problem though.

Let me know how it goes.

Cheers,
Brian

------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
14 yr project just completed! Took first place in Tri State Mustang Club 65-73 Modified class!!
'67 Mustang Coupe Restomod, 472 Motor at about 500 hp, C-6 Tranny w/high stall convertor, 9" rear w/3:50 gears and Detroit Locker, Power Disc brakes all around.
---------->>>>> Got Displacement? <<<<<------------

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460-67Stang
Gearhead

Posts: 195
From: Southern Ohio, USA
Registered: Feb 2001

posted 11-29-2001 10:46 PM     Click Here to See the Profile for 460-67Stang   Click Here to Email 460-67Stang     Edit/Delete Message   Reply w/Quote
Gary - just came across this from another post......

=====================
Hello All,
My dad and I just did this conversion this past weekend. (single to dual M/C).

We used a 1967 Dual master cylinder and the pushrod that came with the Dual MC. We were so frustrated for about an hour because we couldn't figure out why there was no pressure building up (pedal to the floor).

Just as we were about to pull out the new MC, we compared the new pushrod to the old pushrod. The older one was about 1 inch longer. We bolted that old pushrod in BINGO! Pedal was instantly back to normal.

NOTE: use original pushrod!
=============

I'd Check your pushrod length.
Brian

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Gary
Gearhead

Posts: 725
From: Sarasota, Fla. USA
Registered: Jun 99

posted 11-29-2001 10:51 PM     Click Here to See the Profile for Gary   Click Here to Email Gary     Edit/Delete Message   Reply w/Quote
Brian, I remember adjusting the shoes out back so the drum would just go on when replacing the brakes. After thinking about whats going on I decided to manual adjust them again using a screw driver with the drums on....well I was able to adjust another 20 clicks before I could barely move the wheel then backed off a few. Just doing this has made a huge difference! Tomarrow I'll try bleeding them when I find someone to help and hopefully that will fix my problem.
Really the back brakes start to work first I believe with slight pedal pressure, as more is applied the fronts do most of the braking (primary) I think what was happening is the shoes were so far from the drums that all the pedal was going to the rears never making contact thus doing nothing to apply the fronts....well only in laymens terms but this seems to be the case as Now I have some pedal with only adjusting the shoes out as far as I could to the drums, tomarrow I'll bleed all four again.
Thanks for the help, no don't have a manual but it's on my Xmas list. For what it's worth anyway as Iv'e modified just about everything on this car so the book may not be of much help in alot of areas.
I may have to re-write a new manual for the next owner....LOL

[This message has been edited by Gary (edited 11-29-2001).]

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SteveLaRiviere
Administrator

Posts: 33988
From: Saco, Maine
Registered: May 99

posted 11-30-2001 07:36 PM     Click Here to See the Profile for SteveLaRiviere   Click Here to Email SteveLaRiviere     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Gary:
Brian, I remember adjusting the shoes out back so the drum would just go on when replacing the brakes. After thinking about whats going on I decided to manual adjust them again using a screw driver with the drums on....well I was able to adjust another 20 clicks before I could barely move the wheel then backed off a few. Just doing this has made a huge difference!

Cool! That was my first suggestion...

------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC
My Photo Page
Christmas shopping? Why not use the Mustangsandmore.com Bookstore?

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SuperDave
Gearhead

Posts: 123
From: Tacoma, WA USA
Registered: Jun 2000

posted 12-01-2001 12:14 AM     Click Here to See the Profile for SuperDave   Click Here to Email SuperDave     Edit/Delete Message   Reply w/Quote
Just read all this for the first time. I have used a brake adjusting caliper for drum brakes for years. To use it, first you adjust the caliper to fit the inside diameter of the drum. This sets the proper shoe adjustment measurement on another part of the caliper. You then adjust the shoes out to meet the caliper. Install the drum, etc. are you are done. No further adjustment required. A great time saver!

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