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#34364 - 04/07/07 10:09 PM Re: brake ratio? [Re: poorboy]
poorboy Offline
master

Registered: 01/19/03
Posts: 6525
Loc: Freeport IL USA
Just putting out an update. I got the master reinstalled and have varifiedthat indeed the master is delivering fluid flow from both resivors while it bolted on the car. One posibility is eliminated. blead out the lines and took the car for a short drive. Not much change. The brake pedal pad bolts to the swing brake arm, I modified the pedal and added an inch and a half to the over all arm. Finally got a chance to drive the car a little, before it got cold again. The longer pedal greatly improved the feel of the brakes, power wise. I'm going to modify the pedal assembly to improve the way it sits, but the concept worked. Pedal effort is much better, but the brakes still have room to improve.

Next up is to bypass the porportationing /combinnation valve thing for the rear brake line. I have the fitting, now its a matter of getting in there to remove the lines from the fitting. I will have to pull off the front fender to be able to get my hands in there, so expect another delay to the information train.

I'm taking this one thing at a time so I know what solves the problem. At least at this point, it looks like it's not going to be one big, real expensive fix, but posibaly several small (cheaper) fixes. Gene

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#34365 - 04/08/07 06:30 AM Re: brake ratio? [Re: poorboy]
moparx Offline
Dreaming of implants

Registered: 09/03/03
Posts: 9750
Loc: north of coder
glad to hear you are making progress ! of all the systems on a vehicle, brakes are [in my opinion] the most important ! they can be a real pain sometimes to figure out. remember : it's not speed that kills, it's the sudden stop that does ya in ! keep us posted gene.

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#34366 - 04/16/07 04:12 PM Re: brake ratio? [Re: moparx]
Fig Offline
member

Registered: 04/13/05
Posts: 167
Loc: Torrance, Ca
_________________________
1937 Plymouth R/S Coupe 440/727

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#34367 - 04/17/07 10:01 PM Re: brake ratio? [Re: Fig]
poorboy Offline
master

Registered: 01/19/03
Posts: 6525
Loc: Freeport IL USA
Fig, Thanks for taking the time to take and post the pictures.

I managed to get the porportioning valve bypassed. Made no difference. I did jack up the rear end so the tires were off the ground, started the motor and put the trans in drive. If I push HARD on the brake pedal, the rear wheels will slow and finally stop turning. Pumping made no difference either. At this point I'm thinking I need to completely rebleed the entire brake system. After that I will pull off a rear drum and have someone push the brake pedal to see if the shoes are moving. I'm running out of logical explanations, but I don't want to jump to conclusions until I have reblead the brakes and can watch the shoes for movement (or lack of?)

Just for the record, I did a test drive on a back hard surface road. From 60 I can push the brakes hard enough to stop the car fast enough to have the passenger seat back flip forward, but I have to push hard. I'm kind of thinking maybe I need to add another inch or two to the brake pedal length. Might be the next step after bleading and watching the shoes. Gene

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#34368 - 04/18/07 10:41 AM Re: brake ratio? [Re: poorboy]
Fig Offline
member

Registered: 04/13/05
Posts: 167
Loc: Torrance, Ca
Is your master cylinder for a disc/drum or disc/disc car? I remember something about a restrictor that you remove for a disc brake car, but you leave it in for drum brakes.

Are you sure that you have the rear brakes plumbed to the correct side of the master cylinder? I was thinking that the rear of the master cylinder was the rear brakes, I plummed mine up that way and had to redo it.

Can you just move the brake rod hole on the arm tio change your ratio? I think that I drilled a hole something like 3/4" closer to the pivot point to change my ration to 6 to 1.
_________________________
1937 Plymouth R/S Coupe 440/727

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#34369 - 04/18/07 11:47 PM Re: brake ratio? [Re: Fig]
poorboy Offline
master

Registered: 01/19/03
Posts: 6525
Loc: Freeport IL USA
The master I have is the dual purpose Corvette style master. Both resivors are the same size, it has line fittings on both sides of the master (4 fittings total, comes with plugs to plug whichever side you don't use.) I'd thought about the posibility early on that the lines may have been in the wrong position so I switched them at the master, made no difference.

The brake pedal I have has the pedal on one side and there is an extra drop from the pivot shaft to connect the master cylinder rod to. It off sets the master to one side of the pedal by about 2" for what I presume to be steering column clearance. It was a street rod manufactured piece. Relocating the master's connecting rod hole may be something I will look into once I figure what I need, but it may put a bind on the rod to master angle. The pedal is designed to have a pedal pad screwed into the arm, so its real easy to alter the length of the arm itself, least for now.

I think I may have discovered my problem today, but I have yet to test drive the car, once I can be sure the problem has been corrected, I will tell all. Stay tuned. Gene

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#34370 - 04/19/07 06:44 PM Re: brake ratio? [Re: poorboy]
moparx Offline
Dreaming of implants

Registered: 09/03/03
Posts: 9750
Loc: north of coder
after you re-bleed the rear, take the drums off & make sure both pistons in the cylinders are working. i have seen one freeze up where only one piston was working. this also had a very hard pedal effort.

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#34371 - 04/19/07 09:56 PM Re: brake ratio? [Re: moparx]
poorboy Offline
master

Registered: 01/19/03
Posts: 6525
Loc: Freeport IL USA
OK we have brakes!

When last I left you, I had bypassed the rear line portion of the brake porportioning valve. I want to note here I had very good fluid flow at this point, almost emptied 1/2 the resivor in the time it took to connect two lines to the union fitting. Bypassing the valve made no difference but I thought maybe I had air in the lines. Yesterday I put the rear on jack stands and pulled the rear tires (makes it easier to reach the bleader screws.) I opened the bleeder screw on the driver side rear cylinder to allow it to gravity bleed.

For those of you that may not know what gravity bleed is, on cars (or trucks) where the master is higher then the wheel cylinders, you can open the bleeder screws and gravity will draw all the air out of the lines, you leave the screws open until the fluid is flowing without air boubles, then close the bleeders. This works best by opening one bleeder at a time, per axle. Start with the bleader closest to the master. When the fluid flows air free, close that bleader and open the other bleeder screw on the same axle. Be sure to watch the fluid level in the master as it can empty very quickly and if the master goes empty you have to start all over. You can do one bleeder from the front and one from the rear at the same time or you can do just one at a time. It is a very effecent way of bleeding the brakes, but can be somewhat slow.

Back to the story. After opening the bleeder and leaving it open for 1/2 hour, I had very little fluid! Should have almost emptied the master in a 1/2 hour. I made sure the bleeder screw was not pluged, it wasn't. So I closed the bleeder and moved forward to the brake line connection on the master side of the rear brake hose and seperated the connection. Great fluid flow, closed it back up. Went to the axle end of the brake hose and disconnected the line going towards the wheel cylinder that I had very little fluid flow from. Got great fluid flow from the hose! Disconnected the other end of the line from the wheel cylinder. The fitting was tight, but the line fell off after only a turn or two! Sure enough, the last two threads were almost stripped off the line fitting! Must have been cross threaded. At this point, I'm not taking a chance on the wheel cylinder. I pulled off the brake drum and the shoes were soaked with what I first thought was gear lube! Didn't smell like gear lube, and there were no tell tail signs the axle seal was ever leaking. Called my favorite auto parts house and ordered a new brake line, wheel cylinder and new shoes. One of the perks with owning your own shop is the parts store deliveres the parts. After cleaning everything up I reinstalled the new brake line and wheel cylinder (making sure it it NOT crossthreaded) I opened the bleeder screw while I reinstalled the brake shoes. As I am finishing up the shoe installation, I noticed brake fluid running inside the backing plate. Closed the bleeder screw and the fluid flow stopped. This is where I add that I have gravity blead many brake sysyems and have never encountered brake fluid on the inside of a backing plate! Now I knew what was likely on brake shoes. So I checked the other side and sure enough, those shoes were wet also, not as bad as the first side, but wet none the less. I replaced those shoes and cleaned everything up (on both sides), and buttoned it back up. The threads on the inside of the wheel cylinder were rusty (this was a new wheel cylinder last year) so I suspect it has been leaking all along, but just wasn't leaking enough to show up on the outside or in fluid loss.

Today I drove the car, its nice to have 4 wheel brakes! The car stops very good. I still think the pedal effort is still a little high, so some more modification of the brake pedal is on the horizon. I have extended the length of the brake pedal about 2" and may go another inch. Once I get something I like, I will pull the pedal assembly and make a perminate alteration.

So the bottom line to all this was a cross threaded fitting at the wheel cylinder, and the wrong brake pedal ratio. After a year of putting up with poor brakes, boy, do I feel dumb. Gene

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#34372 - 04/23/07 11:26 AM Re: brake ratio? [Re: poorboy]
Fig Offline
member

Registered: 04/13/05
Posts: 167
Loc: Torrance, Ca


I would have to write a book to tell about all of the "dumb" things that I have done while building my car. That's part of the fun , my neighbor calls me do and redo .

I'm glad it's fixed
_________________________
1937 Plymouth R/S Coupe 440/727

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#34373 - 04/23/07 09:26 PM Re: brake ratio? [Re: Fig]
poorboy Offline
master

Registered: 01/19/03
Posts: 6525
Loc: Freeport IL USA
I understand that do and redo thing. Been there, still doing it.

We put a little over 100 miles on the coupe this past weekend. Its nice to have functioning brakes. Gene

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#34374 - 04/24/07 07:11 PM Re: brake ratio? [Re: poorboy]
moparx Offline
Dreaming of implants

Registered: 09/03/03
Posts: 9750
Loc: north of coder
gene, glad you have brakes now ! it is pretty amazing what a "small" thing can cause unending aggrivation & hair pulling[as well as adding to a guys "vocabulary"]. when you get your pedal length how you like it, it will be interesting to see what you started with & what you end up with. keep us posted on that. again, congratulations on gettin that fixed !

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#34375 - 04/24/07 07:46 PM Re: brake ratio? [Re: moparx]
poorboy Offline
master

Registered: 01/19/03
Posts: 6525
Loc: Freeport IL USA
I think I'm just going to pull the pedal out and see where its at now and will probably just go to the 7:1 manual pedal ratio. I will let you guys know what it originally was and what is is now, before I go to the 7:1, I'm not messing with this thing much more. I will take a few pictures of the pedal while its out of the car.

I have other lesser issues to attack, replacing cracked glass, window weather striping, windshield wipers, squeeks & rattles, the list is still pretty long. At least now its OK to drive while I hash out the details. I want to thank you guys for your ideas, thoughts, and support. Gene

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