So the brake line to the back rusted out and now the brake light is on. the front resevior is empty and the brake pedal goes to the floor but the car still stops but barely. The leak comes from under the back drivers door and there is no links or connections under there, just straight line. My guess is that its one piece from the ABS unit to the rear axle but that just seems too long. Nothing detailed about it in the service manual. Does anybody know the size and length of the brake line.

Very common for rust belt cars. Yes, that line goes all the way from the front to the back. Take it off, and match up the fitting sizes and tubing size. Just cut the line so you can get a socket right on the fittings. It will come out much easier, and you have to replace it anyways. Bring the fittings into the parts store and they will fix you up.

You have two options to fix. One, you can buy bulk line and flare it yourself, or two, you buy a couple of pre-made sections and a coupler. I have done both, and both are perfectly safe. Before you go to the parts store: crack the rear bleeders on the wheel cylinders to see if you can open them to bleed. If they break, add those to your shopping list:rant2:

I can't say for sure the exact length, but it is all one piece from the cylinder back to the union over the rear end, I did mine a couple of years ago. If you're going to do it yourself, you'll need to go to your local parts store and buy some fresh brake line. My store sells it in increments of ten inches, 10, 20, 30, 40. I can't recall exactly what I used, but it doesn't have to be spot on.

Damn, I've never took the hub off the back wheels because I was scared of whats back there. If the bleeders break, are they hard to get out? I have this feeling that this is going to turn into new back brakes, hardware and lines.

These things are supposed to be double lap flared. I have a flare but is this done with a regular flare or is this a different one? Also, the manual shows only one line going back but when I got under the leak about mid way back, there looked to be two lines. Is one for something else?

It is one line. The other line is fuel.

Pretty common huh? I have a New England 90 FWB and I can't even get a mechanic to work on the brake lines here in TN. They say its a "liability". Whatever.

Well, I got under there again and theres alot of rust and I dont know if this will be an easy job. I might give it to the shop. The bleeders look decent and still have the rubber boot covering it but the connection in the back looks terrible. And my jack is leaking fluid with every pump. But then again, its not like I have to be careful with the line. Oh, why not try.

Damn, I've never took the hub off the back wheels because I was scared of whats back there. If the bleeders break, are they hard to get out? I have this feeling that this is going to turn into new back brakes, hardware and lines.

I bled the brakes on my '83 Oldsmobile last year for the first time since new. I nearly destroyed the bleeder trying to unscrew it. I eventually took it to a shop to be bled, and they told me if you get it stuck in there, then you pretty much have to replace the caliper. Fortunately that was not the case for me. We got it out, and replaced them.

My problem was I used a 12pt. wrench instead of an open-end wrench. Then I basically wore the head to nothing. As I recall, GM used 10mm hex on the bleeders, for which I was missing my open-end.

Moral of the story: use an open-end wrench. ;)

Actually, you should use a line wrench. I don't own them, however, so I use a good open end of the correct size on tubing fittings that need to be reused, and I use a six point on bleeders. Socket on fittings that are getting replaced after cutting the line.

Hmmm, I have space in my new roller cabinet tool box for line wrenches... off to ebay:thumbsup:

http://www.autoeducation.com/flare_wrench.jpg

the bleeders moved very easily so they are going to be ok and I took the hub off, it looked good too. too bad one of the connections is rusted together. damn i need some line wrenches.

I have never seen line wrenches (tubing wrenches??) work on rusted fittings. You might as well use vice grips. You're lucky the bleeders aren't frozen, you should buy a lottery ticket.

You really don't need line wrenches. Like I suggested, on the line that is getting replaced: just cut the tubing right at the fitting, and use a socket. You won't round it off this way. When you install the new line, start it by hand, then snug it down carefully with a GOOD quality open end that is the correct size (no metric on Imperial, etc).

Damn it Jay, I should have listened to you. Now I have to get a new cyl. cause my friend rounded it with vise grips

lol, we all learn the same way. Remind me sometime to tell you how I know transmission fluid doesn't wash out of hair:helpless:

Oops, I thought you were loosening a fitting in the line itself and I usually vice grip them. Even so it's still better to cut it and use a socket like Jay said. On the wheel cylinder I usually do break it off and use a socket. That sucks that you have to change the wheel cylinder after the bleeder came out so nice. Are you sure you can't get any size socket to pound onto that rounded nut and get it turning? sometimes when I have a really rounded nut or locking lug nuts I can pound a 12 pt socket on it and get enough grab to loosen it. I also use heavy duty Prell or Head and Shoulders to wash out tranny fluid conditioner lol.

As it turns out, we were able to get the fitting out and not have to change out the cyls. So I replaced the line from the ABS to the rear brake hose, the brake hose with T adapter and the lines going to each cyl and bled the brakes. It was my first time bleeding the brakes and it was easy so now I think I'm gonna do it to all the cars.

FYI..our brake pipe is an american size, our brake pipe fitting is an american size with European fine thread. The flare on the pipe from ABS to rear hose is a bubble flare but from the rear brake hose to thecyls is a double lap flare. Why all the inconsistancies?

Sorry I'm so late to this party. One of my biggest helpers for getting the rusted lines and bleeders to separate is an acetelyne torch with a brazing tip.

FYI..our brake pipe is an american size, our brake pipe fitting is an american size with European fine thread. The flare on the pipe from ABS to rear hose is a bubble flare but from the rear brake hose to thecyls is a double lap flare. Why all the inconsistancies?


Because the ABS unit is manufactured by Bosch. The Euros use the bubble flare, and domestic uses the double flare. Did you do your own flares, or buy pre-made tubing?

I made my own. What I did is buy the adapters to turn the bubble flares into double lap flares and flared them myself. I did a single flare cause I didnt have the flare adapters but that went bad the next day. I was gonna double flare but the the head goes. I try to be so good to this car but anytime I fix something, something bigger happens. Now I know never to get a 307, they may be decent motors but this car has ruined there rep for me. But I love this car, my first Caddy and my favorite body style

Please, please, PLEASE... do a proper double flare or take it to a mechanic. Even if you do the bends, just take the tubing in and give them the tubes to flare.

We don't want to lose any members around here...:eek:

Single flares are not safe period. You can do like Jay says or buy a double flaring kit and a piece of brake tubing and practice your double flares. I even double flare copper tubing on furnaces because single flares are just too cheesy and always cause me problems.

PS: maybe you shouldn't buy the lottery ticket because I have never heard of a 307 living a short life.

Well I'm having issues with this brake system again. I let the brake problem sit along with the car for the winter and now I'm back at it. I did do a double lap flare but now the brake fluid isnt making it past the proportioning valve. I know its not the master cylinder or the ABS. The fluid makes it to the proportioning valve but not out the other side but only on the front line(rear brakes). I was reading the service manual and it was saying that if the front brakes fail, the valve will switch all braking effort to the rear brakes and the valve will have to be manually reset with some tool. I was wondering if this would be the same if the back brakes fail, will I have to reset the valve manually? Or is the proportioning valve bad?

I have run into this a couple times and it's no fun. One of my mechanic friends told me years ago that when this happens he takes the car for a ride and applies the brakes very hard several times and the proportioning valve will snap out of it. Since my cars are usually old, this seems to only work 50% of the time for me.

I've been driving it around and nothing, can I take it apart?

When I tried to replace them in the past I couldn't do it. The parts stores said they couldn't get them and the dealer said they were discontinued. Now we have Ebay lol:

http://cgi.ebay.com/ebaymotors/GM-Proportioning-Combination-Valve-Disc-Drum_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q3a 2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q 3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZite m180345661377QQitemZ180345661377QQptZMotorsQ5fCarQ 5fTruckQ5fPartsQ5fAccessories

oops I see that one is for an older car but I have seen them before for my big Caddys.

yea I saw those but im gonna take it off to see if I can do anything to it

I took the proportioning valve off and thought maybe I could run without it. The lines would go from the master cyl to the ABS, then to the brakes. Would this work?

Hello, im so glad i foud this thread, i have just impprted a 1970 eldorado (to the uk) and am having a lot of fun wasting time on the rear brakes.
After replacing the rear right brake line from the t junction to the hub i cant get the fluid to pump up the tube!
I know the fluids there because i can get it to squirt out of the t junction but not up the pipe!?
I took it to the shop and they couldnt do it either (it wasnt a brakes specialist but i dont have much choice as uk mechanics are a bunch of pussies and get scared of yank tanks)
I can only presume that the proportioning valve is stuck in the "front brakes only" position.
What can i do to reset the valve, Tap it? slam the brakes on? take it off and shake it?? Buy it flowers?
This is driving me mental!

If one brake line failed the others may fail within days. My advice would be taking care of all of them right away. Been there done that.

yeah god idea, for the moment though i just need this one done to pass the uk mot test..until i get that i cant get it registered or plates or even keep it on the road and i have no garage or driveway!:bomb:
So i need this done asap..

Ive just had a closer look at the valve and there seems to be a switch hanging underneath it.. does anyone know how this works, does it push in or mave sideways? its stuck at the moment.

Actually, you should use a line wrench. I don't own them, however, so I use a good open end of the correct size on tubing fittings that need to be reused, and I use a six point on bleeders. Socket on fittings that are getting replaced after cutting the line.

Hmmm, I have space in my new roller cabinet tool box for line wrenches... off to ebay:thumbsup:

http://www.autoeducation.com/flare_wrench.jpg



Dont get junky ones. If theres one tool not to buy cheaply this is it. Junk ones just bend and will strip the bolt. Especially on old rusty break lines. Get some snap on, or mac.

Actually, you should use a line wrench. I don't own them, however, so I use a good open end of the correct size on tubing fittings that need to be reused, and I use a six point on bleeders. Socket on fittings that are getting replaced after cutting the line.

Hmmm, I have space in my new roller cabinet tool box for line wrenches... off to ebay:thumbsup:

http://www.autoeducation.com/flare_wrench.jpg

We always called those nut rounders. I've never tried Mac or Snap on but the Craftsman's will round them very nicely. After they are rounded then I have to use the Vice Grips that I should have used in the first place. Just one more reason many people hate working on brakes.

Hi, after a few hours wasted pumping the pedal for a mere dribble of fluid my neighbour helpfully pointed out that i needed to loosen the brake fluid resevoir cover to allow for the displacement of the discharged air at the drum.
So this is what i have learnt about bleeding rear drum brakes on a 1970 eldo...

Start with the rear right (passenger) drum.
Push in and hold the small pin reset button on the compensation valve - mine was stiff so I had to very delicately use a g clamp to push and hold it in- it only moves about a centermeter.
(sits below the master cylinder, has a bunch of lines going in from the master cylinder and then out to the brakes)
Loosen the resEvoir cap retainers and just let it sit on top.
keep the resevoirtopped up with oil throughout the bleeding.
Get a friend and continue with the old-pump pump pump hold... Under bleeder-tighten bleeder and repeat till no more bubbles.
now thepedal should feel nice and hard. Check resevoir us topped upand release the reset button.

For the record when the resetbutt

Sorry for that mashed up text in the previous message..i was typing on my iphone!
Also i realize mine is a fwd but i had such a bad time figuring this out i thought i should share it anyway!

I'm still having issues with mine. When you say small reset buttom on the valve, are you talking about the part that has something plugged into it on the top of the proportional valve or the other thing in the front with nothing going to it?

I'm pretty sure we don't have a reset button on the RWD prop valves. They are reset by balancing the pressure. Easiest way after bleeding is to make some hard stops.

I can attest! I tried on a fuel line, it cracked as soon as I put it on. Do not ever use single flare!

And the brake lines in the rear, one side fitting is different size than the other at the rubber lines on the 94-96 FW's.... Joy..... Makes it fun!

Please, please, PLEASE... do a proper double flare or take it to a mechanic. Even if you do the bends, just take the tubing in and give them the tubes to flare.

We don't want to lose any members around here...:eek:

So I'm still having issues with the brakes. I still have no rear brakes and now the front brakes are dragging really bad. To the point where, if I'm going slow enough, I dont have to hit the brakes to stop. I dont move when I'm at the light with no foot on the brakes. Also, when I hit the brakes, they are really sensative. I havent got a chance to look yet but this is a new venture for me, just trying to find out where to start.