tires and wheels Another Big Brake Upgrade Question

[lsixt]

1974 2002 (Non-Tii)...

Stock rear wheels, upgraded front disk Volvo Girlings...

New stock brake M/C (bought the M/C prior to the brake upgrade)

Here's the issue. I've bled the brakes about six times. RR, LR, RF, LF... bled all of the Girling bleeders from top to bottom....

Using a pressure bleeder system....

No matter how much I bleed the system, my brake pedal goes to the floor with no braking power... If I put the front wheels off the ground, spin them and apply the brakes, they stop, but when I'm driving (keeping one hand on the E-brake handle), I litterally have no brakes.

Before you all start yelping about driving with no brakes, the car isn't tagged yet... the test driving is on a closed area behind the garage.

One more thing... with the pressure bleeder on and all bleeder screws closed, when I apply the brakes, almost always I'll get some bubbles work their way up the pressure bleeder hose.

I've read about all I could find on MC and big brake upgrades... Bottom line from what I've read is that a stock MC should work - not saying it's the best solution, just from what I've read it should work.. Tii MC seems next step, but I want to make sure I'm not missing anything.

Thanks,

Len

[Guest Anonymous]

This is not the first time your question has been asked nor will it be the last. IF you SEARCH the archives, you will note similar responses.

Let's go back to the beginning. How was your system functioning prior to the "upgrade?" If it was doing well, then you might be able to eliminate the master cylinder as the source of your problem.

Even if your Master cylinder (whatever kind it is) worked before, keep in mind this is hydraulics 101, it has to create pressure via your foot and if there is a ripple in the seal or the bore of the cylinder - oops, not much if any pressure. Although uncommon, even brand new master cylinders have been known to fail. By changing to a different setup, or by even changing pads or shoes, you change the working stroke of the master cylinder piston. By doing that, if you have a used master cylinder, you may be forcing the piston over rusted or even smaller areas of the bore that may cause immediate wear of the seal and voila, no pressure.

I know everyone seems to love the pressure bleeder, but here's what I would do: Try the old fashioned method. Have someone put their foot on the brake pedal and make sure the fluid is being forced out of the bleeders. If it is not, you have a master cylinder replacement in your future. If the fluid is being squirted from the bleeders, then its caliper issues.

Good luck,

[Guest Anonymous]

1974 2002 (Non-Tii)...

One more thing... with the pressure bleeder on and all bleeder screws closed, when I apply the brakes, almost always I'll get some bubbles work their way up the pressure bleeder hose.

I guess I missed this. Bubbles = air in the system. Air compresses. Brake fluid does not. You either have a leak or you introduced air into the system which must be purged. For the moment, discard the pressure bleeder and use someone's foot to bleed the brakes. Could be a very small leak at any of the hose/pipe connections. With air in the system, you may have brakes, not just very good ones, especially when they get hot. But you seem to indicate no brakes. That's a lot of air or a bad piston (MC, calipers or rear brake cylinders).

Good luck, and after you get your brakes sorted out, dont hold back. Tell us how your use of seafoam was a life changing experience! lol

[Guest Anonymous]

Can't leave this alone. Where are the bubbles? The catch tank/jar? If so, the bubbles MAY just be air being drawn around the bleeder screw threads on the outside of the calipers or rear brake cylinders.

[TobyB]

Did you change the master before you did the upgrade, or as part of it?

It kind of sounds like air in the master, or a non- functioning master.

I'm with Sylvan- ditch the pressure bleeder.

However, on all my cars, you can just let gravity

bleed the calipers. Doesn't always work when the master's dry,

but I pre- fill the master on the bench.

The other thing I've had happen is that the seals in the calipers can over-retract

the pistons. Usually that results in a pedal with long travel, or one that

takes 2 pumps- and then I get a real solid pedal. It's possible that you

still have some air in there (it almost always takes several days for all of it to get out) AND you have hyperactive seals.

The fix is to stand hard on the pedal, repeatedly. On the race car, when I

went to 528 calipers, I spent a whole morning with a terrifyingly long pedal-

and when I finally got real heat into the pads and some confidence in the brakes, I got in it hard enough to settle them out. Now I overextend the

pistons a bit, and coax them back with the pads.

No, the tii master's not necessary at all. 0 out of 3 of our cars use it...

t

[lsixt]

lots of stuff....

The car was "stock" 7 years ago when I started a rebuild. Stipped to the bone and acid dipped. So, in terms of how they worked before, they worked as you would expect for a old used car.

Bought a lot of new parts when I started, including a new MC... Not knowing at that time if I was going to stay stock or not. As you know, I went for the front upgrade....

I haven't been able to get any "pressure" since I hooked up the brakes. I've not tried the buddy foot on the pedal method yet, but I will later today if my wife agrees to humor me.

The "bubbles"... when I have the pressure bleeder on and all bleeder screws shut... if I "pump" the brake pedal, I'll see some bubbles come up OUT of the brake fluid resivor

[john_a]

You mentioned the car was stripped & reassembled, new m/c & front caliper setup, stock rear. And the pedal goes to the floor.

When you put the car together, had you confirmed the adjustment of the rear brakes? The rear shoe-to-drum clearance can make a very large difference in pedal travel! Adust the rears with the drum clamped on by either the wheel, or use large washers & open lug nuts to tighten the drum against the rear hub. Adjust the shoes over-tight to see what happens with the brake pedal travel.

I agree with the other posters that you may still have air & it's time to try a conventional brake bleed (one person working the pedal & another on the bleeders.)

[Marty]

I would try tapping the master cylinder lightly to see if that will dislodge any bubbles. Also on the calipers are the bleed screws pointing upward, you would not be the first person by far to get them reversed. As has been said above adjust your rear brakes and bleed with the parking brake off.

[TobyB]

if I "pump" the brake pedal, I'll see some bubbles come up OUT of the brake fluid resivor

Ahhh. Loosen the fittings on the master (one in front, one in back is enough)

then get a pan underneath it. Now get some pressure on the reservoir,

and let a bit of fluid (and hopefully, air) out of the master.

It sounds like you might have an air- locked master. They really don't

work so well unless they're mostly full...

hth,

t

[lsixt]

I'll try that with the MC....

One more item...

I am not having any issues with the clutch... she works fine... also, I'm not losing any fluid as the level stays right where it is...

Now, the clutch and brake pedals are at the same level inside the car. But I have to push the brake pedal at least 2 inches before the brake lights come on and then another inch or so (three inches in all) before I can feel any brake pressure... at that point I'm almost to the floor and putting it to the floor isn't enough to stop me from a 5MPH roll within 20 yards...

UGH...

[gerrynj]

"Bought a lot of new parts when I started, including a new MC... Not knowing at that time if I was going to stay stock or not. As you know, I went for the front upgrade....

I haven't been able to get any "pressure" since I hooked up the brakes."

Ok - this is the clue I was looking for !!!! is that you probably installed the MC dry. Trying to blead the brakes will either not work and take forever. I just did the same thing of a VW "Thing" (remember those!!!). We could not bleed the system even though we had no leaks. What I did is crak the lines coming off the MC and start bleeding the system at the MC - using a trust buddy to pump the pedal. Once we bled tha MC, we worked to each corner and bled the calipers/drums. It tool 3 or 4 tries but each successive time, the pedal became harder.

Try bleaading the MC by cracking the brake line at the MC - hold the brake pedal down, close the line, pedal up - repeat several times and clean off the brake fluid becore it attacks the paint.

gerry

[JohnC]

if I "pump" the brake pedal, I'll see some bubbles come up OUT of the brake fluid resivor

It sounds like you might have an air- locked master. They really don't

work so well unless they're mostly full...

hth,

t

I just did a complete overhaul including a new MC, and had the same problem. I pumped the brake pedal about 20 times until I didn't see any more bubbles. This seemed to help work the air out of the MC. I then bled the brakes two more times, using a vaccum bleeder). That solved the problem.

[lsixt]

Well, well, well....

I got more "pedal" but it's late, I'm old, and tired... so tomorrow perhaps we'll give it a test....

Here's what I did...

Right behind the booster, in the pedal box (external outside the firewall).. there are two arms that have adjustment forks in them... Well I turned in the one that is connected to the brake pedal (making it shorter)... I guess I gave it about 5 or 6 turns clockwise. This shortened the travel that the pivot has to make before moving the upper arm to the MC.

I didn't muck with the one that goes into the MC...

Anyway, like I said... it appears that I have more pedal now. Test drive tomorrow perhaps.

Thanks all.

[Emyers]

I will be willing to bet you have the calipers on the wrong side....left to right and right to left. nipples should be pointing up if I remember correctly....friend and I did the same thing some years back..went thru about two large bottles of bremsen fluid before we figured it out.

Earl

74 02 Lux

02 M Roadster

72 Volvo 1800ES

[lsixt]

I'm fairly sure the calipers are on correctly. The nipples don't point up. All three point straight out...

The odd nipple is on top, and the two opposing nipples are in the middle.

See photo.