I started bleeding the brakes on my T-bucket project this weekend. It's a completely brand new system, and i've saled up all the leaks I've found. The problem I'm having is I can't get a firm pedal. There doesn't seem to be any more air in the lines, and there are no leaksfrom any fittings. It seems though that it is leaking from the master cylinder cap. Any suggestions? Thanks, Barn-core.
more info please, what master? what brakes? disc, drum? any prop or residual valves? could be a ton of things
The cap leaking is "a" problem, but not "the" problem. Worry about that after you get a pedal. First off, if drum brakes are involved be CERTAIN they're adjusted! Otherwise you could be chasing a ghost
I've got disc front, drum rear. I'm using a Speedway underfloor kit for the master. No prop. valve, or residual valve. It's not that I'm not getting good pedal, I'm getting no pedal. If I pump the pedal they'll get more firm, but as soon as I release it, they're back to the floor.
did you bleed the master cylinder before you installed it? the peddle usually wont let you compress the pistion all the way. it probably has air trapped in it and you wont get it out after its installed. bleed the master cylinder in a vise first.
possible you don't have the rod adjusted properly.I've also seen when you push the pedal all the way to the floor, it ruins the seals in the mater cylinder, even if its new.Never go all the way to the floor.
the reason i said loosen the cap is because it acts like a capped straw.. best way i can put it... like when you put a straw in liquid, then cap the top and pull it out, and hte liquid stays in it till you let off.... maybe the master isnt letting the fluid go all the way in?
Did you say you do NOT have residual valves? If the M/C is under the floor you MUST have a 2# and 10# else the fluid will drain back into the M/C. Are you getting fluid out of the bleeder valves? Sometimes on a new M/C the plunger will stick down if the pedal was pushed without fluid in it. Do you have the rubber under the cap? That rubber expands to take up the space as fluid is pumped out and also provides a seal. Do NOT run without it. There is a small vent hole in the cap and air should not get to the fluid because the fluid is designed to absorb moisture.
this is the exact problem, i had on my 39 chevy...the rod was to short..wasnt making contact..i had to end up making a rod ..after i made a new rod..bled the right rear cylnder 1 time and started getting decent pedal from there....
I just came in from the garage doing the same thing on my T, with the same pedal setup...lol Did you let the master run dry during the bleeding process ? I was bench bleeding mine on the chassis and the supplied threaded plug blew out and sprayed me and the freshly painted chassis.
The master was bench bled before, and all parts are there and accounted for. I never ran the master dry either. I'm getting plenty of fluid from bleeding, and there doesn't seem to be any air left in the lines. Looks like the popular answer is residual valves. I was hoping to have it out for the first time this weekend, looks like maybe not. Thanks guys, I'll let you know how it goes. Barn-core
I have the same set up with the residual valves and the adjustable proportiniung valve. I have been at it for a couple of weeks and still can't get a good peddal.
Do you have the right size brake line? You need volume to push the cyclinder. like haveing a 1/4 hose vs a 1/2 in hose. You may get pressure but do not have enought force[voulme] to push. Just a thought I have disc on the front and drums on the back and had a soft to the floor petal till I Adj. the drums. Just a thought Acechev55 Acechev55
What calipers are you guys using?? The "metric" calipers could be the LOW DRAG version and as a result will be very unlikely for you to get an instant firm pedal due to the seal design. The Low Drag calipers were origionally designed with seals that were on a slight angle - the result of this was that in use it would retract teh piston to eliminate brake pad drag. If you look at the origional applications you'll notice they also used a "fast fill" master cylinder with the Low Drag calipers - this syle m/c was used to eliminate the kinds of problems you guys are describing. OTOH - I've talked with guys who used the "metric" calipers with nothing else "special" - which leads me to wonder if theirs had the low drag seals in them or not. One more thought on bleeding. if you just trickle the fluid out - you are likely to be moving the fluid so slow that it actually moves past any air bubbles. Residual Pressure valves are NOT a "new fangled" part - before throwing them into the mix first make sure you don't already have one in your master cylinder. If the M/C's origioanl application had a combination valve in teh mix then the m/c will not have them built in. I am assuming you have a disc/drum master - right? Spongy pedal is almost always a result of air in the system. Eliminate THAT before pulling your hair out. I've also seen guys mount their calipers backwards - the bleeder valve needs to be mounted at the HIGH POINT in the system.
So along the lines with this thread, I posted earlier that I had the same setup only with rpv's and proportioning valve. This is my question. Why would the small chamber try and spurt fluid out the top on the down stroke of the pedal when the big chamber does the opposite ? It does the spurting thing on the return stroke followed by fine bubbles. It's almost as if it's sucking the fluid from the lines. It was bench bled, the rpv's are facing the right direction and no leaks anywhere.
I'd like to tag on a relevant brake question of my own. What happens if I set up my brake MC and lines without bench bleeding the MC? Is there anyway to correct this?
Disconnect the lines and get some inverted flare plugs. Put the plugs in where the lines go and bench bleed it on the car.
I just did a brake system like the one that you are discribing on a buddies truck. discs brake front end from MAS, master under the floor from speedway and drums in the rear on a 56 chevy rear. Ran 3/16" lines in the entire thing and necked them down to smaller lines at the front brake hoses. I did not put residual valves in the system but it does not loose pedal and the pedal feels good. What do the residual valves do?
I noticed that mine does the same thing, and was wondering why. I got ahold of a few residual valves today, and was wondering if it is better to install them closer to the master, or to the T?
Susposed to be close to the master, it's that way in the Speedway diagram and a brake article in Rod &Custom.
It's a pain to bleed a M/C that hasn't been bench bled, but it's still doable. Matter of fact I just did it yesterday - I was busy mocking everything up and I realized I had forgot to bench bleed my m/c. SO being lazy I simply loosened up a bleeder - attached a hose to it and cranked the pedal with one hand while using my thumb over teh hose end to "open" and "close" the line - it worked absolutely fine. No magic here.
The spurting on the return stroke followed by fine bubbles is a sign of air in the system. Seprate idea but also make sure your compensation ports (the small ports) are not blocked or plugged with muck/dirt. Both compensation ports should spurt when you first apply the pedal - until they are covered by the brake seal - if one continues to spurt after the seal passes - that's an indicator that the seal is bad.
That's what I was thinking with the air still in the system. I couldn't find a volunteer to pump the brakes so I made a make shift vacume bleeder. I made it out of my girlfriends old breast pump, I guess I didn't leave it on long enough. It worked pretty good though...lol
Residual valves should make no difference in your pedal "feel". If you don't have any pedal at all, that's not your problem. Not a bad idea to add them, but it's not going to cure this problem. If you can pump up the pedal, you've got air in the system somewhere. I'd start by re-bleeding the master cylinder, then re-bleed the entire system. If you still don't have good pedal, it may be the master cylinder itself. This wouldn't be the first time I'd seen a bad master right out of the box. Try that, and somewhere along the line, you'll find your problem, and you will have brakes. And I wouldn't rule out the push-rod/ linkage. Just for the record, No pedal= open in the system If you have to pump it up= air in the system Firm pedal that fades= internal leak in the master cylinder Low firm pedal= mis-adjusted brakes
I sent an e-mail to Speedway about my problems and they asked for my address and would send out a new master cylinder. Now that's some customer service that I don't mind having. Good prices and good service, who would have thought such a thing exsists..
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