Hope someone has some insight, I'm at the end of my rope. Mostly brand new brake system: GM Calipers (82 Monte Carlo on Mustang II) Ford 8" Rear w/ Drums (78 Granada) GM Style master (Dual Chamber) Believe 1-1/8" Bore, could be 1" 7" Single Diaphram Booster Higher pedal ratio. (Will measure and calculate later at home) Master has been bench bled several times. Cannot bleed the air out. I've tried several different check valves/one way bleeders/ etc. I have an injector but it's broken. I specifically bought the injector because I hate bleeding brakes, but have to do this one the old-fashioned way and it's not effing working. Anybody got any ideas at all? Even the easy stuff...it's been three late nights of trying and no progress... Thanks! Mike
One more thing: I tried plugging the master ports and it holds pressure. I'm not convinced it's not the problem though.
I've had a couple weird ones where I couldn't expell air from the system until I gravity bled the system
In my experience new systems always wanna give you grief - the easiest method I have found is to LEAVE the bleeders open - and stroke the pedal - it may **** some air in on the return stroke, but so what - keep doing it until you get close - then proceed as normal, pumping - bleeding - pumping. Inspite of what some may say - this has worked for me several times.
I always just get a buddy to push the pedal while i open the valves and just bleed the living hell out of it until it's good to go. If you're getting a lot of air after giving it hell I'd start looking for a leak or opening somewhere. It's supposed to be a closed system so something's gotta be pulling air in.
Can't get a good gravity bleed either...The components are all new this month, truck was parked (with working brakes) two years ago. No leaks during down time. Brakes even worked two months ago when we pulled it off the trailer. I have no reason to suspect leaks in the plumbing. Can the master be drawing in air but not leak?
??? M/C mounted where ? under floor,firewall. If under floor residial checks both front and rear? Adjust the rear brakes up to dragging. booster to M/c pushrod too long? Pedal pushrod got some free play?
mc on firewall, rear brakes adjusted right up...pushrods all up to snuff...little slop in the pivot but not so much to cause a problem.
don't have real details, but a guy I know had same type of problem. then switched disc units front side to side so that bleeders were at top
Read this...you may need different calipers or go to a quick take up master cylinder. http://www.mpbrakes.com/uploads/do***ents/lowdrag.pdf
I had the same issue with my coupe. I found the calipers were highr then the master cylinder, a removed the calipers, installed a block of wood between the pads, and bled them with them hanging, worked perfect!!! I had tried bleeding this for two weeks with every kind of power bleeer available and wasted two GALLONS of fluid, with calipers hanging I was done in twenty minutes, hope this helps
Let's go back. What makes you think there's still air? Where is the air? At the M/C? At the wheel cyl/calipers? Just one wheel cyl/caliper? How are you bleeding? Pumping the brakes and then opening a bleeder? Not recommended as that airates(sp) or foams the fluid sometimes at the point of air, making it harder to bleed. I push the pedal down.... ONCE, then crack the CLOSEST bleeder to the master, repeating til solid fluid comes out, against what I've learned through the yrs. This puts solid fluid quickly to the nearest wheel, allowing ONLY fluid to be pushed to the furthest wheels
EXACTLY THE PROBLEM I HAD when I first put my system together. Seemed like I still had air in the lines because I couldn't get a firm pedal (no matter how many times it was bled, vacuum bled, bled to death, BUT it was actually because I had the 'metric' calipers up front, which were the 82 Monte calipers. I kept everything else the same, but switched to 78 Firebird calipers (which look absolutely identical in every way to the Monte 'metric' and the problem was instantly fixed. The 'metric' caliper was a bright idea by GM to increase mileage by having the pucks retract slightly from the rotor to reduce drag, but you need the 'quick uptake' master cylinder to make them work. Easier to just swap the calipers to non-metric.
I did the gravity feed on my first car, the master cylinder was up on the firewall. When I did my 32 I used the hand held mightyvac type bleeder. I was able to pull more of a vac***e and get the brake fluid to flow a little faster. Not sure if that had been mentioned.
So '78 Bird calipers are interchangeable with '82 Monte, with the exception of the low drag "feature"?? This scenario would mean a conventional master has virtually no chance of ever bleeding the low drag calipers. In light of this, a little more history may be relevant: The previous builder used a '99 Geo Metro master and booster. Even though it was far too small for the application, it would have been a quick-takeup style and been able to compensate for the calipers...sound accurate??? (Hope so, peices may be falling into place...)
Correct. I do not know why the Monte ones are referred to as metric, as the Firebird calipers bolted right up to the same caliper hangers as the Monte ones using the same pins and all. Apparently the only difference is internal and requires the quick uptake MC that has a stepped bore that initially throws a bunch of fluid downline to get the pucks back up against the rotors and then the second step of the bore gives you the brake pedal to bear down with. Without the right MC, all the pedal travel is used up just getting the pucks back against the rotor and there is no pedal travel left to give you the brake power to bite down. It drove me nuts trying to figure out what was wrong and I had all kinds of experts recommending changing pedal geometry, MC location, etc. All stuff that would have ****ed to re-do. I made a post here on the HAMB asking for help and ElPoloko was the first to mention the 'metric' caliper, but I ***umed that couldn't be the problem because they couldn't be metric since they bolted right up to my otherwise non-metric car. ha, ha Then I found that same info on the MPbrakes website that Hakerbilt posted, swapped calipers and it was fixed in a matter of minutes for cheap. Try it, I do think that is your problem.
I will swap calipers. I'm more than convinced that they are a problem. While I'm working on that, I'll ask if there is any possible reason under the sun I can't bleed the rears. (I've thrown out everything I thought I ever knew on this system.) Is there some link, even in a dual circuit system, that would cause my rears not to bleed because of the goofy calipers on the front? I'm not running a combo valve, pressure reducing to the rear only.
I think I may have an answer to my own question...if I have a proportioning valve in the rear line, and due to my mismatched master/calipers, I will not be able to bleed the rears till I sort out the fronts. Since the fronts don't work I get effectively zero line pressure. A proportioning valve reduces line pressure to keep the backs from locking up. So reducing from zero makes...smaller zero. Or am I talking myself into circles?
Disc/drum systems usually require a metering valve for the front brakes to keep them from locking. It slightly delays the front pressure giving the rear brake cylinders a little time to overcome the resistance of the return springs on the rear shoes. As, the others have said, I think your bleed problem is due to mis-matched conponents.
Try to bleed one circuit at a time. Block off the rear at the master with a plug. Make sure not to bottom out the piston in the master cylinder it will ruin the master cylinder.
Yup...only thing that is new is the booster/master/pedal ***y. The previous builder used a booster and master from a 99 geo metro. While it was small and I had to give the brakes a couple of pumps, it did work. I think even though it was small, it had the neccesary low pressure circuit to get the discs going, even though it took a couple pumps. It never had any nose-dive problems before, but it may develop them now with a proper size master (once I get matching calipers) You all have been tremendous help, by the way...I was starting to lose hope! Mike
you have the aftermarket "vette" style M/C, yes? do you have the front brakes hooked to the larger of the two reservoirs, and the rear to the smaller? Do you have a 10 psi residual in the rear line? If yes, and you DO need one, what brand is it? Wilwoods have a reputation for causing issues the metric calipers are referred to as such, because they take a 10mm x 1.5 thread banjo bolt, whereas the earlier calipers use a 7/16-20 thread banjo bolt
Vettes had 4 wheel disc brakes with equal size front and rear reservoirs after 66. 66 and earlier had single, juice jar style reservoir. If the M/C has 2 different size reservoirs, I personally would not call it Vette style. That would be front disc/rear drum. Something you won't see in Vettes
I am having the same prob. All new everything. MII front and 9" rear with the residual valves and prop valve. MC is under floor. Arm is unaltered from stock shape and length. I just cant seem to get it pumped up
look real close at the casting. The front reservoir IS a bit larger. The cap is symmetric. Typical disc/drum have VERY different size reservoirs that are easily distinguished. It's a common mistake on the aftermarket street rod "vette style", I've seen it A BUNCH of times. Typically it's on underfloor mounted units, but it never hurts to ask.
Hmm...ok, so the master may still be in question. The reservoirs are not decidedly different in size. I won't say one isn't slightly larger than the other, but it's not obvious at a glance. I'll try to remember to grab the casting number off of it tomorrow. It has only two ports, 1/2" and 9/16" I think..using adapters to get down to 3/8". Cap is indeed symmetrical. If my master is a true disc/drum then the residual should be built in, no? I'm not using an external one. I made a trip to the parts store, and the 78 'bird calipers are decidedly bigger than the 82 monte carlo...so now I have no idea what calipers to get to work with a conventional master cylinder. I had them look up the master for the monte and it isn't an option for me. Clearance for one reason and aesthetics for another. It's all plastic and ugly... I've tried hooking the lines up both ways, disc to front, disc to back, etc...no effect. I thought we were on to something with the regular calipers, maybe we still are....it's just that '78 firebird isn't it...
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