Technical Help with Brake Combination Valve Question

What about the piston seal? It has nothing to do with piston return?

If the rotor pushed the piston back to rest, it would have to be warped or the car needs a wheel bearing adjustment.

 

Bob,

Look up the word facetious.

 

Keep going your just proving your ignorance, number one all you said about dual masters etc absolutely is what I was saying, show me in the article you posted where a proportioning valve reduces pressure when the brakes are applied, at no point does it reduce pressure it slows pressure rise to the rear in relation to the front.

Go out and lock up the back brakes first and see what the vehicle does, you absolutely do not want the rear locking up first. According to you every tech in Canada is taught wrong, that’s something….

Anyway I’m done arguing with someone who is just here to try to prove how much he knows even though he clearly doesn’t…

 

These seals on the switch spool.



I have dealt with multiple one side brake failures due to rusted lines and never once has one of these switch spool seals failed and caused loss of the fluid in "good" side. Maybe that type of a failure is common in your area; but I've never heard of it around here.

 

If you can't explain it simply you don't understand it well enough . Albert Einstein .

 

Maybe if you re-read that article without moving your lips it will dawn on you what the article is trying to tell you.

 

If they (seals) would stop the leak-over, the pintle would also block the failed circuit once it shifts. It doesn't do that, correct?

Those are there to stabilize the pintle to slide freely.

 

Most everything I have read here is simple. This is not atomic theory.

 

Well, the flow is very small, I'll grant you that, but it happens on every pedal depression/release cycle. It is exactly equal to the master's piston displacement. And, since fluid is not compressible the sealed system acts like a solid. I visualize the fluid mass moving from master to wheel as one unit, and in reverse. But it does 'flow' thru the system in a minute amount. That 'minute' part is why there is no need for multiple ports from the master to one end of the car/truck as has been stated. They're only there for plumbing convenience, at least IMNSHO.

 

The simplest answer appears to be to eliminate the OEM type proportioning valve and use only the 2&10 pound residual valves and a manual proportioning valve..............then all the discussion about the OEM style proportioning valve becomes irrelevant. Might consider incorporating some fittings in each system where a pressure gage could be inserted to verify the pressure without opening the system. That should help when adjusting the rear proportioning valve, and verifying pressure in both systems. Refer to the diagram posted earlier.

 

I’m done with you, can’t fix stupid.

 

DAMN! Sunday services over already?

Yeah you are right, stupid and ugly. Maybe a self-awareness course may help you with your depression and lack of self-respect.

PREVIOUS STATEMENT-

See, now we know your word is no good either. Did you bother to actually read the TECH ARTICLE? It has pictures. I don't have the inclination to put you on my knee and read it to you.

 

Trying to read and cipher the OP's original post, it seems like the booster was bad (wouldn't return fully). It was either bad or the system was adjusted incorrectly (pedal and/or MC).

The valving was secondary as everyone saw that fiasco and began jumping in with this theory and that theory (including pascals). He needs (IMO) to get everything (pedal-linkage-booster-MC) mounted/adjusted correctly and go from there. You couldn't even ask him a question with someone playing mine is bigger than yours.

Only HENRY knows what the original owner did and did not do and where he sourced the kit and/or parts. Did anyone notice one brake line running on the underside of the frame rail?

We now return you to your regular programing. Have a nice day.

 

Can the rest of us put our shit shield's down now???

 

I'm looking forward to the next brake problem thread already, they're never too far away, and with a new recruit on board it'll be splendid!

I'm missing @manyolcars sage words in these matters.

Chris

 

I found a rebuild kit for the master cylinder...

Here is the rebuild kit from Performance Online, $26.86 plus $9.90 shipping.

https://www.ebay.com/itm/172792889663

Also, their kit looks similar to what I have (not sure what the previous owner put in) but I'm assuming I have this so called "GM corvette style master cylinder". The geometry and features look very close alike.

https://www.performanceonline.com/49-51-MERCURY-MERC-FULLSIZE-CAR-POWER-BRAKE-BOOSTER-KIT/

Note I painted some parts of mine black where there was surface rust.

I wonder if I can rebuild it, or if I should hunt for something else that will fit the rest of my parts. I'm not sure what car year/model to look up if I went with something else from Napa for instance. I see Speedway carries universal M/Cs hmmm.

I found this but don't know if the quality is trustable
https://www.ebay.com/itm/263575005095

 

I just love the ignore function of this group....

 

I'll ask the question again... does anyone know if I need any special tools to clean where the piston seals ride if rebuilding a master cylinder? I found a kit I referenced in an earlier post above to rebuild the M/C I have (1 inch bore corvette style M/C).

 

To the best of my knowledge, you hone a cylinder Prior to rebuilding it . along about early 80's it became cost prohibtive to rebuild . Rebuilt M/C & wheel cylinder are very inexpensive , IMO , have never had a bad one , otherwise I wouldn't still use them ! Spend your $$ & time as you see fit !

 

oh ok thanks maybe i'll look for a rebuilt one from Napa.. I don't know what tools are used to hone a cylinder so maybe its not worth pursuing.

 

There really isn't a simple answer to the what tools question until you know the condition of the master. It will not be capapable of being rebuilt without major machining and relining if the bore is heavily scored. Or it might be possible to clean it up with some wet and dry paper on your finger. Light scoring might be saved by honing using a fairly cheap tool on a drill. All fairly simple stuff but impossible to predict whats required in advance, which is probably why for many replacement is the go-to route.

Chris

 

makes sense thanks!

 

Listen,

The MC you have is a CHI-COM piece of sh!t, ain't no doubt about it. Most everything you buy today in kit form is crap. It is senseless to throw a kit into it.

You need to buy a NEW QUALITY MC (RAYBESTOS/CENTRIC), not a rebuild as they are crap also (NAPA as well).

I think you posted that you bought a new booster. You will need a specialty tool to set correctly the BOOSTER to MC rod adjustment.

Now most new design MC's do not come with a RESIDUAL PRESSURE VALVE as to what period the MC was designed for. Industry went to wheel cylinder cup expanders around 1971 or so. You have to know if there is one in the new MC. If none you will need the #10 inline in the rear drum circuit. You DO NOT WANT compound RPV's in the circuit. Do you know what style rear brake assemblies are?

You have to determine what style front calipers you have. Most kits now supply off-shore GM design floating calipers. There is a difference in no-drag calipers as they require a different style MC (quick take-up) to operate them properly (if they are GM style floating with metric bleeder screws, they are most likely no-drag and using a MC w/o this feature will result in slow application and low pedal). You will also need the #2 inline RPV in the front circuit as the MC reservoir level is below the caliper reservoir level (fluid drain-back).

That GM STYLE COMB VALVE needs to go. No reason for it (in this instance). Most GM RPV include a rear circuit RPV within the valve assy. IMO, you do need a front circuit (DISC) METERING VALVE (stand alone). That is your choice. At the minimum, an ADJ PROPORTIONING VALVE (WILWOOD - and read the instructions very careful as how to setup and adjust). I hate the things (other than an off-road track car) but sometime you have little choice.

Mount the BOOSTER/MC COMBINATION on the rail (bench bleed the MC with a bleeding kit) MC outlets then either blocked with block-off fittings or gauges) (if bled and you have a hard pedal with the block-off fittings installed, the MC is good) and make sure all linkages/adjustments are correct (incl pedal actuation), then fashion all brake lines.

There is no easy to correct the mess you have inherited. It needs to be fashioned correctly or you may bust you a$$ and/or lose the car (or even possibly worse).

 

- METERING VALVE FUNCTION -

https://www.freeasestudyguides.com/brake-metering-valve-test.html​

 

Thanks for all that advice. I was able to get in touch with Performance Online and asked them if their boosters and MCs are USA made and they said no, that they are overseas made and pretty much impossible to find anything not made in China... which we all know isn't true.

I don't know what wheel cylinders I have in the rear and to take the wheels off I would have to take the exhaust off and unbolt the airbags and drop the axle. I inherited quite a mess! Would photos of the front calipers give much of a clue as to what type they are?

I will look for a quality MC. As for the booster, im still unsure what to do any why the damn thing returns so slowly compared to my old one when out on a bench.. it sat for 5 years and was advertised as "new" on ebay and maybe the seals are bad.

 

https://www.freeasestudyguides.com/brake-metering-valve-test.html

Is not right, nose dive is not an issue, stopping the car straight is the issue.

 

PERFORMANCE ONLINE (POL) doesn't have much of a reputation.

... DAMN ...

Yes, a photo might help. Check the bleeder screw for SAE or METRIC.

Hold off on the MC until you see what style caliper you have.

In other words, the booster is off the car and on the bench, MC disconnected? The PB push-rod will not extend fully? It is no good.

 

You mean IN YOUR OPINION ASE has no clue as to how a braking system is designed to work?

Please explain (to me - as others refuse to learn) how rear end rise and front nose drive will not allow the car to stop straight.

Even if the fronts lock the car will continue straight (in direction of slide) and the CORRECT PPV will stop the rear from possibly coming around.

When will you guys realize that mud wrestling with a pig is a no winner? ...

 

Thanks,

On the bench, when I push the push rod in on the "new" TuffStuff booster, it comes back out quite slowly, it does extend fully back but its slow and way slower than my old booster... and my notion is it sat shelved for 5 years and the seals are no good. would that be possible?

 

Someone here did figure out GM LOW DRAG CALIPERS are usually in included in these low quality conversion kits -

https://www.jalopyjournal.com/forum/threads/gm-metric-low-drag-calipers-fixed.1202460/