Technical Help with Brake Combination Valve Question

Man..... Do I miss the OLD H.A.M.B! ........Those that were there, would know what I mean......

 

Let me get this straight. You have two boosters, one a take-off (known bad) and a new booster that you think sat on the shelf for an extended period? If the new booster fully returns, I would go with that one as it is hard to diagnose on the bench. At the most you would have to buy a new booster if once installed within a correct system it did not operate correctly.

Two questions, what engine is in it and do you know how much manifold vacuum it produces? The rear brakes are drum? Are they OEM or have been upgraded? Can you get a shot of the pedal assy?

READ THESE -

https://www.fordmuscle.com/tech-sto...ct-brake-booster-with-tuff-stuff-performance/

https://www.tuffstuffperformance.com/

When we figure out the front caliper type, we can figure out a correct MC. Try to take several photos on the caliper and how it is mounted.

 

www.classiccarrestorationclub.com/video/combination-valve-014796/

 

Sorry ekimnerbo, more incorrect brake valve information.

 

What do you find wrong with the description Bob?

 

Pretty much everything KULTULZ, but I'm not going to amuse your false interest in exchange for more of your sarcastic demeaning BS. Been there many times.

SDrocker, sorry your initial thread has morphed into some personal crap, but I hope you were helped in spite of it.

 

So,it appears that there are a myriad number of opinions and facts and the OP will have to sort through them and see what makes sense to him. I'd start with making sure the vacuum canister holds vacuum. If you have another vehicle that you can temporarily run a hose to and maybe hook up a vacuum gage as well, you should be able to determine if it has a leak. If not I'd move on to checking the master cylinder. Rig something up in a vise and see if both the front and rear ports get pressure when you apply pressure to the pedal. That one thing about using a special tool to keep the shaft from moving forward and cutting off the supply to the brake might be all thats wrong, so see if both circuits get pressure and if recentering the shaft lets it work.
Then you can start working on whether you have a bad system and who gave you good advice. Its a learning experience, so think about what and how you can perform simple tests and work your way through the issue. It just may be something really simple to fix.

 

I have to agree...

 

Well Bob, I am sorry you feel that way.

But how in the world is the man supposed to figure out what is wrong when everyone and their brother throws incorrect information/wives tales at him? I have read things on this thread that are simply astonishing/unbelievable.

 

Can you share with others exactly what you find incorrect in that video?

 

Read post #27....

The aftermarket is trying to convince buyers they need one when the reality is these don't work as advertised.

 

The only place where reducing or delaying rear brake force is almost always needed is in pickups. First one I experienced was a 58 Ford that got a 55 Chrysler hemi/Powerflite swap. All was well until the first time I had to do a panic stop, it was a really panic. But, instead of reducing rear brake force, I increased the front.

this was mid-60s remember. So, I grabbed the front brakes from a 56 Chrysler, really good 12"drums to replace the 11" Fords. Turned the inner bearing and seal surface on the spindles down to fit the Mopar drums, outer bearing was the same. New brake hoses and done! Felt like near perfect balance to my 22YO self.

There were advantages to having a Dad that owned a salvage. God, I still miss him.

 

THANK YOU! for the reply.

You are correct, there is no need for a universal COMB VALVE in a DISC SWAP to an older vehicle. The PPV is not calibrated for the vehicle. But on the other hand, an ADJUSTABLE PPV is not the correct solution either. The PDV is not necessary either, while the METERING VALVE is (IMO) along with properly serviced and adjusted rear drums.

As for the video, I think he gave a pretty good description of a COMBINATION VALVE (two or more valves contained in one assembly) although he left out a few details.

I think what is going on is they are either up-selling or want to include the PPV in the kit to cover their a$$ if you bust yours. Same as the ADJ PPV, it is meant for an off-road vehicle not street cars. You will see the DISCLAIMER somewhere in the kit listing.

There is a huge difference between servicing and modifying a brake system.

 

I think its obvious that a combination valve that's working properly is a good set-up............hence the millions of them installed in OEM vehicles. Yes there are pros and cons as to when and how they are the best choice, but set up properly, they work well. There are nuances as to what works best with different systems, so putting the wrong one in place can have a detrimental result. There seems to be no shortage of disagreement here. Basically the inability to make a know good part work within a cobbled up system isn't the fault of the part. Replacing the part with another known good part may produce a similar result to the first part............we have all done that on one thing or another.
Here is some info from MasterPower Brakes who have a pretty good idea about what works and what doesn't. Also here is a book which is no longer published apparently, but available used on Amazon for less than $5. I guarantee there is at least $5 worth of good information in it...........







Like I said earlier, the simplest solution may be to eliminate the combination valve and use individual components, but it isn't doing any good to debate the combo valve any further........so look at the information thats available and see what applies to your situation. I'd get a copy of this book and figure that the guy who wrote it probably has good info in it.

 

Key word, OEM. Each PPV (usually incl with a COMBINATION VALVE) is calibrated for a dedicated vehicle.

You cannot take an off-shore sourced GM STYLE COMBINATION VALVE copy and expect it to work on any modified brake system. Even when you take an OEM DISC/DRUM system and say change front/rear brake size or even tire size changes, that will affect the factory calibration of the OEM PPV on that particular application.

There was (is) a true adjustable PPV. They are now rare and if you can find one, very expensive and will require a rebuild. This valve was used on OEM FORD, GM, MOPAR and AMC. For a kit vendor to even suggest using this copy is dangerous and ill-advised.

 

This is what happens when you drop into the middle of a thread without reading it from the beginning. With that said... You're too generous with praise for that 'good description'. Those 'few details' left out are critical for making an informed decision. I suspect their pushing of these has more to do with lawyers than good engineering along with a bit of greed.

Master Power Brakes is engaging in the same smoke-and-mirrors as all the other vendors when it comes to combination valves. Their statement about their combination valves, 'Containing a Metering Valve, a Proportioning Valve and a Pressure Differential Switch, this is a perfect solution for obtaining the proper brake balance and safety within the vehicle' is patently false as two of the three functions either aren't needed or aren't calibrated to any specific combination. To their credit, they do offer a stand-alone metering valve which should be all that's needed on a Hamb-era vehicle unless the owner installs a brake warning light. I have yet to see one of the light switches on these connected to anything on a pre-'67 car, and I've seen more than a few. If you're working with a '67-up vehicle or plan to install a brake warning light on an earlier car, the light switch has value although the 'proportioning' part still won't be right.

As to whether the metering valve is really needed, ponder this. Prior to '67 and the federally-mandated split braking system with the warning light, these valves didn't exist in the OEM systems, including disc/drums. I'm not aware that these were inadequate brakes in spite of their single-circuit design. Yeah, they left some on the table in terms of safety, but that's not what I'm talking about.

The eye-opener for me was my '70s-80s Jaguar ownership. These have 4WDB systems and use NO valves of any sort. Their brakes work very well with one exception; while Jags have myriad issues, the brakes/suspensions aren't any of them. No proportioning valve, I assume that's because Jag designed proper balance into the system. Although it's worth noting that Jag used the same brakes on both their sedans and sports cars. Apparently, any difference in front/rear bias was too small to worry about. Also no metering valve, but Jaguar was clever here. By using a two-piece piston, the rear brakes are partially applied before the front brakes, once the rear piston contacts the front one, regular brake pressure is applied to both ends. Simple plumbing: fronts connected to the front half of the master, rears to the rear half, done. That cut-away GM disc master shown appears to that type, although I'd need one in my hand to verify that.

Leaving the mandated brake light warning switch and the one shortfall in their system. Because there is a pressure differential inside the master, a warning light of that type can't be used; the light would blink every time the brakes are applied. No doubt freaking out the owners. Jaguar's solution was a brake fluid level switch; low fluid, the light comes on. In a typical Jag 'WTF' moment, for some inexplicable reason they used a wine cork (no, I'm not joking) as a float which would soak up brake fluid and sink in about 5 years. Most cars have the light disconnected because of this. I have no idea how Jag got this past the feds, but they did. Their cars were like this until 1989, they switched to a very weird ABS system in '90. There is a float cure however; some imports featured a remote reservoir like the Jag but used a magnetic switch with a sealed float. IIRC, the one I used was off a '90s Mitsubishi, problem solved. For you guys with under-floor masters, this may be something worth looking into.

I'm not saying that following the vendor's recommendations will result in a poor or unsafe system, merely that they're selling you parts that don't do what they say they do and costing you extra money and effort to install.

 

A quick follow-up. It seems that dedicated proportioning valves were used on the OEM single-circuit disc/drum systems, but they're no longer available new. All you can get now is the usual 'universal combination valves' with all the baggage that entails... For what it's worth, I did a disc conversion a number of years ago (entirely home-brewed) and used a single-circuit master with no valve and had zero issues.

 

where is the support strap that comes from the booster mounting plate to the tube crossmember

 

Cast iron adjustable K/H proportioning valves were used on some early disc/drum FoMoCo vehicles, which I'm using on my '32 and '40. The adjustable valves available today are a much better choice than any fixed value prop valve on any custom disc/drum or disc/disc brake system.

 

You have to do all that? What happens if you get a flat?

 

!!! BINGO !!!​

 

To me, the point is that virtually any brake system can be made to work satisfactorily and well, but there is always room to improve it or make it better with testing and engineering. Backyard builders do not have that luxury or the time and money to try to refine their brakes to the inth degree. They just want a system thats decent and reasonably easy to assemble. There are a lot of NON-OEM vehicles that have been cobbled together using a generic combination valve. Sometimes there are problems when combining aftermarket parts to make one system..........thats not any different than assembling a smallblock Chevy a thousand different ways using aftermarket and factory parts and then having to sort out a problem. Not saying that no one is ever going to find a problem with the combination of parts they chose, but I'm also not going to say that everyone should disregard the use of a combination valve. Remember, lots of times we are not buying new combination valves, but using existing ones that may have come on the vehicle. Someone buys a pedal assembly and the power brake set up that comes with it...........is it always going to cause a problem when he puts it in his old car? No, and thousands of them have been done that way. The rear end may also have been swapped in place from yet a third vehicle......and it may/may not work just fine. People have to expect to do a little problem solving when doing this stuff. Is their system going to work as well as a factory engineered system? An awful lot of them do work just fine with cobbled together systems that have used an unknown combo valve. We can debate perfection here, but a good usable and safe system can be had without having an engineering degree, just dirty fingernails and hard work.

 

If I get a flat on either of the rear tires it will be a miserable time...... I guess that's the price to pay for laying frame.

 

Might want to consider carrying one of those tire repair kits and battery powered air pump for a bandaid fix if ever needed.........

 

↑
"... My point being, I don't think there's a lot of " calibration " associated with those valves, I believe they're pretty generic..."

The above is a quote from a PM discussing those 'combination' valves from another member. I decided this would be another good post for this thread.

I won't disagree with that statement. For me, it's more of a philosophical issue with how these are marketed. Touted as a 'must have' item by most of the aftermarket, their inability to clearly articulate the exact function of them only makes me suspicious. IMO, they're an unneeded complication in most cases, particularly for our uses.

Prior to the 1967 federally-mandated split braking systems, these valves didn't exist. The first disc/drum systems with a single circuit used a proportioning valve only, and a dedicated one for that specific vehicle to boot. No metering valve or warning light. Enter the split braking system in '67 and the requirement for a warning light. I'm firmly convinced that the only reason for these is a place to install the light. The 'metering' and 'proportioning' functions were an add-on for unknown or minor reasons. Possibly to baffle us with BS... 'I don't know what that is, but if the OEMs think it's important I better have it!'

Then along comes Jaguar and their take on a split system. Their 4WDB systems up until going to ABS in '90 don't use ANY of this. This was a world-class system for its day, with racing success to back that claim. They did include a 'metering' (or more properly, a 'delay') function into their master, but that's it. No proportioning needed as they carefully sized the front/rear brakes.

Need further proof? Both Baer and Wilwood are well known for their brake expertise, and neither one offers a metering valve. Baer sells two basic adjustable proportioning valves, that's it. Wilwood offers more choices (all of which have adjustable proportioning) including a 'combination' valve but upon examination you'll find it is just a proportioning valve, no metering function but does offer a place to install a pressure-operated brake light switch (the 'combination' function).

So let's recap how useful these combination valves are... I doubt if any HAMBer is going to install a warning light, so that's useless. If your front brakes lock before the rears without a proportioning valve under testing, that's also not needed. Anti-dive is actually controlled by the front suspension geometry, so delaying braking may or may not do anything. Baer and Wilwood obviously don't think it's important, I suspect Jag did it because they ran their suspensions a bit soft for ride quality so some dive could be expected. But it doesn't seem to be actually 'needed' and may have more to do with what front shocks you run.

I'm not going to spend $50+ for something with little or no use.... plus the hassle of installing it.

 

OK ...

All hunker down in your bunkers and pull your plastic sheets up as there is going to be incoming ...

FORD used a METERING VALVE prior to 1967.

These JAGUARS you keep referring to, are they DISC/DRUM or DISC.DISC?

Someone needs to pull out an accurate textbook and read the purpose/need for a METERING VALVE on a DISC/DRUM setup.

Most of what you post is IMO and may not apply to all enthusiasts. I know it doesn't apply to a professional repair shop (hopefully).

The days of vehicle specific and calibrated PPV's are over. What is being sold by these so-called kit companies is off-shore CHI-COM GM copy junk that will most likely bust you a$$ at some point. The same regarding the SPINNING-THE-DIAL and hope it works so-called PPV's.

Let The Games Begin ...

 

This is what I'm running in my car, it was $69 back in 2014. But it works well and is simple. I have the rear bias wide open and the car stops very well. I have never had to adjust it.

https://www.summitracing.com/parts/clp-apv-db

 

What a rabbit hole that question sent me down!!
I decided to go to Summit and look at all the valves, blocks etc available and see what specs were listed.

Never made it through all of them, just 'cause there's way more than I expected. But what I found were were these tidbits:
1. None of the non-adjustable versions stated an pressure or ratio or % info.

2. Those adjustable ones were either 100psi minimum, 1000 max or 100 min and 3000 max.

3. All the adjustable versions state 57% reduction.

4. I couldn't locate one featured as I would prefer, IF buying one. GM style, combo, pressure switch too, and adjustable. So if one wanted a warning light (and I do) you have to start with the copycat, then add a fitting for a pressure switch if needed, then an adjustable valve. Plumbing nightmare if trying to make things look neat, especially if using firewall mounted master, like me.

5. Real shocker was the pricing of one, a Ford racing adjustable looks to be the cheapest adjustable. And looks cools, blue oval and all!

I assume, bad to do I know, but got start somewhere that the min/max pressures are from the input ports. And that the 57% is the amount of pressure reduction available to the rears.

I wonder what the responses would be if we asked every seller for tech info?

 

I think the main problem is the PPV misunderstanding in how and why -

https://shop.wilwood.com/blogs/news/how-does-a-proportioning-valve-work

Excerpts From Above Site -

One needs to read the entire TECH ARTICLE.

The term COMBINATION VALVE ( a unit containing a minimum of two types of brake valves) seems to cause the confusion. One has to understand what each valve incorporated into the COMB VALVE is designed to do.

The article goes on to state -

Now with all of this said, you need to read this DISCLAIMER -

​

 

hello
for arguments sake, IF you did have a underfloor master cylinderBUT the fluid containers fluid level was in a seperate resorvoir with a level above the front caliper pistons ever so slightly, why would you need a 2ilb one way valve to prevent siphoning? is it atmoshphereical pressure or barometrics or some other kind of wizardry