Understanding a Combination Valve

[@pompeyroad]

Great Vid, my son did a disc, disc conversion on my 55 Belair and it has never been right...I think you just fixed my problem.

[@derekcrymble9085]

Thank you so much for getting back to me , with such a wealth of excellent information . The internet needs more guys that are so helpful , and know what they are talking about . I feel good about moving forward with this project now. You are a gentleman , many thanks again .

[@DeerbrookSouthernRR]

This helped me a lot. I’m doing a disc conversion on my Grand Prix and this was the only video that actually showed me how to modify the factory valve

[@ansonwill1999]

Yeah I'm struggling with one right now and I do appreciate your help I understand now

[@designsinorbit]

After removing the metering valve for disc/disc and plugging it, will I 100% for certain need an adjustable metering valve in line with the rear brakes? Or might I be ok as is? Thanks!!!

[@manuelhuerta5515]

Thanks for sharing the facts on the combination valve I installed a disc to disc on my C1500 but can't find the right fitting for the rear port and the front port size they r different from the old valve that I removed but I did plug the top port but thanks for the information.

[@derekcrymble9085]

Fantastic information . You helped me greatly . I am doing a drum -drum ( 1965 Pontiac) . I want to stay as close to original as I can , but am installing a dual master / combination valve assy. Thanks for the rod tool tip . I was not able to find a drum / drum combination valve . So I am wondering if I should add an adjustable proportioning valve (SSBC #A0707-1P) to the rear line , just after the combination valves' rear line . Do you think it would be good to dial in the rear separately ? Again great vid. !

[@ClassicCarRestorationClub]

Hi Derek, There is no substitute for safety, so I applaud your decision to upgrade to a dual reservoir master cylinder. The drum/drum combination valves, simply has the front metering valve disabled, the same as the disc/disc combination valves, and the disc/disc combination valve will work in its place. For your setup you could simply run your front line to a splitter to go to each wheel and put an adjustable proportioning valve on the rear brake line, and leave out the combination valve entirely, I'll attach a couple links to metering blocks that simply join the splitter to the rear proportioning valve, some also include pressure switches to operate brake lights. On drum brakes you do need to maintain 10psi of residual pressure in the lines, from the factory the master cylinder had a check valve in the line port. With a new dual reservoir master cylinder it may or may not have check valves in the ports, so I always drop a couple of 10psi residual pressure valves in the lines to the front and rear DRUM brakes. Disc brakes only use 2psi of residual pressure and if the Master Cylinder is mounted high on the firewall, the weight of the fluid in the lines produces the required 2psi of residual pressure. Here is a link to one source for a residual pressure valve: www.speedwaymotors.com/Wilwood-260-13784-Red-10-PSI-Residual-Pressure-Valve-with-Fittings,233816.html The SSBC proportioning valve you listed will work well and here a few links to proportioning valves I have used: www.speedwaymotors.com/Adjustable-Proportioning-Blocks-With-Brake-Light-Switch,6160.html www.speedwaymotors.com/Wilwood-260-11179-Adjustable-Proportioning-Block,41747.html www.speedwaymotors.com/Speedway-Compact-Adjustable-Brake-Proportioning-Valve,1979.html www.speedwaymotors.com/Adjustable-Proportioning-Valve-Block-Brake-Distribution-System,66525.html Wrench Safe, Mark Classic Car Restoration Club Video Membership

[@done7689]

How do you unstick it if it does get stuck? Mine is stuck to the front after changing calipers

[@TheIanmurphy]

When the centering valve moves to one side, can brake fluid still flow through that side? I.e. if I have a brake leak in the back will it completely block fluid to the back and only use the front or will it let some fluid through to the back?

[@everettpangle1861]

Hey bud I just replaced my metering valve on my 1978 chevy 1/2 ton pickup also replaced new brake lines brake shoes, drums and a new master cylinder. But I still can't get my rear brakes to bleed? Do you have any advice? Thanks

[@lauradahlus]

How does one re-center the pressure differential valve as it got triggered while bleeding my brakes? 🤔

[@ClassicCarRestorationClub]

Hello! Great question. The 'Ask an Expert’ section is for members of our online community. I would be happy to send your question off to the experts. To get started, please provide the email associated with your paid membership. Thanks!

[@derekcrymble9085]

how do you re-center it ?

[@ClassicCarRestorationClub]

Hello Derek, Thank you for contacting us. Great question! The ‘Ask an Expert’ section is currently for members of our online community. By becoming a member, you will have access to our expert’s knowledge in classic car maintenance and restoration. With your membership you will also receive discounts on products and hours of Premium video content. If you are interested in becoming a member to the Classic Car Restoration Club, please click on the special offer below: go.classiccarrestorationclub.com/a19769 If you have any further questions, please chat, email, or contact Customer Service at 1-855-706-3534. We greatly appreciate your business! Sincerely, Michael Classic Car Restoration Club Video Membership

[@carlheinz6699]

My burning question is: are there any differences between GM & Ford proportioning valves, or are they all Universal Fit??

[@ClassicCarRestorationClub]

Hi Carl, While it is true that most aftermarket conversion kits use a GM style proportioning valve, The fundamental function f the combination valve remains the same regardless of the year make and model. So what is different? As mentioned in the video the combination valve includes a metering valve for front disc brakes and a proportioning valve to the rear brakes. The proportioning valve ONLY comes into play during hard or panic braking. It prevents a surge of fluid from rapidly reaching the rear brakes that would otherwise result in locking up the rear brakes and put the rear in skid causing a loss of control. The proportioning valve is tuned to the vehicles braking system as larger and heavier cars are less prone to lock up the rear brakes, while lighter cars can easily lock up the rear brakes. It is best to use a proportioning valve from a vehicle with similar size and brake system, otherwise an adjustable proportioning valve is a good alternative. The metering valve to the front brakes comes into play during normal braking, it is only present in front disc brake cars and prevents the car's front end from diving as the brakes are applied in NORMAL braking. Bottomline: Ford, GM & MoPar proportioning valves can interchange ... but pay attention to the size of the car they are from and they have similar braking systems (i.e. drum/drum, disc/drum, disc/disc). Mark Classic Car Restoration Club

[@carlheinz6699]

You have no idea how much this helps! Thank You so very much!!!!!!!

[@scottgaskin8574]

I'm having this problem with my k1500 now.new master cylinder good fluid to the front but very little to the back I've bleed them real good 2 times, I get a good pedal until I start my truck then goes to the floor

[@ClassicCarRestorationClub]

Great question! The ‘Ask an Expert’ section is currently for members of our online community. By becoming a member, you will have access to our expert knowledge. With your membership you will also receive discounts on products and hundreds of hours of Premium content. If you are interested in becoming a member, please click on the offer below: go.ClassicCarRestorationClub.com/C40459

[@cecilcarruth13]

1976 F 250 Hi I have a 2 wire to the switch.My new one has 1 wire to the switch what do I do? Thanks

[@lauradahlus]

Twist them together then insert in switch

[@vgslife9640]

what type of tool do you use to remove the lower pressure switch ?

[@ClassicCarRestorationClub]

Hi Rob, The switch is simply a brass rod with a notch out of it. HOW IT WORKS: The brass rod shifts position if either the front or rear brake circuits lose pressure. A steel pin in the combination valve that is wired to the dash brake warning light is then grounded and completes the circuit and turns on the light. When bleeding the brakes the rod can shift also, that is why it's a good idea to remove the wired steel pin and replace it with a warning switch centering tool while bleeding the brakes. Here's a link to one source for the tool: www.speedwaymotors.com/Speedway-PV2-PV4-Proportioning-Valve-Bleeder-Tool,296895.html and here's a link with Bob Wilson demonstrating how to rebuild a combination valve: www.classiccarrestorationclub.com/video/proportioning-valve-rebuild-011335 Mark Classic Car Restoration Club

[@daytonwoodford4386]

tkx ccrc I have a 1995 Chevy K1500 4X4 sick & tired soft peddle-turn disc/new pads-front-rear -soft peddle-ABS module won’t bleed-replaced it =replacement leaks-part not manufacturer any more no one rebuilds them -master & brake booster replaced =soft peddle [mechanic not replaced yet] so I dumping these ‘F-N’ ABS going with a conversion combination valve -viewed it here the tube -liked your breakdown of its functionality tkx..don’t get sneeeeeeezed on 💉💉

[@neilmackenzie8345]

The warning switch does not ground out to complete the circuit so the brake warning light comes on , it is a switch itself the plunger part goes up and down to complete the circuit or break the circuit , the rod in the middle has o rings so is not grounded , test it yourself , then correct you video