Offtopic because I am dealing with a 23T Bucket pickup. Helping my stepbrother. Here's what we got. Ford Explorer master cylinder, front disks that are probably a Granada or similar, rear disk explorer 8.8 axle. I understand many Explorers do not use a proportioning valve from the factory. I assume this function is taken up by the RAB stuff?

I guess my question is "Could the proportioning valve actually be integrated in his master cylinder somehow?". He was told that by someone, and it just doesn't sound right to me.

I am inclined to add a proportioning valve off an 80s whatever to his system, but am unsure what would happen if I stack two p-valves by accident?

My 53 was much easier. I just installed components off five different cars/trucks/vans and the brakes work perfectly without any tweaking whatsoever.

 

I don't have a definitive answer, but a prop valve is mainly used for disc and drum with different transfer rates. All disks mean the same amount of fluid is pushed to all four corners with the same effect. That said if the Granada disks (caliper) are different size than the explorer, then a prop. valve may be needed, but I'm not positive. I don't know about the Explorer having a prop. valve built in.

edit: I do know the 88 turbo coupe has something built into their mc. But it might be part of the ABS, too.

 

Unless this MC looks a lot differently from the ones we are used to seeing I doubt if it has any kind of internal proportioning valve. If it doesn't have one externally then it either doesn't need one or as you said the proportioning function is handled some other way in this system. I don't think you could go wrong by adding an external one. That's my opinion and I'm sticking with it...

Tell your step-brother to dump the dune buggy and build a TRUCK!

 

Appreciate the advice guys. I'm heading over to look at the dunebuggy in a minute. I am also of the opinion that you couldn't easily hide a P-valve into a standard MC without changing the appearance considerably. Perhaps adding an adjustable P-valve is prudent with this ultra-light, short wheelbase creation. I checked a site a moment ago, and saw four different MC choices listed for a 95-97 Exploder. Ford is never going to quit that are they?

 

There isn't a prop valve in the Ford master cylinder. GM was the one that did but it was two big cylinders that screwed into the master cylinder.

This may or not help but I converted my 1999 Mercury Mystique to rear discs (factory option). For my setup the master cylinder and the rear prop valves were the same (same part number). I didn't have ABS but the ABS system on this car did still use prop valves. This is also a cross brake system (ex. Front left and rear right brakes are connected with vise versa on the other side). The prop valves were a small cylinder to which the rear brake hoses screwed into.

 

I would go to my after market auto parts man with your m/c part number. Have him pull one from stock, open and look at the diagram of construction, or look in a overhaul manual for same info. You still need sequence front/back braking for the back first and directional control. You may need a manual adjustable p-valve as most T's have such large rear tires. I haven't seen a T with front brakes in a while.Have a great day,chuck

 

Explorer MC? I don't think so. It had a non-power brake master cylinder that looked suspiciously like something one might find on a 74 Maverick. We'll be buying an adjustable P-valve and residual valves.

 

Hey fatfenders, long time no see... I just went through this whole ordeal with the brakes. The residual valves are mostly used if the the MC is mounted under the floorboard and basically keeps pressure in the line so the fluid doesn't flow back to the MC due to gravity. This eliminates the soft pedal at start ups or the need to pump the brakes at first to get a firm pedal. If your mounting the MC on the firewall, you probably won't need the residual valves, although most people still put them in regardless. As for the proprotioning valve, that regulates the amount of brake fluid pressure in the line. Because the pressure is different with disc in the front and drum in the rear, a proportioning valves is installed in the line going to the drum brakes. The fluid is then adjusted by the valve so the rear drum brakes don't lock up when the brake pedal is applied. Since your running disc on both ends, you should be OK without one. If for whatever reason the disc brakes lock up then it's always easy to install a valve somewhere along the line. As far as residual, I know they come in 10lbs and 3 lbs. I believe the 3 lbs are for disc and drum are 10 lbs residuals. Or do I have it backwards? Anyways, I'd install what you got, fire it up and see how they work. You can always add to the lines with no problem to fine adjust. Good luck. IMO- Don't buy the cheap proportioning valves or one from another vehicle. I recommend the Wilwood Proportioning valve. They are about $50 but won't do you wrong. Don't save money on your brakes.

 

Combination valve, two functions.

Metering valve: Applies pressure to the rear brakes first to insure stability during braking, this helps keep vehicle in straight line.

Proportioning valve: Since more weight is in the front of the vehicle, the front requires more pressure than the rear brakes, this valve dictates the percentage of total pressure that the front and rear brakes receive. This requirment is why hot rodders use a adjustable valve as their setup is non standard. All brake systems should have a combination valve, drum or disc. Under normal braking everything may seem great, but if your vehicle locks-up or starts jumping around during heavy braking, this could be the problem. I hope this helps. Have a great day, chuck

 

Go to www.nationaltbucketalliance.com The public BBS and Tech Form will get you the answers you need. The recommended M/C for a bucket is one out of an early mustang or vega. You don't want a bore any larger than 1", 7/8" is even better. As for the proporting valve, put an adjustable one in the rear line. Good Luck

 

Fenders, you could install 10 prop valves in a systen and if all are set to center, it would be like having them in nuetral and they do nothing to balance the system. Some guys use a master with the external metering and preset prop valves but then add the adjustable prop valve so they can set the proper bance for weight and disc/drum AND it is also used for disc/disc systems when the discs are from different donors, or if you put 4 cly calipers in front or rear only AND to compensate for weight differences. I would put one in anyway as 48.00 is cheap insurance to fine tune the brake feel of the finished car or truck. I have Corvette master/booster,Volare front and 8.8 Exploder rear and have re-ajusted after tire size change, oak install, and full tank. I likee a lot.

Jon