proportioning valve

Topic: proportioning valve (Read 1960 times) previous topic - next topic

proportioning valve

February 21, 2006, 06:17:27 PM

i bought an adjustable prop. valve w/ 1/8 NPT inlet/outlet, and i dont see where i can put it in. it's not like a mustang that has a union you remove on the firewall.

also, this valve didnt come with any adapters. does anybody know what size the fittings are on the lines underneath the M/C?

on an 88 t-bird, BTW.

proportioning valve

Reply #1 – February 22, 2006, 08:09:25 AM

i have a JEGs prop valve on mine. mine is an 84 though... from my master cylinder rear line it goes down to a stock prop valve with a brake light sensor on it... so i simply disconected the stock one and found the adapters to fit the original lines. i still have the front brakes running though the original valve with the sensor unplugged. and good luck on getting the fittings right, best bet is to take it down to autozone and make them figure it out!!! ha ha ha... not really, just do all the install in the parking lot of autozone, then track brake fluid all over there floors so it eats the paint, and when your done have one of the guys pump your brakes for you so you get all the help you need to do the job right at one place. sorry if this made no sense, i have no clue what kinda valve you got or anything about an 88.

proportioning valve

Reply #2 – February 22, 2006, 02:00:09 PM

Did you put rear disc brakes on your car or something? Just curious.

This may be a bit of an FYI, but for you guys putting rear disc brakes under your Birds (or cougars), if you swipe the factory proportioning valve from a Turbo Coupe you can use it without needing an aftermarket proportioning valve (since the car is already set up for four wheel disc). Only difference is that the Turbo Coupes had a 1/4" brake line running to the rear of the car, I think drum brake cars (including mustangs) all used a 3/16" line.

proportioning valve

Reply #3 – February 22, 2006, 04:29:11 PM

i'll take a picture of where i put mine if you want, i cut the line that went to the rear of the car, then ran that to the valve and another... so yeah it was a pain in the ass but it works.

proportioning valve

Reply #4 – February 22, 2006, 05:03:57 PM

Quote

Only difference is that the Turbo Coupes had a 1/4" brake line running to the rear of the car, I think drum brake cars (including mustangs) all used a 3/16" line.

So what does that mean? Do you have to run new brake line from the prop valve all the way to the rear or can you use an adapter of some kind?

proportioning valve

Reply #5 – February 22, 2006, 05:54:12 PM

I'm using the stock prop valve on my 87 sport with Turbocoupe disks at all 4 corners. Bias seems fine so far as I can tell... I.e. I'm not locking up the rears before the front brakes. Pedal feels fine and the car seems to stop as well as my Turbocoupe did with the electric brakes. That's probably the reason I haven't bought an adjustable prop valve yet... I dont seem to need one. But that might change when I start autocrossing. We'll see...

proportioning valve

Reply #6 – February 22, 2006, 07:59:50 PM

Quote from: Dogcharmer

I'm using the stock prop valve on my 87 sport with Turbocoupe disks at all 4 corners. Bias seems fine so far as I can tell... I.e. I'm not locking up the rears before the front brakes. Pedal feels fine and the car seems to stop as well as my Turbocoupe did with the electric brakes. That's probably the reason I haven't bought an adjustable prop valve yet... I dont seem to need one. But that might change when I start autocrossing. We'll see...

interesting........

proportioning valve

Reply #7 – February 22, 2006, 08:00:47 PM

Quote from: Red_LX

Did you put rear disc brakes on your car or something? Just curious.

This may be a bit of an FYI, but for you guys putting rear disc brakes under your Birds (or cougars), if you swipe the factory proportioning valve from a Turbo Coupe you can use it without needing an aftermarket proportioning valve (since the car is already set up for four wheel disc). Only difference is that the Turbo Coupes had a 1/4" brake line running to the rear of the car, I think drum brake cars (including mustangs) all used a 3/16" line.

didnt turbo coupes have ABS? and yes ive swapped to sn95 rear disc.

proportioning valve

Reply #8 – February 22, 2006, 08:14:39 PM

Yeah they had ABS, but the prop valve had nothing to do with that, it was all in the MC. After my factory ABS MC took a dump last summer I converted to vac-assisted brakes and I didn't have to touch the prop valve.

Oh, and what I said about the 1/4" line, they ran a 1/4" line to the back because the disc brake calipers require more fluid than the little cylinders in the drums do. Apparently you don't HAVE to put in a bigger line though. And yes, you can go to napa and get an adapter, that's not the only one you'll need anyway, the front port on the MC is a 5/16" so you need a reducer for that. Napa has all kinds of brake adapter fittings though, so it's easy to find everything you need.

BTW I did a writeup on converting to a 2-port master cylinder in this forum a few months ago, should be able to find it by searching my posts.

proportioning valve

Reply #9 – February 22, 2006, 11:07:18 PM

Quote

I'm using the stock prop valve on my 87 sport with Turbocoupe disks at all 4 corners. Bias seems fine so far as I can tell... I.e. I'm not locking up the rears before the front brakes. Pedal feels fine and the car seems to stop as well as my Turbocoupe did with the electric brakes. That's probably the reason I haven't bought an adjustable prop valve yet... I dont seem to need one. But that might change when I start autocrossing. We'll see...

same here. i havnt touched my current tbirs but my previous sports brakes worked perfect when i swapped in a turbo coupe rear with the disk brakes. the fronts were left alone. nothing was done too the MC or "prop valve". never had a problem...

proportioning valve

Reply #10 – April 19, 2006, 04:41:11 AM

ok well then i just did the rear end and converted over to disk brakes and i never had a problem with my drums but now i dont seem to get enought pressure to my rear brakes but my fronts work fine so could i be having a mc problem or am i having a problem with my car just not giving my disk brakes enough pressure?

plz help im at a dead end ive bleed the breaks for about 2 hours today and there is no more air in the lines and my caliper doesnt move.

proportioning valve

Reply #11 – April 19, 2006, 01:55:15 PM

Did you not do anything with the proportioning valve?

I would say that first you need to either "gut" the factory proportioning valve and add an aftermarket prop valve, or put a turbo coupe on in its place, and see how that works.

The factory master cylinder is pretty marginal for four wheel disc but it should still work good enough.

I honestly don't know how these other guys that "never touched" the factory master cylinder or proportioning valve got everything with rear disc to work. The factory prop valve is not set up to control rear discs, which require more fluid than drums.