has anyone readjusted the stock brake proportionning valve. If so how.

if you're an engineer and machinist i'm sure it could be done! but an easy solution is just to buy one of the many aftermarket adjustable prop valves.

i though i saw that you are running BMW brakes up front, in which you might get away with just a simple T fitting. test it in a safe environment before getting in traffic!

Try this: Adjustable proportioning Valve

I have the T fitting but I am a little weary to use it. However, I have a lot better pads and BMW calipers up front now so I think it will be fine.


That is a good price for a proportioning valve for Jwest.




My project for today. Now on to the back of the car.

..I would get the adjustable prop valve...but thats just me.

BMW calipers on the front of mine and threw away the P valve about 4 years ago. Works great.
Elliot

That is reassuring, I think that is the way I am leaning, as I want as much brake power as I can get. Elliott, what kind of pads are u running

There are some 3 year old threads on this board that tell how.
but better to just buy an adjustable valve.

as I remember... to adjust the stock valve you use a longer bolt than the stock adjuster bolt. This opens up the rear lines more.
how much longer I don't remember.

brant

The stock one has an adjustment. But I can't say how much difference it makes either way. The allen bolt sticking out the end is the adjustment. I've never used it and I can't attest to any unexpected issues it might cause. Play with your brakes carefullly.

One of our AZ teeners damn near drafted a white paper on the subject. Some creative searching on PP might bring back some of his charts and graphs. Good information. I can't remember who it is.

Use a T.

Pelican Parts has a blurb about this adjustment. I also heard a tee would be good also. If you wanna use a tee, you might get the feel of it if you opened your stock unit all the way by screwing in the stock bolt at the end of the valve. They mention trying it a little at a time and test runnig it on an empty road.


Lemeno since I have to do the same to mine soon. Thanks for the speed bleeder link.

I always give into the minimalistic aproach! Less schmit to worry about. Say good buy to unwanted pounds and hello to acceleration!


Purist Minimalists strike agin, YES! Vee vill be vatching you.

First off,

it is NOT a proportioning valve. It is a DAMPER, meaning that it softens the BLOW to the rear calipers so they dont lock up when you slam the brakes on. It does NOT control the amount of fluid to the rear calipers.

Putting the tee in place works fine with larger than stock calipers up front or good sticky brake pads on stock calipers up front and crappy Pep Boys pads in the rear.

A lot of things have changed since 1970 when it comes to brakes and materials.




B

Have I told anyone what I think about the BMW calipers?? LOL

It makes no sense to me why anyone would want to introduce more heat into a rotor that has trouble keeping up with the smaller pads on the stock calipers.


Make sure your stock stuff works well. You'll be fine. Promise.



B

Is there any truth to the rumor that the stock proportioning valve traps air which is a problem when bleeding the brakes, often resulting in a spongy brake pedal? And that he cure is to bleed the proportioning valve before doing the rear calipers?

Yes it can. Go with a tee you will love it.

I have to agree with Brad on this one.
But on the same note I varied the recipe a bit. I have stock early calipers up front with Porterfield R4S pads. and stock late front calipers in the rear. with some sort of lesser pad.
I was experiencing lock up of the rear tires before the front. So a backed off on the proportioning valve adjustment. Took lots of skidding on a old set of tires to finally tune it in. (same shitty tires front and back)

My braking distances with new Hoosiers is dramtically better. the fronts can lock up before the rears if I want but that's expensive. Threshold braking baby.

DON'T screw with your brakes unless you "really" know what you are doing.

I agree with Brad, but I figured I would try these out. I wanted mostly to get rid of the proportioning valve in a safe manner. I figured BMW calipers up front would make sense. I don't race the car and mostly wanted better feel and brakes to bite a little better for when the wife drives (makes me nervous). Here in PA the temperatures are a lot more moderate, so I am hoping that they don't fade too much. I tired to redo the stock brakes and was still not happy. I have a T fitting that I am going to try that out. If that does not work I will go with a proportioning valve from Summit racing.

What would a 911 set up cost and refresh my memory as what I need to do. What else is there that works and that will not cost more than the car is worth.

Thanks for all of the input

There seems like a lot of potentially misleading advice in this thread that could confuse people into thinking that you can put a TEE into a stock setup car and it's an 'upgrade'. It is not safe. If you have stock brakes, you are stuck with some sort of proportioning valve.

There are two things about your setup that I would do differently:

1. BMW Calipers.... I'm with Brad. I've posted several times on the topic - I'll leave you to dig up the details and avoid boring everyone again.

2. Braided brake lines.... These are bad for a bunch of reason often rehashed on here.... again... I'm not going to bore everyone again.

I went to a 911 setup (A-calipers - chosen for the brake bias) on the front of my car, and got rid of the stock prop valve. I think there is truth in air getting trapped in the stock valve.

If I were you I'd go back to rubber lines, stock calipers. Replace everything if it hasn't been done already. I'd get an aftermarket adjustable prop valve put it in the stock location. I'd adjust it in the wet buy adding in rear bias one click at a time and locking up all 4 in a corner (in a large parking lot) to see which end loses it first. When it starts to handle like an early 911 you've gone too far. Back it off a couple of clicks and you should be done.

Thanks for all of the info. I am aware of the issue with stainless braided lines and BMW brakes. I'll keep an eye on them and I always inspect my car everytime before I drive it. I have had two brake line blow on me in the past (lesson learned). I have the BMW calipers already on and only went that way after rehabing and playing with the stock system. I know a lot of people say they are fine when new and totaly sorted out. I sorted them out like new and can say I still did not like them. I figured I would try the BMW brakes. I'll admit not the best solution but what do you want for under $275.00 with calipers and new hardware, high end pads, new braided lines, hard lines, speed bleeders, and fluid flush.

That being said I think the BMW brakes are noticably better than totaly sorted out stock brakes. JUST MY OPINION! I have a stock master cylinder, stock rear brakes with stock proportional valve, BMW calipers up front with braided lines and porterfield R4s pads. I plan on adding a T fitting in place of the proportion valve and will then test to make sure the rears don't lock up first. If the do I'll add the summit racing proportion valve.

NOTE OF CAUTION DO NOT REMOVE THE PROPORTIONING VALVE ON THE STOCK SYSTEM, IT IS NEEDED. IF YOU REMOVE IT AND THE BACK BRAKES LOCK UP BEFORE THE FRONT THE CAR WILL SPIN OUT OF CONTROL.

Wilchek, in my lowly opinion you stacked the deck in the 320i calipers favor. you put Porterfield pads in them and wala got better braking.
put porterfield pads in stock calipers and you will get the same wonderful braking. and the stock stuff is lighter.

I agree the porterfield pads are a lot better. I am thinking about buying some for the stock calipers and running a test to see if it really made a difference going to BMW calipers. I only bought the BMW calipers becuase they were a fresh rebuild, painted, and I got an awesome price. The true test of a 914 owner (what does it cost). Who knows if they are better because of the pads or because they are a little bigger but I like the way they feel now. Anyone have a stock set of portfield R4S pads they are selling cheap (almost worn out would be OK, I know more heat if they are worn, but it would give me an idea if BMW calipers make a difference).