Proportioning valve again

[89 Gary]

It seems I'm getting conflicting views on how the prop. valve should be set up. Bottom line is I have the tubular control arms so I will not be attatching the valve to them. When the "actuator/flapper" is loose on the valve or disconnected,it doesn't push down on the two pins. I'm assuming this means that little pressure will be directed to the rear brakes,which is what I want (?) when no passengers are in the car. I also have Baer front brakes which throws a wrench into the equation. So, does anyone know for sure how I install this valve as I'm having it put on tomorrow. Thanks

 

[jcostantino]

I can't find any notes on how the lever works but:

What ever action the lever takes when the car is jacked up and the back left strut is fully extended, this is the "full open" position. I would think that the pins being fully out would be full flow because it would be easier to machine the valve that way.

Jeff

 

[jcostantino]

Taken from SHOTimes.com:

Adjust your brake bias: The SHO has a sophisticated front/rear brake pressure proportioning valve that not only adjust for static weight distribution, but also adjusts for dynamic brake bias while the weight shifts forward during braking. It measures stopping intensity by measuring changes in rear ride height. Fortunately, it is also easily adjustable. The ideal setting is to have the front brakes lock just 5-10% prior to the rears, ideally under all traction conditions, but dry pavement is usually the compromise. Any change in tires, springs, brake pads, ride height, weight, rotors, etc. can require a change in the brake bias to get back to the ideal. If ABS equipped, it is important not to let the ABS do this load compensating, because if it kicks in at only one end, the other end of the car is not braking at optimum. (This could be the reason some ABS cars have taken slightly longer to stop than a non-ABS version.) Maximum tire traction is achieved at about 5-10% tire slip. The hardest part about testing this setting is not flat-spotting and ruining a set of tires. (Testing ABS cars should be much easier.) It's very likely the Ford setting is more conservative than ideal, (just like understeer) and you could likely dial-in a little more rear brake to help the over-worked fronts, and improve your stopping distances. Try lengthening the adjustor rodlength near the left rear lower control arm 1/4 in. at a time, until the rear tires lock first on dry pavement. Then back off 1/2 in.

 

[89 Gary]

Well see,I read your quotes earlier. When you have the suspension extended you'd want very little flow because you don't want to lock up the brakes and that's what you don't want to do? When you have a load in the car you want more flow for more braking power? My manual says when you want to decrease rear brake pressure you move the adjuster sleeve toward the valve body. To actuate the valve this sleeve must move. But now though,it takes more control arm movement to make this move because the mounting bracket is further away from the sleeve now. So without confusing myself I guess I need to know-more brake pressure for more flow or less flow. AND-pushing pins down is more flow or less flow?

 

[89 Gary]

JCOS- for what it's worth you were right on and I have my answers-that being that to lengthen the rod gives more pressure and thus more braking power. NOTE- to those of you who have lowered your vehicles with the stock rear control arms-you have told your brakes to add more pressure to the rear-you need to adjust your rod length!!!!!!! AND-the "flapper" gives less pressure when not engaged or "pushing down" on the valve pins. I will eventually weld my bracket to my tubular arm. This link tells all++++++++http://www.babcox.com/editorial/bf/bfe29726.htm

<small>[ March 28, 2002, 08:35 PM: Message edited by: 89 Gary ]</small>

 

[jcostantino]

I've been told that completely removing the lever from the proportioning valve is the way to go and I verified one person from the SHOtimes list has removed the lever completely. But at least 3 others that I have seen said they zip-tied the arm to the valve so I'm going to say that is the way to go.

The more the suspension is compressed; the more pressure goes to the valve. Supposidly it's safe (read: nobody has crashed as a result) to disconnect the arm and zip-tie it to the valve body itself IF you have ABS.

Best thing to do is follow the directions on adjustment I posted above to adjust yours properly if you don't have ABS. If you do, and you're daring, you can fix the arm so that it's providing max pressure (as if suspension were fully compressed) all the time.

Jeff

<small>[ March 28, 2002, 10:05 PM: Message edited by: jcostantino ]</small>

 

[Shoboy3]

jcostantino:
I've been told that completely removing the lever from the proportioning valve is the way to go and I verified one person from the SHOtimes list has removed the lever completely. But at least 3 others that I have seen said they zip-tied the arm to the valve so I'm going to say that is the way to go.

The more the suspension is compressed; the more pressure goes to the valve. Supposidly it's safe (read: nobody has crashed as a result) to disconnect the arm and zip-tie it to the valve body itself IF you have ABS.

Best thing to do is follow the directions on adjustment I posted above to adjust yours properly if you don't have ABS. If you do, and you're daring, you can fix the arm so that it's providing max pressure (as if suspension were fully compressed) all the time.

Jeff

Well, I just completely removed the lever from the proportioning valve. Beat the **** out of the brakes and neither rear rotor is hot to touch. Driver's is warm and passenger's is barely warm. The fronts smell like they cooked themselves. I believe removing the arm works in the opposite way you are thinking. Since the arm is gone it can not put pressure on the pins and therefore very little flow is to the calipers. With the arm removed it is acting as if there is no load on the suspension and therefore the least amount of flow is to the calipers.

 

[89 Gary]

Shoboy-that is correct,under normal circumstances when no other load is in the car/trunk (just you) your rear brakes are at minimum pressure. You might have a corroded prop. valve which allows almost no pressure at all. But,you'd have to get a pressure gauge and hook up to rear bleed pins (one at a time) to see just how much it registers. The shop manual gives specs and any decent brake shop should be able to do it? At least a Ford mechanic should. Good Luck and keep us informed.

 

[AutoXSHO]

Removing the arm is unpredictable - sometimes you'll see full braking, sometimes not. Ask DeaconBlue. The only reliable way to do it is to zip tie, bolt, weld, glue, the lever so it is in the "full open" position. Otherwise you will see little or no rear brake usage.

If you have the big front brakes I think it's safe to say that the increased leverage and pad area up front is going to overwhelm the rear brakes even with no load in the back. I would bypass the valve completely and see how it works.

I've been running around with full rear braking (and '96 front brakes) for several months now with no unfortunate side effects. The nice thing is I have full braking all the time.

John V

 

[Shoboy3]

AutoXSHO:
Removing the arm is unpredictable - sometimes you'll see full braking, sometimes not. Ask DeaconBlue. The only reliable way to do it is to zip tie, bolt, weld, glue, the lever so it is in the "full open" position. Otherwise you will see little or no rear brake usage.

Ok, I just do not see how to zip tie the lever in the fully open position is gonna work. If the fully open position is when the pins are depressed (load on suspension), I am gonna zip tie this lever to the control arm (and it will stay)? What about removing the worthless POS Ford called a Proportioning valve and which they charge $90, and have full pressure to the rear brakes?

 

[JustinSchick]

Shoboy3
What about removing the worthless POS Ford called a Proportioning valve and which they charge $90, and have full pressure to the rear brakes?[/QB]

This has been done by a few, and is only recommended if your car has ABS back there. I will have it accomplished on my 92 soon. You can machine a set of plugs to replace the valves like John Hrinsin did, or wait until they're publically available from SHO Nut. Or, remove the unit entirely and replace with an aftermarket proportioning valve. If I remember correctly there are caveats to this as well - check the SHOTimes archives for posts from Gary Morrell and John Hrinsin (and others) about it.

 

[AutoXSHO]

Unfortunately it's not as easy as removing the proportioning valve (which should be called a load switch because it truly is binary in nature) and installing an aftermarket proportioning valve due to the way the SHOs brakes are set up. It could be done, but for street use, it's not worth the trouble.

It really is not that hard to get under the car and determine which way the lever moves the pins with the suspension compressed (full fluid flow). You can always try it fully open and see if you like it (like me) or if you hate it (like Scott).

My personal opinion is I'd like to use the rear brakes as often as possible, not just when I have a load of people or big bags of luggage in the trunk wink .

John V

 

[89 Gary]

For what it's worth------since I have no abs (89),and since I have Baer's up front,I will set up my rear's for FULL braking force (lever applied on pins,pushing down on the pins). Reason? You have @1000 psi in front system and 600 in rear . With Baer's in front you still get @1000 psi BUT the braking force is greater because of the larger size and dual pistons. BUT-the rear's still have the same 600 psi AND the same braking force which is now much less than the fronts (proportionately). So in effect it's like lightening the load even more than when no one is in the car----HENCE,I'll go full force on the rears--Any cross examinations are welcome and encouraged. Happy Easter

 

[DeaconBlue]

First off your '89 doesn't have ABS, so watch yourself. You don't want the rear end locking up and swapping ends on you. Not good on a slick road in traffic.

Well with the 13" Baer's up front and the stock solid rear disc on my '95, I removed the rear brake proportion valve connecting arm. The only problem was that one the pin assemblies became frozen in the positition which restricted fluid flow, resulting in only one of the rear calipers providing any braking action. I removed the pin assmeblies and installed plugs which now allow full fluid flow to both the rear calipers, all the time. I don't have any idea on what the line pressures are front or rear, but the brake balance has greatly imporved and the stopping distances were reduced. Since I have ABS, the potenial for rear lock up is greatly reduced. I have since upgrade my rear brakes to the vented 11.6" setup for even better overal performance.

<small>[ March 30, 2002, 10:07 AM: Message edited by: DeaconBlue ]</small>

 

[89 Gary]

Deacon-haven't you seen my request for your rear update mod? I saw the thread mentioning it but thought you were going to have someone make some "parts". I also want to upgrade to bigger calipers/rotors in rear. Thanks Gary

 

[89 Gary]

I jacked up the rear of my car today with the E brake on full-well,the left side wheel was locked but the right spun easily even though the E brake was supposed to prevent it. My stock (since 89 with 262k miles) prop valve also has stuck in the low pressure/force position!!!! (I disconnected linkeage a few years ago since I have tubular control arms). I got under car and tried to force the pins down with the flapper but NO WAY! They are frozen also---so beware if you have older car. I will replace valve next week and let you know what happens.

 

[Shoboy3]

Found out, the reason my rear brakes weren't working was because the idiot who replaced the calipers, and all the other componets must not have bled them correctly. Now the rears get nice and toasty after a short drive.

89 Gary:
Maybe you could look into some sort of aftermarket solution for the valve. The stock one is a POS and definitely not worth the $87 if you are just going to zip tie the arm. Maybe you could even contact SHONut about their plugs to replace the pin assemblies, I believe they cost around $25 but contact Nick to be sure.