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Well....one thought that comes to mind....I know for me to add 200 extra pounds in the trunk to test things would not be that difficult...I'd just throw my old parts that I have already replaced on the car...that'll get you 200 pounds at least!  Bob
An ounce of prevention provides a pound of cure!
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The pressure reducing valves were at least used for the models including 1996 through at least part of 1999. It very well may have been on most if not all models from 1995 all the way to the end of Cougar production in 2002.
It is easy to identify on the car. It is between the end of the steel line and the rubber flex line sort of at the front of the rear wheel well. They are about 2" to 3" long and roughly the diameter of your thumb.
Both drum rear brake cars and disc rear brake cars had them. Both ABS and non ABS had them. The drum and disc systems used the same part number, and the ABS cars had a different part number. I can only guess that the ABS valve must have been able to accomodate the rapid fluctuation of pressure generated during an ABS event. The EBD equipped cars may not have had them, I don't know.
I am not fully aware of the details of how EBD works. I received the service managers overview when Volvo introducted it. Basically it uses the ABS system to control rear brake pressure and can apply the rear brakes much more agressively under some circumstances. On some cars (including the Volvo when it was first introduced) it made a banging noise when in use. The noise was unlike the rapid pounding of ABS, more of a two or three repeat "pop pop pop". When driving cars with EBD I cannot tell the difference between them and a non EBD equipped car.
Other than trying a new set of valves, I would not recommend messing with them. I have driven cars with the rear bias was too high and it can be really dangerous.
The technical information posted by the two brake experts is far more than I can provide.
Jim Johnson
98 SVT
03 Escape Limited
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Originally posted by btrautman: Well....one thought that comes to mind....I know for me to add 200 extra pounds in the trunk to test things would not be that difficult...I'd just throw my old parts that I have already replaced on the car...that'll get you 200 pounds at least!
Bob
I appreciate the "test it out" spirit of your suggestion - but the "add weight to trunk" idea is not well thought out at all.
The problem has nothing to do with weight transfer, minor changes in spring weights, weight bias etc. It is about rear brakes that BARELY ... yes BARELY work.
If you capped your front brake lines, so had rears only and drove around town taxi like, you would never know anything was wrong. Yet your rear brakes would be excessively hot after many 60% threshold stops.
So how can adding weight to the rear have ANYTHING to do with this problem?
On the limit near ABS use, by all means weight distribution can have big effects. But not when you ae well away from lock up on either end.
BTW - I checked and I don't have any PRV where the steel line means the rubber one.
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I understand your point but have no experience in this matter....I'm just trying to come up with a "functional" use of all these old parts I have......  Bob
An ounce of prevention provides a pound of cure!
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Originally posted by 99fordsvt: Originally posted by btrautman: Well....one thought that comes to mind....I know for me to add 200 extra pounds in the trunk to test things would not be that difficult...I'd just throw my old parts that I have already replaced on the car...that'll get you 200 pounds at least! 
Bob
I appreciate the "test it out" spirit of your suggestion - but the "add weight to trunk" idea is not well thought out at all.
The problem has nothing to do with weight transfer, minor changes in spring weights, weight bias etc. It is about rear brakes that BARELY ... yes BARELY work.
If you capped your front brake lines, so had rears only and drove around town taxi like, you would never know anything was wrong. Yet your rear brakes would be excessively hot after many 60% threshold stops.
So how can adding weight to the rear have ANYTHING to do with this problem?
On the limit near ABS use, by all means weight distribution can have big effects. But not when you ae well away from lock up on either end.
BTW - I checked and I don't have any PRV where the steel line means the rubber one.
Ok. So cut to the chase. You don't want to hear all the mumbo-jumbo data we have offered you. That's fine, we can handle rejection~! lol
Stop wasting your time here reading all of this and do the following:
Pull the calipers and rebuild or replace them. Lube the slider assemblies properly. Replace the rubber hoses. (looking for debris in them) Inspect all hard lines for kinks. Flush the hell out of the lines and even blow them out to be sure. Turn the rotors nice and pretty. Put in some new pads.
In the end, if it works and you're happy with the results you'll know what the problem was- lack of maintenance. On the other hand if it works just like before; call me and I'll sell you a 11.75 rear rotor replacement and you can elevate the rear bias.
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Originally posted by 99fordsvt:
I just replaced both rear calipers, probably unecessarily. They are bleed and have new pads and rotors.
FWIW I had the same symptoms before changing all the components. Fluid does squirt out during bleeding, but not super strong. I ordered some Powerbleeders - can't hurt but probably won't help.
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"Absolut Rara."
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"Absolut Rara."
Joined: Sep 2000
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so, let me get this straight, you want to know why your rear brakes are working normally? and refuse to believe any explanations of how they work normally? and still insist that something is wrong, because your rear rotors don't get as hot as the front rotors?
And you have the balls to insist that I don't understand what is going on? all based on your excessively scientific thermal data gathering technique of throwing snow on the rotors?
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rara, what exactly made you think that just because you are an oem brake engineer who is actively involved in racing you are not only qualified to speak here but infact know what you are talking about? and do you honestly think that your fancy schmancy science can hold water compared to his snow on the rotor method of analysis? j/k hahahaha
seriously though, thanks for all of the good info in the thread todd, jim and rara. the rest of us have found it rather educational.
00 black/tan svt, #2052 of 2150, born 2/1/00
formerly known as my csvt
"Nothing in the world is more dangerous than a sincere ignorance and conscientious stupidity." -Martin Luther King, Jr.
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Originally posted by 99fordsvt: Ah - so just what IF I have a bad EBD feature in my ABS?
Hey Rara, Todd and Jim have you ever in your years of experience with brakes ever seen anything go wrong with ebd or any other kind of bd system? Call me  but im gonna go out on a limb and guess no. Just a guess though. 
98 csvt t-red.. sho-shop intake, b&m, fidanza, spec1 clutch, Torsen, DMD,optimized Y& TB, Brullen, rear strut bar,h&r's,17" konig traffik's.
"I say what I mean and I do what i say"
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Joined: Nov 2001
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CEG'er
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Originally posted by my csvt: rara, what exactly made you think that just because you are an oem brake engineer who is actively involved in racing you are not only qualified to speak here but infact know what you are talking about? and do you honestly think that your fancy schmancy science can hold water compared to his snow on the rotor method of analysis? j/k hahahaha
seriously though, thanks for all of the good info in the thread todd, jim and rara. the rest of us have found it rather educational.
Rara, Run for President and you don't have to be qualified in a damn thing and there would be many people willing to listen to you!
Bob
An ounce of prevention provides a pound of cure!
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