Thoughts about residual valves (1 Viewer)

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pbgbottle

pbgbottle

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i noticed there was quite a few post's about RDB and got me thinking, mine aren't ideal either . the rear does lock in emergency situations for me also .prop valve all the way out .. brakes are not perfect but most times i'm happy ,better than the old drums .i started thinking about the residual vavles I have none in mine,front or rear circuit . 78 /40 master .i was thinking about trying the 2lbs after market ones . for the fun of it i checked the parts catalogue and this is what i saw ,toyota uses the same part # for both front and rear on this master WTH !
would they really be the exact same part .?? anybodies thought on this .

heres a pic of the front part #'s
valve (front) (Medium).JPG
 
Last edited:
Will these 2 lbs. residuals restrict your circuit pressure to 2 lbs.? Weren't the originals regulated to 10 lbs.?
 
ya! on a rear disc brake conversion they recommend you just take the rear one out . i was thinking of adding a front residual valve to the rear circuit . 2lb. but the parts catalogue list's them as the same part .so what are they 10lb or 2lb . i think i should be adding one back into my front system as well .
 
The question I have is that if you remove the valve to achieve more pressure, why would you want even less pressure than before for your discs?
 
JJS said:
Will these 2 lbs. residuals restrict your circuit pressure to 2 lbs.? Weren't the originals regulated to 10 lbs.?
Click to expand...


Residual pressure valves do not restrict circuit pressure; they keep a specified amount of pressure on the device beyond the master cylinder, when the master cylinder is sitting in a released position. Drum brake wheel cylinders typically use a 10-pound valve and disc brake calipers use a 2-pound valve.
 
Both MCs I've gotten from Toyota for my '78 have been set up for 4 wheel drum brakes. I currently have no valve in my front circuit and at least it seems to work without dragging and heating to 1000f like it did when installed as shipped. I'd love to know where to get a 2 lb RV if I should have one.
 
You can get them from Summit.
 
I can't believe this has not been discussed a zillion times?????
(a) You need an adjustable proportioning valve to correct the front-to-rear pressure ratio after disc brake installation. The factory prop. valves are not adjustable.
(b) You need a 2lbs. residual valve in the rear to hold the rear pads up to the rotors. If you don't have a residual valve at all, you will always have to pump the pads up to the rotors. If you keep the stock 6lbs. residual valve in the master cylinder, you will constantly be applying the rear brakes (until the pads melt themselves onto the rotors).
 
i think it has been discussed alot ,i was more curious about the same part #'s for front and back residual valve's (disc up front),question how does the fluid climb all the way back up the line and into the master no springs on calipers ? ,how much pressure is there actually in the line from gravity. didn't fj40's come with front disc . in the U.S. after 75 ? as per FAST EDDIE said his was set up for drums all around ,
 
Downey said:
You need a 2lbs. residual valve in the rear to hold the rear pads up to the rotors. If you don't have a residual valve at all, you will always have to pump the pads up to the rotors.
Click to expand...

What about the stock front circuit? I have no valve now and I do not have to pump. The valve that came stock (New OEM Toyota) caused dragging and heating, so I took it out after much frustration, trial and error.
 
i have none in either circuit also ,but lately it has felt like i have had to pump the brakes ,that was why i was thinking about the 2lb. was also thinking i could just throw a 2lb one in from another master .instead of buying the aftermarket valves .
 
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