Stubborn brake bleed issue/soft pedal after D1 -> D90 caliper upgrade
#11
Ok, then that's just the feed for the Right Rear (RR) Circuit. After doing this brake upgrade a few times I can say 100% I never had to bleed from the modulator. And as you know there is no bleed screw like on the RRCs (3).
The only "soft pedal" problem I had after replacing to the D90 bits was on one truck the MC went, and on another both the MC and the Servo Vac Booster went. Now was this because the new parts caused the problem, no. On both trucks when I got them they were already behind on maintenance (fluid flush etc). So putting the new bits on and then bleeding the system put the MC and Servo over the edge. Lesson learned, now when I do this upgrade I just add the MC and Servo to the budget list right from the start.
As for a method for bleeding the fluid, I really don't do anything special. I do it the RAVE method. Only thing is I use FIRST a handheld Mighty Vac at each caliper (starting P Rear). Then bleed the MC.
90% of the time the pedal pressure is spot on, if not I do the "press and hold" pedal method with helper. Pedal pressure is then gold.
The ONLY headsup re: having someone ( ie a shorter person) pump the pedal for you (in your case it was your wife) is to be sure they have the seat close enough to get FULL Pedal Travel! Sounds simple enough but often overlooked.
You'll get this sorted!
And for a fancy spec drawing of the modulator > http://inform.wabco-auto.com/intl/dr...d026d0416a47ea
The only "soft pedal" problem I had after replacing to the D90 bits was on one truck the MC went, and on another both the MC and the Servo Vac Booster went. Now was this because the new parts caused the problem, no. On both trucks when I got them they were already behind on maintenance (fluid flush etc). So putting the new bits on and then bleeding the system put the MC and Servo over the edge. Lesson learned, now when I do this upgrade I just add the MC and Servo to the budget list right from the start.
As for a method for bleeding the fluid, I really don't do anything special. I do it the RAVE method. Only thing is I use FIRST a handheld Mighty Vac at each caliper (starting P Rear). Then bleed the MC.
90% of the time the pedal pressure is spot on, if not I do the "press and hold" pedal method with helper. Pedal pressure is then gold.
The ONLY headsup re: having someone ( ie a shorter person) pump the pedal for you (in your case it was your wife) is to be sure they have the seat close enough to get FULL Pedal Travel! Sounds simple enough but often overlooked.
You'll get this sorted!
And for a fancy spec drawing of the modulator > http://inform.wabco-auto.com/intl/dr...d026d0416a47ea
#12
Passive method used. Same result.
1. Crack open PR bleed nipple.
2. Helper in the truck (father-in-law this time) slowly depress pedal to the floor and hold.
3. Close nipple.
4. Repeat 4 times.
5. Switch to DR and steps 1-4.
6. Switch to PF and steps 1-4.
7 Switch to DF and steps 1-4.
I saw zero bubbles for all 4 calipers.
I am beginning to think it's a case of bad timing with either the MC or Servo because the pedal gets much more travel as soon as the motor is started, and requires a couple pumps to firm it up.
Not sure what the next best step.
A. Local shop do a bleed?
B. Invest in a dedicated caliper bleeder like the Mityvac?
C. New Servo and Master Cylinder?
D. All of the above?
E. Drive the Rover off a cliff?
1. Crack open PR bleed nipple.
2. Helper in the truck (father-in-law this time) slowly depress pedal to the floor and hold.
3. Close nipple.
4. Repeat 4 times.
5. Switch to DR and steps 1-4.
6. Switch to PF and steps 1-4.
7 Switch to DF and steps 1-4.
I saw zero bubbles for all 4 calipers.
I am beginning to think it's a case of bad timing with either the MC or Servo because the pedal gets much more travel as soon as the motor is started, and requires a couple pumps to firm it up.
Not sure what the next best step.
A. Local shop do a bleed?
B. Invest in a dedicated caliper bleeder like the Mityvac?
C. New Servo and Master Cylinder?
D. All of the above?
E. Drive the Rover off a cliff?
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