454 no more

So my brake pedal went soft. So far I've replaced the rear pads and drums, cylinders, springs and adjusters looked good. All new brake lines, including flex lines. New rotors and pads, cleaned and lubes, calipers look good. New master cylinder, brakes bled repeatedly and the pedal is soft. Bypassed the abs modulator, bled the brakes and same thing. I'm at a loss, the booster is definitely working . Anyone have any ideas??? I'm at a loss....

I would like to replace the modulator but everyone says there on factory back order and wishes me luck finding one!!!!

Jim5870

I heard somewhere that there is a pin on the proportioning valve that you
need to pull and hold out while the rears are bled.

maybe368

Are the rears adjusted right? And, have you checked rockauto? They are are always available there because they have a system where you can send yours in and have it rebuilt...Mark

maybe368

According to the FSM, that is only if you are going to pressure bleed...Mark

454 no more

I'm not sure the modulator is the problem, mine is bypassed and my brakes are still going to the floor. Rockauto website says temporarily unavailable, where else can I look?

maybe368

I am not sure where to get one, A1 Cardone is the outfit that rebuilds them, maybe you can contact them directly. I also don't think it is the modulator. Maybe your mc went. Like I said earlier, the rears just slightly out of adjustment can send them to the floor...Mark

maybe368

Rockauto shows a Raybestos #ABS570044 modulator for a 90. What year is your rig? Mark I was looking at their site again and I see that they have the same part called a modulator (what Dodge calls it), A hydraulic valve and an actuator assembly, the are all the same part...

454 no more

mc is brand new, im stumped, any ideas would help

Bencie

I agree with maybe368, try tightning the rears up with the star wheels one at a time till the wheel locks then back off a little till its free, that should make a big difference on your pedal, if it doesn't then maybe your reman master wasn't remanned right.

maybe368

I have been posting in 2 different brake threads, here is what I was referring to above, from the other thread:

The rear brake adjustment is very important for the mental well-being of these brakes. Make sure that the parking brake cable is loose, turn wheel and adjust brakes until they drag a little, pump the brakes a few times to center everything, back off the adjuster until the don't (or barely) drag and repeat, always repeat...I found that I had to do this 2 or 3 times to get them right, then adjust the parking brake...Mark

454 no more

Here's the latest, re adjusted the rears, pumped the brake, adjusted again. Thought it made things better, but two seconds down the road, same problem. I'm going to replace the new master with another one cause that's the only thing I can see it being.
So far ---
New master
New drums and shoes
Calipers cleaned and lubed
New pads
New brake lines
New flex lines
New e brake cables
Bled repeatedly

Same problem....... Good thing I love this truck!!!

Any tips on the bleeding procedure? And if a new master solves the problem, should I reconnect my abs modulator?

KD93

Unless you have a problem with locking your wheels, I wouldn't bother. I haven't had to look for a 'new' M/C on my truck, but I would pay more for a NEW one, (if they're still available) not a remanned one. Most of the stuff that's remanned was sent to Mexico or Brazil or wherever and done by a guy getting paid a couple of Peso's a day. Do you think it's going to be quality? Not likely. In saying that, it sounds like Rockauto has it covered.

maybe368

What gets me is that this EXACT problem has occurred to so many of our rigs and we still don't really know why. In thread after thread, people throw parts at the braking system until they work acceptably. One only has to do a search on brake problems to see that this is true. My brakes work great, but that is after replacing EVERY component, and I am still not sure what actually fixed them, or if I will have brakes the next time I need them. I almost never get any air from the modulator valve when I bleed them and that seems strange. I am at a loss and can only say that what worked for me was replacing EVERY component, it's a sad day for my diagnosing skills......Mark

454 no more

I hear ya.
I've almost replaced everything, it's getting expensive, not to mention dangerous! My brakes were just gone one morning. As I understand it , if your modulator fails, you pretty much lose your rear brakes. Luckily the truck was empty, but I couldn't imagine if I had been pulling a dump trailer loaded!

Feel free to post brake stories here, the more info the better! Hopefully I can get this sorted out and add something positive to the saga!

97catintenn

I think it's still the rear brakes that need adjusting again. Lift up the rear and see how much adjusting you have to do just to get a little drag...I bet it's quite a few clicks.

If you have a little drag, than nevermind...move on to master...