Brake push rod to long?

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gtxdude

gtxdude

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Finishing up Wilwood disc brake set-up, (disc in front, drum in back). Went through original distribution block for front and have rear drums by themself with adj proportioning valve. Seemed like rear drums never had enough fluid coming through when bleeding, decided to come back to them. Front discs bled and seemed to work just fine. After done, discs won't release far enought to turn rotors. Had put in adj push rod which even after cutting off is still pushing in valve some. MC is A1 Cardone from Oreillys, 10-1571 with .937 bore (everyone says stay under 1") I switched from power to manual. Not sure if right MC or why adj push rod is still to long. Looking for a little help here. I've talked to Wilwood and they have helped but turning to you guys now. :banghead:
 
The MC MUST return all the way. Otherwise the piston will block the port in the bottom of the MC and won't release pressure
 
I would think this is a pretty standard swap, why such a difference in push rod length?
 
The MC p/n doesn't mean anything to me, is it a disc/drum MC or a drum/drum MC application?

If the latter it's likely got an RPV in the front output. Can confirm by pushing on the pedal a couple of times, and then with the pedal fully up crack a front bleeder screw. If it does anything more than just dribble the MC has an RPV in it.
Easiest way to deal with that is to remove the brake tube from the MC and run a tap into the center of the little sealing cone in the port on the side of the MC. Choose a tap that would use a hole about that of existing as it's tap drill size. What will happen is that once you're nearly all of the way thru the tap will bottom out on the bits that make up the RPV. At that point the tap will start extracting the sealing cone. Gonna be a small tap, so go easy. Once the sealing cone is out the RPV plunger and spring can be removed and the cone re-installed.

With the original H block, do you know if the shuttle pin is centered? If it isn't you will have little to no bleeding on the side that the pin has been pushed towards. Re-centering it should clear up the problem. If the pin has moved far enough you brake warning light should be on.

If my lack of familiarity with things MOPAR means that I'm all wet, then kindly disregard.
 
Easy to determine if the rod is the problem. Loosen the nuts on the master cylinder, if the brakes release, you know your on the right track.
 
It is a disc, drum MC. I removed the rod and that did help but they were still rubbing a little.
 
gtxdude said:
It is a disc, drum MC. I removed the rod and that did help but they were still rubbing a little.
Click to expand...

You do have the front disks hooked to the rear section of the MC?

(Residual valve in the section feeding rears)
 
They were turning free till bled and brakes applied now there dragging a little. I did check again just to make sure brakes were hooked up to correct bowls.
 
I think it is normal for new disk pads to drag a little. The calipers don't retract them much. It is just the rotation of the square O-ring that pulls the caliper piston back. After use, the pads will wear to match the rotor surface exactly, then there should be a gap as they pull back.
 
try bleeding the brakes again. The wildwood calipers seem to want to hold air causing the brakes to lock. Ive installed three wildwood front disc kits and that's pretty normal from what ive seen. As far as the pushrod being to long, are you seeing the pedal way up off the floor??? I have that problem with two of my three cars and tried the adjustable pushrod on one with no help. The adjustable was also way to long.
 
On my '65 Valiant I just made the push-rod adjustable. Didn't even know that I could buy such a thing. No pic, but one could be taken if interested.
 
Thanks Bill that's what I wanted to hear. I will bleed again & yes the peddle is up as far as it will go & adj brake rod was still to long. Vitamin c, what did you do for rod? Check back in morning. :)
 
well, I bought a spare rod from a member here for the reason of cutting it to length. Not my first choice, but Im out of ideas. I was under the impression that all manual rods were the same length, and now I know that is not true. Of the two spare rods that I now have, one is about 1/4'' shorter. not sure what cars they are from, and even what lengths are currently in my cars, but im going back at it and compare lengths with what's currently installed. My 68 valiant is very far off the floor and has to have something done. My next thought is master cylinders. Ive seen two different styles, one that uses a snap ring to hold the internal cylinder in, and (what I have) the style that uses an el cheapo metal tab, held in place by a flat head Phillips screw. Im saying the snap ring style holds the cylinder farther into the bore of the master cylinder in turn letting the pushrod fit farther into the master cylinder and lowering the brake pedal. Ive been unable to locate the snap ring style or identify what and where they come from. both cars im having trouble with are cars that had the power brake booster removed. one was a power disc car and the other was a power drum car.
 
I ended up taking the adj rod out (got from Mancini) and cut about 1/2" off each end (where it threads together). Put back together and appears I now have room to spare and can still adj it out if needed. Not sure if that's the end of it, I'm sure I'll be back with something else real soon. thanks
p.s. this also was a power brake booster car, just a different set-up
 
yea, I tried cutting the adjustable rod, but still couldn't get it short enough.
 
FWIW mine is a power m/c used manually. As I had to make the 4 to 2 adapter I made it with the bits to capture the push-rod such that it can't fall out of the rear of the m/c. And I ran into that as well, almost couldn't make it short enough.
 
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