4-wheel disc brakes on an "A" Body...???

[RedFish]

I tried to answer this yesterday and got a paragraph and a half when I hit a button to make a sign and lost what I had types....so that pissed me off and I quit.

SO I will try it again.

After obtaining the new Brake Diagnostic Kit and some of the fittings and lines missing :angry5: ...called the supplier and they sent more fittings and lines. We hooked up to the brake lines and check pressures. Got pressures between 600# in the front and 700 - 800# reading at the rear "T"...to try to get to the calipers was a real feat. And they came in at 700#. The disc brake people said to make sure the rear caliper bleeders are level with the ground (they come and are installed at a 15 degree angle down).....so we took the rear calipers off and made sure they were parallel with the ground and re-bled the lines with the rotor bungee corded into place to have something to expand to. Things look better now but we are in another situation with the wheel spacer. (we noticed that the wheel is wobbling) so before we put everything back together....we are attacking this problem also. So we are in a holding pattern at the time.

"Bleeder parallel to the ground" doesn't sound right to me. I'm picturing only venting have the cavity . Set the calipers on top the rotor or somewhere with the bleeders pointed due north/straight up/ 90 degrees to the ground.. Open the bleeders and let it free bleed to remaining air out. No need to pedal pump bleed, just open the resivoir and keep it poured full.

 

[GMachineDartGT]

Might want to try a pressure bleeder. Either way, chances are you won't have enough line pressure for proper braking.

 

[67Dart273]

............"Bleeder parallel to the ground" doesn't sound right to me........................ Set the calipers on top the rotor or somewhere with the bleeders pointed due north/straight up............

Yep. Especially with a "swap" situation, you may have the calipers positioned differently from original intent, differnent hoses, etc. The IMPORTANT thing is to get the bleeder to the HIGHT POINT in the cavity

 

[HemiDenny]

Jim...did you find some quality 1/4" spacers for the rear???? I was surfin' Jegs site and saw some dandys there.....anymore thought on sending the calipers to Right stuff for a "look see". anything new on Sheppard???

 

[62BT409]

Jim...did you find some quality 1/4" spacers for the rear???? I was surfin' Jegs site and saw some dandys there.....anymore thought on sending the calipers to Right stuff for a "look see". anything new on Sheppard???

Tod and I ground down the caliper a bit, got the wheel to fit. Had another friend (Boss in a machine shop) take the rear studs and cut them down. Had the rotor bushings cut in half to be as thick as the rotor since we did away with the spacer idea (because the wheel without the space did not wobble anymore) Should be altogether by Friday. The make another appointment with Shepard.

Brakes seem to be better now...will know more from a road test.

 

[HemiDenny]

hows the clearance now between the tire/leaf spring???....apparently the studs were too long without the 1/4 spacer...any change with the clamping power of the rear calipers??

PS.. Jodee and I wish you,Sarah,and Todd a happy Thanksgiving.

 

[66plyValiant]

I used the 13" front, 11.75 rear Dr. Diff Kit, with MP 1.032 master, stock disc/drum prop valve and HYDROBOOST. Pressure checks reveal exactly 50% of the brake pressure to the rear (perfect bias for these cars), modern feel and absolutely outrageous brakes.

Guys, there is no substitute here for spending $$ on the right parts. Dr Diff Kit and hydro unit is a $2500 investment period. If you aren't willing to go the distance for OE style (PBR calipers), properly engineered parts, stick with the 11.75s up front and drums in the rear. Quality Carbon pads are available for the single piston calipers, good fluid, braided hoses and you have a good package.

I have hydroboost on my car too, except its running the factory drum brakes. it stops like it never did before.infact I have no reason for disc brakes now it would throw you through the windshield if not careful. its a unit I paid $25 for:cheers: factory for a 94 chebby diesel

 

[1970PAValiant]

just a quick question, did you check your break pedal position, depending on the position will give it a string or weak pedal

 

[SixSpeedSS]

The rear calipers are doing their job now. They needed bled while the bleeder was parallel to the ground (even pointed slightly up as in the picture below). I know we talked about that on the phone and you (Denny) stated that was done, but ultimately that was the fix. I would imagine if the rear calipers are bled at anytime in the future, this will have to be done. One would think that when Right Stuff designed the system, they would have kept this in mind. I wouldn’t imagine that having the caliper at the 3 o’clock position would have any effect on the rear braking as having them at the 2 o’clock position. This would have made this whole situation better.

We pulled that calipers, moved the lower mount to the upper position, & reinstalled the caliper pin. Then we bungee corded the rotor in place and bled the whole system again. When we put it all back together, started and put it in gear, the rear brakes held far better than before. Obviously if I give it a good bit of throttle, they’ll spin. I think once the pads get burned in they will hold even better.

Just an FYI…
With the pressure gauge on the end of the line coming from the front of the car, we had almost 1000 psi. Then I went to the T on the rear axle and had 850-900 psi. I think the reason why we had such low pressure directly at the rear calipers is because there was still air in them.


As far as the clearance from the tire to the spring – there is about ¾”. That should be plenty. With one of the rear wheels being slightly bent, the tire still did not contact the spring. Jim is going to locate another 15x8 wheel in the meantime.

Happy Thanksgiving to all!

 

[HemiDenny]

when I did it(in WV) I loosened the U bolts on the rear....placed a foor jack under the nose of the pig and jacked untill the bleeders were horizonal(even checked with my angle finder on a socket/extension over the bleeder screw)after that procedure we(dave had come to WV to assist me)had an extremely hard pedal and it was very close to the top....however it still took a great amount of pedal pressure to keep the rear wheels from spinning at idle....however at that stage the incorrect distribution block(front disc/rear drum) had been installed...when I changed it back at Jim"s garage we did not rotate the housing to get the bleeders horizonal...I must have wrongly assumed we had already bleed all the air pockets out of the caliper....

 

[jedrattle]

I have hydroboost on my car too, except its running the factory drum brakes. it stops like it never did before.infact I have no reason for disc brakes now it would throw you through the windshield if not careful. its a unit I paid $25 for:cheers: factory for a 94 chebby diesel

How hard was this thing to mount up to the mopar? Any pics?