need brake guru advice

[Sheepherderspecial]

well i thought i would be a good son and fix the brakes on dads 92. had lots of pedal travel and lots of shudder. so i put new rotors on the front, one new caliper, new pads, the rears were way out of adjustment and needing shoes, put new shoes on. i then flushed the lines with new fluid and bled about a quart through everything. got in, put foot on the brake(had good hard pedal) and when i started it up the pedal slowly and smoothly went to the floor. I bled some more, still the same. found on here a post about bleeding the rwal valve so i did that. no better. saw that it was wet around the master cylinder. so i replaced it last night with a new bendix 11775. then bled everything again. STILL THE SAME THING!!! you can pump and push all you want with the engine off and have a great feeling brake pedal. as soon as you start the engine , you can push the pedal to the floor.

what am i missing here.

sorry for the novel, had to vent somewhere.

Thanks

Eric

 

[Philip]

Did you replace the rear drums or have them turned?



Did you replace all the small parts on the brake shoes?



Did you replace the self adjuster parts?

 

[Sheepherderspecial]

Did you replace the rear drums or have them turned?



Did you replace all the small parts on the brake shoes?



Did you replace the self adjuster parts?

just had the drums skimmed



all the small stuff was fine i had replaced all that the last brake job

and the adjusters all seemed to work fine

and i adjusted the shoes till they had a ever so slight drag when i installed them

 

[Philip]

Set your emg brake and see if the pedal feel changes. If it does. Then you need more brake adjustment on the rears.



If the pedal didn't change bleed some more or take the RWALK valve out of the system. It has been noted for causing problems with low pedal.

 

[Paychk]

You could also check the rear wheel cylinders, when you install new shoes the seals will get pushed deeper and they can get damaged by crap in the cylinders.

 

[MLKramer]

I have had problems like this on everything from my motorcycle to my truck. Brake bleeding can be really hateful at times. I use a Mity-vac vacuum powered brake bleeder with good results. It seems to get all of the air out of the lines when conventional bleeding fails. Works for me, hope this helps you out.

 

[Ggg]

Correct me if I am wrong.

Since you changed the master cly. isn't there a dimension the booster rod sticks out past the mounting surface for the master cyl. ? If it is too far in then there needs to be too much travel in the booster- thus causes excessive pedal travel. Just an educated guess, your issue is with the vaccuum assist. How much vaccuum does the pump pull?

I also will adjust the rears so there is a fair amount of drag, the new shoes will wear into the curvature of the drum and the drag will all but go away very soon.

One last thing, and I do not think it has anything to do with your pedal problem. JMO so don't take offense, it is not good practice to do something like change a caliper on only one side of an axle. Whatever you do on one side should be done on the other side of the same axle.

I know you only set out to help your ol-man, I hate it when projects like this get out of hand. But remember every good deed never goes un-punished.

Sorry for the long post, Good Luck.

 

[w gilmer]

Sheepherderspecial I Have A 99 Auto And I Had A Problem. I Also Pulled All 4 Cylinders Replaced Front Calipers Roters Along With Rear Upgrade Cylinder And All New Rear Hardware. Spongy Brakes!! Tried For Weeks To Get Rid Of Air With Mighty Vac Also A Pressure Bleeding Tank As Well As The Standard. Finally Replaced Master Cylinder. Bench Bleed As Per Instructions. No Help. Reinstalled Old Master Cylinder And Bench Bleed It. some Better But Not Ok. Bench Bleed The New Master Cylinder Again And I Got Some Air Out And I Couldnt Depress Plunger At All. Reinstalled And Had Pretty Good Brakes But Not Perfect. pressure Bled All 4 Wheelagain. That Was The Trick. The Air Has To Be Out Of Master Cylinder Before You Install It On Truck. I Was Using Raybestos P/n Mc390426. Instructions Were In Box On Bench Bleeding. You May Have Other Problems. I Hope This Will Help. Waltgilmer

 

[rvaughn801]

I have been adjusting rear brakes, trying to get rid of excessive pedal travel. Now I have the brakes making noise on each wheel rotation. Test driving, the pedal sinks but it will stop if it is the pedal is pumped. I installed plugs at the master cylinder, and the pedal is hard with the engine on. With the plugs in the master cylinder, the pedal would sink if the m. c. was bad, right? Where should I look next?

 

[Paychk]

Sounds like the ABS valve is internally leaking into the accumulator, if it is, disconnecting the wire harness will do no good. Search the forum for ABS/bypass/fittings, install those and see if it gets better, if it does then you can decide whether to replace the valve or leave the fittings in.

 

[BHiggins]

I think Philip and Paychk are steering you in the right direction. I had the same problem and plumbed a new brake line around the rear wheel anti-lock valve and the problem went away.

 

[rvaughn801]

I pulled off all the wheels and the rear hubs. I have a little brake fluid seepage from the driver's side wheel cylinder. In the back, the drums have a little ridge but look good. The shoes are about half worn. I hate to replace shoes, since the "worn-in" shoes have more contact area. But given the weeping fluid, it would be stupid not to do cylinders and shoes, right?



In the front, the rotors look worn. I turned the rotors 60k ago, they should probably be replaced. I have not pulled the calipers off the rotors, but it appears the inside pad on both sides is wearing a lot faster than the outside. Is this due to the caliper piston pushing on it?



The rear brakes look daunting at best. I have done brakes before, but I am by no means a great mechanic. Are they tough to take apart, any special tools? With such a small wear ridge, is it necessary to have the drums cut? Does anyone have any good experience (drum turning wise) with NAPA or the like?



I bought two Weatherhead fittings to bypass the RWAL. Is the best setup to use a tubing bender to bend the lines, or to use a short rubber brake line? If a brake line, any idea what sizes or type?



Thanks!

 

[Philip]

The brake line is 3/16's. For this size line I just bend it with my thumbs. LOL If I need a real tight bend I have a close quaters bender from Mac Tools. Plus I have a couple of other type of benders.



Turning drums is only as good as the person running the machine. If I am rplacing shoes or pads. I always turn the drums/rotors. I also turn new drums/rotors. You wouldn't beleave how far out of round I have seen new drums/rotors.

 

[Greenleaf]

I spoke with an engineer @ a brake workshop and was told that the rotors must be turmed after install with the hub. The drums ... ... ..... he said they will be out of round. They just are. If they are turned when new they will be out of round as soon as they are put into use due to several reasons. Hot/cold. Operating in water when hot. Applying the park brake when hot. etc. etc. etc. will immediately transform a true drum to out of round. He said it you set a "true" drum on end the effects of gravity will deform the drum to out of round... ... ... ...



What he said anyway. You cannot believe everything I suppose.

 

[Sheepherderspecial]

well first i want to thank all of those that replied. your advice was most helpful. i have made some good progress i think. and what i did you ask???

Bleed the brakes till my girlfriends legs were shot. :-laf then let it set a day.

my best guess was that there was still some air somewhere, and by letting it sit, it worked its way back to the m/cyl. at least now i can slide all four wheels in the driveway if i want.

again thank you all

Eric Bloom