Brakes. WTF am I not doing / doing wrong?

[96-2D-Hoe]

New MC was bled and installed. I bled the brakes, then ran the ABS bleed a couple times. Then I bled all the brakes again. Pedal sucks. I even tried one man manual bleed with the pedal thinking there may be something in the MC. And then pressure bled them again. Pedal still sucks. Just off 1 gal fluid through it today.

I really thought I would get a decent brake pedal today, but no chance of that.

What am I missing / doing wrong?

 

[wjburken]

New MC was bled and installed. I bled the brakes, then ran the ABS bleed a couple times. Then I bled all the brakes again. Pedal sucks. I even tried one man manual bleed with the pedal thinking there may be something in the MC. And then pressure bled them again. Pedal still sucks. Just off 1 gal fluid through it today.

I really thought I would get a decent brake pedal today, but no chance of that.

What am I missing / doing wrong?

Is your pedal still very stiff or too soft?

 

[96-2D-Hoe]

Too soft. Too much travel and low brake force

 

[wjburken]

Too soft. Too much travel and low brake force

Have you checked all your brake lines at your calipers to make sure they aren’t bulging?

 

[Doubeleive]

might have low vacuum, have you checked the line and vacuum pressure?

 

[96-2D-Hoe]

Have you checked all your brake lines at your calipers to make sure they aren’t bulging?

Not when pressing the pedal. They look in decent shape although they are the originals.

might have low vacuum, have you checked the line and vacuum pressure?

I don't think so, but I will check it.

 

[Larryjb]

Check that you put the calipers on the correct sides. They will mount on opposite sides but the bleeders will be below the feed line. In this situation, you won't be able to bleed the air out of the calipers.

 

[96-2D-Hoe]

Check that you put the calipers on the correct sides. They will mount on opposite sides but the bleeders will be below the feed line. In this situation, you won't be able to bleed the air out of the calipers.

I've not changed them, but I'll check.

 

[96-2D-Hoe]

After driving for an hour the brake force isn't too bad. Fine for cruising but still not really good enough. I did notice the front digging in so the rears aren't engaging much.

The system must still have air in it. I'm going to pull the MC off to swap out the reservoir, bleed it again and start again.

I'm sure the triple loop in the hard brake lines next to the MC isn't easy to clear air out of. Can't imagine what use it actually has apart from trapping air.

Definitely not putting another Autozone Duralast MC in it no matter what happens. I'll buy a Delco from RA if I have to.

 

[iamdub]

After driving for an hour the brake force isn't too bad. Fine for cruising but still not really good enough. I did notice the front digging in so the rears aren't engaging much.

The system must still have air in it. I'm going to pull the MC off to swap out the reservoir, bleed it again and start again.

I'm sure the triple loop in the hard brake lines next to the MC isn't easy to clear air out of. Can't imagine what use it actually has apart from trapping air.

Definitely not putting another Autozone Duralast MC in it no matter what happens. I'll buy a Delco from RA if I have to.

I was about to say that you may have a defective MC.

 

[96-2D-Hoe]

I was about to say that you may have a defective MC.

I was thinking the same. It's either that, or I didn't bleed it properly.

As I still had a MC with a leaky reservoir that I was going to return I just swapped seals out and have bench bled it and put that one back on. No bleed yet as truck was still a bit hot.

I wanted to bench bleed both of the ones I have to see which seemed better but only had 3 plugs so I could only do one at a time. Now I just bench bled the one that was on there yesterday and it seems a bit firmer stroking it than the one just I put back on.

Relentless BS. And I've been through it multiple times before. Will find out how this turns out shortly.

Thanks for all the replies.

 

[east302]

Does pumping the pedal improve it? If so, that’s usually air from what I’ve read. If not, I’d look at the shoes and bring them out a little.

 

[96-2D-Hoe]

Does pumping the pedal improve it? If so, that’s usually air from what I’ve read. If not, I’d look at the shoes and bring them out a little.

Earlier today I noticed pumping did not improve it. I think the pedal is way too low and soft to be the just shoes. They're not really that far off, but they are properly bedded now and I should do that anyway.

I've just put a different MC on and 1/2 gallon fluid through it and I don't think it's much if any different than before I started today.

I don't think the ABS is getting bled properly. Has to be that. Tomorrow I will set the ABS off on some loose ground a couple times and then try bleeding again. That's how I got a decent pedal before.

 

[rchurch5945]

When I decided to re-do my brakes I replaced every part in the whole braking system except for the hard lines (calipers, rotors, drums, MC, etc). Even replaced the rubber lines with stainless steel lines. Ended up with a soft pedal that went almost all the way to the floor. Bled, re-bled, bled again, bled ABS...no change. Decided to just drive it since they did work. The more I drove it the better they got. After maybe 200 miles they worked the way they should. I've driven over 2000 miles and no problems. Even though I adjusted the back drums to what I thought was good enough and drove it backwards around the neighborhood to self-adjust them I think they just weren't adjusted as needed and as I drove they self-adjusted to where they need to be. Now have a good, solid pedal!

 

[exp500]

If you are pretty sure the MC is working correctly, Just a pedal height problem, Take off a rear drum and check clearances and hardware. If there ls ANY weeping at wheel cylinders or if the adjusters are stuck,free adjusters and lube threads and REPLACE wheel cylinders. If its been 100-200K miles, replace wheel cylinders.They get sticky and don't hold clearances. Also make sure you get the right Diameter cylinder. larger diameter means more braking force but more pedal effort/travel/ smaller diameter means less pedal effort but rears could hit before fronts.

 

[exp500]

Looking at this some more, you have been posting numerous brake issues instead of keeping it in one Lo-o-o-o-ng thread. Help us out here help you. List what you have replaced. Give part numbers. Post a pic of your glove compartment door decal showing your brake codes. Could be a mismatch on master/wheel cylinder sizes. Brakes arent that bad with the right parts. Discount and AZ sometimes Irish create there own problems, but you/us have to solve them.

 

[Larryjb]

I wonder if air got introduced into the master cylinder between the time you bench bled and installed it. This air would then be trapped in the master cylinder and would never come out with bleeding at the wheels. You could try bleeding the lines at the master cylinder while it is on the truck.

 

[JonnyTahoe]

I had a similar issue with my 95 years ago. Had not done any brake work in years and had to learn proper bleeding all over again.

 

[96-2D-Hoe]

Thanks for the replies and suggestions.

RPO for brakes is JB5

Brake pedal was reasonable but rear brakes had issues. I recently changed everything on the rear with Delco. While doing that I accidentally let air in the MC. The fluid in the reservoir had some greenish crap in it which was a sign of seals leaking. So because it also had air in it I decided to change the MC.
I've had issues with the MC's and I've screwed a couple up.
But that's basically where I am now.

Front pads and rotors were changed a few years back with cheap auto store crap. Rotors have hardly any wear, the worst pad out of 4 had at least 1/2 left.

MC and brake booster are not leaking. Pedal doesn't continue to travel and brakes will stop the truck.

I went through this a few years ago and had the same issue. I bought a Tech2 basically to do the ABS bleed as driving to loose ground setting it off, driving home and bleeding multiple times does work but it's a huge PIA and I hoped the Tech2 would mean I didn't have to do that again. I also bought a Motive kit hoping it might help flush more air out than regular bleeding.

Apart from adjusting the rears up a little more I'm 99% certain everything is as it should be. I inspected the fronts last week, and the rears a couple hundred miles after they were installed, just a couple weeks ago.

I don't think I'll do it today, but I will try setting off the ABS and bleeding again to see if there is any improvement. Seems to be the only option I have at this point unless anyone knows better.

 

[96-2D-Hoe]

I've just put a different MC on and 1/2 gallon fluid through it and I don't think it's much if any different than before I started today.

I only felt the pedal last night, but I now just drove the truck and there was some improvement. Still a lot of spongy travel but less force on the pedal to actually stop and a firmer resistance at that point. I'll adjust the rear up first and then I'll set the ABS off and bleed again.