Why do my brakes suck?

[agent orange]

Ok, heres the deal. Ive been throwing time and money at my brakes for a while now and im still not satisfied. Lemme give a little rundown of the parts im working with and what ive done so far. Ive got a new T-100 MC, 4runner calipers, new shoes out back with matching new wheel cylinders, and new stainless brake lines. Im pretty sure my booster is fine, the pedal rises as you pump it with the engine off like its supposed to.

My problem is i have a really s***ty brake pedal. The first inch or inch and half of pedal travel takes almost no effort at all, with the pressure building nicely on the last inch or so. I can push the pedal all the way to the floor, and i know i shouldnt be able too. Ive bled the MC twice with 2 different methods, ive run about a gallon of fluid through the bitch, and im pretty sure the drums are adjusted right. I didnt adjust them until tight and back off like the FSM said, i only used the ebrake, but i spun the drums to check them out and i could hear them drag most of the way around, and they definiitly got tight on a couple spots. I need to adjust the ebrake cable (it takes like 11-12 clicks to set), but if the shoes were any tighter i dont think it would spin.

So, what else should i do. I dont need to adjust the brake pedal itself, as ive got only about 1/4 inch of travel till the pushrod engages the booster, but is there an adjustment to set the distance between the MC and the booster? Do i need to set the shoes per the FSM to get them to be right? Do i adjust with the wheels on or off?

Sorry for the novel guys, i just didnt know how to make this short.

 

[90FJ62]

I would start with bleeding the brakes if it has not been done recently. Next I would adjust the rear brakes. use the FSM for this but basically jack up the back and adjust till the wheels dont spin with the tires on and then back off 5 clicks. I think (sorry dont have FSM with me right now.) See if that helps

David

 

[lonelydriver]

i'm exactly in the same situation as you agentorange. upgraded to 4runner caliper/master cylinder. I've adjusted rear flushed the master and lines couple of times and still the pedal gets stiff near the end of the travel and then hits the floor.....
its driving me

 

[agent orange]

Well, driver, hopefully someone will chime in because i too am losing my mind (more rapidly than usual). I gotta get this fixed though, its scary to attempt steep obstacles knowing that if i cant make it anyone behind me better look out! All i can think of is that perhaps there is an adjustment i need to make to get the booster to engage the MC right. What really pisses me off is before i put in my residual valve, i got good pressure once i pumped it twice. Now i get pressure to the rears right away, but never really get good pressure built up.

 

[roscoFJ73]

Well, driver, hopefully someone will chime in because i too am losing my mind (more rapidly than usual). I gotta get this fixed though, its scary to attempt steep obstacles knowing that if i cant make it anyone behind me better look out! All i can think of is that perhaps there is an adjustment i need to make to get the booster to engage the MC right. What really pisses me off is before i put in my residual valve, i got good pressure once i pumped it twice. Now i get pressure to the rears right away, but never really get good pressure built up.

I adjust my rears until they are just scraping and back off just enough to stop them scraping THEN adjust the handbrake.

There is some adjustment between the brake pedal lever and MC.
Be careful what you do there,consult the FSM

 

[Jan-78FJ40]

Hi Agent,

adjucting the rears with the handbrake is not an efficient way. many trucks don't have the automatic adjusters at all. so you need to adjust them by hand, with the little wheel, as described in the FSM. then the hand brake.
second, do you know if the push rod of the booster is touching the push cylinder of the master? if not, there is the travel distance.
third, did you bleed the LSVP as well? if not, start there, it likes to trap air.
finally, are your wheel bearings tight?
j

 

[Chase77]

I wish someone had an easy answer to this. I've also done the 4Rnr upgrade and my breaks still suck. I've bled 3 times now and would take it to a shop but dont know what they're gonna be able to do that I cant. Im beginning to wonder if the only solution would be disks in the rear......

 

[agent orange]

Hi Agent,

adjucting the rears with the handbrake is not an efficient way. many trucks don't have the automatic adjusters at all. so you need to adjust them by hand, with the little wheel, as described in the FSM. then the hand brake.
second, do you know if the push rod of the booster is touching the push cylinder of the master? if not, there is the travel distance.
third, did you bleed the LSVP as well? if not, start there, it likes to trap air.
finally, are your wheel bearings tight?
j



Ok, i guess i need to readjust the drums, they arent far off though, i know that for sure. I dont know if the pushrod of the booster is contacting the MC, thats what im currently thinking may be the problem. The only thing is, when the engine isnt running the pedal is very stiff and does not have the play in it that it does with the engine running. How would i go about adjusting that distance if i determine there is travel there? I have bled the lspv as well as all 4 corners very thouroughly. I have no idea how tight my bearings are, how would that affect the braking? Thanks for the ideas everybody.

 

[sk8salomon]

this might sound stupid, but i had similar issues and found the front brake line (driver's side) crushed like a pancake near the axle. of course, i found this after new pads, system flushed twice, and lots of cussing.

 

[Jan-78FJ40]

Ok, i guess i need to readjust the drums, they arent far off though, i know that for sure. I dont know if the pushrod of the booster is contacting the MC, thats what im currently thinking may be the problem. The only thing is, when the engine isnt running the pedal is very stiff and does not have the play in it that it does with the engine running. How would i go about adjusting that distance if i determine there is travel there? I have bled the lspv as well as all 4 corners very thouroughly. I have no idea how tight my bearings are, how would that affect the braking? Thanks for the ideas everybody.

To adjust the pushrod you have to take the brake master off, and then you can pull the pushrod out of the booster. It has a washer on the front that is adjustable.
I asked about the wheel bearings, since loose wheel bearings will cause the wheel to be a bit loose, and movement pushes the brake pads apart. Consequently you have a lot of pedal travel until they are tight again.

what happens when you press the pedal with the truck off, and then start it up (while maintaining pressure)? does the pedal sink far?
j

 

[GZERO]

did you bench bleed the MC?

 

[Toadhopper]

I noticed a couple of you guys (Chase 77 and Agent Orange) who posted problems had the 4runner calipers and a 62....did you bleed the LSPV?

 

[agent orange]

Ok, update. I went out and pressed the pedal down with the engine off and when i started the motor the pedal dropped about an inch. I noticed that after the pedal engages the booster its really easy for about an inch and then it gets rock hard. I think that i need to adjust my booster pushrod. Thanks for the help Jan78, i hate to have to take off the MC again and rebleed but i imagine its the only way to get to the booster pushrod right (aka i cant just let it droop out of the way with the lines on it)?

Oh, and to the people who raised the bleeding issues, like i said ive been bleeding all four corners and the LSPV for about a month with no change, and ive bleed the MC twice with different methods in addition to bench bleeding when i first installed it.

 

[chicago]

Hey Agentorange,
I have the same problem as you. Stock calipers, I replaced the MC with bench bleed, new shoes front and rear, rear adjustment with the wheel off (spun till it siezed backed off till it was barely scraping) bled the system including the LSPV THREE TIMES, ran the booster test, and it came out fine and now Im on the same page as you...thinking it might be the gap between the push rod and MC.
If I touch my rig again before I get married in June the little womans gonna kill me , so Im looking forward to hearing about how yours comes out.

Chicago

 

[Jan-78FJ40]

Ok, update. I went out and pressed the pedal down with the engine off and when i started the motor the pedal dropped about an inch. I noticed that after the pedal engages the booster its really easy for about an inch and then it gets rock hard. I think that i need to adjust my booster pushrod. Thanks for the help Jan78, i hate to have to take off the MC again and rebleed but i imagine its the only way to get to the booster pushrod right (aka i cant just let it droop out of the way with the lines on it)?

Oh, and to the people who raised the bleeding issues, like i said ive been bleeding all four corners and the LSPV for about a month with no change, and ive bleed the MC twice with different methods in addition to bench bleeding when i first installed it.

You might get away without disconnecting the lines from the master. On my truck the LSVP is is right below the master, bolted there with the same washers that hold the master to the booster. If you take the 4 washers off, the master can be moved forward a bit, to get away from the studs on the booster. Like this I can pull the push rod without having to re-bleed.
Be careful to not adjust the rod too long, otherwise the brakes will drag. I think the manual says that anything from none to 1mm distance between rod and the inner surface of the master where it touches is fine.

jan

 

[agent orange]

I fixed them! I adjusted the drums until they were stuck, and then backed it off until i could turn them, and then kept tightening until it had a good bit of drag to it but i can still turn it 360 deg without it hanging up. I can feel the brakes (especially the drums) start to build pressure right away as soon as i get on the pedal. It turns out that for whatever reason my booster is strong enough that sitting at idle i can get the pedal to bottom out if i really pump on it, but the brakes still work great. Even with the LSPV raised as high in its bracket as it will go i cant get the tires to lock up, but it really hauls itself down well now. I guess that has something to do with my wheel/tire combo weighing 100 lbs. I did check the booster pushrod play today and it was just fine. So, as i stand now, im happy, and considering its only been bled once since the system was cracked open it can only get better from here. Thanks a lot for all the help everybody, and to those who have a similar problem, try getting the drums nice and snug, it (mostly) fixed my problems. Now i can finally devote some time to getting the rest of my rig the way i want it.

Matt

 

[lonelydriver]

so orange, is your pedal still bottoming out?

also when u checked the pushrod on the m/c did u have to disconnect the lines or were u able to do it with the lines still connected. Thinking bout workin on the rig tonight.

-Kevin

 

[agent orange]

so orange, is your pedal still bottoming out?

also when u checked the pushrod on the m/c did u have to disconnect the lines or were u able to do it with the lines still connected. Thinking bout workin on the rig tonight.

-Kevin

Yes, the pedal still bottoms out when i try and bottom it out with the truck parked, but i build sufficient pressure to really haul it down with only moderate pedal travel now. Its odd, but when im parked it seems like the brakes are gonna be mush because it just goes to the floor without much effort, but as soon as i actually try and brake its rock hard.

I did have to disconnect the rearmost brake line, i put a brass plug in that hole and then loosened the front line so that i could rotate the MC down and away. I would say youd be hard pressed to get to the pushrod without taking off at least one line.

 

[dd113]

Rear brakes are all the issue with 60 pedal travel. Witht the 4 s***ter calipers you need the larger MC which is sounds like you have but the 80 series pre ABS might be better. Sounds like piston and cylinder dont match.

 

[agent orange]

Rear brakes are all the issue with 60 pedal travel. Witht the 4 s***ter calipers you need the larger MC which is sounds like you have but the 80 series pre ABS might be better. Sounds like piston and cylinder dont match.

Ive got a 1 1/16 T-100 MC, which is probably a touch big for the application but i bought it figuring it would be more suitable if i ever chose to do rear disks. Do you think that too much MC bore would make me have plenty of braking power but still allow me to bounce the pedal all the way to floor at rest?

I had no idea what a huge difference having the drums adjusted right would make, its friggin awesome, its like having a new truck almost.