80 series brakes

[Electric80]

Having troubles getting decent braking after rotor /pad/caliper and hose replacements. Have bled brakes multiple times , pressure bleed, suction, and foot pump. Fluid appears to be clear without any air bubbles. Can not get enough pedal to activate ABS and braking is very poor. Pedal slowly goes to floor with truck running. Any help or advice would be greatly appreciated.

 

[pappy]

Master cylinder?

 

[lurch]

Brake Booster?

 

[LX450JC]

Try bleeding the braking proportioning valve above the rear axle

 

[REKCUT]

Three shots in the dark for you there. Could be any of these but some are easier than others. From your post it sounds like its a bleeding issue as i don't see the booster or master cylinder going bad if it was good before your replaced brake lines and then bad after. The abs system can be very difficult to bleed and a lot of folks, myself included, will delete that item. Very inexpensive and can be done with toyota parts as I guessing that many 80s if other parts of the world did not have abs. I was not going to delete a normal working abs system but when mine started acting up I wasn't going to spend a bunch of money fixing it.

 

[alia176]

Just a WAG here but check to see if your vac booster is actually holding vac by removing the hose from the front of it and sticking a manual vac pump on it. That shiny nipple thing directly in front of the vac canister is a check valve and make sure it is in fact working one way. They don't go bad frequently but things do age and lose their effectiveness. That rubber grommet in the pic can get brittle over time and introduce air into the booster.

If the booster not holding vac, there is a tiny pin hole leak in your vac booster diaphragm. If you need to replace it, search the 80 section for a less costly replacement option.

here's what it looks like from here: 80 Series 1FZ Brake Vacuum kit - https://absolute-wits-end.com/80-series-1fz-brake-vacuum-kit/

@Electric80You appear to be new here! Did you introduce yourself previously? If so, I'm not able to place you! Would you please update your location and the signature line with your vehicle info, mods, etc? It'll help people diagnose your ride better. Just as another data point, I was never able to activate ABS on dry pavement but I have larger tires.

 

[Electric80]

Thank you, I will try these out. Proportioning valve has been bled several times along with all 4 wheels. I ordered a new booster hose as the one on it is pretty dry and cracked on ends. Check valve appears to be operating correctly, only allows vacuum but ordered new valve and grommet as well. Appears to be at about 15 on vac from engine side. Not sure if I should be able to hold vac on the booster inlet, can not seem to get any with hand bleeder pump. Jumped abs solenoids to hopefully bleed any possible air from abs but need to get some more fluid to continue bleeding attempts.

 

[alia176]

Thank you, I will try these out. Proportioning valve has been bled several times along with all 4 wheels. I ordered a new booster hose as the one on it is pretty dry and cracked on ends. Check valve appears to be operating correctly, only allows vacuum but ordered new valve and grommet as well. Appears to be at about 15 on vac from engine side. Not sure if I should be able to hold vac on the booster inlet, can not seem to get any with hand bleeder pump. Jumped abs solenoids to hopefully bleed any possible air from abs but need to get some more fluid to continue bleeding attempts.

Sounds like you've been busy with your troubleshooting, nice job! The booster should hold vac but it'll take a while to suck all the air out of it using a manual vac pump.

We can get our 80s together and do a side by side comparo to see what might be the issue with yours.

 

[Electric80]

Sounds like you've been busy with your troubleshooting, nice job! The booster should hold vac but it'll take a while to suck all the air out of it using a manual vac pump.

We can get our 80s together and do a side by side comparo to see what might be the issue with yours.

Would you happen to know where the correct part numbers are for the booster hose , check valve and grommet? The dealers all show the parts numbers from the wits end list aren't for that vehicle. ( the pics look the same though on the wits end page) also trying to find a good number for the booster to firewall and booster to master gaskets.

 

[alia176]

Sorry bro, i don't have any p/n handy. I typically go here to grab p/ns.

Sure you can't just call up Witt's end and get what you need? Joey does all the hard work for us, usually.

 

[Electric80]

Update.... replaced booster and master with brand new oem parts, booster hose, check valve, brake lines and bled multiple times once again. Also used wiring method found on here to jump ABS while bleeding to hopefully bleed out any other trapped air. Bled master cylinder separately before starting. Brakes still would not grab like they should. Could literally stomp on pedal just in garage and it would still only roll to a stop. Had tried previously engaging on dirt roads to activate abs but did not really grab enough to make a difference. So this morning, thanks to the icy/snowpacked roads I was able to take it out up to around thirty or so and get on the brakes hard enough to actuate the abs multiple times. I did this about 20 to 30 times as well as engaged the center lock a few times to allow it to lock up without the abs. Took it back in the garage and bled them once more with the old fashioned pump and hold method. Didn't seem like any more air came out but fluid was a solid steady flow. Took it back out and brakes are working the best they have since I have owned it. I believe the main help was being able to engage that ABS so many times to possibly free up any air that may have been in there, though unless it came back out the master, not sure where it went.

 

[alia176]

Wow, that perseverance finally paid off! Great job amigo.

 

[Electric80]

I guess just don't open your brake system unless it's the winter and snow is predicted!

 

[alia176]

I guess just don't open your brake system unless it's the winter and snow is predicted!

I am very curious about your username, how did you come up with that? Maybe you have an intro thread and talked about it, sorry if I missed it.

 

[Electric80]

I am very curious about your username, how did you come up with that? Maybe you have an intro thread and talked about it, sorry if I missed it.

Sorry, nothing exciting. I was an electrician, hence the electric, the 80, I honestly have no clue where that came from.

 

[alia176]

Sorry, nothing exciting. I was an electrician, hence the electric, the 80, I honestly have no clue where that came from.

Well, that works amigo . Hope to meet you in person at the next breakfast coming up at Daily Grind.