Brake pedal still spongy

[OREGON85]

I just swapped a bunch of brake parts, calipers, rotors, lines, etc. My pedal was spongy before, but now it is really bad. I bled the brakes well and I can’t get any more air. If the engine is off it is just okay, but with the engine running the pedal goes right to the floor. What do a need to look at next?

 

[COS80]

Pressure bleed

 

[mrsleeve]

Pressure bleed

This is about the only way your going to get it

 

[ikarus]

Did you bleed the lspv?

 

[OREGON85]

Did you bleed the lspv?

Yes

 

[robnicko]

have you confirmed the gap between the Booster pin and MCyl is in spec and not too great a gap?

Also, you may want to try having a broomstick or something maintain pressure on the pedal overnight (take out brake light fuse) as it will hold the MCyl open allowing air to travel back up to and escape at the MCyl. Will only work on non ABS vehicles though
This is a trick done on motorbikes, especially the front brakes and does work.

 

[BILT4ME]

I just swapped a bunch of brake parts, calipers, rotors, lines, etc. My pedal was spongy before, but now it is really bad. I bled the brakes well and I can’t get any more air. If the engine is off it is just okay, but with the engine running the pedal goes right to the floor. What do a need to look at next?

What order did you do the bleeding?

LSPV
RR
LR
FR
FL
LSPV

I have found bleeding the LSPV a couple times helps.

Do you have any obvious leaks anywhere?

I also started out by letting the RR gravity bleed for a couple hours while I worked on other stuff. Just crack open the bleeder with a hose and let it drip into a pan. Made it go faster for the rest of it.

 

[OREGON85]

I tried three different orders:

RR, LR, LSPV, RF, LF
RR, LR, RF, LF, LSVP
LSVP, RR, LR, RF, LF

No bubbles at all and still spongy.

When I put my foot on the pedal it engages where expected then slowly sinks to the floor. No bubbles and no signs of any leaks. I’m stumped. Maybe the master cylinder is leaking internally?

 

[COS80]

When I put my foot on the pedal it engages where expected then slowly sinks to the floor. No bubbles and no signs of any leaks. I’m stumped. Maybe the master cylinder is leaking internally?

That's the tell-tale sign of a bad MC.

 

[Trail Teq]

Did you let your master cylinder run dry during all of this? If so it will need bleeding. Even if you didn't, take it off and bleed it so you can be absolutely certain there is no air in it. Don't attempt to bleed it on the car.

Remove the master cylinder and bench bleed it. Use one of the kits that feeds the outlet ports back into the reservoir with clear hoses. Pump until no more bubbles or air are in the hoses.

Reinstall master cylinder making sure not to press the piston.

Now bleed as per FSM: Passenger rear, driver rear, passenger front, driver front, LSPV last.

You need to do the LSPV last. If you follow the brake lines under the car you'll see why, that's why they put it in the FSM to do it last. Don't do it mid-way because it's between the front and rear it will just be a headache. Just speaking from experience having done this dozens and dozens of time.

When bleeding at the calipers/LSPV, have a second person help you. Attach a clear tube to nipple, and feed it into a bottle of brake fluid so the tube is submerged.

Have the person in the car pump the brake pedal 2-3 times until firm, then ask them to hold the brake pedal down as hard as they can. With the pedal held down, you under the car should now crack the bleeder nipple. Only crack it a quarter - half a turn, and only for as brief a time as possible. Crack it, then immediately tighten again. When you crack it, you will see bubbles shoot out of the nipple into the clear hose, immediately close the nipple again. When cracked, the pedal in the car will also drop to the floor, make sure your helper does not let that pedal rise AT ALL. Even the slightest rise in the pedal will suck in air again.

Repeat the above process until you get no more air bubbles come out of the caliper/LSPV you are working on. THen repeat it another 5-10 times for good measure. Then move onto the next bleeder in the order. When doing the LSPV last, it will likely take you longer. You can also undo the adjustment arm and pivot the LSPV to maximum/minimum height in order to assist with bleeding.

Having bled 80 series brakes countless times, the above method is the only method that has worked 100% of the time for me.

 

[fjbj40]

In my experience after bleeding the system take it to a gravel rd and apply the brakes to engage abs system several times.
Then bleed system again.

 

[WESBC]

You can activate the ABS following directions in the thread below.

Is there a way to trigger ABS actuator to combat spongy breakes?

Truck info: 1994 LC with ABS So after some brake work (Caliper replacement with pads) I had spongy brakes. Wasted good amount of brake fluid trying to bleed them. I suspected that Air was trapped in ABS actuator but short of buying the SST tool or driving on Ice I did not see a way to trigger...

forum.ih8mud.com

Did the same thing as you thinking it would get better, pressure bleed and activating the ABS did the trick for me. I also had a new MC and booster and still felt spongey until I activated the ABS.

 

[OREGON85]

Can I bypass the ABS? I didn’t even install the ring on the axles last time they were out, so I don’t have ABS anyway.

 

[77mustard40]

Can I bypass the ABS? I didn’t even install the ring on the axles last time they were out, so I don’t have ABS anyway.

You can remove it , several threads on that. I deleted my ABS and LSPV and have great brakes after doing so, best free mod I’ve done to my 80.