Spongy and poor brakes fixed (sort of) (1 Viewer)

[landtank]

Well I have some improvement to report. I bought the speed bleeder for my LSPV. When installed it was difficult to install and when I had it tightened down it still passed fluid.

So I cut down a M7x1.0 tap so it could fully chase the treads with out damaging the seat and then the bleeder would seal when tightened.

After this I bled the LSPV and the pedal responded with better height and firmer feeling.

I'm still not completely happy but I had an errand to run and want to bleed the rear brakes as well now.

 

[NKP Garage]

For you guys bleeding brakes. General concensus on any vehicle is the following order:

* Bleed at the master cylinder first. If there's no bleed screw at the MC, simply loosen the fittings that hold the hard lines on that go out of the MC and bleed them.

* Bleed the caliper closest to the MC next. On US cars this will be the front left

* Bleed the caliper opposite to the above next. On US cars this will be the front right

* Then the rear left

* Then the rear right. Then both front's again

This process will get just about any stubborn bubbles out that may be hiding in the lines.

 

[lacruiser]

For you guys bleeding brakes. General concensus on any vehicle is the following order:

* Bleed at the master cylinder first. If there's no bleed screw at the MC, simply loosen the fittings that hold the hard lines on that go out of the MC and bleed them.

X2. this is pretty much like an on-the-car bench bleeding. Will save tons of wasted fluid pushing all that air through the system.

* Bleed the caliper closest to the MC next. On US cars this will be the front left

* Bleed the caliper opposite to the above next. On US cars this will be the front right

* Then the rear left

* Then the rear right. Then both front's again

This process will get just about any stubborn bubbles out that may be hiding in the lines.

Now this is interesting. I've always heard to bleed the farthest from the MC first, then work your way closer.


Another tip. don't shake the brake fluid, tiny bubbles get trapped and will coalesce into larger bubbles in the system. I always bleed again the next day after the truck has been sitting overnight, and I always get a bit more air out of the system.

 

[Ebag333]

For you guys bleeding brakes. General concensus on any vehicle is the following order:

* Bleed at the master cylinder first. If there's no bleed screw at the MC, simply loosen the fittings that hold the hard lines on that go out of the MC and bleed them.

* Bleed the caliper closest to the MC next. On US cars this will be the front left

* Bleed the caliper opposite to the above next. On US cars this will be the front right

* Then the rear left

* Then the rear right. Then both front's again

This process will get just about any stubborn bubbles out that may be hiding in the lines.

You forgot our LSPV.

Here's what the FSM states (for a '97).

2. BLEED MASTER CYLINDER
HINT:
If the master cylinder has been disassembled or if the reservoir
becomes empty, bleed the air from the master cylinder.
(a) Disconnect the brake lines from the master cylinder.
(b) Slowly depress the brake pedal and hold it.
(c) Block off the outlet plugs with your fingers, and release
the brake pedal.
(d) Repeat (b) and (c) 3 or 4 times.

3. CONNECT VINYL TUBE TO BRAKE CALIPER BLEEDER
PLUG
Insert other end of the tube in a half-full container of brake fluid.
NOTICE:
Begin bleeding air from the brake caliper with the longest
hydraulic line.

4. BLEED BRAKE LINE
(a) Slowly depress the brake pedal several times.
(b) While an assistant depresses the pedal, loosen the
bleeder plug until fluid starts to run out. Then tighten the
bleeder plug.
(c) Repeat this procedure until there are no more air bubbles
in the fluid.
Bleeder plug tightening torque:
11 N·m (110 kgf·cm, 8 ft·lbf)

5. REPEAT PROCEDURE FOR EACH WHEEL

6. BLEED LSP & BV

It's interesting that they say to bleed the LSPV last.

 

[RedTacoma]

Biggest issue is when air gets trapped in the ABS actuator. No amount of brake bleeding will solve that unless you force ABS to kick in. Had that on my other vehicle.
I was going to ask, for LC, is there a simple way to trigger ABS ?

 

[NKP Garage]

You forgot our LSPV.

Here's what the FSM states (for a '97).




It's interesting that they say to bleed the LSPV last.

Noob question time. What are they referring to with LSPV and BV?

 

[landtank]

Load Sensing Proportioning Valve, as you add or subtract weight in the back the height difference alters the braking force to the rear brakes.

 

[NKP Garage]

Load Sensing Proportioning Valve, as you add or subtract weight in the back the height difference alters the braking force to the rear brakes.

Gotcha

 

[CreeperSleeper]

One of these days I'm going to rip all of my ABS crap out of my 80...

 

[landtank]

I'll be putting e-locker axles under a 92 in a couple of week's. It will be interesting to see how the pedal feels without the actuator in the system.

 

[hawaiicruz]

I'll put my two cents in. I always start closest to the MC, as its a shorter distance for the bubbles to go, then go to the back and work my way up. I also use a shadetree unpolliticly correct trick an old Volks mechanic taught me. I open the bleeder valve and hold my finger tightly against it, as my assistant slowly pumps the pedal. Fluid gets everywhere, and all over me but my finger stops the air from going back in. when I cant feel anymore air bubbles on my finger, I close the valve and bleed normally( pump,pump, pump, open then close) this trick takes allot of fluid but makes the job go 4 times faster

 

[turbocruiser]

For you guys bleeding brakes. General concensus on any vehicle is the following order:

* Bleed at the master cylinder first. If there's no bleed screw at the MC, simply loosen the fittings that hold the hard lines on that go out of the MC and bleed them.

* Bleed the caliper closest to the MC next. On US cars this will be the front left

* Bleed the caliper opposite to the above next. On US cars this will be the front right

* Then the rear left

* Then the rear right. Then both front's again

This process will get just about any stubborn bubbles out that may be hiding in the lines.

Not to argue too much but this is exactly the opposite of how to bleed the brakes on our 80's. I agree with the MC first if it is required to bleed that but you always go from furthest to closest with the bleeders then lastly the LSPV.

 

[coax]

I think it might have to do with a combination of the LSPV, long bypass line and ABS system.

No one has mentioned this yet, but I think the reason that having the car running helps with bleeding is the ABS system. On many cars with ABS, you have to have hook up a machine to activate the ABS to actually bleed out the air in the various parts of the ABS control box. Other cars, simply turning on the ignition, will give power to the ABS to allow fluid movement through the system better.

Actually running the engine, as opposed to just powering the the ABS with the ignition on, may have no benefit beyond making it easier to push down on the pedel if bleeding with the pedel pump method.

FWIW, a friend of mine had to replace the MC on his unlifted '96 about a month ago, and has been battling weak and spongy breaks since. Full bleed after MC install, no luck. New rotors and pads helped some. Took it to a shop to have them bleed it, and still no improvement.

Hot ticket for his cruiser ended up being what Brian mentioned above. Took it to the stealership and have them use the SST to acutate the ABS while bleeding (or so am told). 170 bucks later the brakes are back to normal feel.

Not sure how much this helps as he was quoted some crazy amount of money in the area of 600 to actually buy the sst (This is all second hand, and I guess assumes that tool 09990-00150 does indeed actuate the abs and isn't just for diagnostics? Makes me wonder as the FSM doesn't mention this tool in the section on bleeding the brakes.)

Corey

 

[Ebag333]

Makes me wonder as the FSM doesn't mention this tool in the section on bleeding the brakes.

Normally you should not need to bleed it.

However, if you have a leaking line, or get lots of air in there and don't bleed it all out, it's feasible for air to get trapped in there.

 

[PHIL O]

for me, everytime i open the MC, i bench bleed it on the car (since our MCs are perfectly level on the brakebooster) making sure that return lines are submerged in fluid while bench bleeding. then connect hardlines. bleed the MC again from the fittings of the hardlines starting with secondary pistons then the primary. then work from farthest caliper going to the nearest. to remove the possibility of air getting drawn back in after cracking bleeders, i do the vinyl hose trick. make sure the hose fits snug on the bleeder then submerge the other end in fluid. in this way, air bubbles are very noticable. even the tiniest of air bubbles could be seen.

 

[NKP Garage]

Not to argue too much but this is exactly the opposite of how to bleed the brakes on our 80's. I agree with the MC first if it is required to bleed that but you always go from furthest to closest with the bleeders then lastly the LSPV.

Why furthest away first? Doesn't logically make sense. It's not going to be any different on the LC than it would be on any other car/truck. I'm curiuos what the reasoning behind furthest first is.

 

[Northernstar]

When you bleed the brakes do you need to put a block under your brake pedal, or can you push it all the way to the floor? I read somewhere about putting a block under your brake pedal so you don't push the MC farther than it was intended and somehow damage it's seals. Since I read that I wondered if not using the block could have contributed to my soft brakes. I too have some dead travel in the pedal at first, but once they start to grab they work great.

 

[RedTacoma]

Why furthest away first? Doesn't logically make sense. It's not going to be any different on the LC than it would be on any other car/truck. I'm curiuos what the reasoning behind furthest first is.

I believe it is due to different type of brake system, thats why FSM recommends doing like that.

 

[turbocruiser]

Why furthest away first? Doesn't logically make sense. It's not going to be any different on the LC than it would be on any other car/truck. I'm curiuos what the reasoning behind furthest first is.

For me the main reasons to do this in this order are 1st - the FSM recommends it in that order and 2nd - almost every vehicle I've owned (only ever owned 4WD or RWD though) recommends this order. Haven't given it much more thought than that however I've always assumed that the thinking is the longest run has the most potential air problems and contamination problems all other things equal, followed by the second longest run etc. I think the LSPV is probably last due to its combined circuitry (as in front circuit/rear circuit) and also due to the location being higher than any other breather. HTH.

 

[lacruiser]

When you bleed the brakes do you need to put a block under your brake pedal, or can you push it all the way to the floor? I read somewhere about putting a block under your brake pedal so you don't push the MC farther than it was intended and somehow damage it's seals. Since I read that I wondered if not using the block could have contributed to my soft brakes. I too have some dead travel in the pedal at first, but once they start to grab they work great.

Yes, a block under the pedal is a good thing. Or be very careful not to push the pedal (during bleeding) further than it normally travels during hard braking.

The reason is there is an area inside the end of the cylinder that never sees the rubber seals, (the plunger with the seals on it never gets pushed down that far) and that area's surface will become dirty over the years. If you push your seals into that area, they will pick up that dirt, and that is never a good thing when you're talking about hydraulics. Pushing the seals into the dirty area will lead to premature failure of the seals.