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

[Brian894X4]

Sorry this post is so long, but I wanted to add these thoughts to the board for anyone else who is having the sames issues I had to hopely help them out......

So, after about 2 years, I finally have the brakes working about as good as they probably ever have. although there is a little caviat, which I'll get too in a second.

When I first got the rig it had extremely spongy brakes with huge amounts of pedal travel. The following are the various things I've tried and their results.

The PO had aftermarket pads put on by Midas not long before I bought it and I was certain the idiots just didn't bleed the brakes properly.

After bleeding the holy hell out of the brakes, using the pedle pump method, there was only a tiny bit of improvement. Took it to a dealer to have them power bleed. It helps a little bit more.

Bled some more at home, it helped a little more. Had a dealer power bleed them again, it helped a little more but still wasn't that great. At this point, I became convinced, after reading numerous posts with same issues that 80s have a major problem with air getting trapped into the system that is extremely hard to get out. So I just figured I would bleed and bleed and bleed till the problem was fixed.

The dealer pulled the master cylinder checked it and then made an adjustment between the master cylinder and booster and that helped a little more.

I then replaced the aftermarket pads on all four rotors with new OEM pads. This, along with yet another home bleed, but using a new power bleeder, made yet more improvement, but still not completely up to par. But at this point, I figured it was everything I could do for the moment.

The dealer mechanic suggested that I had aftermarket calipers and they might be affecting the braking performance with what he described at larger passage ways in the calipers. I eventually replaced the calipers with OEM remans. No significant change. I also noted that there was very little difference between the "aftermarket" calipers and my reman units, which led me to believe in fact the units I took off were probably also Toyota reman units that were only a few years old....Doh!

I did bleed the system thoroughly and that helped a little bit more. Overall, spongy brakes were much improved, but pedel travel before any braking still seemed to be excessive, so I then adjusted the pedle dead spot to within spec and that improved pedle feel a bit.

At this point, pedel travel was OK, but not perfect, spongyness was improved a lot from when I bought it, but still appeared to be more than normal. But then I noticed a degrading of brake performance. Especially in panic stopping. I had adjusted the LSVP valve to compensate for my 2.5" lift about a year earlier.

To make a long story short, my LSVP valve appears to have gotten bent at some point and was causing very poor brake performance in it's current location. I tested numerous valve adjustment and found that moving the rod either too high or too lower seemed to severely restriction front braking, which still seems odd, but that's what happened. In the end, having the valve (remember it's probably bent) in the stock location on my 2.5" lifted rig seems to give the best front/rear bias. Brake feel improved a little bit more. Panic stop performance improved a lot. As a note here, the LSVP is original has not been replaced yet.

Finally, the latest chapter. I just added new OEM rotors to replace the aftermarket rotors, which were getting a bit thin and were warped and another set of OEM 80 series pads (the old pads had about 30% left). After bedding the pads in, the brakes feel better overall than they ever have before.

Pedel is firm and braking occures when I expect it too. And it stops right the hell now, when I slam on the brakes. The pedel has "slightly" more overall travel than the average car, but some indicate this normal. Pedel "feel" is definately better and very good over all. And I get some braking force over almost the entire travel of the pedel, whereas before, there a lot of travel, but a huge dead spot.

But all is not rosey. I have another issue that has cropped up. During panic stop testing, I've noticed that ABS doesn't "appear" to be kicking in. In fact, the rear will fishtail a little at the upper end of the panic stop, which indicates it may not be anti-locking, plus there's no pedel pulsing like there used to be when anti-locked used to kick in. So, not sure what's going on here. I haven't opened up the rear brakes since I replaced the rear pads more than a year ago, so it could be one side is a getting a little grabbier than the other.

 

[Brian894X4]

The brakes on these rigs were more than adequate when were stock, with road tested performance that matches or exceeds the 100 series, when both rigs were new and even with me pushing just over GVW, brake performance is VERY good now with all these fixes, so I think the problem is not inadequate brakes from the factory, but rather how the brakes are maintained.

I don't think any one single fix solved the problelm, but rather almost every step helped a little bit. But in the end, I think the two biggest factors were bleeding the brakes over and over again, plus a combination of brand new OEM pads and rotors.

My theory is that is the long pipes, plus probably the extra bypass pipe and combination of ABS system traps air that is very hard to bleed out of the system. I also believe there's a possibility that thin rotors and thin pads contribute to the length of pedel travel and sponginess as the pistons have longer to travel to achieve the same braking force relative to the pedel position.

This is an issue on all cars and some manufactures recommend adjusting the pedle or master cyclinder to compensate for pads wearing down. Most pads last 40-60K miles or even longer, but on the 80 pads and rotors go really quick, probably because of the excessive weight compared to the size of the brakes, so pedal feel is going to degrade quickly, like within 15K and thus be more noticable. Add the fact that pads are replaced more often, that gives a lot more oppertunity for air to get into the system than on a rig that might only be cracked open once or twice every 100K miles.

I did notice that the brake fluid in the rear brakes during this last bleed was darker than the fluid in the rest of system. I'm guessing that may be because when the LSVP got out of whack, the rear brakes were doing a lot more work than normal.

 

[turbocruiser]

Cool posts thanks for that. Am I understanding right that you are still locking up the rear end on sudden stops?

 

[landtank]

I've been fighting spongy brakes for a while and did a front axle job on a truck this weekend. Part of the work included swapping out the calipers and yes the brakes got real spongy afterwards. Well after bleeding and trying a method the other guy likes we actually got the pedal up to where I think it should be and nice and firm. We are going to try my truck next weekend and if this works on that thing I'll post back.

 

[turbocruiser]

I've been fighting spongy brakes for a while and did a front axle job on a truck this weekend. Part of the work included swapping out the calipers and yes the brakes got real spongy afterwards. Well after bleeding and trying a method the other guy likes we actually got the pedal up to where I think it should be and nice and firm. We are going to try my truck next weekend and if this works on that thing I'll post back.

Ahh come on don't make us wait for what you did! One thing that I've learned, and some people probably think I'm crazy saying this cause this shouldn't matter much technically, is to bleed the brakes with the engine running. I also always have the pumper (usually my wife) push the pedal three times to prime it, hold it hard while I open the bleeder and close it right before pedal bottoms. We repeat this over and over at all points till that point comes out clear and without even the tiniest of bubbles. For some strange reason this makes a major difference on my cruiser. HTH.

 

[Ebag333]

Ahh come on don't make us wait for what you did! One thing that I've learned, and some people probably think I'm crazy saying this cause this shouldn't matter much technically, is to bleed the brakes with the engine running. I also always have the pumper (usually my wife) push the pedal three times to prime it, hold it hard while I open the bleeder and close it right before pedal bottoms. We repeat this over and over at all points till that point comes out clear and without even the tiniest of bubbles. For some strange reason this makes a major difference on my cruiser. HTH.

I think running the engine moves more fluid, and makes the pumper's job much easier.

The other thing I do is keep the bleeder screw closed enough to maintain pressure in the system. If the fluid is getting sucked back in, then it's too far open and there's not enough pressure. For some strange reason, this makes a major difference on my cruiser. HTH.

 

[NKP Garage]

* Speed bleeders are a great addition to ANY car if you don't have them already

* Air in the lines is usually the #1 culprit of spongy brakes, after that it is usually worn/glazed rotors and worn and/or cheap pads

* Flushing your fluid and replacing with synthetic also helps to get that last little bit of performance from them as the synthetic fluid is more resistant to heat and will perform just a tad better

* Check vacuum hoses going to the brake booster

 

[Truckasaurus]

I agree with flushing the brakes. Synthetic is nice, of course, but just fresh fluid can show improvement. Another area to note with our 12-17 year old vehicles is that the rubber brake hoses may have bulges, which means weak points which expand under pressure, and that pressure isn't getting to the pistons in the calipers.

Keep posting up good information, B4x4.

 

[UCBerzerkeley]

Has anyone tried the Slee Rotors by Powerstop? They are aftermarket, but tote improvement. OEM anything hasn't failed me yet, but I'm not expert

 

[landtank]

well,I have a speed bleeder for my LSPV coming in. The one in there is trashed and Toyota doesn't sell them as far as I can tell. I'm thinking everyone's issue is with that thing, we'll see.

 

[FirstToy]

here are the sizes for speedbleeders
https://forum.ih8mud.com/80-series-tech/165192-speed-bleeder-lspv-size.html

 

[turbocruiser]

I think running the engine moves more fluid, and makes the pumper's job much easier.

The other thing I do is keep the bleeder screw closed enough to maintain pressure in the system. If the fluid is getting sucked back in, then it's too far open and there's not enough pressure. For some strange reason, this makes a major difference on my cruiser. HTH.

Exactly.

I agree that running the engine moves more fluid and makes the pumper's job easier but I suspect there's something more to it than just that; I think either the higher pressure or higher volume helps "clears" entrapped air in areas throughout the system more effectively and efficiently.

I also absolutely agree that the bleeder screws should get completely closed on each cycle, I've never done that any other way on any vehicle; I'd think the air bubbles would get sucked in somewhat if the screws were left open as the pumper pumped the pedal ... plus any old fluid from the previous purgings could get sucked in too. If that is a shortcut I've somehow never heard of it. Additionally, without the screws getting completely closed you can't "multi-pump" the pedal prior to opening the screws. What I'm talking about here is having the pumper pump the pedal three times from top to bottom, holding hard at bottom, then opening the screw to let the fluid out, then completely closing the screw prior to the pedal bottoming out all the way. My theory here is that the combination of engine on and "pedal primed" is what really forces all the air out relatively rapidly. HTH.

 

[Bjordnolf]

For what its worth I had a dramatic improvement in my brakes when I put on all new Slee brakelines but I would but the same would be true for new oem. Also got a bunch of speedbleeders and only 2 out of 5 worked. If you havent put new lines on that may be all your truck needs to get it feeling how you want.
thanks

 

[Brian894X4]

well,I have a speed bleeder for my LSPV coming in. The one in there is trashed and Toyota doesn't sell them as far as I can tell. I'm thinking everyone's issue is with that thing, we'll see.

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.

As far as Slee's rotors, I think the 80 rotors get a far harder workout that we give them credit for. There's a reason these pads only last 15-20K miles when others can last twice as long. It's not because the Toyota pads suck. It's because the rotors are working extremely hard to stop the vehicle. The 80 brakes are not inadequate, but unlike many brakes are probably working at the upper engine of their design limits far more often. Also, a lot 80 owners drive up and down hilly roads and steep grades, that can really chew up brakes and test their limits. With this in mind I think slotted and/or cross drilled rotors would be a real benefit to the 80 just to keep the brakes cooler and help them last longer.

The only reason I didn't go with Slee rotors this time around is that I needed them right now and with OEM rotors, I at least know they will work with Toyota's baseline engineering standard for the 80.

 

[NKP Garage]

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

Also has to do with the brake booster helping when the engine is running. It doesn't hold any brake fluid, but it definitely helps to pump more effectively when there is vacuum present during idle.

 

[Ebag333]

I also absolutely agree that the bleeder screws should get completely closed on each cycle, I've never done that any other way on any vehicle; I'd think the air bubbles would get sucked in somewhat if the screws were left open as the pumper pumped the pedal ... plus any old fluid from the previous purgings could get sucked in too. If that is a shortcut I've somehow never heard of it. Additionally, without the screws getting completely closed you can't "multi-pump" the pedal prior to opening the screws. What I'm talking about here is having the pumper pump the pedal three times from top to bottom, holding hard at bottom, then opening the screw to let the fluid out, then completely closing the screw prior to the pedal bottoming out all the way. My theory here is that the combination of engine on and "pedal primed" is what really forces all the air out relatively rapidly. HTH.

I think you misunderstand a bit.

I do not completely close the bleeder screws....in fact once I have them set I don't adjust them at all.

I don't know the exact figure I use, but if 0% was totally closed and 100% was totally open I set them to about 20%. Because they're mostly closed, when you pump the pedal (even with the engine off) it generates more pressure in the system than can quickly escape through the bleeder. As long as you don't let it sit too long between pumps, you can sit there and do nothing other than watch the brake fluid ooze out.

Because you can (quite easily) generate more pressure than is being released, you can keep the system at or near max pressure with the bleeder cracked.

You will know that the bleeder is too far open if you (or your helper) let up the pedal and you see the fluid move backwards. If you let up the pedal and it keeps moving in the same direction, you're set.

This makes it very easy to bleed by yourself if you don't have a helper. It's also much faster than the "okay, now down....wait....pump three times.....ok, wait.....no, stop.....okay, pump...." method.

If you do have a helper they can pump away to their hearts content and it won't cause any problems if they pump too soon or too late.

It's similar to the pressure bleeding, where the master cylinder is pressurized to push fluid through, and you simply crack a bleeder open and watch it drain out. Except instead of using an external pressure source, you're using the vehicle itself to keep the system pressurized.

Clear as 'MUD?

 

[IdahoDoug]

I don't fully understand how this works with the bleeder mostly closed and no helper. If you're not pressing on the pedal, the system pressure is zero. Also if you're laying under the truck watching fluid drip out, then the fluid is moving so slow it will not push a bubble along the brake line and out. The bubble(s) will get into the caliper and sit there if there's a cavity for the pistons that's higher than the bleeder. Or somewhere else in the line.

To me, the best way to bleed brakes is to get maximum flow rate. I achieve this by having the helper pushing on the brake pedal before I crack the bleeder, then I shut the bleeder before the brake pedal hits bottom. I repeat this as fast as my helper can keep up with my "Up" and "Down" commands. Max flow moves bubbles along the best. As many of you know I have awesome brakes on my cruisers and now that I see the different ways folks are 'bleeding' I understand how some are perhaps not getting all the air out after replacing components. Ebag, I'm not saying to change anything here. This is working for your vehicle and it's likely because yours has never had air introduced into its system that needs purging. Mine's the same way since I've done its bleeds since it was new.

Just another data point.

DougM

 

[Ebag333]

I don't fully understand how this works with the bleeder mostly closed and no helper. If you're not pressing on the pedal, the system pressure is zero. Also if you're laying under the truck watching fluid drip out, then the fluid is moving so slow it will not push a bubble along the brake line and out. The bubble(s) will get into the caliper and sit there if there's a cavity for the pistons that's higher than the bleeder. Or somewhere else in the line.

I know it seems counter-intuitive, but it works.

Let me see if I can explain it in a different fashion....

Lets say that with the bleeder wide open you get 10 PSI of pressure (made up number) when you press the pedal down, and -10 PSI of pressure when you let it up. This means that if you keep the bleeder open, you won't get anywhere because it'll suck up what it spits out. Hence the need to close the bleeder between pumps.

Now lets say that with the bleeder closed you can achieve 100 PSI maximum. Once you hit 100 PSI any more pumps are a waste, it just can't get to more than that.

So lets use my method, and crack the bleeder slightly open, to the tune of where it will bleed 1 PSI per second. If each pump adds 10 PSI of pressure, this means that you are adding more pressure to the system than it's letting out, which means you can still (easily) achieve the maximum pressure. Because the system is pressurized (9 PSI the first pump, more each subsequent pump) you will be pulling fluid from where it can easily come from, which is the master cylinder/reservoir, not the cracked open bleeder. If you're bleeding at a rate of 1 PSI per second, it would take you 100 seconds to go from 100 PSI to 0 PSI--giving you plenty of time to hop out an check it periodically.

Now my theory is that it works somewhat similar to soda. While soda is carbonated, it should in theory be chock full of air. But soda bottles come pressurized, and even the relatively small amount of pressure in the bottle will prevent air from forming.

By keeping the system at higher pressures (which the opening/closing method has a much harder time of doing) it's not so much that air will form as that air will be less likely to move back up the brake lines. A system under pressure is less likely to have any movement in it, be it the brake fluid or air.

The trick is to open the bleeder enough to get air out, but not so much that you lose pressure. I've found that while brake fluid moves slower, you get the air out more quickly and use less fluid. YMMV.

Ebag, I'm not saying to change anything here. This is working for your vehicle and it's likely because yours has never had air introduced into its system that needs purging. Mine's the same way since I've done its bleeds since it was new.

Oh if only that was true. I've royally screwed up my system. I've introduced air into the master cylinder (that was fun to get out, took two large bottles), had to replace the rear calipers due to a broken aftermarket pad (which destroyed a piston and rotor, had to use about half a small bottle of fluid to keep the master cylinder topped off on the 5 hour car ride home), and let plenty of air into the lines while changing pads.

As I've said before, the truck will stop on a dime, and mine does surprisingly well given the lift/armor/tires/etc. I've had to test panic stops in both (hers on the freeway when a small sedan slammed on its brakes in front of us, and mine on a very steep downgrade....with a 3k lb boat behind me).

I'd take either of our trucks for stopping over my folks F150, and hers over just about any sedan I've driven. Both vehicles are currently completely OEM (for brakes). I hope to upgrade mine to the 100 series pads soon, and will probably upgrade hers to 100 series pads when we do a front end job (hopefully in 10k-30k).

 

[lacruiser]

Has anyone tried the Slee Rotors by Powerstop? They are aftermarket, but tote improvement. OEM anything hasn't failed me yet, but I'm not expert

My 91 has rear drums, and the fronts are upgraded to the 93-97 larger rotor/calipers, and I also run the 100 series pads.

I bought the powerstop rotors directly from powerstop, along with a set of their Z36 Pads. I also bought all the latest braided brake lines from Slee, so I have no more rubber lines.

Doing all this made a HUGE night-and-day difference in my braking. This truck had a problem stopping before, and now its the best it's ever been since I bought it in 2002. The pedal is nice and firm, and the brakes come on strong as soon as the pedal resistance is reached.

 

[turbocruiser]

Not saying it won't work, just that in my mind you want to achieve maximum pressure and maximum volume. You can't do that with the bleeders even partially open. Again, it might work well enough, its just counter-intuitive to me.