Wilwood BBK, spongy pedal

[qwikz28]

Guys-

I installed a Wilwood 4 piston setup last Fall and the brakes are now spongy on hard braking. Braking pedal was softer than I hoped, but I could still lock them up. Did an autocross today, and I realized it just won't cut it. I don't know if I just didn't bleed them well enough, or if my MC needs to be bench bled, or my ABS block needs to be cycled during the bleeding process. Either way, I don't know where to start. For what its worth, when I bled the brakes with a Motiv power bleeder, the rear brakes went fine, but the Wilwoods seemed like very little fluid was coming through the screw.

Any help is appreciated, and I'm willing to pay to get them working well. Even a referral to a NNJ shop that could get me there. I hate brakes and I can never get them right.

[MyFirstZ]

Try letting them gravity bleed for a little and then just old fashion pump and hold. That's at least what I do when installing bbks here. They are brembos but shouldn't differ to much

[198esp1]

is the pedal soft on the first application then hard on the second pump
1. flush with a quality race brake fluid
2. check all sliders on all calipers, pad tapper
3. check front wheel bearings/ ask me how i know
4. check rear axles
5. could be a wrong caliper size pistons

[qwikz28]

Try letting them gravity bleed for a little and then just old fashion pump and hold. That's at least what I do when installing bbks here. They are brembos but shouldn't differ to much
I'll try that. Very small amount of fluid was coming out of the fronts, though. Perhaps the Motiv wasn't giving it enough pressure because if i closed the screw, a small burst of fluid would come out after and then taper off.

is the pedal soft on the first application then hard on the second pump
1. flush with a quality race brake fluid
2. check all sliders on all calipers, pad tapper
3. check front wheel bearings/ ask me how i know
4. check rear axles
5. could be a wrong caliper size pistons

Pedal is pretty soft on each application. Fluid is Motul 600 and everything looks good from what I can tell. Front hubs are both new, and rear axle was just rebuilt. BBK is f-body specific too, so I'm pretty sure its right.

Gonna pick up another bottle of Motul fluid and try again without the Motiv, I think. Don't really know what else to do.

[sweetbmxrider]

Braided stainless lines?

[qwikz28]

Braided stainless lines?

All around. Stock rear calipers and rotors. Porterfield R4S pads all around.

[sweetbmxrider]

Well with the above suggestions, you can bleed the system from the master down for the fronts and see where the pressure is strong and where it is weak.

[1320B4U]

Issue or adjustmet w/the proportion valve? How was the pedal feel prior to the install?

[198esp1]

Issue or adjustmet w/the proportion valve? How was the pedal feel prior to the install?

Is it still soft after you pump the pedal a couple times

[qwikz28]

Well with the above suggestions, you can bleed the system from the master down for the fronts and see where the pressure is strong and where it is weak.
I admit I have no idea how to do that. How would I tell where pressure is strong?

Issue or adjustmet w/the proportion valve? How was the pedal feel prior to the install?
No proportioning valve. I figured since the OEM brakes are strongly rear biased, picking up stronger fronts would even it out. Or else, I could install one after if needed.

Is it still soft after you pump the pedal a couple times
Yes, although I assume it isn't leaking because when the car is off, the pressure builds up and stays built up.

I think I need a professional to take a look at this. I'm in way over my head.

[grazi]

When you bench bled the mc, was it on the car or on a bench. I mistakenly tried to bleed the mc on the car and since the mc was on a small angle, it couldn't get the air out. I was having the same problem so I pulled off mc and bled in a vise and got a lot more air out.

[qwikz28]

When you bench bled the mc, was it on the car or on a bench. I mistakenly tried to bleed the mc on the car and since the mc was on a small angle, it couldn't get the air out. I was having the same problem so I pulled off mc and bled in a vise and got a lot more air out.

I didn't. I always thought bench bleeding the master was for an original installation. Did I mess that up?

[sweetbmxrider]

That's a good suggestion. I merely meant removing the line at the master, bleeding, and assessing the amount of pressure you are seeing. Then move to after the abs and do the same. If you find a point where it trickles out like at the bleeder, maybe you found your issue.

[qwikz28]

That's a good suggestion. I merely meant removing the line at the master, bleeding, and assessing the amount of pressure you are seeing. Then move to after the abs and do the same. If you find a point where it trickles out like at the bleeder, maybe you found your issue.

Got it. I'll summon some help to make sure I'm doing it right. Do I need to cycle the ABS with a Tech2 to bleed the ABS block?

[sweetbmxrider]

That would help, some other generic scan tools can as well. I would just be interested in pressure out of the master and pressure out of the abs block, both front feed lines. I believe there are bleeders on the block itself too but I wouldn't touch them yet. First thing first, start simple here with the previous suggestions and work your way to what I said.

[qwikz28]

Gotcha. I'll work on it this week. Thanks for the tips, guys.

[qwikz28]

Its been a crazy week at work and didn't get to work on the car, but have been thinking it might be worthwhile to replace the master. I recall hearing these cars tend to develop leaks at the master, and my car tends to sit for extended periods. Think it might be worth it to start there and rebleed and hope for the best?

Thanks again in advance.

[2MCHPWR]

my experience with wilwoods, although in c5.
I had long travel and mushy pedal. Car is track only.
With car off, i would pump pedal to get it to be firm. Without lifting my foot off the pedal, the pedal would slowly go back down to the floor. So I replaced my master (I think it was cheap, near $100). And that fixed my issue.

[qwikz28]

I think its wise to do it now and spend the $100 while I'm in there anyway. I'll look for a good quality reman unit.

Some research also suggests its wise to put the car on jackstands and trip the ABS before bleeding (in the ab sense of a Tech2 that can do it manually). No hurt in giving that a try also.

Thanks for your help.

[qwikz28]

I finally got my car buttoned up (mostly on account of Midwest Chassis dragging their feet). I replaced the master cylinder (bench bled), added the wilwood prop valve, replaced the rear calipers with reman units and then bled the system. The brake pedal feels worse. It sinks a bit after you build up pressure when the car is off, and feels like you're steppin in thick mud while the car is on. I didn't bother trying to drive it. The pedal doesn't go all the way to the floor, but there is a good amount of sinking after it builds pressure.

Strangely, the pressure issue I was having before is fixed. When I'm bleeding, the pressure is strong. I checked thoroughly and there are no leaks to be found. Everything looks good.

I'll pay someone to fix it. I'm serious, PM me if you are willing.

[MyFirstZ]

Were you using conventional pump and hold or a pressure bleeder ?

[qwikz28]

Were you using conventional pump and hold or a pressure bleeder ?

pump and hold. I wasn't getting good enough pressure out of the pressure bleeder. Gave up on it.

[qwikz28]

I found this thread: http://www.frrax.com/rrforum/index.php?showtopic=13033&hl=ABS++block++bleed

I might try this tomorrow. Also, is it true that 4 channel cars are bled in the order of RR, LF, LR, RF? I found that on FRRAX also. If its true, I may have found my problem.

[NJSPEEDER]

I was always taught to start at the furthest point and progress back to the master. That would be RR, LR, LF, RF, ABS block, and finish with the MC. Starting with a bench bled MC of course.

Some things to remember as you are bleeding, always pull the pedal all the way up and hold it there when adding fluid to the MC. Also go through all bleed points twice, then drive around enough to bed the pads, then go around again since regardless of how much time you spend bleeding without high pressure reverse fill equipment it is nearly impossible to get perfectly air bubble free so take a short drive with a few low speed hard stops to knock any air that may be in the system loose.

-Tim

[qwikz28]

I was always taught to start at the furthest point and progress back to the master. That would be RR, LR, LF, RF, ABS block, and finish with the MC. Starting with a bench bled MC of course.

Some things to remember as you are bleeding, always pull the pedal all the way up and hold it there when adding fluid to the MC. Also go through all bleed points twice, then drive around enough to bed the pads, then go around again since regardless of how much time you spend bleeding without high pressure reverse fill equipment it is nearly impossible to get perfectly air bubble free so take a short drive with a few low speed hard stops to knock any air that may be in the system loose.

-Tim

I was under the impression that our ABS block doesn't have bleeder fittings. Only the 3rd gens. I don't think there is enough braking power in it to do any hard stops. It's pretty bad.

Do you know of any shops that can do the high pressure reverse fill stuff? Preferably a shop that knows how to deal with aftermarket big brake kits?

[NJSPEEDER]

I don't know if Josh at JS Performance has any of the reverse bleed equipment but I would certainly trust him to sort things out. Sorry I don't know of anyplace closer.

Or you could simplify and just get rid of all that fancy schmancy anti lock safety BS and go with a nice Wilwood triple reservoir manual set up. Cleans up the under hood by getting rid of that big ugly vacuum line and just happens to save a good bit of weight. :-P

-Tim

[qwikz28]

Haha I would love to do that but it would be a lot more fab work than I am able to do. Josh's is a bit too far for a brake bleed.

I found a few reverse bleed kits on Google. Will that do? For example: http://www.autoanything.com/brakes/74A5484A0A0.aspx

Going to do more research to see what it takes. I'd much rather buy a tool that will help me moving forward. The local speed shop recommended I reach out to a shop in Pompton Plains that a Vette guy they know uses, so that will be the fallback for now. I just need to get the car drivable ASAP.

[sweetbmxrider]

I finally got my car buttoned up (mostly on account of Midwest Chassis dragging their feet). I replaced the master cylinder (bench bled), added the wilwood prop valve, replaced the rear calipers with reman units and then bled the system. The brake pedal feels worse. It sinks a bit after you build up pressure when the car is off, and feels like you're steppin in thick mud while the car is on. I didn't bother trying to drive it. The pedal doesn't go all the way to the floor, but there is a good amount of sinking after it builds pressure.

Strangely, the pressure issue I was having before is fixed. When I'm bleeding, the pressure is strong. I checked thoroughly and there are no leaks to be found. Everything looks good.

I'll pay someone to fix it. I'm serious, PM me if you are willing.

If you have the wheels in the air and are holding the brakes, can you turn the tires by hand? If you have good pressure, I would imagine you just have to do a few low speed stops gradually increasing pressure to get the pedal to firm up. Its a normal master on the car? Where did you install the prop valve and why? Just for basics, you have the calipers mounted correctly with the bleeders up and your hoses aren't flipped around or otherwise improperly mounted/run?

[MyFirstZ]

There may be a few euro shops that might be able to help you out. You still in suffern?

[qwikz28]

If you have the wheels in the air and are holding the brakes, can you turn the tires by hand? If you have good pressure, I would imagine you just have to do a few low speed stops gradually increasing pressure to get the pedal to firm up. Its a normal master on the car? Where did you install the prop valve and why? Just for basics, you have the calipers mounted correctly with the bleeders up and your hoses aren't flipped around or otherwise improperly mounted/run?
The brakes hold the wheels, but I doubt they will be able to do any emergency stops to trip the ABS unless I find some gravel or something. I did the prop valve because my ABS is quite intrusive, so I figured I could balance the brake force to get the car to stop harder under threshold braking. All the hoses and bleeders are on correct for sure.

There may be a few euro shops that might be able to help you out. You still in suffern?
I'm going to try that reverse bleeder kit before throwing in the towel. I did a bit of research and it seems to be geared towards problems like this. After that, I'm going to call around, but I'm in Mahwah now by Ramapo College.

[NJSPEEDER]

When you reverse bleed there is one thing that usually isn't mentioned, put something under the pedal so it is held all the way up. Most of the reverse bleeding kits are only about 10-15 psi which isn't enough to lift the pedal and get the last bit of volume needed into the master.

-Tim

[qwikz28]

When you reverse bleed there is one thing that usually isn't mentioned, put something under the pedal so it is held all the way up. Most of the reverse bleeding kits are only about 10-15 psi which isn't enough to lift the pedal and get the last bit of volume needed into the master.

-Tim

Thanks for the tip, Tim. Will keep that in mind. I have a new issue with the rear axle being extremely off center when I lowered it to the ground, which will need to be remedied first.

[qwikz28]

If you have good pressure, I would imagine you just have to do a few low speed stops gradually increasing pressure to get the pedal to firm up.

FYI- You were spot on with this. Pedal is very firm right now, but the stopping power still isn't great enough to lock up the tires on pavement. Basically, once you push harder, it just gets mushy and doesn't brake as hard as you would like. Going to try some other methods this weekend and report back.

Thank you guys for your help.

[sweetbmxrider]

Its tough to diagnose this without being hands on with it. I'm a little confused though, you are trying to lock the wheels up on a car with abs? What you are describing though with the mushy feel to the pedal sounds like there is still issues. Where did you add the prop valve? Sounds like there could be issues with the rear brakes.

[NJSPEEDER]

Do you still have an original master and booster? Seems odd that the pedal would have pressure then fade as you pushed harder. Almost sounds like the booster isn't holding pressure or regaining properly. Air in the system is usually mushy right from the top.

Not exactly sure how to test a booster, I'm sure there is a way to get a vacuum gauge on it to see if it is bleeding pressure or struggling to regain.

-Tim

[qwikz28]

I only replaced the master and added the prop valve between the master and the abs block. The prop valve is wide open so that shouldn't be a problem. I tried a few times to trip the ABS but there just isn't enough braking force to get the tires to slip.

Tim- what you are describing is what is happening. It's just that the pedal builds pressure right away, but then fades as you try and push harder.

I got that reverse bleeder in but I'm going away for the weekend and didn't get a chance to do it this week. If the new bleeder doesn't work, then I'm going to have a professional diagnose it. At least I know the car is driveable at this stage.

Again, thanks for the help guys. I know its hard to diagnose over the internet.

[sweetbmxrider]

What are you trying to do with the prop valve? A hard stop on gravel or sand will trip the abs.

[qwikz28]

What are you trying to do with the prop valve? A hard stop on gravel or sand will trip the abs.

Historically, the ABS in this car would be quite intrusive. I figured I could balance out the braking power to higher the braking threshold. I figured since everything was out, might as well do it now. It was a cheap part anyway (or at least relatively).

[89 Trans Am WS6]

Im not sure If i would go back to the ABS block and MC after doing the wheels. If your getting nice amounts of fluid at the wheel id be afraid of introducing more air by going back up the line.

Never really gave it much thought...I was always taught furthest from master too, and apply that to the wheels..but if i had a complete new system or a lot of air I would do MC first, then abs block, then RR LR LF RF..hrm..if it works..it works lol

Most important thing Tim said was pushing all the way down. I cant tell you how many times ive had brake jobs get worse after bleeding because the guy I put in the car to pump the pedal was doing it half heartedly..usually busy texting or something. It shouldnt be a easy casual thing for the pumper..he should be pushing down hard and making sure he follows through with pressure as the pedal drops when you open the bleeder. It should feel like a leg workout. Move the seat up all the way if your short like me and cant get it all the way to the floor!


EDIT: Did you check the depth of the hole in the back of the new master? Was it the same as the old master? Sometimes they can get remann'd funny and that will throw you for a loop too. Same goes when replacing a booster..gotta make sure the pushrod inside is the same as the one your taking out.

A booster thats leaking vac wont give you a soft pedal, in fact it would be overly hard. You can disconnect the booster (pluggin the vac line of course) and start the car and the pedal should be like a rock. The booster is the assist. Without it you have manual brakes. It also has no bearing on anything while the car is off, except the fact the lil pushrod inside it has to push against the master properly.

[NJSPEEDER]

Historically, the ABS in this car would be quite intrusive. I figured I could balance out the braking power to higher the braking threshold. I figured since everything was out, might as well do it now. It was a cheap part anyway (or at least relatively).

I haven't heard of this being done before, please keep us posted on the results.

How do you define "intrusive" as far as the ABS kicking in? Are you referring more to the balance and stability under threshold braking or more do you feel the ABS is cutting into the braking force before it is entirely necessary?

ABS is a great driving aid if it is balanced properly and being used properly. ABS, just like standard brakes, work best when you roll onto them. Roll quickly, but still roll into the pedal. The idea being to have the chassis weight move onto the suspension and settle into the tires before you get to the bottom of the pedal. If a driver only stabs the brakes, expecting the ABS to make up the difference, it will bounce the suspension just the same as standard brakes and reduce the amount of braking traction available.

I am going to ask around among the contacts and sites and see if I can turn up any specific knowledge on either mechanically balancing or a way to reprogram the ABS system. It is possible that among all of your upgrades you are operating to the far edges or outside of the factory tables.

-Tim

[BonzoHansen]

reprogramming ABS? huh

where in the system is this prop valve you installed? what wilwood front calipers are you running?

Reman m/c, ugh. Why cheap out there? But i don't think that is your issue. Sorry, i digressed.

You can buy pressure gauges to measure fluid psi at the calipers.

[sweetbmxrider]

I'm a little confused too. Before the abs was too intrusive. Now, it isn't intrusive enough?

[qwikz28]

When braking power was strong, it felt like the ABS was constantly interfering under threshold braking. Basically, I assumed it was a matter of balance, which is why I added the prop valve. I don't suspect there is anything wrong with my ABS block, aside from the suspected trapped air. The issue I had with my brakes predates the addition of the prop valve. Right now, its installed between the MC and ABS block. It's wide open right now, and shouldn't be contributing to the issue at all. Prop valve is a wilwood unit with prebent lines from SJM Manufacturing. Front calipers are Wilwood SL4R with porterfield pads all around.

I went with a reman master just because I didn't know what else to get. I did a quick search and it seems that was the common replacement. I stuck with Centric for the reman because I've had success with their parts in the past.

By way of an update, the reverse bleeder helped a lot, but the pressure was so high, the fluid was gushing out of the threads of the bleeder screws of the rear calipers. Pedal firmed up a bit more and the braking power is decent but not enough. I've given up on it, and am looking for a shop that can handle it. The pedal holds good pressure and there's no leaks to be found, so I don't know what else I'm doing wrong here.

[NJSPEEDER]

Have you been able to drive it to determine if it still a better initially then fading? That is the part that worries me. I have a feeling that getting the pedal feel to some level of consistency throughout operation is going to be the key to solving this.

[qwikz28]

Have you been able to drive it to determine if it still a better initially then fading? That is the part that worries me. I have a feeling that getting the pedal feel to some level of consistency throughout operation is going to be the key to solving this.

Oh, it's definitely not fading. Pedal doesn't move if you place constant pressure. However, if you increase pressure, its spongy.

[qwikz28]

Took the car to a Radical dealership this morning for a pressure bleed. I figured they work on high end cars all day so this should be a breeze for them. I got the car back not too long ago, and the pedal is actually softer than when I gave it to them. They said they did find a bunch of air in the lines.

Not sure whether to go back to them or just cut my losses and find a different shop that can diagnose the problem. I'm seriously stumped right now. I don't know whats happening and its really depressing. It's holding pressure and they said it felt great when they took it out for a drive. It's definitely not great.

[Tru2Chevy]

I would call them up and go for a ride with them - preferably with the same tech that drove it before you got it back. See if he notices a difference between how it felt before and how it feels now. :shrug:

- Justin

[qwikz28]

I actually called Wilwood and got some tips as to what needs to be done. Those calipers don't like pressure bleeders, so he told me to rebleed the fronts with the two person method. HUGE difference. It's definitely getting there, and its certainly driveable the way it is now.

I sold my old wheels to a kid with the six piston version of these calipers and asked what he did. He told me without using a Tech2 to autobleed the ABS a few times and rebleeding each time after, you won't get a good pedal. I've always wanted a snap on red brick which can autobleed also, so I'm going to look for one to use and keep trying. I'm much more hopeful now.

Thanks everyone for the tips. I'm really appreciative, albeit frustrated with this car.

[Tru2Chevy]

Glad to hear that things are moving forward at least. Hopefully autobleeding the ABS will be the last part to getting everything you can from the new setup.

- Justin

[qwikz28]

Glad to hear that things are moving forward at least. Hopefully autobleeding the ABS will be the last part to getting everything you can from the new setup.

- Justin

Thanks. I hope so too. I hate to give up on what I started.

[qwikz28]

Problem solved. Spoke to a guy from Connecticut who I sold my old wheels to. He has the 6 piston version of these brakes and had the same problem. It turns out, these calipers have a small piston area and require an aggressive pad to work properly. I was using a street pad that was not stopping the car, thus requiring more pedal pressure and giving the illusion of a spongy pedal. I took his advice and switched to a race pad that came with the kit.

First stop out of the driveway felt the same. Second stop to chat with my neighbor, similar but a little more grab. Third stop at the end of the block for a stop sign, I stopped 20 feet short of the stop sign and hurt my chest on the seat belt. There might be a bit of air left in the system, but it stops so hard with such little pedal effort, that I don't see it bothering me ever.

Thanks for everyone's help in this thread. The brake system is definitely vastly improved from the diagnostic efforts.