Wilwood BBK, spongy pedal
 

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.

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

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

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.

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.

Braided stainless lines?

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

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.

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

I admit I have no idea how to do that. How would I tell where pressure is strong?

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.

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.

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?

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?

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.

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

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.

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.

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.

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.

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.

I found this thread: http://www.frrax.com/rrforum/index.p...++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.

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?