No brakes, pedal sinks to the floor, need help.

I purchased an AP Racing BBK and installed it this week. I installed and treated as new and bled the brake system immediately after I installed. I did the traditional two man pump the pedal. Well, I took the car for a test drive on tuesday and noticed the brake pedal was a little squishy. I took it out again yesterday and the same thing, seemed like the pedal was sinking a little farther. I asked Chris and Erron about bleeding the AP's and they mentioned you have to bleed those calipers from both sides, meaning bleed each row of pistons independantly.

Well, today I had a friend come by, Tom, and we re-bled the brakes. Now I have zero brakes. The brake pedal won't firm up and just keeps sinking to the floor. You can hear air rush into manifold when the car is off and when the car is running if you depress the brake pedal the car starts to surge and the boost gauge hunts.

If you pump the brake pedal it will eventually build pressure but if left undisturbed for 10 seconds or so if you try depressing it again it will sink all the way to the floor. You can hear air from the booster escaping and entering the plenum. I verified all the check vales are good and they're installed correcly with the stop pointed toward the brake booster from the plenum. Arrows on the tube are pointed correct also. I also took 4 different check valves and swapped them out with the one from the brake booster. Got the same result so I don't think the problem is the check valve.

There's no active fluid leaks and when you hit the brakes with the car off the pedal still sinks to the floor which leads me to believe fluid is bypassing and is making me think the master is bad, but I don't know, I've never had one go bad so??? I have a spare I'm going to throw on but I can't confirm wether or not it works. Is there some sort of bench test I can perform to check it before install?

As far as priming the replacement master before install, do I just lock it in a vice and run hoses from the ports back to the reservoir and push on the main rod with a screwdriver till it stops bubbling? Any tips on prepping a replacement master would be splendid.

BTW, I pulled the entire brake booster and master assembly. Hopfully someone has ran into this and can help me out!

Need help, no brakes!

Sounds like master to me. When mine went bad, if you spiked the brake it'd build pressure, but if you did a normal apply, it would just go directly to the floor.

Your bench bleed procedure is pretty much spot on. You can check your old master cylinder this way too. Cap the ports and see if you get any resistance from the piston.

Yep, If you apply slight pressure to the brake pedal and it sinks to the floor it is the master cylinder.
Jeff

Changed the brake booster, brake master, proportioning valve and the ABS HU and nothing. Put back on old brakes and viola. The person selling the kit sold me locked calipers. The calipers are seized and the pistons don't float. The pedal dropping to the floor was actually the proportioning valve cracking open and engaging the rear brakes because the fron't wouldn't clamp. Hopefully the guy I bought them from will issue a refund and I can send them back to him or will pay for me to send them into AP and have them rebuild them if it's at all possible.

I'm really disappointed... I gave him over $1500 for them and spent nearly 16 hours dicking around with the brakes and come to find out he sold me absoulte garbage brakes. AKA, AP Racing 6 pot calipers with seized pistons.

In this thread I just posted... http://www.3sgto.org/f62/complete-92...tml#post158843

Quote:

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Originally Posted by J. Fast

Tim, dude, the AP Racing brake kit you sent me has seized calipers. These brakes don't work man. I'm going to send you an email and we're going to work this out. I talked to my best friend Erron Spalsbury who has the same AP Racing Calipers and after discussion it was determined these things were locked up. I'm not going to do anything with this kit until we talk about this. I'm actually going to ask you refund me for the cost for repair to send them to AP to have them fixed or I can send them back to you and you can issue me a refund. I paid you over $1500 for these and they don't work.

I literally changed my brake booster, brake master, proportioning valve, and ABS and come to find the calipers are locked and they won't clamp. The floating pistons don't float anymore man... they're welded to the calipers... We can work this out, I'm going to be straight up with you and everything will be laid out. If you need me to post a video and post pics with Eroon I certainly can do so.

You've got my number, I'd like to speak with you.

Jeremy

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I'll let you guys know how this goes...

every single piston on both calipers are seized?

i find that hard to believe. you cant put a channellock on any piston and push them in?

No mention of them being sezied or needing rebuild by the seller... I was actually going to but the XYZ. According to Tim, "they work great". Umm, no they don't. I know a thing or two about a thing or two, they don't work at all and I'm not going to dick around with them. I don't rebuild AP Racing calipers professionally and am wise to not dick with them until I talk with Tim.

Installing brakes is pretty simple right, 5 lug nuts, two 17mm bolts on each caliper, a 10mm to 17mm braided line, some brake fluid, 4" pad/piston claps and a bleeder. Did that and no worky. Bled and bled and bled, and swapped everything out on the brakes (spent two days pulling parts off my racecar and parts car). The grease on these is actually baked or petrified. It's not slippery, it's hard like porcelin. These need to be serviced by the MFR.

Ya, I'd like to see how they look. Jer, you going to bring them up tomorrow I hope? Give me a call man.

Quote:

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Originally Posted by Erron Spalsbury

Ya, I'd like to see how they look. Jer, you going to bring them up tomorrow I hope? Give me a call man.

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Ya, for sure I will. I'm working a half day downtown at Decaur Place, I have a constuction walk with Catholic Charities at noon. After that I'll be on my way.

You know how I obsess with hangups, no worries, car is already put back together and running. I took it down to the Old School Car Show this afternoon. Got lots oand lots of compliments and holy shit's!

I was getting a little worried about the brakes. I have a dyno session scheduled at Mac on Tues. Glad we found out the problem. Glad I talked with you an Gary.

Really hate to see this kind of thing, hopefully y'all can work it out.

Alright, so Erron and I dissected the BBK and determined the issue. The brake pads that Tim shipped with the kit are waay out of spec. Last time he used them he probaly had no brakes because when I installed them I had no brakes. They were actually a few mils shorter than the full excursion depth of the caliper pistons. The first time I installed the BBK and bled the brakes, when the pistons came forward they extended too far and were bottomed out at full excursion and locked forward and hence resulted in zero brakes. Surprisingly the brake pads had over 1/2 of material left on each so when I came to find compare the mil spec compared to errons I discovered the pads are nearly 1" think on each side of the rotor. When you wear them down to 1/2 that's it. How you discover you're brakes are low is by watching the brake reservoir fill height. When it get's to the low height you have to change the pads. If you don't the next way to find out is having your pedal sink to the floor when the pistons hit full excursion. There's no ring hook or brake pad feeler for low pads it's you either know how much you have left by measuring with a mic or the pedal sinks, you lose all brakes and you go farming.

Erron was able to get these back online, thanks bro! Tim, sorry man, what you sent me didn't work at all and I jumped the gun. You have to understand where I came from as there was 1/2 of pad material left on each face of the brake pads and the rotors were freshly turned with 1MM machined out of them. My expectation was to have brakes when I installed what you shipped. I only needed to manipulate the pistons from their locked forward excursion point and install new pads. I got absolutely no warning from you for having no brakes. I can't believe you ran these brakes down this far, all the way to having no brakes at all... that's pretty dam scary.

I'm going to buy some new pads, chalk things up to experience and hopfully enjoy these.

Thanks all, sorry for the blahh, thanks for the brakes Tim.

Jeremy

Alright, so Erron and I dissected the BBK and determined the issue. The brake pads that Tim shipped with the kit are waay out of spec. Last time he used them he probably had no brakes because when I installed them I had no brakes. They were actually a few mils shorter than the full excursion depth of the caliper pistons. The first time I installed the BBK and bled the brakes, when the pistons came forward they extended too far and were bottomed out at full excursion and locked forward and hence resulted in zero brakes. Surprisingly the brake pads had over 1/2 of material left on each so when I came to find and compare the mil spec compared to Erron's I discovered the pads are supposed to be nearly 1" thick on each side of the rotor. When you wear them down to 1/2" ( OEM stock pad size) that's it. How you discover you're brakes are low is by watching the brake reservoir fill height. When it get's to the low height you have to change the pads. If you don't the next way to find out is having your pedal sink to the floor when the pistons hit full excursion. There's no ring hook or brake pad feeler for low pads it's you either know how much you have left by measuring with a mic or the pedal sinks, you lose all brakes and you go farming.

Erron was able to get these back online, thanks bro! Tim, sorry man, what you sent me didn't work at all and I jumped the gun. You have to understand where I came from as there was 1/2 of pad material left on each face of the brake pads and the rotors were freshly turned with 1MM machined out of them. My expectation was to have brakes when I installed what you shipped. I only needed to manipulate the pistons from their locked forward excursion point and install new pads. I got absolutely no warning from you for having no brakes. I can't believe you ran these brakes down this far, all the way to having no brakes at all... that's pretty dam scary.

I'm going to buy some new pads, chalk things up to experience and hopfully enjoy these.

Thanks all, sorry for the blahh, thanks for the brakes Tim.

Jeremy