Brake Problems

[SHOracer14]

Ok this is a classic example of a SHO repair. Just a simple replacement of pads and rotors and painting calipers gone awry. Ok I replaced the front pads and rotors and just the rear pads as well as painted the front calipers. I put everything back together and bled the lines. For some reason the pedal goes directly to the floor and I have no brakes! If I pump on the pedal it builds up pressure and helps me stop a little bit but not as well as it should and then the pressure relieves itself unless I constantly pump the brake. Ok there is a weird gurgling noise coming from under the hood by the master cylinder like fluid dumping into an open container. I thought maybe the master cylinder had an internal leak so I changed that out with a good used one (this my still be my problem I just don't want to pony up the dough yet). So I replace the MC, bleed at the primary and secondary lines and then bleed at all four corners. Still no change. SO I go ahead and replace the front calpers thinking maybe the pistons are bad. Replace those and bleed again. Still no change. So talking to a couple of people they think that if my rear lines are bad may cause air to have gotten into the lines. So I change the rear lines and left rear caliper (which began to leak for some reason) and again bled the lines (my E-brake is disconnected BTW) but still no change. There are no leaks in any of the lines and I am getting pressure at all four corners when I bleed them. Thinking maybe I didn't do a good enough job of bleeding the lines I bled them again in the RR,LF,LR,RF pattern and still no change. I have absolutely no leaks at any point in the braking system. Now the only other thing that comes to mind (since I've replaced damn near everything and it worked before I pulled the calipers off to paint and put pads and rotors on) is something with the ABS. I decided to see if I could make it come on by pumping up the pressure and smashing it and I can get the ABS to kick on and then the pressure in the system goes back down (pedal goes to the floor). Now I sitll have that weird noise up by the master cylinder like fluid is dripping into an empty container (only when I let off the pedal). Is there anywhere else for my to bleed? Is there a check valve that may have opened on the ABS pump? Could the ABS pump be bad or is it possible that the brand new looking master cylinder I picked up could be bum? I'm out of ideas... PLEASE HELP ME> (I've been without the SHO for a week now).

 

[Ishodu]

My bet is you have air in the ABS system. You need a some tool to make the system pump so you can relive the air. I am not too familiar with this though.

 

[pjtoledo]

Jim, one thing we didn't do was to take the cap off the reservoir and look for bubbles while the pedal was being pumped. But, as there can only be just so much air in the system, I would expect them to stop sometime. Have you tried the ABS on a loose surface yet?


Perry

 

[MI-SHOFEAR]

You bleeding sequence is wrong.
RightRear
LeftRear
RightFront
LeftFront
Start from the farthest and work closer to the master cylinder. You may still have air in all the lines, or one of the lines. Try a power bleader next. You can get one at the autoparts store. looks like a hand vaccum pump.

Jeff

 

[Howdy_Doody]

I'm thinking that the very first time you pumped the brakes, the master cylinder bottomed out and you damaged it internally. Don't know if you it's replaceable or if there is a kit but that's where I'd look.

Whenever I do a simple pad change, I always do a few short pumps of the pedal to get the pads seated against the rotors, so as not to damage the MC.

 

[F-22 Raptor SHO]

You didnt add the stipulation that Perry Helped you...that explains it...kidding of course.

How much bleeding did you do? When I replaced my lines from the master cyliner to the abs control module (all 4 lines)....I didnt have any problems with the antilock mod gettin air in that wouldnt come out. I also had one line to the LF that was replaced. My total bleed amount was over a quart. I essentially replaced every bit of fluid in the system. Bleed each wheel from furthest to closest to the mastercyl until I saw new, clean, bubble free fluid coming out. I did this with the motor running BTW.

Bleed procedure: Inside the car guy pumps the brakes hard 4 or 5 times till firm and the holds the pedal down while I open the valve. I close the valve while inside guy has pressure on the pedal the entire time. I do not keep the valve open until fluid stops coming out, I close it as the fluid has backpressure then repeat the procedure.

 

[SHOracer14]

AH HA!! I just found out what the gurgle noise is! I decided I'd try bleeding the MC again and see what happens and one of the lines wouldnt thread back in (the sliding nut on the end is stuck to the tip of the line but fixed now) since I lost all the fluid again I decided to just pull the MC and start looking for clues. Upon putting a bright light in the area where the MC was I noticed something that should not be there... brake fluid in the brake booster! The old MC looked like the seal was leaking when I pulled it off but it never had any pressure problems... every once in awhile I would have to add brake fluid and now I know why. After I pump the fluid out of the booster that noise should go away. Now, after I bench bleed the MC and bleed all the lines for about the fiftieth time I hope I have more luck. F-22 I will use your method (I did not have the car running when I bled). I sure hope this fixes it... I hate doing stuff twice and this is much more than twice.

 

[pjtoledo]

Interesting,,,the way I see it, your SHO should now go faster when you stomp on the brakes. DIBF,,yep, Direct Injection Brake Fluid!!!! All that brake fluid being sucked into the intake has got to add gobs of power!! Or, do those gobs turn into globs in the vacuum plumbing and manifold? Does this mean both master cylinders were bad??? I can see where fluids in the vacuum booster would cause pressure problems. Since you are having to constantly pump the pedal to keep stopping the big issue must be on the "out" side of the master cylinder. Lets tell the guys here that it sounded like fluid was gushing from the ABS assembly back the the MC. (we used a stethoscope) That goes back to my theory of a bad check valve or something in the ABS unit. But hey, like I said, it was just an educated guess on my behalf. Keep doggin' it, and NO MORE TALK OF TAKING IT TO A DEALER!!!!!!!!!!!


Perry

 

[SHOracer14]

Well after extracting the brake fluid from the brake booster (turkey baster) and reeassembling and then bleeding yet again.... the SHO is now back on the road. Chris (speedy_91_SHO) and I stayed up until 2 am Tuesday night to get it back on the road. Perry the old MC was horrible when I took it off and looked like part of the seals were missing. The new MC is just fine I just didn't notice the fluid in the booster before because I did the work in my driveway as it was getting dark. Now that I had it in a well lit garage I happened to noticed something moving around inside the booster as I was rechecking everything. The weird thing is that no matter how many times I bled the system no air came out... but as soon as the fluid was out of the booster a bunch of air came out at every corner. Well that was a weird one but I'm glad it's finally fixed and I can enjoy my SHO again.

 

[Bob Gervais]

You bleeding sequence is wrong.
RightRear
LeftRear
RightFront
LeftFront
Start from the farthest and work closer to the master cylinder. You may still have air in all the lines, or one of the lines. Try a power bleader next. You can get one at the autoparts store. looks like a hand vaccum pump.

Jeff

I'm not 100% sure about other gens, but I know the Gen 3 braking system is set up so that the RR and LF are on one circuit, and the LR and RF are on another, making his bleeding procedure correct. Doug Lewis informed us of that a while back on the V8 list, I'm pretty sure the other gens are set up the same way.

 

[MI-SHOFEAR]

I'm not 100% sure about other gens, but I know the Gen 3 braking system is set up so that the RR and LF are on one circuit, and the LR and RF are on another, making his bleeding procedure correct. Doug Lewis informed us of that a while back on the V8 list, I'm pretty sure the other gens are set up the same way.

They are on the same "circuit", but the lines have to split somewhere. Lets just talk about the rear. The lines come to a block before the rear axle and one line goes to the left and one to the right. You always start with the bleeder that is furthest away and move closer to the master cylinder. This ensures that ALL the air in the system is bled out.

Jeff

 

[SHO#7]

I'm not 100% sure about other gens, but I know the Gen 3 braking system is set up so that the RR and LF are on one circuit, and the LR and RF are on another, making his bleeding procedure correct. Doug Lewis informed us of that a while back on the V8 list, I'm pretty sure the other gens are set up the same way.

Yes, I belive that they are. In fact most cars have this set up. And there are many different names for it. I use the term "Dual Diagonal"

 

[JTSHO]

yeah brake fluid in the booster sucks...been there done that, hopefully your booster will hold up, normally it kills the booster. now i only use brand new bendix master cylinders, you may want to run a "drip" top end cleaner through the vaccuum system to clean the brake fluid out of it, that is of course if it filled the booster and got out into the vaccuum system.

 

[Bob Gervais]

They are on the same "circuit", but the lines have to split somewhere. Lets just talk about the rear. The lines come to a block before the rear axle and one line goes to the left and one to the right. You always start with the bleeder that is furthest away and move closer to the master cylinder. This ensures that ALL the air in the system is bled out.

Jeff

You're not getting the point. If the LR and RF are on the same circuit, the RR would have nothing to do with it.

I've never had any problems bleeding either way, but when a guy like Doug, who works on these all the time tells me I'm doing it wrong, I tend to listen.

 

[SHOblime]

DD brake systems are indeed bled differently...the procedure would be LR/RF, RR/LF...are we saying the 1st and 2nd gen SHOs have a DD system? I'm going to be bleeding my brakes this afternoon, maybe I need to check....

 

[Bob Gervais]

From what Doug said, they are DD.