mark kibort

Thanks to some bartering with Brian, he has sent me his 928international SS brake lines. I put them on this morning, and my worst suspision came true. My broken bleed fitting, that still seals, was not availible for use during the bleading process. when you take the lines off the calipers, you obviously are going to get air through the system as the air in the new lines are filled and flushed. So, what do i do? risk the caliper repair to extract the broken fitting, which has not caused me any issue with bleading as I just use the outside fitting thinking that the fluid must pass through the inner caliper reservoir?

well, the result of using only the outer fitting to bleed, created air that was trapped in the inner part of the caliper. So, what I did, was remove the caliper, turn it upside down and while on the ground, fit an old rotor to fit inbetween the brake pads, to allow bleeding from connecting tubes that normally are on the bottom and connect the two caliper sides.
I loosened the connector tube ,which is not facing up and any air in the air in the caliper, not is able to be flushed out at the connection. I bled it from there the tradition way.

Anyway, I think it has worked. pedal is firm as a rock and with a set of new pagid blacks, ready for the next race next month.

Does anyone know if this technique will work? Its a hassle but, normally, Ive never had any issues with brake bleed without the one bleeder being gone.

blown 87

As long as you get all the air out, the how you do it is not important, so yes that will work.

mark kibort

Its a major hassle if it works, but as I mentioned, for years Ive been able to bleed a soft pedal with only the outside bleeders. However, it didnt really work with the new air introduced with the changing of the lines . I used a pressure bleeder, old fashion way, and neither worked. I guess if there is an air pocket, not so much bubbles in the fluid, that wouldnt be pushed out the bottom lines, into the outside caliper section and then up to the outer bleeder.
makes sense, unless there is there is some design contruction difference of the caliper inners that I dont understand. Anyway, by turning them upside down, im assuming Im allowing the air to rise to the connector tube fittings and by bleeding them there, the same effect occures. Seems to have worked. Ill see i it works.

by the way, the flat rotors are working well and show no signs of cracking or warping.

IcemanG17

How does the pedal-brakes feel? If the pedal is firm and the power is there...they must be fine!!!

Glad they worked out for ya.....they weren't doing any good sitting in my garage!

WallyP

One of our customers replaced his master cylinder, then bled over three liters of fluid thru the system. The pedal still hit the floor.

I asked if he bled both screws on each caliper - he didn't know that there were inner screws. Bleeding all of the screws gave him a solid pedal with no problems.

So, the answer is that the outer bleed screw alone won't get the job done if there is really air in the system.

mark kibort

Yep, I believe it. I dont know what shape air takes in the lines, but I bet when you boil the brakes, the bubbles are probably pretty small and maybe can be carried through the bottom line. only when there is a major void, would that inside bleeder have to be used and in my case, that certainly happened I imagine. the upside down trick probably go it, as the pedal is rock hard now and wasnt so when I was messing with the outside bleeders only, the driver side has the inside bleeder intact, and by using that, it helped, but the other side wasnt done. It was really bad. ok for street driving but would be murdurous on the track. I think i got it. Now, the holbet car has new shiney SS brake lines. It looks very racey now!!

mk

Daniel Dudley

Sounds like you did it. Any way to test them before you go to the track ?

borland

I would fix the damaged bleed screw anyway. Especially because of the type service (track).

I use a MityVac to flush the brake fluid on my S4. The vacuum flushing works great, however I had considered using a "T" adapter.... on each caliper in order to flush from both bleed screws at the same time.

But after considering this ...

- The fluid flow path from the brake line to the outer bleed screws is through the inner pistons,
- Fresh brake fluid is lighter than the older brake fluid and would tend to sink to the bottom as well as mix, and
- Flushing the outer first then inner provides a better fluid mix,

my thinking is the 'T' adapter would require a larger quantity of flushing fluids than if done the normal way, which for me is to:

- flush the Outer bleed screw first,
- then flush the Inner bleed screw second.

mark kibort

but doesnt the fluid travel from the inner reservoir to the bottom connection pipe and then to the outer reservoir? Probably doesnt matter which way or order you do it. I just thought of something as well. these calipers can be installed in front of the rotor like the rears. in which case, you would swap the bottom connection pipe with the top bleeder screws . this means, what i did worked because the calipers are symetrical. However, it was messy.
I dont want to fix the broken bleeder, because I am almost positive it will turn into a big mess of destruction trying to get the remainder of the bleeder out.

borland

Mark,

The WSM doesn't specify any order for doing the two bleed screws.

I'm just saying it probably takes more brake fluid to do an adequate job of flushing if you do the inner one first. Yes the only way for the fluid to move between sides is through the external jumper line at the bottom, but the path is through the inner pistons.

I assumed you rounded off the hex on the bleed screws by using the wrong wrench. There isn't much room on the back side to get a grip with vise-grips, so you might want to remove the caliper to a work bench where it would be easier to get the old one out, then replace it with a new bleed screw.

mark kibort

Hard to say what way would cost more fluid.

As far as the bleeder goes, it broke off clean. but, the sealing part never even moved. Had it have been rounded off, that is no match for ViceGrip-Man!

mk

Lizard928

Mark,

the calipers are not the same. You cannot simple remove the connection tube and swap ends.

The pistons are different sizes for the leading and trailing edges of the pad.

shmark

Mark, as hard as you drive and as fast as that car is, I'm constantly amazed at the level of engineering going into it. We put brand new SS lines and rebuilt calipers on our $500 LeMons car, and you better believe we made sure all bleeder screws are in good shape. There are some places where it's just a good idea to do it right, and incredibly enough it's cheap too.

mark kibort

are you sure? Think about it, the calipers on the same side of the car will always have the leading and trailing edges correct. I remember someone talking about conversion of the front calipers to the rear of another car where the caliper would simply be rotated to the front of the rotor, rather than the back as we have them on our cars. this was to require swaping the connection tube with the bleeders. If so, then what i did was correct, and should work, as it seems it did.

dr bob

The left and right calipers should not be swapped when ther are different size pistons. This applies to your S4 brakes. The pistons are staggered sizes so that the pad pressure and are consistent. If the calipers are swapped from front of rotor to rear of rotor, for instance, you would use the same caliper but move the crossover tube and bleed screws.