brake trouble!!!!!!

mikey · 05-28-2000, 09:08 AM

I just finished doing the 320i brake upgrade, and put the old stock front calipers on the rear. I bled all the calipers as per directions, but the damn pressure in the master cylinder just seems to fade away after pumping it up. There is no more air in the system, and I went around each caliper six or seven times already, as well as two quarts of fluid. Could my master cylinder be shot? It looks very old and rusty. Do they just go out like that??
And there are no leaks anywhere, I checked thoroughly.

Mike

[This message has been edited by mikey (edited 05-28-2000).]

oredith · 05-28-2000, 09:59 AM

i assume fluid was coming out when you were pumping and bleeding the breaks?.. i don't think the MC is the cause of your problem. First off, you're sure all the bleeder nipples are on the TOPSIDE of the caliper, right?.. if the bleeder valves are in the right place, and you followed the bleeding procedure, the proportioning valve might be the cause of your problem, air can get trapped in that. you can bleed that by cracking the line at the prop valve (the line that comes from the front of the car)

good luck,

Jeff

mikey · 05-28-2000, 10:23 AM

Actually, one of the rebuilt calipers that I am using in the rear has the bleeder on the bottom. It is on the drivers side. It looks like the rebuilder used a right sided caliper and turned the pistons around so that it can be used on the left. Would that make that much of a difference???? Also I thought that if I was getting a nice stream of fluid out of the rears, that there would be no air left in the prop. valve.

Mike

oredith · 05-28-2000, 11:49 AM

the bleeder has to be on the top, or else you'll never get rid of the bubble sitting on top. with the bleeder nipple pointing down, you can be sitting there bleeding the system for hours and hours without any effect (as me how i know).. i feel your pain though, swimming in brake fluid is about the worst thing possible, followed closely by tranny fuild, and then motor oil.. you haven't truely worked on the car until you've swam in all of the above..

good luck,

Jeff

turbo2.0 · 11:18 AM

Jeff says: .. you haven't truely worked on the car until you've swam in all of the above..
I thought it was supposed to be "swimming in all that stuff in the rain in the autocross pits."

mikey · 05-29-2000, 04:32 PM

.......so just because of that bleeder being on the bottom, the pedal will go to the floor after bleeding all calipers????? I got an exchange on order from Kragen. I hope that is the problem. This one day job has turned into a 2 week job, because Kragen keeps fu-ki-g up the part order. First they ordered the wrong calipers, then they order two left side, etc etc etc. All with two or three days in between. I just want to get driving my 914 again!!!!

oredith · 05-29-2000, 04:52 PM

sam says: "swimming in all that stuff in the rain in the autocross pits."..

jeff replies: "that's only if you're caught off guard.."..

joke aside, you're not going to be able to bleed the brakes correctly until you've got the right combination of calipers.. sorry mike, but you're going to have to tough out those two weeks.. hope you come out happy with the end results.. i was..

Jeff

campbellcj · 05-29-2000, 06:30 PM

Jeff - who did you have machine your 320 calipers? Poop boys sells rebuilt ones (even w/o core) pretty reasonably but I have no clue who around here can machine them for me. GPR gets around $400 for their "kit" which includes pre-machined new calipers, but that is about double my target.

- Chris C.

BenI · 05-29-2000, 07:04 PM

Good luck with the brakes-I had similar trouble after rebuilding all calipers and MC, and it didnt go away till I put in a new MC.

My question is who is Poop Boys. Is that pep boys? I want to upgrade to 320s but am shopping around right now. Thanks

John Rogers · 05-29-2000, 07:13 PM

You could have pulled the caliper and turned it over with a spacer the thickness of the rotor and bled them and then put it back on. Additionally get some Speed Bleeders, they are worth their weight in gold. They are approx $16 for 4 at Pep Boys. Good luck.

DK914 · 05-29-2000, 09:10 PM

Tell me more about these "speed bleeders." Are they one-way check valves for the bleeder nipples? Also, anyone have any experience/advice/warnings about those vacuum bleeders? They look like a good idea.

mikey · 05-29-2000, 09:17 PM

I bought the rebuilds from Kragen for 34 bucks each. Rebuilt by A1 Cardone. Pads were another 16 bucks per side.

Mike

neilca · 05-30-2000, 04:31 AM

Mikey
The bleed screw has got to be on the top of the caliper. But that may not be your only problem. Brake cylinders work in abou an inch and a half stroke most of there life. When you bleed the brakes you go past the normal stroke area and bottom out the cylinder. Well there is crude in the cylinder that kills the inner seals. Sounds like you blew the master cylinder when you bled the brakes. I know about this because I have done it myself. No lesson better learned than experience.
neil

oredith · 05-30-2000, 05:49 AM

To Chris:
I had mine machined at a local machine shop, charged me ?.. 15/caliper.. ? can't remember exactly. depending on the year of your car though, i've been told by MTZ that earlier struts allow you to put the 320i's on without any machining. you'd have to test that yourself though, i've never tried to confirms that. if you're out of luck finding local machine shops, e-mail Sam, he might have some ideas..

For Mikey:
I'd do what John suggested.. take that caliper off, but don't disconnect it. turn it upsidedown, and bleed it as if it were on the correct side. that should get rid of any bubbles in there. that way, if the problem persists, you can proceed to check other points in the system instead of waiting 2 weeks to find out.

good luck,

Jeff

John Rogers · 05-30-2000, 06:25 AM

The ??? on the Speed Bleeders, yes they are replacement vent screws with little spring loaded check valves inside. You attach the tubing, open the screw approx 1 1/2 turns and pump away. They have a web site: http://www.speedbleeder.com/ and they are sold through many outlets such as Pep Boys, etc.

oredith · 05-30-2000, 07:00 AM

John:
do you remember which size speed bleeder you used for the 320i calipers?..
http://www.speedbleeder.com/size.htm

any idea if they're the same ones that are used on the stock 914 calipers?..

TIA,

Jeff

campbellcj · 05-30-2000, 08:56 AM

Thanks Jeff. I am almost positive I need to machine them (Mike Z. said 70-72 don't, but mine's a 73). Sounds like Kragen is a little cheaper than Pep Boys -- I think Pep Boys was around $150/pair rebuilt with no cores (around $115/pair with cores). The Pep Boys around here have no parking anyway -- last week I had to park 2 blocks away.

I'll try to find a machine shop around here who can do it but otherwise maybe I'll head out your way.

Chris C.