Brake Pedal To Floor

[Mackay]

I have a question I was hoping to get some input for. I have a 1975 2002 that has been de-smogged. After bleeding and adjusting the brakes many many times, the best we are able to get from the brake pedal is about 90% uninhibited pedal travel with roughly the last 10% having any feel/resistance. Also, in regards to comments on the rear drums being worn/out of adjustment, we have tried adjusting the shoes to the point where they are seized against the drums and then pushing the pedal, resulting in the same symptoms of nearly no pedal feel. We have deleted the brake booster and fabricated a pedal box that fits the OE master cylinder and I am wondering if this would cause our problem? We also have all new hydraulic lines including braided steel from BLUNT. The pedal pushrod length/action is not the problem and has been checked. We have also upgraded to the volvo front brakes and e21 vented rotors, and have bleed them properly UIO (upper, inner, outer). We have pressure bled it and manually bled it multiple times. The reservoir is in its orignal location at the high point of the system. Have not bled the clutch but that's a separate circuit so it shouldn't matter. Does anyone have some input or ideas or links where this has been answered? I've done a great deal of searching myself so please don't be a dick and tell me to use the search.

Thank you,

Mackay

[pkbinplano]

pressure bleeder ?

[roadhog0]

Bingo, you got it. The going boosterless with the stock master is probably your problem. Is the brake firm once you get it to the point it works?

[Mackay]

Yes, the pedal is firm once it finally does get feel in the last 10% of travel, but this last 10% is too little too late to effectively drive a car. Any ideas for a solution, AE master cylinder sounds like?

[inkatx2002]

after replacing all components in rear with oem drums, etc, new calipers in front, and new ss lines all around, I would estimate 12 hours of using my mity vac and loving wife to pump the brakes until all air was out of my system.

Friend strongly recommends a pressure bleeder connected to the brake fluid reservoir. Did you go that route?

[M3M3]

sounds like you need a new master cyl.

[nbristow01]

sounds like you need a new master cyl.

+1 That is how mine was reacting and I decided to replace it. New one worked fine and fixed the issue

[roadhog0]

Yes, the pedal is firm once it finally does get feel in the last 10% of travel, but this last 10% is too little too late to effectively drive a car. Any ideas for a solution, AE master cylinder sounds like?

Was this an issue before you changed the setup to no booster? I have a feeling it's something to do with the preload and travel in your MC since it doesnt have a booster.

[Mackay]

I'm thinking that since it is probably either a bad master or only designed to work under vacuum, I may as well get a wilwood and call it a day.

[tim385]

Going boosterless ...Tii master cyl or E12 put a pressure residual valve in your rear line 10 lb one, change the brake lines around so you have all rear off one part of the master cyl and all front off the other part . Not the way it is normally set up . Use good pads not crap, put in a proportioning valve in the rear line , that way you can get your pressures right . Thats what Im running , great pedal nice and hard , up near the top,stops great .

[Koblenz]

Resurrecting an old thread.

 

I have replaced; master (that was a PITA), front rotors, rear back plates, shoes, cylinders, drums, front hoses and bled the hell outta the thing. The rear hoses appear to be new enough and braided.  Should I replace those?  Yet my pedal has about 80% travel before it responds.

 

Where do I go next?  Booster, calipers, strip club?

[M3M3]

did you bench bleed the master?

 

pressure bleed system?

 

you still have air in there somewhere.

[Koblenz]

I'm afraid to ask on a public (potential humiliation) board.  How do you bleed the master?  No pressure bleed, pump the pedal with foot bleed.

[tim385]

It seems like a lot of people have this problem. You have to use a pressure bleeder and the first step is cracking off the metal lines on the master 1/2 turn usually will do let it run until you get clear fluid(no bubbles)then do the usual bleed process.......now do it again.I have never managed to get a good pedal first time round.Buy plenty of brake fluid as well, give the nipples a good open time.

A pressure residual valve in the rear line helps, most boosters have it in the circuit but when you remove the booster that goes as well . A 5-10 lb valve seems to work well with rear drums and a 2 lb works well with rear discs.Proper rear brake adjustment PRIOR to this is very important, dont expect to get a good pedal without adjusting the rears first...including the hand brake(E- brake)while your at it.If your adjusters dont work FIX them.If you have old hoses or unknown hoses ...REPLACE THEM. Make sure your rear slaves are not leaking ,These are cheap to replace if you have the small diam ones go up a size.If your master cyl is suspect ...REPLACE it, I have had little success with rebuild kits.

[M3M3]

try searching on "bench bleed". basically it is filling the MC with fluid on the workbench...before you install it. this gets fluid into all parts of the MC and the air out.  method tim describes above about cracking the fittings open is step two in the process.  and yes, the best way to do brakes is with a pressure bleeder (NOT vacuum).  they are cheap and everyone should have one in their toolbox.

 

yes, it takes a bunch of fluid.  in a new system that is dry, you can keep reusing the same new fluid so you don't have to buy more than a quart.

 

air bubbles will still remain around the pistons in the calipers.  you really have to drive the car around a bit to knock it to the bleeder valve, then rebleed the entire system.

 

Tim likes to recommend a residual valve in the rear.  i have to disagree.  stock 02/tii MC's (LHD) have a residual valve built into the MC(not built into the booster).  do not need another one for drums, and it should be removed for disks.  disks in the rear must be qualified.  if they are the VW/audi/Wilwood CPB calipers, do not put a residual valve in.  the internal parking brake mechanism keeps the piston out.

Edited September 23, 2013 by mlytle