Master cylinder upgrade?

XLRVIII said:
try this on your brake booster.. still trying to help ablient my azzhole appearance.

Get some starting fluid.. spray it around the check valve.
if your engine speed increases.. WALA.. bad check valve or brake booster
Replace the check valve and repeat the test.
If it still does it.. brake booster time..

WHICH.. changing a brake booster on a mark 8 is a server PITA
I wouldn't wish that job on anyone.
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Forgot about this post, this was my method of leak detection. Albiet, I was a bit rushed when I did it before, so I won't rule out operator error, but I will give it another go when I'm not pressed for time so's I can be sure. Really hope it's not the booster though, I don't look forward to that job.
 
If your booster is indeed bad... DO NOT buy the vatozone cheapie booster... odds are it will be bad nib... spend the extra money for the Ford part....
 
luxuryrules said:
Forgot about this post, this was my method of leak detection. Albiet, I was a bit rushed when I did it before, so I won't rule out operator error, but I will give it another go when I'm not pressed for time so's I can be sure. Really hope it's not the booster though, I don't look forward to that job.
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yea... the booster job sucks...been there done that.

Sorry I came off as an azzhole, but I am what I am..and that's all I am.
(lol)

IMHO I'd rather be a helpful Azzhole than a "nice person" with nothing to add/offer as help...
how many "nice" people read your post and closed the window without trying to help?
{look at the thread views number to get an idea)

Again, sorry if I was an azz..

and dont take the babyfood spoon comment to heart..
trust me, your not the first person to "SEE" the babyfood spoon.

It's actually just a "running joke" between a few of us regular azzhole members.

Get back to me with details once you've looked further into this..I promise I wont whack you with the babyfood spoon again.."once is enough". HAHA
 
XLRVIII said:
Get back to me with details once you've looked further into this..I promise I wont whack you with the babyfood spoon again.."once is enough". HAHA
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No worries mate, I learned the first time, lol.

What sucks is that a pretty thorough search yielded no leak. That does not, however, rule out an internal leak - which is entirely possible and I sincerely hope it is not.

Kinda leaves me between a rock and a hard place. Is there any possibility this could be the master cylinder, or is it time to just bite the bullet and do the brake booster?
 
luxuryrules said:
No worries mate, I learned the first time, lol.

What sucks is that a pretty thorough search yielded no leak. That does not, however, rule out an internal leak - which is entirely possible and I sincerely hope it is not.

Kinda leaves me between a rock and a hard place. Is there any possibility this could be the master cylinder, or is it time to just bite the bullet and do the brake booster?
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if it were me..I might chunk a master cylinder on there..they aren't that expensive nor hard to replace.
you might get lucky and "we missed the diagnosis" and it might be the MC.

as hard as the booster is... I'd chunk a MC at it and say a small prayer
 
XLRVIII said:
as hard as the booster is... I'd chunk a MC at it and say a small prayer
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Yep, that's what I was afraid of. I don't plan on saying this too often, but I hope you're wrong, lol.

KK, system has been flushed a couple of times. Heck, I even broke down and went to the stealership to ensure the ABS module was properly flushed.
 
Sorry for the off-topic, but why the :q:q:q:q are you guys bashing cobra brakes?

The stock mark brakes might be adequate for stock 16" wheels, but with 18"+ they don't keep up.
I've got 19" wheels, and the cobra front brakes made a world of difference in braking performance.
 
I had a similiar problem after i changed my hubs and my rear rotors to cobra rotors(moved caliper). My pedal after was very soft and unpredictable. I thought maybe it was cause the rear caliper was spaced a little different fro the stock location. Being frustrated, i pumped up my booster while driving and jammed my brakes super hard. I broke my master cylinder doing that(think i bent rod) Soooo - i changed the booster, fixed the bent rod, but still had bad pedal feel. After that , i bought a vacuum pump to bleed the brake. The pump worked good because i changed the fluid with it too-just keeped pumping.

MY PEDAL FEELS ALOT BETTER. 8x better.

also brake lines do flex too under braking. Sometimes too soft??
any nice thoughts
 
Russo said:
Sorry for the off-topic, but why the :q:q:q:q are you guys bashing cobra brakes?

The stock mark brakes might be adequate for stock 16" wheels, but with 18"+ they don't keep up.
I've got 19" wheels, and the cobra front brakes made a world of difference in braking performance.
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Thats what im saying!!! I wonder why race cars have larger brakes? If the stock mark brakes were so good no one would upgrade.
 
luxuryrules said:
Are you sure? Every brake booster problem I've ever dealt with has been the opposite - it leaks, and the pedal gets harder to push because when it doesn't hold vacuum, it's not offering as much assistance as usual. I wouldnt' say "harder like I thought it does" rather "harder like I have felt it do." For the brake booster to make the brakes feel softer would mean it is offering too much assistance - and that would also have the effect of clamping the brakes harder.
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Just adding my 2 cents in but I had a bad brake booster a while ago, and those were exactly my symptoms. The car just didn't want to stop and the pedal was very hard. Replaced the booster and all of the sudden I can stop again, so I would say you're right on your assumptions based on my personal experience.
 
XLRVIII said:
if it were me..I might chunk a master cylinder on there..they aren't that expensive nor hard to replace.
you might get lucky and "we missed the diagnosis" and it might be the MC.

as hard as the booster is... I'd chunk a MC at it and say a small prayer
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F***. I threw a master cylinder at it and got a little bit of improvement, so there must have been some internal seepage of some sort. Even still, it's not where I want it to be. Another pass with starter fluid around the booster & valve for a vacuum leak yielded nothing, so it's almost gotta be an internal leak.

Methinks if it starts to worsen I'll do the booster (since that is the only component of the braking system I haven't replaced yet), but as of right now it's not yet worth $300 and a severe PITA job. Yet.

As an aside - thanks for making an appearance over in the 'other' part of the forum, good to see you putting those azzhole skills to use, lol!
 
Anybody have any advice on making this job easier? Stuff I should be aware of before starting to rip things apart?
 
Take the hood off
Take the wiper cowl off
Take the driver seat out

These three things would have made the job alot less painful.

you will be spending a fair amount of time upside down under the dash unbolting the brake pedal from the back of the booster.

If your not a small guy like I'm not.. the three things listed above will make the job alot less painful and frustrating.

Leave yourself a minimum of 4 hours to get this done if it's your first time.
 
Yeah, booster isn't that bad, just time consuming. I'm skinny with small hands though, so these tight jobs aren't so bad for me.

Also, when you take off the m/cyl from the booster, make sure the rubber seal is still good.
 
For reference, a failed booster can be either a pedal that's too low and lacks resistance, or a pedal that is much too firm.

And to save the argument, I even made sure to get some supporting documentation:

Brake Pedal Too Firm. If you step on the brake pedal and all of a sudden it feels like you're doing leg presses at the gym with a new personal trainer, your brake pedal may be too firm. This symptom points to a few potential problems, all of which need to be fixed as soon as possible.

Vacuum Problems: Your brakes are easier to press because of a brake booster that gives your foot the strength of 10 men. This booster uses vacuum to help you activate the brakes. If there is a vacuum leak somewhere in the system, it won't have enough negative pressure to do its job. Check the vacuum system for leaks. If you find none, your brake booster is probably bad and will need to be replaced. This can be tested by a shop if you want to be sure.
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Brake Pedal Goes Too Far Down to Stop. If you step on the brake pedal and it feels like it's going too far down before you start to slow, you might have the following problems:

Bad Brake Power Boost Unit Finally, if your brake booster goes bad you'll have low brake pedal issues. Most brake boosters are vacuum controlled, so a special vacuum measurement device that connects to the brake booster is needed to check it. If it's bad, you'll have to replace the boost unit.
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Remember, a booster can fail in more than one manor, which will give you different results.




Reference: http://autorepair.about.com/od/troubleshooting/ss/ts_brakes.htm
 
Long story short, do a full diagnosis, checking for vacuum, fluid level, fluid contamination, brake line obstructions and the like.
 
NateRW21 said:
Long story short, do a full diagnosis, checking for vacuum, fluid level, fluid contamination, brake line obstructions and the like.
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I've got those last three covered, haven't done a vacuum test. Two questions... one, my book doesn't tell me how much vacuum it should have, what should it be at?

And two, if it's an internal leak in the power booster, as I suspect and it seems Tommy does too, would that show up in the vacuum test? I'm inclined to think it would.
 
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