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Posted by: Aaron Cox Apr 4 2005, 11:06 AM

ok... so my pedal was uber firm 3 months ago.....and just the other day i dont feel all that confident in my braking ability...i mean it stops... but the pedal is no where near as firm as it used to be....

resevoir is full.... no leaks....anywhere
6 month old SS lines.....
PO's 19mm MC
rebuilt M calipers and
non leaking and one rebuilt rear caliper....

is my MC dying a slow and scary death? i like my pedals rock firm....

oh...btw i KNOW in the future i will be using 986 brakes..... can i use a 19mm MC with those? or will i have to buy a new one at that time

Posted by: SLITS Apr 4 2005, 11:08 AM

Get some of Scott's Viagra....he says take two and it'll be stiff again.......

Posted by: tat2dphreak Apr 4 2005, 11:19 AM

bleed 'em!

and bleed the prop. valve. how old if the fluid? what kind of fluid?

Posted by: Aaron Cox Apr 4 2005, 11:21 AM

QUOTE (tat2dphreak @ Apr 4 2005, 10:19 AM)

bleed 'em! and bleed the prop. valve. how old if the fluid? what kind of fluid?

castrol super dot 4 fluid.....

6 month old fluid....

Posted by: URY914 Apr 4 2005, 11:23 AM

Let it BLEED!!

Posted by: Aaron Cox Apr 4 2005, 11:26 AM

QUOTE (URY914 @ Apr 4 2005, 10:23 AM)

Let it BLEED!!

tis my plan.....

i have no knowledge of how old the master cylinder is..... i used a mirror to see that it is a 19mm.........

how would air have gotten in to the sytem? no leaks.... resevoir is always full....


oh well....

Posted by: nebreitling Apr 4 2005, 11:26 AM

bleed and find out.

Posted by: nickg Apr 4 2005, 11:56 AM

did you try levitra? and remember if your pedal stays hard for longer than 4 hours....consult a dr

Posted by: Type 4 Apr 4 2005, 12:06 PM

How old are the Hoses?
You may have a hose that is failing, look for blisters on the hoses.

Posted by: Eric_Shea Apr 4 2005, 12:11 PM

I smell money...

I'm pretty sure you need all new brakes on that car Chimp

Posted by: Eric_Shea Apr 4 2005, 12:12 PM

Seriously... you're getting air in there somewhere. Everything tight?

Posted by: SLITS Apr 4 2005, 12:19 PM

QUOTE (Type 4 @ Apr 4 2005, 11:06 AM)

How old are the Hoses? You may have a hose that is failing, look for blisters on the hoses.

with s/s lines, they won't blister...they'll leak

Posted by: Aaron Cox Apr 4 2005, 12:19 PM

steve....

hoses are six months old. brand new stainless lines at the time.... all fittings are tight.....but i will go double check them.....

i smell a bleeding brakes BBQ!

what does a failing mastecylinder feel like?

Posted by: lapuwali Apr 4 2005, 12:24 PM

At a stop, mash the brake pedal HARD and hold it down. If it slowly sinks, then you very likely have an MC leak. Have you checked under the carpet at the pedal cluster? MCs frequently leak down the pedal pushrod, and get brake fluid all over the floor under the carpet.

Water or air getting into the system will cause mushiness. Non-silicone brake fluid likes water, so over time, it will absorb atmospheric water however it can, such as through the reservior vent hole. Usually this process takes a couple of years to show up, but it can happen faster if it's been exceptionally humid recently.

Posted by: Eric_Shea Apr 4 2005, 12:27 PM

Check your pedal assembly... if your M/C is going South you'll probably see it there first. This is how it felt on the -6 last spring before I rebuilt everything. I had brakes but... they had to be pumped and if you pumped hard enough they went down fast. The tray was full of fluid.

Yank the carpet and pull the board. Stick your finger in the tray and see if it's damp.

Posted by: Eric_Shea Apr 4 2005, 12:29 PM

Does water compress more than brake fluid?

Posted by: Grimstead Apr 4 2005, 12:58 PM

Hey Aaron,
My brake leg is in good shap if you need some help

Bill

Posted by: Aaron Cox Apr 4 2005, 01:00 PM

QUOTE (Grimstead @ Apr 4 2005, 11:58 AM)

Hey Aaron, My brake leg is in good shap if you need some help Bill

roger that.....

im like 5 miles from you...sefas club/green river (sierra del oro)

ill let you know...

thanks bill

Posted by: Eric_Shea Apr 4 2005, 01:31 PM

I thought about that today when I sent Bill calipers off to him. I was wondering how close you were to each other.

Bill seems like a very nice guy... don't be corrupting him Aa-ron

Posted by: Aaron Cox Apr 4 2005, 01:33 PM

QUOTE (Eric_Shea @ Apr 4 2005, 12:31 PM)

I thought about that today when I sent Bill calipers off to him. I was wondering how close you were to each other. Bill seems like a very nice guy... don't be corrupting him Aa-ron

you know me eric.....

yeah, i wish he could joined us at the ginormous BBQ on saturday......

Posted by: Grimstead Apr 4 2005, 01:35 PM

I figure it's in my best interest since he's a lifeguard at the city pool my daughter goes to.

Posted by: Aaron Cox Apr 4 2005, 01:37 PM

QUOTE (Grimstead @ Apr 4 2005, 12:35 PM)

I figure it's in my best interest since he's a lifeguard at the city pool my daughter goes to.

too funny.....

Posted by: SLITS Apr 4 2005, 01:40 PM

You've got to watch A-aron Admin. Being founder and President of the Corona Gay Boys Club, he has recently acknowledged the error of his ways and is praying upon fellow 914 club members daughters, wives and girlfriends in his attemp to go straight.

Posted by: Eric_Shea Apr 4 2005, 01:41 PM

I was gonna say... as long as it's not the pool your "son" goes to.

Posted by: Aaron Cox Apr 4 2005, 01:43 PM

you guys suck.....

im not gay.....ron (slits)started that after a heated debate and i called him an old phart...

Posted by: SLITS Apr 4 2005, 01:54 PM

QUOTE (Aaron Cox @ Apr 4 2005, 12:43 PM)

you guys suck..... im not gay.....ron (slits)started that after a heated debate and i called him an old phart...

iszatso!

Posted by: Grimstead Apr 4 2005, 01:58 PM

QUOTE

I was gonna say... as long as it's not the pool your "son" goes to.

What? I thought everyone was being a little tooo nice to me around here

QUOTE

im not gay.....ron (slits)started that after a heated debate and i called him an old phart...

Not that there is anything wrong with that....

Posted by: Aaron Cox Apr 4 2005, 02:00 PM

Posted by: lapuwali Apr 4 2005, 02:19 PM

QUOTE (Eric_Shea @ Apr 4 2005, 10:29 AM)

Does water compress more than brake fluid?

No, but water lowers the boiling point of the brake fluid, and boiling fluid feels just like a system full of air: much more compressible than non-boiling fluid.

My money is on a leaky MC, but if there's no sign of a leak, I'd change the fluid.

Posted by: Eric_Shea Apr 4 2005, 02:22 PM

Now I'm with ya...

But after 6 months there shouldn't be "that" much water in there. Which is why I'm with ya again... M/C.

Posted by: Aaron Cox Apr 4 2005, 02:27 PM

QUOTE (Eric_Shea @ Apr 4 2005, 01:22 PM)

Now I'm with ya... But after 6 months there shouldn't be "that" much water in there. Which is why I'm with ya again... M/C.

yarg....

ill pull that acces cover/pan thing and check out the MC....

i hear they are a royal PITA to change....




one more thing... how hard is it to put in a tee instead of the pvalve?

Posted by: Grimstead Apr 4 2005, 02:30 PM

On a much more important note (because it has to do with me)

QUOTE

I thought about that today when I sent Bill calipers off to him.

Woo Hooo!

Posted by: Grimstead Apr 4 2005, 02:35 PM

QUOTE

yarg.... ill pull that acces cover/pan thing and check out the MC.... i hear they are a royal PITA to change....

I don't they are that bad.

I should have my 19mm showing up this week, maybe we can set up a MC party? If nothing else, I'm sure screw it up (I mean, fix it up ) easy enough.

Posted by: Eric_Shea Apr 4 2005, 02:43 PM

Hey Bill... take a lookie

Hey Aaron, T-valve is a breeze. Much easier than the M/C.

Posted by: Eric_Shea Apr 4 2005, 02:44 PM

Sorry Bill... forgot this.


Attached image(s)

Posted by: Andyrew Apr 4 2005, 02:50 PM

Aaron.. its about as easy as replacing the front rubber brake lines.... (the rears are a pain, which is why I didnt say it... lol)

Andrew

Posted by: Eric_Shea Apr 4 2005, 02:57 PM

QUOTE

ill pull that acces cover/pan thing and check out the MC....

I'd start inside. There's really no place for the fluid to go but in... you might see some weeping down your firewall by your mount but, if it's bad, all the fluid will be forced into your pedal assembly pan. Take out the carpet, get a 5 or 7mm hex key (can't remember which) and a 10mm socket... take the pedal board out and have a look-see.

Posted by: pete-stevers Apr 4 2005, 03:03 PM

QUOTE

Get some of Scott's Viagra....he says take two and it'll be stiff again.......

sometimes you just gotta do what you gotta do...

Posted by: Grimstead Apr 4 2005, 03:06 PM

Woo Hooo

Sorry for the Highjack aaron

Posted by: balljoint Apr 4 2005, 04:04 PM

You can't compress a liquid.

Boiled water = water vapour = gas

You can compress a gas.

Posted by: Eric_Shea Apr 4 2005, 04:08 PM

twas my point in asking...

Posted by: Joe Ricard Apr 4 2005, 08:40 PM

So I have a theory on brakes that progresively get worse.

THEY JUST DO THAT
Since brake fluid is Hygroscopic (it absorbs water)
heavy use of the brakes can make enough heat to turn the water into steam which when cools leaves air bubbles.

6 months is a long time for brake fluid. In my opinion.
Hell I even bleed the Exporer brakes every 6 months. change fluid nearly every year.
The 914 gets a bleed before every Autocross so thats once a month. Sometimes I get little bubbles sometimes not. But it is on the "nut & bolt check list"
Stock early calipers with 17mm M/C. Seems to be better than 19mm. I like it.

Posted by: Eric_Shea Apr 4 2005, 09:24 PM

QUOTE

Hell I even bleed the Exporer brakes every 6 months. change fluid nearly every year.

Yeah, but didn't we determine in a previous thread that you were crazy?



OK, OK...maybe with all that rain you Californicators have been having lately, some has made it's moist little way into Aaron's brake system and...

I hope Joe's right... If so, it'll be slightly less expensive than a MC rebuild. I thought that six months was a short period of time but.

Posted by: mrihop Apr 4 2005, 10:08 PM

The moisture in the fluid hypothesis is interesting because I have also noticed the pedal being a bit mushier and it travels a little lower. I haven't checked if my MC is bad yet. I'll try to get a helper to bleed my brakes tomorrow if I have time. I've been adding DOT 4 to my system as I've bled the brakes in the past.

To check the MC, you don't need to be driving, you just hold down the pedal hard in the driveway, and if the pedal starts to fall, the MC is no good. Bleeding the brakes can be hazardous to the MC if you're not careful. If you press down much lower than you normally push for stopping hard, you'll run the piston in the MC past all the crap that has built up and ruin the unit.

If you want to run bigger than 19mm in the future, you'll need a lot more foot pressure as you'll begin to loose the hydraulic advantage, but you'll also gain a lot more pedal feedback because every little bump in a caliper will be read by your leg.

Posted by: Grimstead Apr 6 2005, 02:09 PM

Hey Aaron,
So what's the 411 on this? I got my 19mm yesterday and will hopefully be putting it in this weekend, perfect time to work on yours....
Bill

Posted by: Aaron Cox Apr 6 2005, 02:11 PM

well... i figure i will just bleed all 4 corners this weekend.....
all depends on college workload this week...

keep me posted on what your upto tho....
MC's are a pita to install from what i hear....