924Board.org

[B]

hello

I am having some problems with the brakes - I do not appear to have any.

I have changed the front disc and rotors and rear shoes and wheel cylinders. I have also changed to the braided lines. I also changed the check valve and put it in in the exact same direction as the one that was in there already.

Everything appeared to go together ok with no visible leaks.

When I began to bleed the system (using dot 4 non synthetic fluid - a change from the dot 3) the brake pedal would not build pressure it goes virtually all of the way to the floor. I went back around again and the pedal moved up slightly but not what I would consider a noticeable amount (1").

Is there something else I should be looking for or checking?

Would there be a problem changing over fluids?

Or is it the . . . master cylinder?

I have limited ideas and experience with this

Any help would be greatly appreciated -

thanks very much
Sean
_________________
1979 924 n/a
BAE turbo
5-speed snailshell

[Grenadiers]

Get yerself a Mityvac MV8000, for self-brake bleeding and vacuum checking. Both features help a lot with our cars!

http://www.amazon.com/Mityvac-MV8000-Automotive-Brake-Bleeding/dp/B00265M9SS
_________________
'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

[v8carreragts]

Or buy speed bleeders. I bought a set for my mini van and now I will buy them for everything. You can bleed the system by yourself without anything else.

These are bleeder screws with check valves in them. I have a pressure bleeder but will probably never use it again.




http://www.speedbleeder.com/
_________________
84 944--924 Carrera GTS clone w/520HP Chevy 302 V8--RUNNING!
2015 AUDI Q7
2013 Dodge Charger R/T AWD HEMI
2013 Chevy Cruze

[StienbargerR]

You can also rent a bleeder kit from a parts store if you are tight on cash. I rented a hand pump type, and it helped tremendously. Also, make sure your rear brakes are adjusted. Sometimes if the drums arent adjusted properly it will feel like your brakes are bad. An easy way to test that is pull the handbrake up part way, and test the pedal. If the pedal feels better, you just need to adjust the drums out a little.
_________________
1978 924 NA
-250lb lowering springs, Euro Pistons

[B]

thanks everyone -

more bleeding - I will also try the hand brake and pedal test to see if there is a difference

I am going to borrow a mity vac today to see if that helps

speed bleeders look very cool - and would definitely help as I have been at the whim of everyone else's schedule trying to bleed these - my 10 year old son's calf muscle's are getting a good work out though

Am I using the correct fluid - dot 4 non synthetic? I thought I read somewhere on here that that is the fluid to use.

thanks again
Sean
_________________
1979 924 n/a
BAE turbo
5-speed snailshell

[v8carreragts]

DOT 4 is fine. Dot 4 has a higher boiling temp than DOT 3. This is basically the difference.
_________________
84 944--924 Carrera GTS clone w/520HP Chevy 302 V8--RUNNING!
2015 AUDI Q7
2013 Dodge Charger R/T AWD HEMI
2013 Chevy Cruze

[!tom]

You might have to bench bleed your master cylinder.

If your master cylinder goes dry, it can get air bubbles in it that can be very difficult to remove. The technique to remove them consists of essentially recirculating the brake fluid from the ports directly back in the top so you can pump the M/C hundreds of times in quick succession to purge the air.

Other than that, gravity bleeding can work quite well; it's far easier than pumping the pedal. Calliper/cylinder seals that are well used may very well hold back brake fluid, but they may not hold back air. So, pumping the pedal can sometimes just suck air into the system past the seals. Gravity bleeding prevents this.
_________________
78 924 NA
5-lug

[B]

thanks

bench bleed?

not to sound stupid but how do you gravity bleed the master cylinder?

I do not believe the system went dry - but it may have gotten close while working on the system and waiting for correct parts ( I had to do some back and forth shipping to get correct seals)

sorry I have not had good luck with brake stuff and it is one of those things I do not want to get wrong.

thanks again
Sean
_________________
1979 924 n/a
BAE turbo
5-speed snailshell

[Slam]

Bench bleed is literally that - pull the MC out of the car and bleed it on your workbench (some completely immerse it in brake fluid to be sure all the air comes out).

You may have an issue with adjustment rather than air. You say you R&R'ed the rear cylinder, but did you adjust the rear brakes? It may be that you're at the end of the cylinder's travel but can't get contact with the drum. The rears will pressure up before the fronts, so rear brakes that aren't right will afeect everything.

Good luck - these things can drive you nuts!
_________________
'88 944 Auto - may or may not resurrect

[B]

thanks

I am getting some pedal but still spongy -

I will re-check the backs I thought I had them to an ok spot - but for some reason they still seem out

and I agree - these do have a tendency to test you

Sean
_________________
1979 924 n/a
BAE turbo
5-speed snailshell

[B]

oops forgot to ask - - has anyone heard of an aerated line?
_________________
1979 924 n/a
BAE turbo
5-speed snailshell

[SlayerSST]

--

[fiat22turbo]

[B]

hi everyone -
I still seem (I think) to be having trouble with this brake thing
I finally got back to the garage this weekend and bled the brakes again - I did this twice more to ensure that there appeared to be no more air and the fluid was as clear as what I was putting in.

The fluid matched clarity and color of what I was putting in and I had no more bubbles coming out of the bleeder valves.

The pedal still felt mushy(?) but not too much worse than my focus that also has a disc and drum setup. It did not go as low as before -thankfully.

I was still able to pump it up about three times hard to increase pedal and hardness (this seemed to be the same with the hand brake on or off)

As expected when I started the car the pedal dropped - about 4" which seemed a lot to me - after about 30 seconds or so I could pump the pedal (2 or 3x) to get it within almost 2-3" of the stationary clutch pedal

Anyone have any ideas on what else I should check?

SlayerSST and Fiat22turbo - I am not sure that I am following exactly what you mean - pump up the brake 5x then just loosen or actually remove the line from the master cylinder? does that sound right?

sorry about the long post - this is getting a little frustrating watching the car sit through another summer

thanks again everyone for your help with this -

Sean
_________________
1979 924 n/a
BAE turbo
5-speed snailshell

[fiat22turbo]

Sounds like there is still air in the system or you have a bad master cylinder.

Did you check that the pushrod from your booster was adjusted properly before mounting the master in place? That could lead to the pistons not moving enough to move the fluid/air around.

Make sure your e-brake is adjusted as well as your brake shoes. Adjust until you can feel that they drag slightly and then back off on the adjustment a little.

Bench bleeding is where you pull the master cylinder and place it in a bench vise. You run lines from the outlets of the master cylinder into the reservoir, which is full of fluid. The ends of the lines are submerged in the fluid. Then, you slowly begin pushing on the pistons of the master cylinder to bleed the air out of the master cylinder before mounting it in the car and bleeding the rest of the system.

This might help as well:

http://www.stoptech.com/tech_info/wp_howto_bleedbrakes.shtml

Some other interesting articles on braking systems:

http://www.stoptech.com/tech_info/tech_white_papers.shtml

Good luck.
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)