Soft Brake Pedal

[Syborg Twin Turbo]

Re: Soft Brake Pedal

There was a topic on this years ago.

Shoot me an e-mail and i'll forward you the old syty.net topics that helped me.

Basically you need to bleed your brakes without pushing on the pedal and you need to go out and brake hard a whole bunch of time to get the ABS unit "Airless" it took about 5 time of gravity bleeding and truck thrashing to get the air out of the ABS Unit

 

[Syborg Twin Turbo]

Re: Soft Brake Pedal

Jeff Stabell
01/21/98 09:39 AM

To: SyTy@syty.org @ SMTP
cc:
Subject: Brake Bleeding Tips

It seems there has been a few questions on brakes the past couple of days
so I thought I would throw my 2 cents into the ring.

Brake Work/Bleeding Tips:
1. Brake bleeding generally only necessary when a Caliper or Wheel Cylinder
is replacedor other parts. A brake pad change does not require any
bleeding.

2. When changing a caliper or wheel cylinder, to prevent a lot of brake
fluid from flowing out the open (unscrewed) brake line do this: Use a old
broom handle and a vice grip to push the brake pedal down and hold it. Put
one end of the broom handle through the steering wheel and down against the
pedal and push down hard. Then take your vice grip and grip it on the
broom handle just below the steering wheel. The vice grip should hold the
broom stick down which then holds the pedal down. This will result in an
initial small squirt of brake fluid then it will stop. Otherwise would
continue to drip until you screwed the line back on.

3. When bleeding start at the wheel farthest from the Master Cylinder...IE
Rt Rear then Left rear, then Rt Front, then Left front.

4. Have an assistant help you. Have them pump the pedal 3x. Make SURE
that they are taking at least 3 seconds between pumps (foot OFF the pedal).
On the 3rd press of the pedal have them hold it down and say "OK" you then
crack open the bleed screw (of course have the appropriate clear hose and
1/2 full container to catch the fluid) when the fluid stops being forced
out (only takes 2-3 sec) then close the bleeder screw. Then have the
helper pump the pedal again (3X as above). Do it until you see no bubbles
come out in the clear brake bleed tubing.
It is VERY important to have that 3 second pause when pumping or else the
Master Cylinder will not have enough time to grab more fluid...

5. Check the brake fluid level in the Master Cylinder Reservoir after every
4 th (Wheel Cyl) or 3 rd (Caliper) brake pump. Refill as necessary and put
the cover back on. Failure to put the cover back on will result in Brake
fluid being sprayed all over out the top. Failure to keep the fluid up will
result in the Master Cyl pump more air into the system and then you should
start over and then do step 6.

6. If a ABS unit or Master Cylinder was replaced or brake fluid got too low
when bleeding, then after the initial bleed at each wheel take the truck
out to a safe area and do 2-3 ABS stops from 40 MPH. Then bring the truck
back and repeat the bleeding steps. Should be fine after that.

Later,
Jeff Stabell

 

[Syborg Twin Turbo]

Re: Soft Brake Pedal

ABS PROBLEM?
Date: Mon, 31 Aug 1998 10:12:16 -0400
Sender: owner-syty@syty.org
Hello List Members,
I own a TY with 30K on it and totally baby the truck. I don't know if I
am
having that ABS problem that I hear that our trucks have. Here's what
happens: When driving at high speeds (anything above 70mph on the
interstate highway) and I slam on the breaks there seems to be a loss of
pressure in the breaking system. The problem does correct itself very
quickly, but for that fraction of a second my heart goes into my throat!!!
The ABS light doesn't come on and so far no codes show. The problem only
happened 3 or 4 times. I don't race or beat on the truck at all, in fact
it's a Sunday driver. Can anyone help?? Is this the notorious ABS
problem????? Is there anything I can do to stop it?

From your description it does not sound like a ABS problem. It sounds like
the water trapped in your brake fluid is turning to steam from the heat...a
70 mph stop on dry pavement puts ALOT of heat into the pads and such...
Steam (which is a gas) compresses and you feel the pedal drop a little...or
maybe firm up after pumping 1 or 2 x...when the brakes cool down you are
ok..the steam turns back to fluid (noncompressable)

Brake fluid is DESIGNED to absorb water (called Hydroscopic). It absorbs
the water in order to prevent rusting inside your brake parts. This
"absorption" is the reason everyone always tells you to use a NEW bottle of
Brake fluid and not one that had been open for a while...it only absorbs so
much water....then it is useless for this...Likely your brake fluid has
absorbed it's quota of water and now has some actual water in the
system...hence the steam...

Bad news:
If your brake system has not been flushed about every year or two you could
cause further problems by trying to fix this...
The ABS unit in our trucks is very sensitive to debris in the system and
will clog up....sediment occurs in the brake fluid after a while and if it
is pushed through the ABS unit then it can clog it...there is no way to
clean it...you would then have to replace the ABS unit....This also happens
when you get your brake pads changed and the tech does not open the bleeder
screws when forcing the calliper piston back into the calliper (to fit new
pads)....

SO what to do:
Well, I would suggest you replace all your fluid this way....first pump all
the fluid out of the mastercylinder Res. through the top of the unit...NOT
pushed out the brake system!!! Then take a clean rag and soak it in some
NEW clean brake fluid and use it to clean up any residue left in the Master
Cylinder reservoir You may want to use compressed air at the end to blow
out the reservoir of any left over debris...

Then Fill it up with clean fluid....open each of the bleeder screws one at
a time and let fluid run out till it looks clear...make sure the reservoir
is not allowed to get to low...do the same at each wheel.

After this is done you will likely have to bleed the air out of the
system....then you are done...

Please do NOT put in any of that Silicon Brake fluid...it is very bad for
the seals and reacts poorly with the stock brake fluid...

Please be aware that if the fluid has not been changed regularly that this
procedure still MAY cause the ABS unit problem described above....but the
above procedure seeks to minimise the chance.

Later,
Jeff Stabell
KC....Whooohooo! Can I leave now? (Boss won't like it!)

 

[typhoon92]

Re: Soft Brake Pedal

Good info!!
See my problem is that i have not touched the brake system at all before this happened.What happend is the abs light came on and then the brake pedal became soft all of a sudden?What can it be abs unit?

 

[Syborg Twin Turbo]

Re: Soft Brake Pedal

Good info!!
See my problem is that i have not touched the brake system at all before this happened.What happend is the abs light came on and then the brake pedal became soft all of a sudden?What can it be abs unit?

yep sounds like your unit went bye bye

 

[typhoon92]

Re: Soft Brake Pedal

yep sounds like your unit went bye bye

That's what I thought...

 

[SYO237]

Re: Soft Brake Pedal

Yanking the ABS was one of the more satisfying things Ive done on the Sy and didnt have the guilty feeling I have when yanking stock parts.

 

[typhoon92]

Re: Soft Brake Pedal

I finially solved my soft brake pedal problem by removing the ABS unit and installing the ABS delete kit.