mushy brakes

[hasitha]

Sorry this is a long post, but somebody might notice something I missed if they knew the whole story.

Our 97sc2 5m has about 57k now. For the last year it has been shruddering during braking. So I spent $125 at AutoZone and bought front and rear pads + rotors. When I removed the front wheels, the rotos looked almost unworn and the pads seemed to have about 75% of life left. But the tie-rod ends were shot. So I replaced both tie-rod ends with "Perfect Circle" parts from AutoZone ($35/ea) . The brand name sounds corny, but they are made in USA by DANA which is a known OEM supplier.

Even though the rotors looked fine from the outside, they were grooved and worn on the inside. Inside pads also looked like crap. Fearing seized calipers, I took them apart and replaced and lubed the pins and installed new rotors and pads in the front.

The rear brakes have not been working for a long time. Both rotors were rusted over and right rear caliper was seized solid! After punding for almost an hour I took the pins out and installed new pins. They slide fine now. Then I found out that I need a special tool to compress the rear pistons back in and all the local stores are rented out on the tool. After driving 19 miles (in my dad's car) I got the tool ($55 deposit) and installed the rear pads & rotors.

I used a self bleed kit to bleed the system and removed about 6oz of fluid, and topped off the resovoir. After almost eight hours, the car was ready. After bleeding the brake pedal was quite stiff, but as soon as the engine started and vacuum asssit kiked in the pedal got soft and mushy.
The brakes seem to work fine without the shrudeer (I'm not sure if it was the brakes or the tie-rod ends that caused it in the first place). But the soft mushy pedal feel bugs me.

Also I'm surprised that the stopping power seemed good even with rear brakes not working and only the inboard pads working in the front. It still had better brakes than our Vue. My guess is that I use engine braking and that might have made-up for whatever the brakes lagged.

I'd like any opinions on why the pedal still feels mushy. I didn't drive a whole lot tonight because it was raining and after 8 hours of working, I'm beat. I'll drive around a bit tomorrow and see if fluid level drops which might indicate a leak.

Thanks for any advice.

[amazinghl]

I used a self bleed kit to bleed the system and removed about 6oz of fluid

Did you bleed all 4 side? Did you check if there are bubbles coming out? How does it compare to your father's car?

[Richard]

You're so lucky to have rear discs on an S series. I've been working on the rear drums on mine for 3 days now.

There are a couple of possible reasons why the pedal still feels mushy. Air trapped in the lines seems to be the most logical - perhaps a bleeder was opened too much or not tightened enough when finished. Or the reserviour fluid level became too low while bleeding? Or maybe the pads and calipers haven't adjusted properly yet. Just throwing out ideas here.

[Dr. Bob]

Generally, causes for a soft pedal are:

a) air in the brake lines - (bleed all four brakes until no air bubbles come out)

b) a leak somewhere - (fix the leak, then bleed the brakes)

c) rears not properly adjusted - I'm not sure how they are adjusted with rear disks.

[hasitha]

Originally posted by Richard
You're so lucky to have rear discs on an S series. I've been working on the rear drums on mine for 3 days now. Actually the rear discs were standard with ABS/TCS which was a $695 option back in 1997.

I drove the car around a bit today and the pedal feel improved after a while. While brake feel does not feel all that different at low speeds, it is much better at high speed. Nice, linear, shrudder free, and in a straight line. I'll drive around a bit more and see if it improves. Unfortunately I can't do a full bleed of the system because of the ABS pump. So if needed, I'll have to pay the dealer to do that job.

Also, I have to hold the wheel slightly to left to make the car go straight. Looks like I didn't eye-ball the alignment well when I installed the tie-rods. Oh well, there's another $40 to have a front-end alignment.

Thanks for the feed-back.

-> Hasitha
97sc2 5m/ 02 Vue 5m

[Richard]

If you're absolutely certain that there is no air in the lines themselves and there are no leaks anywhere the only place left is the master cylinder. You can check this by disconnecting all 4 hard lines at the master cylinder, plugging the holes, and depressing the brake pedal. If it still feels mushy then there is air in the cylinder or bad seals.

Here's how to bleed it.
2. If the master cylinder is suspected of having air in its bore, it must be bled before proceeding to brake line bleeding.
2.1 Loosen left front brake pipe (front upper port) at master cylinder.
2.2 Allow brake fluid to flow from front master cylinder port.
2.3 Tighten left front brake pipe into master cylinder.
Torque: Brake Pipe to Master Cylinder: 32 Nm (24 ft. lbs.)
2.4 Loosen left front brake pipe at master cylinder 1/4 turn .
2.5 Depress brake pedal slowly until fluid is seen coming from the pipe nut.
2.6 Once again, tighten left front brake pipe into master cylinder, while pedal is being depressed.
2.7 Slowly release pedal.
Torque: Brake Pipe to Master Cylinder: 32 Nm (24 ft. lbs.)
2.8 Repeat sequence until all air is removed from front (secondary) master cylinder bore.
2.9 Loosen right front brake pipe (rear upper port) at master cylinder.
2.10 Allow brake fluid to flow from rear master cylinder port.
2.11 Tighten right front brake pipe into master cylinder.
Torque: Brake Pipe to Master Cylinder: 32 Nm (24 ft. lbs.)
2.12 Loosen right front brake pipe at master cylinder 1/4 turn .
2.13 Depress brake pedal slowly until fluid is seen coming from the pipe nut.
2.14 Once again, tighten right front brake pipe into master cylinder while pedal is being depressed.
2.15 Slowly release pedal.
Torque: Brake Pipe to Master Cylinder: 32 Nm (24 ft. lbs.)
2.16 Repeat sequence until all air is removed from rear (primary) master cylinder bore.

After this you MUST bleed all 4 corners. Alldata also recommends tapping on the calipers with a mallet to release air bubbles.

Good luck!

[wolfman]

ALL Saturns with 4 wheel DISK brakes from the factory also have ABS. I suspect that there is still air in the ABS actuator motors and that is the source of your soft pedal when the system is under power (vacuum boost assisted and ABS system powered up) I would recommend that you take the car to a Saturn retailer with a scan tool capable of actuating the ABS system and let them bleed it. While it is argueably "possible" to bleed the ABS system without a scan tool, the only "sure fire" way to do it RIGHT is with the scan tool.

[Richard]

On that year S series the ABS bleeds with the rest of the system so there really is no reason to take it to a dealer. 2000+ model years have separate reserviours that only open when the ABS orders them to.

[wolfman]

Sorry Richad but you're wrong. Just look at the ABS master cylinder on a 96' and you will see seperate bleed screws for the master cylinder ABS actuators.

[Richard]

"Now, with some ABS devices, you are actually done no matter what (Delphi's ABS VI found on 1991-1999 S-Series Saturns, for example). Bleed as above, and you are finished. Note that there are some special situations where the retailer will perform a diagnostic bleed of the early ABS units, but this is not within the scope of this article."

http://www.teamscr.com/brakes-antilock.html

[wolfman]

Originally posted by wolfman
While it is argueably "possible" to bleed the ABS system without a scan tool, the only "sure fire" way to do it RIGHT is with the scan tool.

Since we're quoting now...did you miss this part?

[Richard]

It would depend on the year. 2000+ needs to be cycled while 1999 and prior do not.

[wolfman]

So the bleed screws are just there for added expense and looks and I was factory trained how to use them (and a scan tool ) to bleed the master cylinder for no reason....

I am just trying to give you a possible reason for your mushy pedal. As it seems to be there only when the car is running and the ABS system is powered up (and has cycled the actuators as part of it's self diagnostic) it strongly suggests the presence of air in the master cylinder. As you have bled the master cylinder in the "conventional manner" it therefore suggests that if indeed there is still air in the system, "conventional bleeding" is not getting it out, so, bleeding the master cylinder the right way (or as a "diagnostic measure" using a scan tool as the link you provided suggests) would seem to be the next logical course of action. If you do not wish to go to the expense or trouble to do so as a matter of choice to perhaps correct your percieved problem is entirely up to you.

[hasitha]

Drove the car to an old K-mart lot and got to about 30 mph and slammed on the brakes to activate ABS a few times and then bled the calipers again. The pedals feel MUCH better now. Regardless of the proper procedure, activating the ABS a few times seem to have bled (at least part of) the ABS motor. Went to a local shop and got a four wheel alignment ($60) and now the car drives great!

Sad to realize, but my sc2 is an old car now, and 'll need everybody's help to keep it going... much like my old Merkur used to be. At least parts stores know and stock Saturn parts compared to the Merkur where they just had a blank stare when I said Merkur or those who knew wanted un-godly amounts of money for its parts. Thanks for all the help.