1964marco

Hi all

Fitted new 4 pots on the front of my 98' WRX, the 4 pots came off an STi. I have fitted them ok and tried to bleed the hydraulic system in the correct sequence. I have used 5.1 dot brake fluid also.

My problem is that I have brakes all of the time, but sometimes there is excessive travel on the pedal. Sometimes the brakes are instantly there and other times an extra 2 or 3 inchs before the brakes kick in.

My Scooby does have ABS and I've been told that there is a different way to bleed ABS, is this the case?

Hope someone can help

Thanks

Marco

RON

I havew done several Scoobies, with ABS, and recently an Evo8, and i've not followed any 'special' procedure.....

One point though, and please don't take this as me thinking you're daft..... but you have got the bleed niples at the top of the caliper haven't you????

1964marco

Yes, the bleed nipples are at the top.

Do you have to bleed the ABS actuator?

Thanks

Marco

RON

I never have yet.... did you let the system drain right down.. or did you change the calipers quickly then just beeld em..??

1964marco

I first fitted the front calipers having the lines clamped off, then attached lines and bled only the front brakes. After this didnt work I assumed the whole system needed doing, so I bled all 4 brakes in the sequence found on a Subaru manual I purchased.

The manual I have does refer that bleeding brakes with ABS is different than without but.... the 3 pages on that are missing from the manual!

I assumed the system didnt have DOT 5.1 in it, so I bled alot of fluid through ensuring that there was no old fluid in the system.

Do you bleed system with ABS with ignition switch on? e.g activate the ABS pump.

Thanks

Marco

RON

Sounds like you did it all right then....... i always do it with the ignition/engine off...... less risk....

Sounds like someone more brake specific needs to read this... like Stockcar!!! Calling Alyn....

stockcar

sent you an email with a few pointers.................hope this helps
alyn

JohnD

iTrader: (5)

[QUOTE=stockcar]sent you an email with a few pointers.................hope this helps
alyn[/QUOT

Can you share any pointers with the rest of us?
I remember changing the fluid on my 99my when I had it with no special procedure?

JohnD

XRS

Don't forget - the STi IV always had a fairly soft pedal (assuming that's where your new 4 pots came from). Well, mine did anyway.

1964marco

I had the brakes bled through by a garage today.

Still having the problem, however I have noticed that if you bleed all of the air out of the lines, leave the car to stand for a minute or so then pump the pedal, air bubbles are coming back up into the brake resesvoir bottle through the master cylinder. Leaving it longer the pedal dissappears to the floor. You have to pump the pedal 3 or 4 times in quick succesion for the pedal force to increase. Doesnt inspire much confidence driving along a road towards a junction and needing to pump the brakes to slow down normally.

Reminds me of the old days with cars that arent servo assisted. (My servo is working)

Thanks

Marco

Monkeh

i wonder if the rubber seals are worn in the master cylinder ? i had a similar problem on a pug 309, i must have used a gallon of brake fluid and it still had air in it I changed the master cylinder in the end and it improved the feel a lot

samphilpot

did you ever find the resolution to this I have done the same upgrade with 4 pots from 2 pots on the fronts I have purchased different flexi lines but have bubbles coming back up and no pedal unless I pump it a few times

MrRtm

You have a leak or split somewhere, check what you've changed and go from there

John 37

This is a common problem with old master cylinders. When you bleed brakes, ths master cyl does a full stroke. This is well beyond normal travel. The push down sends fluid out of the system. That is replaced by the master cylinder sucking fluid in from the reservoir on the up stroke. If the seals are not perfect but perhaps old and hard, they let air past. That is then pumped into the system on the next down stroke. If you look at the seals, they are working backwards on the suck stroke. Under pressure they work correctly so no leaks.
Replace master cylinder seals.