Brake pedal travel
Submitted: Saturday, May 31, 2008 at 11:48
ThreadID:
58218
Views:
1847
Replies:
4
FollowUps:
5
This Thread has been Archived
Member - steve H (QLD)
Hi all
Ichanged the front right rubber hose on the brakes today due to a small leak which was causing the callipers to stay on slightly.Now the brakes work perfectly except for the pedal travel an extra 50mm down than it did before.As i said the brakes work perfectly but this extra travel feels uncomfortable. I have bled all wheels twice but still feels odd.I had my son in the drivers
seat and when pedal fully down tightened up the valve and repeated many times. Is this the correct way or is there some knak to doing it. I have done it on many other cars and never had a problem.Maybe there was to much preasure before and i just got used to it???
90gq rb30
Steve
Reply By: Member - Mark G (NSW) - Saturday, May 31, 2008 at 12:16
Saturday, May 31, 2008 at 12:16
steve h; your nearly there,when your sure of all the air is out of the system,have somebody squeeze the brake pedal down at a steady rate and as they are doing this nip up the bleeder valve.make sure they are not at the end of the brake pedal travel.this should get you out of trouble,cheers!
AnswerID:
306928
Follow Up By: Member - steve H (QLD) - Saturday, May 31, 2008 at 12:34
Saturday, May 31, 2008 at 12:34
Will do that. Just had the neighbour (mechanic) feel the pedal and said its ok. It seems that having a pin hole in it raised the preasure and i got used to it. Still feels real strange but.
Steve
FollowupID:
572781
Follow Up By: blown4by - Saturday, May 31, 2008 at 18:04
Saturday, May 31, 2008 at 18:04
When you open the bleeder keep it open until the brake pedal has travelled all the way to the floor and make sure they keep the pedal down until you have nipped up the bleeder. Repeat the process until all air is out of the system with the assistant "pumping up" the pedal each time in between you opening the bleeder. All you are doing is letting the fluid and air escape under pressure when the pedal is pushed down, and by closing the bleeder before the pedal is allowed to retract ensures that air is not sucked back in to the system and the master cylinder receives another charge of fluid from the reservoir replacing the fluid and air that you have let out.
FollowupID:
572844
Reply By: Bushtrek - Saturday, May 31, 2008 at 12:57
Saturday, May 31, 2008 at 12:57
Almost certainly you still have an air bubble in the caliper, this due to the lack of "turbulance" during the bleeding process.
One way to try and dislodge the air is to pump up the pressure, then open the nipple while there is pressure on the pedal and with the engine running.
May have to try this several times, as sometimes the air bubbles can be quite "sticky".
If this fails then a pressure bleeder is required.
AnswerID:
306935
Reply By: Splits - Saturday, May 31, 2008 at 13:18
Saturday, May 31, 2008 at 13:18
Steve
I have just been wondering how a leaking brake hose can cause a caliper to stay on. The only way that can happen is (1) there is still hydraulic pressure acting on the caliper piston after you take your foot off the pedal or (2) the piston is partially or completely seized or (3) if you have a floating caliper, the two halves may not be sliding freely on their locating pins or slides.
Seized calipers are very common, particularly when cars get a few years and ks up on them. It might not be a bad idea to
check yours because you might have two problems and a new hose has only fixed one of them.
Brian
AnswerID:
306942
Follow Up By: Member - steve H (QLD) - Saturday, May 31, 2008 at 14:56
Saturday, May 31, 2008 at 14:56
I have been told (by a mechanic) that when you take your foot off the brake that fluid will run back and with a pin hole there isn't enough suction to pull it and could be sucking air. Anyhow I am going to
check the callipers tomorrow and grease the slides just to be sure. Being siezed is a possibility as the GQ was rarely driven up until 6 weeks ago and now it's my daily drive but I only do about 150ks a week so it may need a good workout.
Steve
FollowupID:
572792
Follow Up By: Member - Barnray (NSW) - Saturday, May 31, 2008 at 22:10
Saturday, May 31, 2008 at 22:10
Sack your mechanic. for a start the relief of the brake pads on disk brakes is actually done by the seal in the calliper and the shape of the groove it sits in. The seal is set in a way that it deforms when the brakes are applied and will apply a returning force to the piston (about .002") to remove brake pressure. That is why all slides and other parts must be
well looked after. B
ps Do not grease slides just make sure there is no parts seized.b
FollowupID:
572881
Follow Up By: Member - Barnray (NSW) - Saturday, May 31, 2008 at 22:18
Saturday, May 31, 2008 at 22:18
PS lubricate the pins and bushes with the recommended grease.B
FollowupID:
572885
Reply By: blown4by - Saturday, May 31, 2008 at 17:58
Saturday, May 31, 2008 at 17:58
If you have an extra 50mm pedal travel since you changed the hose, and assuming you did nothing else, then you definitely have a problem that MUST be rectified. You most probably have air in the system and the only way to get it out is to bleed all the brakes lines and you DO NOT need the engine running to do this simple task. ALWAYS start at the the wheel furtherest away from the master cylinder and have someone pump the pedal and hold foot pressure on it while you open the bleeder at that wheel. Best to use a ring spanner on the bleeders as they "round off" easily and if they are very tight be careful not to break them off. Also if you attach a short length of clear plastic tubing that fits snug over the bleeder you can drain the fluid into a container and also can see if any air bubbles come out of the system. As you do each wheel top up the master cylinder and DO NOT let it run out of fluid or more air will get in to the system. The last wheel you do will be the one closest to the master cylinder and if you follow this process you will get all the air out. It has worked for me for the last 42 years.
AnswerID:
306982