Soft Brake Pedal

[thatch]

Hi,

I have 2002 avensis d4d. I recently changed the front passenger side brake caliper with a second hand one. Ever since the car has a soft or spongy brake pedal. The car brakes well enough but the pedal goes way too far in. I had it bled at all four corners manually several times and this has made no difference. I had a brake test done on the car and it passed that no problem. Would bleeding again using a pressurised bleeder make any difference or could it be something else? Thanks in advance for any help.

Paddy...

[Konrad C]

Yes. It will make a difference, in line with a one man bleeding kit.

I found that using a higher pressure may help, but not too high.

Konrad

[Exvec]

You need to bleed it using an Easibleed kit mate,the pressure build up will force the air through the system,i had the same problem on the Vectra when i changed the abs pump on it,

[Druid Boy]

Go find a nice quiet road or car park and give the brakes a good squeeze until the ABS kicks in. At least that way you will have confidence that the brakes are strong enough to overcome the tyres and therefore able to stop you in a hurry.

Often when we work on our own vehicles we become a little paranoid that we may have messed it up. A friend of mine rang me in a panic that having serviced his bike himself he thought it sounded really noisy. 'Put your crash helmet on and see how noisy it seems then' I told him. Not noisy at all as it happened, he was just doubting his own ability.

[Uncle Buck]

This is a regular problem when replacing calipers - a tiny bit of air gets into the system & suddenly your pedal goes all 'mushy'. I've had this happen twice on different cars. As stated already, usually a high pressure bleed will sort it out & give you back that firm pedal 'feel'.

[Konrad C]

Go find a nice quiet road or car park and give the brakes a good squeeze until the ABS kicks in. At least that way you will have confidence that the brakes are strong enough to overcome the tyres and therefore able to stop you in a hurry.

Often when we work on our own vehicles we become a little paranoid that we may have messed it up. A friend of mine rang me in a panic that having serviced his bike himself he thought it sounded really noisy. 'Put your crash helmet on and see how noisy it seems then' I told him. Not noisy at all as it happened, he was just doubting his own ability.

I understand what you are saying, but this should only be a temporary measure because the brakes will still have air in the system. After a while the pedal will be firmer - the air has been compressed into finer bubbles. Repeated heavy braking like descending hills, could cause major brake fade.

A complete high pressure bleed is the safest way to remove the air from the system and return the pedal to the firm feeling you had before.

Konrad

[Exvec]

It has been known before that when changing callipers/pads if the bleed nipple isn't open when squeezing the pistons back in it can cause the seals in the master cylinder to flip because of back pressure,not saying this is your problem but it does happen.

When i work on the callipers / pads i tend to open the bleed nipple back a tad not too much and this will take away that risk

[thatch]

Thanks for the replies. I took it to a local garage today and he used a bleeder that screwed onto the fluid reservoir with a small plastic bottle attached with new fluid in it and then connected it to the car tyre! He probably only drained out about 100ml altogether. This did not help the brake pedal at all. My thinking is that the car tyre wouldn't give enough pressure and also would expect to put at least one litre through the brake system? Phoned around other garages...most of the big garages don't do pressurised bleeding!

[Exvec]

It should have done the trick my friend if he used an easibleed type kit on it.

If the pressure bleeding alone does not work (i.e. the brake pedal remains 'spongy').

Try pressing the brake pedal while the pressure bleeding is in operation (i.e. carry out

pressure bleeding and conventional bleeding simultaneously).

You only need about 20psi to carry out the bleed so the tyre should have been adequate pressure wise.

[thatch]

Just to update...I took off the brake caliper that i had changed and the pads are badly worn to one side on both pads. Best way to describe it is as the pad sits in the caliper the inside of the interior pad is worn long ways nearest the centre of the disc and the outside pad is the opposite of this worn long ways nearest the outside of the disc.

[Exvec]

Right Thatch sounds like your actual Calliper is at fault then,time to get back to the supplier me thinks.

[ianrp1]

I had exactly the same problem with my 2002 1.8 vermont estate. The solution was to thoroughly clean up and lube with suitable brake grease all the spring clips and area that "slide about" in the caliper mounting. I think corrosion gradually builds up and seems to restrct the movement of the caliper - hence the soft brake. My local garage now knows that my calipers need rempoving and thorough cleaning and lubing before thay go back on. Result now always a good firm brake pedal. For the past 3 years.

It also caused a disc to warp badly, and then did exactly the same to a new one - but I had it skimmed as well as stripped and clesned, been 100% OK for 3 years now (2002 from new 140 000 miles!)

[fractureman]

After all this if it keeps happening it is cheap pads. I just done a focus mk1 & discs worn on inner side due to cheap pads.

I use Delphi pads on a mintex disc & works fine.

I changed my brake fluid & sorted all my brakes out fine.

My 99 avensis on 188k is fine on brakes ;)