Brakes - Crap On First Press

[sotal]

I've always noticed that my brakes are a little bit crap the first time you press them in the morning, but I guessed it was something to do with surface rust appearing overnight or whatever and it just cleaned them off a bit, but the last two mornings they have been scary!

It's just the first time I use them hard in the morning they just do nothing what-so-ever and me being sleepy think wtf and go to grab the handbrake, then just before I grab the handbrake I think and take my foot off the brake and press it again and it stops.

Any reason why??? Air in the brake lines? Crap fluid?

It's also fine when I leave work at night after the car has been parked for 8 hours at work, it's just after it's been parked at home for 14 hours overnight.

It had new front pads/discs last April before the MOT

[Bibbs]

Get a fluid change, if you have boiled the fluid it'll be rubbish ..

[daktari]

One of the girls in the office at work had the same problem on her megane. The garage changed the pads and changed the fluid and all was well. So i would think it`s probably a fluid related thing.

[sotal]

Bugger - oh well atleast it's a fairly easy fix. Back discs do look a little wobbly but I'm guessing that won't have any effect.

Brakes are spot on after the first press but it's probably time they had a fluid change anyway. I can't think of any time recently that I would have boiled the fluid though. I've only had to stop hard once and that was because of a stupid Pajero - infact it only got worse since then :ffs:

[daktari]

Bugger - oh well atleast it's a fairly easy fix. Back discs do look a little wobbly but I'm guessing that won't have any effect.

Brakes are spot on after the first press but it's probably time they had a fluid change anyway. I can't think of any time recently that I would have boiled the fluid though. I've only had to stop hard once and that was because of a stupid Pajero - infact it only got worse since then :ffs:

You ought to try a gen5 GT4 ..... Thats a real !Removed! clencher

[mikeb]

I doubt it's the fluid - it's not exactly going to be boiling on the first press of the brakes. It could just be damp on the discs/pads, air in the system, or a slighty dickie servo.

I would try bleeding first, then a pad change - use genuine Toyota, and get new discs if they are shot - these don't need to be genuine.

[sotal]

Front discs and pads look and feel fine and as I said they were only put on just before the last MOT which I think was April.

I don't think Bibbs (not Leeky ;) ) was saying that I was boiling the fluid on the first press, more like he thought I'd boiled it some time before.

I drive down a couple of side roads first in the morning and it's when I come to the main road that I have to press them, I'm probably going a maximum of 15mph maybe 20 if I'm in a rush! and the brakes do absolutley nothing on the first press, this morning I was in second gear and I let my foot out to get a bit of engine braking and it seemed to accelarate! As long as I remember to lift my foot off and press again I'm fine

My initial guess was air in the system - which I guess you get from boiling the fluid? Obviously I could bleed the brakes but whilst I'm at it I might as well change the fluid as I've never changed it and haven't got a clue when it was last done.

Anyone know how much fluid it holds? I pressume it's DOT4?

[Bibbs]

I don't think Leeky was saying that I was boiling the fluid on the first press, more like he thought I'd boiled it some time before.

I'm not Leeky ..

Yeah, if you *have* boiled it, it need replacing ..

And get good pads, and you should be able to run 5.1 fluid ..

[sotal]

I don't think Leeky was saying that I was boiling the fluid on the first press, more like he thought I'd boiled it some time before.

I'm not Leeky ..

Yeah, if you *have* boiled it, it need replacing ..

And get good pads, and you should be able to run 5.1 fluid ..

Oops sorry Bibbs - didn't actually look to see who posted it just thought I'd remembered it was Leeky - oh well ;)

Pads are good - I insisted on Toyota ones after advice on here

May go for 5.1 but as I understand it 5.1 is much better at not boiling unless you do get some water in, then it allows the water to boil on it's own or something and causes a vapor lock. I'm not racing so I'll probably stick with dot 4

[mikeb]

Yes, the boiled fluid should be replaced. But only because it's boiling point will be decreased by the heat, making it more susceptible to boiling again. But I can't believe your fluid is boiling when stopping from 15mph. You don't need to replace the whole lot, just bleed it until the fluid becomes clear.

Boiled fluid doesn't generate air in the system. The brake fluid absorbs moisture over time, and it is the water that evaporates. I don't think your problem is caused by the fluid itself.

When you have the problem, does the pedal feel different (i.e. drops to the floor, or is very heavy)?

I think dot 4 and dot 5.1 both absorb moisture at the same rates. It's only dot 5 that doesn't, but then dot 5 requires a full drain and clean, which is simply not worth it on a road car.

[Bibbs]

Take the advice above .. I'm no brake expert ..

I just know that once you've "boned" the fluid, you have to bin it :)

[sotal]

Yes, the boiled fluid should be replaced. But only because it's boiling point will be decreased by the heat, making it more susceptible to boiling again. But I can't believe your fluid is boiling when stopping from 15mph. You don't need to replace the whole lot, just bleed it until the fluid becomes clear.

Boiled fluid doesn't generate air in the system. The brake fluid absorbs moisture over time, and it is the water that evaporates. I don't think your problem is caused by the fluid itself.

When you have the problem, does the pedal feel different (i.e. drops to the floor, or is very heavy)?

I think dot 4 and dot 5.1 both absorb moisture at the same rates. It's only dot 5 that doesn't, but then dot 5 requires a full drain and clean, which is simply not worth it on a road car.

I know what you mean Mike, it definatley isn't boiling when I set of in the morning. I just imagined it boiling some time before, maybe last week and all the water evapourating that was in the fluid and making air pockets which were now travelling about???

As for the pedal - it feels completely normal - no heavier or lighter than usual.

Just out of interest what is the service life of brake fluid??

[mikeb]

Just out of interest what is the service life of brake fluid??

I think most people say to change it every two years or so. Mine is still on the original brake fluid and front discs! :!Removed!: But I will change them soon, honest. As mentioned the fluid absorbs moisture, and this can cause also cause the abs pump internals to corrode.

I would have thought the pedal would be spongey if there was air or boiling in the system. Your symptoms match the characteristics of damp brakes, but I've never heard of it affecting disc brakes before, only drums.

[sotal]

hum, interesting!

Well I think I'll do a full change of brake fluid as that will then bleed them at the same time. I have owned the car for nearly two years and I've never changed the fluid and it could well be on the original stuff. If that doesn't sort it or make me notice anything else wrong then I'll have to pop it down to the local garage for a once over.

At the end of the day it's no major problem (until I forget one morning!)

[paseoGT4]

sounds to me like you may have a minor leak somewhere, or as other people have said the brake fluid might have gone bad.

[martin_longbow]

Eye, general clean up and flush the fluid. The service life of traditional Dot 3 or 4 fluid is 5 years but given wot's been said I would change it. Dot 4 will be fine, think you will need about 2.5 litres for a full change. I just bought a 5 litre tub of dot 4 for £14

Give your disks a little clean and scrape your pads over Emmery paper (sand paper but my spellign is pash) laid flat but given that you have got Toyota pads it's unlikely to be the pads.

At least if you flush and bleed your system you can note the level when the job is done and monitor any leeks

strange that it is only in the morning after 14 hours idle and not the same after sitting at work but that's cars for you, strange indeed. I would have expected it to be the same on both occasions

[sotal]

Right I was able to test it a bit better this morning as I was a bit more awake.

This is what I did this morning:

Got in car, started up and set off, travelled 3 car lengths to end of road, speed hardly registered. Pressed brake very gently at the top and it slowed down as required until I could see round the corner then I set off, I took the next right without braking and accelerated up to exactly 20mph. Approx half way down the road I thought I better try them incase nothing happened, pressed them as per usual and nothing happened, so I pressed harder and it went a bit soft and the pedal went much further than usual, then the pedal firmed up and the brakes went on hard, ABS even kicked in as I went over a grid. I set off again and pressed the brake at the end of the road and all was normal again.

I tested it last night, and it definatley doesn't do it at night - which I find strange but it's now happened everyday without fail at the same point for the last 3 days running.

[Bibbs]

So it's soft at the first real push .. defo get the fluid done.

Or, pump the brake before you set off. Idon't wanna be reading another "I crashed my car" story please.

[sotal]

So it's soft at the first real push .. defo get the fluid done.

Or, pump the brake before you set off. Idon't wanna be reading another "I crashed my car" story please.

I don't want to be writing one!

[mikeb]

That sounds like air in the system to me. Not sure why it only decompresses overnight though.

[sotal]

I guess the only possible answers to that are temperature? and length of time? I guess it's nearly double the amount of time that it's sat at night compared to when it's sat in the day.

I'll try and get a minute or two to change the fluid on Sunday. Might as well go for a full change to make sure it's in tip-top condition!

Do I need any special equipement like a brake bleeding kit or should I be OK just pumping the pedal with the bleed nipple undone?

It's years since I've done a brake fluid change on a car, I did the bike about 2 years ago, but that was different as you have to reverse bleed that by pumping the fluid in from the bottom.

[mikeb]

You will either need a patient assistant, or a bleeding kit.

[martin_longbow]

As mikeB said. You can let them gravity bleed to help fill up the cylinders but you will defo need one or the other. To reduce the time you need an assistant try

Using a g clamp to push the pistons back into the callipers. Will also help expung the old fluid

let eveything flush out

ensure all pustons are as fully compressed as possible

leave all bleed nipples open and let drip for a little while 10 mins at least

fill at top up point in engine (cant spell reservoir)

keep topping up until you have nice fresh fluid dripping out of nipples

DONT pump brakes with the niples open. It draws air back in.

If you do above then shut all niples get your assistant and then start the old routine

Shut nipples, pump brakes, hold pedal, then open nipples until pedal depresses.

Continue untill no air in fluid, start from front and work to back. Some folks like to put a hose from the nipple into a bottle with fluid in it to reduce the chance of air getting in but I dont. I am happy to clean up garage floor when done.

I always like to leave to settle for an hour or so and have a final bleed after testing on the road

[GT4 BOOSTER]

crack open a bleed nipple , dont press anything and let it drip till your resovoir is emptying , simply top it up and let it run out once more , top it up again and tighten up the nipple , this is how i'd do it. gravity bleeding - if after this its no better have an assistant pump the pedal while you crack your nipples.

sorry didnt see post above , tired you see. been to work 12 hours yet again.

[daktari]

I got one of these.

Which allows you to presure bleed the system using the spare wheels pressure. Very quick and worth the £24

Or you can get one of these from somewhere like Halfords for about a fiver.

Bit slower but still has the benefit of letting you do it yourself.