Weird Brakes

[Parthiban]

Had to make a proper emergency stop while a out a short while ago (an idiot in a van was just reversing into the road without looking), luckily it was only at around 30mph but when I jumped on to the brakes the pedal was rock solid. I really had to push the pedal hard to make the car stop in a hurry.........

Is this something I should be worried about or just a one-off? It was literally just a few minutes after starting the car so nothing would have been up to temp yet.

[colbecoz]

Sounds like you lost pressure in the brake servo unit.. Is your brake fluid topped up properly, or any lights on in dash board?

Had to make a proper emergency stop while a out a short while ago (an idiot in a van was just reversing into the road without looking), luckily it was only at around 30mph but when I jumped on to the brakes the pedal was rock solid. I really had to push the pedal hard to make the car stop in a hurry.........

Is this something I should be worried about or just a one-off? It was literally just a few minutes after starting the car so nothing would have been up to temp yet.

[Parthiban]

Sounds like you lost pressure in the brake servo unit.. Is your brake fluid topped up properly, or any lights on in dash board?

That doesn't sound good, no warning lights or anything, and had my front pads and discs replaced a few months ago so hope the brake fluids ok.

After that the brakes were absolutely fine though.......

[whiteman]

Sounds like it could be your ABS brakes working and doing there job as you say you junped on them really hard so therefore they did not lock up due to the ABS working correctly by putting the brakes on/off very quickly giving you the feeling that the pedal is very hard...

nowt to worry about just the car is looking after you if you know what I mean...just try it again in a safe place...

hope it helps you mate

[ormi]

agree with above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[Parthiban]

See I wondered if it was the brake assist too as I jumped off the accelerator really quick, but then that shouldn't require me to press the pedal harder should it? I thought it was the opposite, the car definitely wasn't going to stop until I really stomped on the pedal.

Tried it again straight after and the car behaved exactly how I normally expect it to, there was a little pedal travel and then you can also feel through the pedal when the ABS is activated.

[Steviewevie]

You don't need to press harder when the ABS is working, no. But when the ABS kicks in the feel of the brake pedal is usually completely different, and it can trick you into thinking the brakes aren't working properly. Usually you can feel it "pulsing" through the brake pedal, which can feel like it's skidding - did you feel something like that ?

[Parthiban]

Yep I felt the ABS pulse after I really pushed hard on the pedal.

[MarsdenDean]

My new car used to do that (Used to be my dads) Lexus Fitted new servo, disks pads and loads of other things just outside warranty for free, as he hit someone due to this. First thing in a morning it used to travel very far with pedal pushed fully hard.

I always pump them a couple of times just to make sure there working!

[Parthiban]

My new car used to do that (Used to be my dads) Lexus Fitted new servo, disks pads and loads of other things just outside warranty for free, as he hit someone due to this. First thing in a morning it used to travel very far with pedal pushed fully hard.

I always pump them a couple of times just to make sure there working!

The definitely doesn't sound good, yep I'll make sure to pump the brakes too, but to be honest, I had reversed off the drive on the brakes (it's an auto) and all felt fine............

[Steviewevie]

That does sound a bit weird Parthiban. I wonder if it's worth taking to Lexus so they can double-check that the ABS is working ok via their diagnostics ? e.g. if you look here there are lots of things that their diagnostics can pick up.

[kev dood]

Wonder if it could have had anything to do with as Just turned the car on and not warmed up, then auto choke would have been out? Revs therefore higher than usual - can that have a similar affect, as "engine" trying to drive car forward with a bit more oooomph than normal?

Might be worth trying it again from cold. Drive down the road then leap on the peddle.

[Parthiban]

Might be worth trying it again from cold. Drive down the road then leap on the peddle.

Ok did the same thing again today, and it did exactly the same thing.........kept doing it all the way down the road and it was only after the 4th start stop that the brake pedal felt fine.

Is this normal that it takes maybe a minute to get the fluids going properly in the system or is it possible I have a fault? After that the brakes are 100% fine (so far anyway).

[Steviewevie]

That doesn't sound right to me, I'm not aware of anything in the braking system that should take time to "warm up" etc.

It might just be that there is some air in the system and the brakes need bleeding.

[Parthiban]

Think I might get this checked out just to be on the safe side, cheers for the replies everyone :)

[MarsdenDean]

Same problem as mine. It took lexus a long time to sort mine, and it still has the odd spell now.

Like i say, they replaced a hell of a lot of parts, and are Mintex pads standard from lexus, as mine has mintex pads on, and there fitted by Lexus Stockport!

Thanks

[Parthiban]

I only had my pads and discs done recently at WIM, is it possible that something wasn't right there? Did you ever find out what was causing the problem in your car? I hope I don't need a new servo as that sounds expensive........ :shutit:

[johnboy]

It does sound like a servo related problem.

[steve2006]

One test you can do is to sit in the car with the engine off and pump the brake pedal several times until the pedal is hard with no travel then keeping the pedal pressed down start the engine and you should feel the pedal drop slightly this would indicate the servo is working.

Another test is to pump the pedal as quickly as possible with the engine running at idle and watch the rev counter it should fluctuate slightly during this process as the servo vacuum demand alters the manifold pressure.

I not familiar with the IS but on mine with traction control it has a high pressure nitrogen cylinder which I believe also has a bearing on the ABS modulator system and there have been cases of this cylinder leaking or running out of it's gas charge.

I would have thought that if it was anything major some warning lamp would be on.

[Parthiban]

Cheers Steve, I'll give those tests a try when I have a chance - yep I'm sure it can't be a serious problem at the moment, but worried that it might progress to something worse, will have to get it checked out as soon as I have some time.