Brake performance & bleeding

[rmaurer]

In the recent wet weather, I tried some braking tests in my '95 M-reg Chimaera 4.0 HC to see how much grip was available and found that regardless of how hard I stood/stamped on the brake pedal, I couldn't get the brakes to lock up, even when quite slippery out. (Sounds stupid, but I'd rather see what happens in a controlled environment before I need them in an emergency!)

While I can brake fairly hard, I cannot get a full emergency style stop...

I've checked the condition of the brake pads and discs and they look ok so I'm wondering if I need to bleed the brakes... If so, is this an easy job (worth attempting myself) or should I book it in?

The pedal itself doesn't feel too spongey and gives initially good response, but then gets very hard to press and then I run out of strength...

Cheers,
Ross

[squirrelz]

That's definitely not normal. I had a damn good slide last week when I forgot I didn't have ABS any more

[trefor]

Maybe your pads are past their best (material condition, not necessarily thickness).

First check the insde swept areas of all the discs by feel (or looking if you can) to see if the pads are making contact properly - the condition of the rear brakes makes a big difference to the feel and initial bite of the brakes (not so much to the overall power of them though). Also check the vacuum pipe for leaks (comes from the driver's side of the inlet plenum and disappears into the inner wing - if you look in the clutch fluid inspection hole you should see it go into the brake servo.

If you don't know when the fluid was last changed then it's worth doing. Ideally go for DOT 5.1 fluid over what you probably have in there (DOT 4). In theory the signal that the brakes need bleeding is either a very long pedal or spongy feelings. Brakes are from the Ford parts bin with nothing complicated to screw up. Bleed from the farthest wheel first, watch the level in the chamber - if you peer into it you'll see there are 2 outlets - not just one at the bottom so you could find air getting in the top outlet (you'll see what I mean if you stick your nose in there!).

Also, a Chimaera will probably lock it's back brakes before the fronts - are the backs locking without you realising?

T/.

[GreenV8S]

quote:In the recent wet weather, I tried some braking tests in my '95 M-reg Chimaera 4.0 HC to see how much grip was available and found that regardless of how hard I stood/stamped on the brake pedal, I couldn't get the brakes to lock up, even when quite slippery out. (Sounds stupid, but I'd rather see what happens in a controlled environment before I need them in an emergency!)

While I can brake fairly hard, I cannot get a full emergency style stop...

I've checked the condition of the brake pads and discs and they look ok so I'm wondering if I need to bleed the brakes... If so, is this an easy job (worth attempting myself) or should I book it in?

The pedal itself doesn't feel too spongey and gives initially good response, but then gets very hard to press and then I run out of strength...

Cheers,
Ross

In my experience knackered fluid makes the pedal spongey, rather than preventing you locking wheels. I've had the symptoms you describe from pads that have been severely overheated but there were lots of other symptoms too like knackered fluid giving a mega spongey pedal, brake dust all down the sides of the car and tyres that didn't have any tread left on them. This was after a very hard track day of course.

Alternatively it is possible the pads are slightly too hard for your use and they've glazed over. This is not common but has happened to me with hard fast road pads after a long rainy motorway journey. I found that driving along for fifty yards or so with the brakes on fairly firmly (left foot braking) restored normal braking.

Alternatively it could be a mechanical problem with the calipers or the brake servo preventing your foot pressure from reaching the wheels. Either way you want to fix it, you should be able to lock the wheels in the dry if you really stand on them, and you should have no difficulty locking them in the wet.

Cheers,
Peter Humphries (and a green V8S)

[rmaurer]

Cheers for the replies...

I think I'm going to replace the pads first. I've seen various pad types being mentioned and understand that the brakes are from the Ford parts bin... Can anyone recommend a particular manufacturer for fast road use and occasional track days (and if you've got the model number, that would be a bonus!)

Are the pads easy to change? I've not got a lot of hands on mechanical experience, though can usually work most things out... Any hints?

[bazza2000]

I've seen That EBC Green Stuff Pads are very good

[kevinday]

If you are going to change the pads I suggest you change the fluid as well. I normally change all the fluid every two years anyway.

[REV-EREND]

I use Tarox fast road pads and there is a good improvement over the standard pads.

Rev.