What should my brakes feel like?

[tobodestroyer]

Hi,

I keep getting the brake warning light on my S2 Avant. In the past I've just topped up the fluid level (hydraulic fluid) and all has been fine but lately the steering pump has been making a noise when at full-lock and it's then that the red light comes on.

Having read the info on Pauls excellent site, s2-central, about brakes I'm beginning to suspect that either the "bomb" or the steering pump is at fault as the brakes do not, and never have, felt as he describes them. I have a big front brake conversion (4-pot American things fitted by QR Sport but re-fitted correctly and safely by myself) with fast-road pads.

The pedal has always been very heavy with a slightly dull feel to it and it takes a fair shove to stop in a hurry; I certainly wouldn't expect it stop in a hurry in an emergency. I'm not a heavy braker and even on track days it seems OK but I've not got 100% confidence in it.

I'm comparing the stopping power to my wife's 1999 A4 Avant 1.9TDI which stops on a six-pence with its standard brakes. It has a nice light pedal and I usually try to throw myself through the windscreen at the bottom of the drive on my first press of the brakes in the mornings when I borow her car. I would expect this sort of performance from my S2, surely?!

So, should my upgraded brakes feel light and bitey or is heavy and sluggish the norm?

Also, is it vital to use the Audi hydraulic fluid or will other makes do?

Am I right in thinking that a worn/knackered power steering pump will affect the braking power and feel on the S2?

How easy/cheap is it to replace this pump if it is at fault? Or indeed the "bomb".

Sorry about the number of questions in this single posting but I'm relying on your wealth of knowledge to help me out here.

Tobo

[Animal Mother]

Don't expect your brakes to feel like those on the A4. I have a Passat (same car basically) and the brakes are awesome, BUT, and its a BIG BUT, they are either off or on. All A4s and Passats are like this in my experience.

The S car brakes (UrS4 and UrS6 are also like this) are much more progressive and are more like those brakes found on older cars. The brakes are "progressive" and allow you to apply as much power as you wish. In standard form, the brakes our cars have a good, but not brilliant, although they do take a little getting used to. The brakes on my UrS6 need a heavy foot to have them stop quickly but they burn speed off in a more controlled manner rather than relying on the ABS like A4/passats do.

With your QRS upgrade I can't comment, but, I have heard that when set up correctly they are a good set.

I can't comment on warning lights or brake bomb failure apart from the brake bomb test you can do by pressing on the brake pedal numerous times until the pedal locks up (OR goes soft, I can't remember). About 30 pumps on the pedal is right.

[Error404]

do you get any warning lights under heavy / emergency braking?
Can you feel any pulsing throgh the brake pedal (without triggering the ABS) ?
Are there any groaning sounds when turning the wheel, especially lock to lock?

There are alternatives to the Goo2000, but must be of a certain type of mineral oil AFAIK. Bombs can be had for just over £100, PAS pumps anything from £150 upwards depending on whether you get an OEM or a repro item.... Repro ones are not very well regarded. You can also rebuild the existing one.

Choice of brake pads will make a difference to "bite" but as Animal said above, the brakes are very progressive compared to newer models.

[tobodestroyer]

OK - I'm going to do some more homework on this as the "bomb" and the PAS pump are not cheap.

I'm going to start by checking the hydraulic system for leaks.

Then I'll drain it and replace with Audi fluid as I don't know what's in the system at the moment. What's the best way to drain the system?

Then I'll get the pump pressure tested and replace if necessary.

Regarding the bomb, when I pump the brake pedal with the engine off and the car cold (stood overnight), the pedal feels quite normal until about the 12th pump when it goes rock-hard. Does this lean towards suggesting a knackered bomb?

Tobo

[S2_Dave]

You can get Goo from GSF at a reasonable price and I wouldn't go anywhere else other than there or Audi, as not using this very specific type of hydraulic fluid will make seals weap and you'll be into biiig money. It was one of the very first warnings I was given.

There was a guy who re-charges the bomb (it hold some silly amount of pressure), but I think he's in America. Only 12 presses would certainly indicate it's the problem (I'm no expert though). I replaced mine on my old 20V with a secondhand item from Sanburn Audi for around £20 IIRC. It lasted as long as the car did.

[s2driveruk]

you can get a new bomb from Paulfern on ebay for about £105 which is a serious bargain, search for bomb on here and i'm sure you will find details.

The brakes on the passat/a4/a6 are so totally over-servo'd like you say when you get back into an S it feel like you are dropping an anchor

The S2 brakes are not blessed with feel in standard trim, upgrade to the 996 setup and they do come alive and the power when you give the brake pedal a good shove is immense, especially with good pads and some heat.

Also check all rubber hoses, if they haven't been changed then expect these to be mushy, my rears were in terrible shape when i removed them. stainless flexi lines will also help with power and feel for reasonable money.

Check S2central.net for the bomb tests and check the tension on the p/s pump belt too
Cheers
David

[newsh]

12 pumps on the pedal is ok.

[Error404]

i concur, both my cars are worse than 10 pumps and no pressure warnings.

Braided lines will help with p-edal feel if not already part of the set-up