Brake Bomb Replace

[5cylinderman]

Does the bomb actually assist the power brakes under normal conditions or does it only just act as an accumulator in the event of a pump failure?

[A1QSHIP]

Does the bomb actually assist the power brakes under normal conditions or does it only just act as an accumulator in the event of a pump failure?

The "bomb" acts as a high pressure fluid reservoir to provide brake assist during repeated on/off braking events. A standard vacuum operated system has a reservoir "booster" (the large metal tank that the brake master cylinder is bolted on to) that holds the vacuum for braking effort assist. Unlike the vacuum boosted systems that only offer a few assisted braking events whenever the brakes are applied with the engine off, the properly operating hydraulically boosted systems offer 20 or more assisted braking events. Vacuum is produced by the engine in the intake manifold at idle, part throttle & during deceleration. With a turbocharged engine there is less vacuum produced in the intake manifold during part throttle than in a normally aspirated engine . During spirited high speed driving with repeated braking events such as at a racetrack the vacuum boosted systems can run out of available vacuum & make brake pedal effort higher. The hydraulically boosted systems do not suffer this condition but you have more complexity, cost & weight with hydraulic assisted brake systems.
HTH, Chris

[varia]

A1QSHIP said it well. And probably it was a nice propaganda/marketing speech back in the days.
But dont forget only audis from that era were using brake bomb, right after that audi got rid of it and went back to vacuum booster. Must be a reason.

[5cylinderman]

I've driven several Sierra Cosworths which had OE power brakes that actually worked. Even the good old Range Rover P38's had decent power brakes, as did the later Classics. Jaguar's XJ6 system even worked well. What in all that's holy did Audi do with their design. I have refurbed calipers all round with a fresh genuine pump, albeit with my ding ding brake bomb pressure alert on start up, and my brakes are still way below average, even with decent pads all round.
I have a new brake bomb on the shelf ready for fitment, but I'm already swayed to go to servo assistance.

[A1QSHIP]

A1QSHIP said it well. And probably it was a nice propaganda/marketing speech back in the days.
But dont forget only audis from that era were using brake bomb, right after that audi got rid of it and went back to vacuum booster. Must be a reason.

First generation BMW 7 series & second generation 6 series had hydraulic assisted servo boost as well. Now I am dating myself.

Chris

[Error404]

The hydraulic system is Audi over-engineering at its finest. I am sure it works great when new and there are some benefits to it. The problem is that in order for the bomb to provide adequate assistance it needs to be properly pressurised. As soon as the accumulator has been manufactured the pressure inside is slowly depleting as the gas leaks past the diaphragm. When the pressure is reduced, there is less force acting on the hydraulic circuit so more of your pedal effort goes into compressing the gas in the accumulator rather than being transferred to the braking circuit, thus you need more pedal effort for the same braking effect and the brakes feel even more wooden as the hydraulic circuit has a damping effect.

The vacuum system is simpler, cheaper and more reliable and coupled to a vacuum reservoir it is just as effective as the hydraulic system on a boosted car. IMHO this is why Audi ditched the system a long time ago.

[PeteRR]

I'm in the same position you are.

I've just re-read my Email, Paul wrote "Around June-July I will have more information when these will be available again."

Has anyone heard any more on the Bomb availability from Custom Auto Craft lately?

[rynaqui]

Pete @ Quattro Corner sorted me on mine

[Tom_]

Guys any experience with remove a bomb system and go over to vacuum brake system on N/A 7A Coupe? I am not sure if its everything right, but i have brembo 4 pots brakes, HAWK HPS pads and brake pedal is still too soft( there is something such a gap around 2-3mm when is no brake power, after that brake power can feel) in my opinion. Brake reservoir is full, need check PAS reservoir. Maybe a new bleeding brake procedure. I am not sure if the brake bomb have a share, or its just air in the brake system. I am not sure, but is there any instruction, how bleed ABS?If there is air at system.

[Kiku]

I have 20vt and right now with one camber v6 vacumbooster with 25mm 7a/3b master cylinder.
* Fronts are 4pot brembo(bmw) 323mm rotors
* Rears s4/s6 43mm girling, 280mm rotors
* No ABS
* No pressure regulator under the master c.

Brakes are Superb, but when there is very hard brakeing - there is quite a lot nosedive.