Brake pedal feel

[simon k]

I had a chat with a brake place and the guy said the same thing about the ds2500, but thought I should go back to the Remsas again and see, I didn't think they were much good, but maybe I have better rotors now?

However, If the brakes are over boosted, then what about reducing the amount of boost?

I don't think I'd remove the booster entirely, there's a small hill near my house and I tried rolling down it with the engine not running and it was pretty hard to stop the car

Putting a restrictor in the vacuum line won't work because the vacuum will still build up to the same level, just slower, so the brakes would be inconsistent from corner to corner depending on how long it was since the brakes were used.

Reducing the total vacuum could be done with a vacuum switch and solenoid valve.

It goes manifold -> valve -> switch -> booster

When the booster has "enough" vacuum stored up, the switch shuts the valve, then you push the brake pedal and the vacuum is released, the switch opens the valve and the vacuum is pulled in the booster again...

[h100vw]

They're squishy from cold Gary, it's just that the pedal will go a bit harder after a stop with the ABS kicking in. The pads are Ferodo Racing something, I got them from Sam.. it was the same with the old pads. From what everyone is saying here, it seems like it's just a Polo thing, but some people have it better than others.

I'll pester Camden GTI, didn't think of him

Matt shut up shop. Never heard him complain about his brakes though.

[sambb]

Yeah they are Ferodo DS2500. Yeah there's better pads around but out of the crop of trackable pads that were actually available off the shelf for the Polo (QFM AR1M, EBC red/green stuff) and the good ones that have to be custom (Hawk), they were the best really. I can tell you they had a better pedal than the Remsas so I wouldnt waste your dollars expecting a better pedal with them and they are hopeless at track speeds compared to the Ferodo's, or at least I found that.
Yeah I'd thought about some sort of restrictor on the booster line too Simon because they are definitely overboosted too, so if you come up with anything I'm all ears. There is the Y-piece vacuum booster jet or whatever the hell they call it. Its on the brake booster line and tee's in a line straight from the TIP. When the mani goes into vacuum the mani will draw on the booster and also suck air from the TIP directly I assume for emissions reasons knowing VW. But I've seen it written that the venturi action amplifies the booster draw. I capped off the TIP line and removed the Y piece in the hope that would help but apart from initial placebo excitment I think it did zilch.
And yep the only way you can heel and toe is to not use your heel. I sought of use the outside edge of my shoe with side force to do it which works way better than having to lift your heel back out and onto the accelerator pedal.

[simon k]

Matt shut up shop. Never heard him complain about his brakes though.

I texted him the other day, he's using the standard parts. He suggested a restrictor in the vacuum line but I don't think that'd work

[sambb]

restrictors in air lines have the biggest impact at fast changes in air speeds rather than slow ones. So a steady state restrictor might be good for that moment when you've been under boost and then climb on the anchors ie the restrictor not allowing the booster to be fully vacuumed in that short time. You may get a harder pedal at that time but weird things could then happen where as the booster comes into play (if say you were in a long braking zone) you might find you pedal pressure has to change. But I imagine it'd be fully boosted no matter what you did at normal vaccum style driving as the restrictor wouldnt be able to play any real part then in being able to prevent the vacuum drawing on the booster because of the almost constant vacuum draw acting on the booster.

[sambb]

vacuum relief regulator. type 2 in this link. purely mechanical. they look to cost as much as a master cyl if you paid someone to do it too! so dont know if it'd be worth it. Basically it like a 'blow-in' valve for vacuum ie opposite to a blow-off valve for capping over-pressure.

How Equilibar Vacuum Regulators Work | Equilibar Precision Control

[sambb]

Controlling brake assist with a vacuum regulator - NASIOC

looks like these guys have played with the idea.

[sambb]

so it seems that Prodrive made a thing called a brake servo spacer.
STI Brake Servo Spacer

It was developed for rally cars that were running anti lag. Anti lag means you dont have inlet mani vacuum long enough to build vacuum in a booster so you can end up with an impossible pedal if running anti lag and a booster. This kit was a way to ditch the booster entirely, fit it in and then run boosterless. Dont know how that would work given that it appears to be a closed system.

[JTop]

What about ignoring the VW system and applying an electric brake option?
Seen this being used in a lot of older vehicles to combat their ancient brake systems
Power Brake - Cruisin Automotive - Dream It Build It Drive It
Just a thought for the pond

[simon k]

It wouldn't be hard to put in an elevtric vacuum pump (various VWs have them, 02 Pass at is one) button run the stock booster but it'd still need a vacuum switch to turn the pump off. Not much different to a switch and a valve..

I'm still digging for a bigger bore MC