How to fix/improve low soft Brake pedal with Residual Pressure Valves and seal lube

[Mini7]

Why can't you just install between the hard and soft lines?

The lines need to be secured. Stock, it’s that flat clip that locks the hard line/flex line Union. As you turn the wheels, the flex line will pull on the hardline.
This bracket is a good alternative and easy enough to fab up in most DIY garages.

Not sure if you can get a rubber lined cushion clamp small enough for the hardline. Two to hold the RPV and another just below the flex line connection. You would need to drill 4 holes and install nutserts to have a secure bolt location for the cushion clamps. Not everyone has a nutsert kit in there garage.

It’s a smart call to secure the lines and fittings. Not many other options.

If you have the stock brake lines, cut the fitting off and drill it out to the size of the RPV if the fitting is big enough......? RTV it to the RPV and use the stock clip to lock it in place. Looking at the pictures, I think the RPV is to large.

 

[GTIfan99]

Sorry, for some reason when I browsed the pics, I thought you'd put them back where you originally had them. I see the brackets and mounting location now. That's a great looking job. Sorry, tired or blind when I skimmed it the first time.

 

[pseudorealityx]

On the "bottom" of the valve, help me understand the need for 2 fittings, instead of a single 1/8" NPT to the flare. Like this: https://www.fittings.space/gbm2p-02zm-m10x10mf

 

[emichel6888]

On the "bottom" of the valve, help me understand the need for 2 fittings, instead of a single 1/8" NPT to the flare. Like this: https://www.fittings.space/gbm2p-02zm-m10x10mf

The only 1/8" NPT to 10M x 1.0 bubble flare I could find turned out to be to short so it bottomed out before touching the compression surface. You can see it on the right in this pic, it was just 2-3 mm to short:

So I went back to this fitting supplier and using these two fittings was the only option they could come up with. I could not find a single fitting that would work, at least not without modifying the fittings, and I did not want to do that. As it is that slightly longer steal fitting just barely fits, it is 13 mm long and the single fitting is 10 mm. If you can find a 1/8" 27 NPT to 10M x 1.0 DIN bubble flare that is long enough to fit please let us know.
That same supplier also sells the one in the pic, which would work if only it weren't 3 mm to short on the bubble flare end. These guys are the only ones I could find that even offer a fitting with this end to end combination. Why does Wilwood use a 1/8 NPT for there valve? Good question, there are other RPV's that use standard flare threads, but I could not find a good single fitting for those either so... Apparently this is not a common conversion adaptation.

 

[emichel6888]

I am thinking i would like to swap out the caliper pistons so they are all the same material. Ideally I would like to swap to all the dark coating since they seem to give the the least amount of piston retraction. But the other possibility would be to use all of the lighter (nickel plated?) pistons and see if those 4 PSI valves will work with consistent piston retraction on inner and outer.
Given how common these calipers are I have to assume there are plenty of options for replacement pistons, they seem to be a standard 42 mm by 30 mm. I have found a few options but nothing from Brembo or Porsche, most suppliers do not provide a lot of details about material and coatings so it seems like a bit of a crap shoot ordering them.
Unless someone knows where I can get the OEM pistons?

I found a European source but my god, for the price I could get titanium pistons so... Looking for some help if anyone knows of a good source?

 

[pseudorealityx]

Racingbrake has SS pistons.

 

[crashracer]

I think your piston area math is off on the multi pot calipers.

 

[TheBlondeFella]

Considering the TTS callipers are basically on the same car as a Golf R (and use the same master cylinder) I'm hoping that they won't suffer from a low / soft brake pedal.
I've already driven a Golf R with RS3 / TTRS 4 pots fitted and they felt fine so I'm hoping the TTS will be the same.

 

[Navi]

my stoptech st40 2 piece rotor kit if firm as a rock once did the OBD11 mods and only the tiniest bit of free play at the top of the pedal, maybe <1/10 of the pedal travel. it is a profound improvement over the stock vw brakes and is now one of my favorite things about this car. and the communication through the pedal with the pagid pads is absolutely crazy, far better than any of the higher dollar sports cars I've owned previously. at first i was worried i might have pad deposits because there was a tiny bit of feeling i could get through the pedal, then I realized I was literally feeling the slots in the rotors through the pads and then through the brake pedal. I'm also using that expensive castrol race fluid.

i am also very very picky and sensitive to how the brake pedal feels on my fast cars and i'm sure this mod you describe above would improve them but this stoptech st40 kit is the best brakes i've ever driven on a street car hands down.

when i turned up the brake pad drying frequency in the rain i did notice a decrease in my mpg fwiw also


one thing i have noticed though is that with this VW if you come off the gas really hard and fast and then immediately go to the brake i think there is some emergency feature where it automatically starts pressing the pads to the rotors so then when your foot gets to the brake pedel in that scenario it is a bit firmer and feels better. i wish i was a wizard with VCDS or OBD11 to make the car do that all the time. (which is probably what your mod here effectively does)

on a side note using titanium shims behind the brake pads made an obvious improvement on reducing heat transfer into the caliper, highly recommend those even for street car if for no other reason than to just extend brake fluid and caliper life

I feel the same way... my stoptechs are super solid and once I ditched the stoptech sport pads, the system is very linear in modulation

 

[emichel6888]

Racingbrake has SS pistons.

I see those thanks, however I am hoping to find a set of those dark coated pistons. Plus the cost is absurdly high, pistons are typically $10-$15 at most unless they are titanium. You can find titanium pistons for less than what they are asking for these SS, and I have not had issues with fluid boiling so why spend all that money?
I am hoping/thinking I can swap out some of the pistons and get the brake pedal even higher and more responsive and not spend more than $40-$50. Maybe just lubricating the outer seals might also do the trick, and I might try that as well, but there is more uncertainty with that option whereas I know those inner pistons already work well with the RPV's so...

 

[emichel6888]

I think your piston area math is off on the multi pot calipers.

I don't think so, but in what way do you think it off?

 

[emichel6888]

Considering the TTS callipers are basically on the same car as a Golf R (and use the same master cylinder) I'm hoping that they won't suffer from a low / soft brake pedal.
I've already driven a Golf R with RS3 / TTRS 4 pots fitted and they felt fine so I'm hoping the TTS will be the same.

If they are using the same piston displacement (and I believe they do) it will feel more or less the same. The only difference could be brake pedal height due to differences in piston retraction. I would guess they feel about the same as what this Brembo caliper feels with the RPV's installed, which is pretty good. How they "feel" at full engagement is mostly affected by the caliper/MC piston area ratio and that we cannot change.
I am just trying to increase pedal height as much as possible at this point.

 

[emichel6888]

I feel the same way... my stoptechs are super solid and once I ditched the stoptech sport pads, the system is very linear in modulation

Yes, we all know the ST40 is a nicer option, it also costs 5X as much so... I hope I am not giving the wrong impression here because these brakes are a really nice upgrade, maybe not as nice as the ST40 but for the cost difference it is like comparing a Golf R to 911 Turbo. If you want the ultimate, you should of just sprung for the 911 IMO. I just see that there is room for improvement in this low cost option so...
However, if you have to spend a lot of money to do that, it kind of defeats the purpose.

 

[Navi]

Yes, we all know the ST40 is a nicer option, it also costs 5X as much so... I hope I am not giving the wrong impression here because these brakes are a really nice upgrade, maybe not as nice as the ST40 but for the cost difference it is like comparing a Golf R to 911 Turbo. If you want the ultimate, you should of just sprung for the 911 IMO. I just see that there is room for improvement in this low cost option so...
However, if you have to spend a lot of money to do that, it kind of defeats the purpose.

That's a pretty flawed way to look at it.

 

[emichel6888]

That's a pretty flawed way to look at it.

LOL good point, you have completely changed my perspective!