2008 Polo GTI 9N3 brakes and brake master Cylinder upgrade - ESP question

[pologtiforfun]

Hey Gav,
That's cool totally understand you get busy at times. Definitely happy to take you're advice on this one and learn from someone like you who has more experience then me on this one.

[h100vw]

Bolted from the outside but access is shocking with the engine being so close.

[pologtiforfun]

Thanks Gav,

i have checked where it is and access is pretty tight.

Just reflecting on your comment

"ESP on the mk4 chassis also has a yaw sensor. More sophisticted than the Polo set up. It has rear drive to control as well. "

Are you saying the mk4 polo gti has yaw sensor over the standard polo or are you talking about the mk4 golf ?

[simon k]

Are you saying the mk4 polo gti has yaw sensor over the standard polo or are you talking about the mk4 golf ?

MK4 Golf... 9n Polo is MK4

[sambb]

I found the ESP sensor under the drivers seat (could have been passengers) and it was a lat/long G sensor. The part number didnt come up with yaw sensing.

[h100vw]

I am talking MK4 Golf chassis, not the Polo, which I would identify as 9N3. That includeds, Bora, 8L S3 and 8N TT

[pologtiforfun]

ok so the polo 9n3 chassis has a dumbed down version of the esp so to speak...

in regards to the MK4 chassis etc...did the yaw come standard or was it an optional extra ?

[sambb]

Just thought I'd let you know mate that the traction controls' throttle cut was successfully cancelled on my car. So if you don't press the 'ESP' button on the dash (which is really just a traction control on/off button), thereby leaving the traction control in its default on position, there now will be no throttle cut but the EDL brake modulation which is factory active below 40km/h is still active. From what I could glean from the tuner, as far as he could see it was a situation where the throttle cut could only be fully on or fully off. We'd been hoping that it could remain in place but have its influence damped down so that it would actually be functional but not so, so it was removed altogether. His concern with killing off the throttle cut was that in wheel spin conditions the ECU might chuck a wobbly and not seeing the rpm arrested as suddenly as it would like, might jam on the EDL braking even more to get the wheelspin into a window it was happy with. I haven't been able to test it from a standing start but if I give it a bit in second up a hill in the wet I can feel the EDL braking working away to maintain traction (which is exactly what I wanted) , but then once you get above that 40km/h threshold you can feel the braking drops out and if you don't have your right foot in the right spot then the wheelspin will increase again. I'm cool with that considering that I'll be on R spec tyres with a lot more grip when I'm on the track, and in the wet I would not normally be that ham fisted with the throttle - I was just doing that to test it. Who knows it may be worth exploring to see if the EDL brake modulation can have its threshold moved up to say 60km/h which would make it pretty functional for the wet I think. For sure its going to need more testing and definitely I need to see how it reacts from standing starts (which is the whole reason why I wanted it). The idea there was that I might be able to launch with higher rpm so that the car isn't as prone to bogging if you only drop say 500rpm from where you should be when you release the clutch, and also I think that the braking will help keep the torsen diff locked. These diffs need torque running through them for the diff to be able to apportion drive so if the braking can keep a wheel that is tending towards free spin attached, then hopefully the diff will stay more consistently 'locked' and not do that left to right switching as it chases each wheel that lets go in succession like it does with the ESP button off.

[h100vw]

Yaw is std on the 4wd models

[vwthunder]

mmmm yeah sounds like the standard BMC is fine, maybe i am just over thinking the issue.

Haha was thinking this from the start but didn't comment, its a polo it requires simple upgrades, its not like putting bigger brakes on a 1970's car where you have to upgrade the Master.
I think Aldo tried to on his car and it was actually worse, dont pay around with something that works (im the king of doing that)

[simon k]

Just thought I'd let you know mate that the traction controls' throttle cut was successfully cancelled on my car. So if you don't press the 'ESP' button on the dash (which is really just a traction control on/off button), thereby leaving the traction control in its default on position, there now will be no throttle cut but the EDL brake modulation which is factory active below 40km/h is still active. From what I could glean from the tuner, as far as he could see it was a situation where the throttle cut could only be fully on or fully off. We'd been hoping that it could remain in place but have its influence damped down so that it would actually be functional but not so, so it was removed altogether. His concern with killing off the throttle cut was that in wheel spin conditions the ECU might chuck a wobbly and not seeing the rpm arrested as suddenly as it would like, might jam on the EDL braking even more to get the wheelspin into a window it was happy with. I haven't been able to test it from a standing start but if I give it a bit in second up a hill in the wet I can feel the EDL braking working away to maintain traction (which is exactly what I wanted) , but then once you get above that 40km/h threshold you can feel the braking drops out and if you don't have your right foot in the right spot then the wheelspin will increase again. I'm cool with that considering that I'll be on R spec tyres with a lot more grip when I'm on the track, and in the wet I would not normally be that ham fisted with the throttle - I was just doing that to test it. Who knows it may be worth exploring to see if the EDL brake modulation can have its threshold moved up to say 60km/h which would make it pretty functional for the wet I think. For sure its going to need more testing and definitely I need to see how it reacts from standing starts (which is the whole reason why I wanted it). The idea there was that I might be able to launch with higher rpm so that the car isn't as prone to bogging if you only drop say 500rpm from where you should be when you release the clutch, and also I think that the braking will help keep the torsen diff locked. These diffs need torque running through them for the diff to be able to apportion drive so if the braking can keep a wheel that is tending towards free spin attached, then hopefully the diff will stay more consistently 'locked' and not do that left to right switching as it chases each wheel that lets go in succession like it does with the ESP button off.

that's very interesting Sam - I wonder what speed EDL is *capable* of controlling - IE how much it can be used before it cooks the brakes

It would be handy for my track tune until I can afford a diff, and I'll probably start doing a few motorkhanas with the polo soon - though 40kph is enough for that

[sambb]

yeah I think itll help getting it off the line wet or dry and probably out of really tight hairpins etc. But above that yeah I think you'd be cooking the brakes if you didnt have an LSD. Lots of cars are running EDL these days though inc many many performance cars so I wonder how their threshold compare to our cars.

[pologtiforfun]

So i upgraded the front brakes to 312mm....also tried the rears but had problems with the 256mm discs ( maybe i didnt get the right 256mm calipers or discs that i purchased, and yes i did have the 6mm spacers..Anyway fronts on and rears a working in progress.

As i rebuilt the front the brakes may need time to bed in the new seals as well as new pads......i do have a long pedal at the moment. I did pressure bleed the calipers.....so see how it goes. braking has definitely improved but pedal is now longer.

didnt do the brake master cylinder yet....might wait for the brakes to bed in, and maybe then re-bleed to see if it improves.

if not i guess its back to reviewing the brake master cylinder upgrade

[sambb]

good stuff. well keep us posted re the master cylinder if anything happens on that front. very interested to see what happens there.

[pologtiforfun]

Finally got some time to look over the rear caliper situation and i believe its similar to a thread by rgvlee, rear brake upgrade. I encountered the same issue with the space or gap on the rear brake carrier hitting the brake disc.....so i'm now looking to get the correct rear brake carrier. And then i can upgrade the rear calipers