Porsche upgrade front not as expected + ABS problem

[Le S2 Audi]

Yeah, it is quite difficult to get the part numbers I have experienced the last few days. Have spent hours and hours online to find info on which pads fits the 429/430 calipers, but with the slow connection I have onboard it just gives me a headache.I think the only solution is to take measurements and fax the suppliers with the dimentions when I get home.......dammit I was hoping to have them waiting for me when I got home.
Thanks for trying though.

Right:- got peed off looking online so I phoned my local Porsche dealer and explained that I was doing this upgrade and that I had bought some pads & dampers from them just a couple of months ago and the guy was then very helpful!!!!

The Porsche brake pad numbers for the calipers 996.351.429/430 are 996.351.949-12 The Porsche price is £172.62 + Vat (15%)

The calipers he told me are from a C4-S.....

Hope this helps with your search

Ken

[audis293]

Right:- got peed off looking online so I phoned my local Porsche dealer and explained that I was doing this upgrade and that I had bought some pads & dampers from them just a couple of months ago and the guy was then very helpful!!!!

The Porsche brake pad numbers for the calipers 996.351.429/430 are 996.351.949-12 The Porsche price is £172.62 + Vat (15%)

The calipers he told me are from a C4-S.....

Hope this helps with your search

Ken

Ahh... now we are getting somewhere I did another search today and voila, came up with this on pelican parts.http://www.pelicanparts.com/cgi-bin/...C%20Each%20%20

Seems like they can be used on many different models. I will check again with this newinfo if they can source the correct pads for me.
Thanks again for calling your dealer

[Le S2 Audi]

Ahh... now we are getting somewhere I did another search today and voila, came up with this on pelican parts.http://www.pelicanparts.com/cgi-bin/...C%20Each%20%20

Seems like they can be used on many different models. I will check again with this newinfo if they can source the correct pads for me.
Thanks again for calling your dealer

No Problem!!

[audis293]

Right....they are still not sure about which pads, so I will take masurements when I get home and send it off so they can see for themselves.

Jumping over to the brake assist issues I "think" I have.
Looking at this hydraulic schematics and bomb dwg, could it be the case that if the power steering pump gives less pressure than it should, and the accumulator does not contain 90 bars of nitrogen anymore, will I then have less brake effect? It seems to me that this could be the case, unless there is some device in the system somewhere that gives a certain pressure to brake booster which is set lower than the pressure the pumps gives and the accumulator nitrogen pressure. A bit difficult to explain, but could there be a valve somewhere which controls the max pressure into brake booster, lets say at 50 bars because that is all the pressure it needs to operate 100%, or should the brake booster have 140 bars which is the pressure the pump gives?

[johne]

The pressure is set by the relief valve in the accumulator not the pump and that's the only pressure controlling valve in the system.

The pressure is measured by a pressure switch on the master cylinder booster. Autocheck monitors the pressure switch and will trigger if the pressure isn't high enough - although it does wait approx. 30 seconds after engine start to allow the pressure to build.

If Autocheck isn't being triggered then it's likely you have the right pressure.

John

[audis293]

Ok, do we know what pressure the relief valve is set at and what pressure the autocheck triggers at? If I understand you correctly even if my bomb is faulty and the autocheck does not give an alarm, the system pressure should be sufficient. My autocheck system works I think as it gives alarm if the car has been resting over the night.

Do you know if the brake booster has some common faults which can cause less brake effect?

Offcourse I might not have a problem. Will find out when I change the pads, but it is interesting to find out how the hydraulic system works on our cars.

I have a new bomb on order as well, so I will change pads first and check, and then I will change the bomb and oil to see if there is any difference, though, the bomb is probably not causing any issues.

Another thing I found out now. I read on the S2 Central that the only oil to be used on our brake system is the DOT4 and NEVER to use DOT5 due to it could cause problems with ABS. Needless to say, I have DOT5 on mine . What is the issues with ABS I could get if using this oil, and again, could it affect brake performance?

[johne]

Ok, do we know what pressure the relief valve is set at

140 bar - approx

and what pressure the autocheck triggers at?

120 bar - approx.

If I understand you correctly even if my bomb is faulty and the autocheck does not give an alarm, the system pressure should be sufficient.

Yes. What you loose as the bomb ages is the depth of reserve pressure not the ability to work as normal when the engine is running keeping the pressure up.

My autocheck system works I think as it gives alarm if the car has been resting over the night.

As it does on many of our cars, but that's fine until Autocheck comes on whilst braking then it's new bomb time.

Do you know if the brake booster has some common faults which can cause less brake effect?

No I don't. The booster is a very simple device so I believe it'll either work or leak!

Offcourse I might not have a problem. Will find out when I change the pads, but it is interesting to find out how the hydraulic system works on our cars.

I don't believe you do have a problem. Compared to many younger cars there isn't that much brake assistance and brake pads, lack of use can all contibute to a difference in feel in the pedal.

I have a new bomb on order as well, so I will change pads first and check, and then I will change the bomb and oil to see if there is any difference, though, the bomb is probably not causing any issues.

Another thing I found out now. I read on the S2 Central that the only oil to be used on our brake system is the DOT4 and NEVER to use DOT5 due to it could cause problems with ABS. Needless to say, I have DOT5 on mine . What is the issues with ABS I could get if using this oil, and again, could it affect brake performance?

AFAIK DOT 5 is silicone fluid which is more viscous & "sticky" than standard fluid which can cause the valves in the ABS valve block to stick. It couldn't be causing the issues you're describing but you can just flush it out with DOT 4 fluid and go back to that. ATE fluid is coloured blue or gold to help you see when it's come through.

John

[audis293]

Thanks Johne,

Will change fluid,pads etc etc when I get back home. Will post my findings

[audis293]

Ok, finally home and have found the right pads for the calippers eventually. It is the FRP 3050 pads with 140 mm x 59 x 17 mm dimentions. Unfortunately no supplier in Norway had these in DS2500 so I went with DS3000. Will test these soon.

I have in the meantime replaced the old hydraulic fluid with new at the same time as I replaced the "bomb" for a new. Found an intersting discovery on the old bomb. The banjo bolt which is used on the pressure hose on the bomb (from the pump) has a small filter in it. On mine there was some **** there but not much.Cleaned this out and put everything together with new DOT 4 brake fluid. I also upgraded rear brakes with the 280 mm vented discs option.

I also pushed the ABS sensor which played up a few mm in and this is now working fine.

So conclusion so far is that the brakes have improved slightly which I think could be the dirty filter on banjo bolt, but I have also changed rear brakes, oils and bomb so it could be several factors. The (!) sign in the morning has also dissaperared after bomb was replaced.

Will test the DS3000`s soon to see if there is any difference.
Stay tuned...

[audis293]

Changed brake pads....OH MY GOD!

Well, finally had the time to change the porche pads for the Ferodo DS3000 pads.
The run-in on these is 25-30 times braking at 50% brake force and hold the brake for about 4 seconds each time.

At first the brakes did not feel any different than before, but went with the bedding in procedure. After a few tests the brakes improved every time. And after the 10`th time I did not recognize the car at all. I now finally know what it means to be hanging from the seat belt harness when braking. The improvement is so huge I can hardly believe it.
I can safely say that my brake issue has now been sorted. The slightest push on the pedal now results in the ABS kicking in.Need some driving to get used to this but I love it
The DS3000 is a pure racing pad but I must say it works pretty darn well on street as well. No need for more brake force thats for sure
Thanks to everybody for their inputs!

This makes me believe that the old pads are somehow destroyed. They were a bit shiny so probably been glazed by the previous owner of the calippers. They are going in the bin asap


Johan