Nicole

Dave Anderson has engineered a new gizmo that connects to the 928s ABS pump, allowing it to run and cycle the valves for bleeding.

We will try this on my car on Sunday, June 21, 2009, starting 1PM, hoping that we finally get all the air out of the system.

If you are interested in watching, please PM me for directions.

SharkSkin

Well.. we had some success with v1.0, v1.1 is engineered but not entirely ready -- though I'm pretty sure it will be by Sunday.

No pressure, eh?

jon928se

Nicole having read and I think contributed to your earlier blake breeding thread I'm wondering if there is a crucial difference between the earlier S4 ABS and later S4 ABS.

My 88SE has never been a problem to bleed and always has a firm progressive brake pedal. Conversely the 90GT has an uninspiring brake pedal - it does work if you push far enough and doesn't sag under load but I've never been able to get it anywhere near the feel of the SE.

Nicole

My brake pedal feel has always been very firm; the pressure point was above the gas pedal. Since the front calipers were overhauled and the flex lines were replaced, the pedal feel has changed. So, it is not a difference in system, but a fault that needs to be fixed. We just need to figure out what causes this.

The factory uses vacuum to fill the brake system. A local Porsche mechanic also uses a (different) vacuum system to bleed. If we don't have any success on the weekend, I might try the vacuum bleeding.

SharkSkin

Jon, it seems that air made its way into the ABS system somehow. My gizmo can cycle the pump and cycle the 3 valves (LF/RF/Rear circuits) to shake loose bubbles. The recent enhancement puts out a square wave of varying frequency to vibrate the valves back and forth between open/closed while bleeding and replaces the oddball ABS relays with standard power relays.

If you look at the hydraulic schematic, there are lots of places bubbles can hide even when power/vacuum bleeding.

Bill Ball

I already told Nicole I would be there. I'm bringing my newly acquired reverse bleeder tool as well as my MityVac suction brake bleeder.

AO

I'll be interested to hear the outcome.

BC

All this talk of "bleeding"

This is the 21st century - we have no use for your wiccen designs.

dr bob

Bill--

Tell us about the 'newly acquired reverse bleeder tool" please. National enquirer minds need to know.

Ron_H

I will also be watching this thread as I need to overhaul my brakes and dread the Nicole Syndrome. This condition has gone on long enough to madden me if it was my car.

Bill Ball

Phoenix Systems.

http://www.brakebleeder.com/index.php

I'm not sure I buy the hype, but a lot of motorcycle guys use this tool and say it beats everything else.

Ron_H

For the price of this tool, I would expect to bleed and bleed and bleed, and not my brakes. My Power Bleeder works for me so far. I'll stick with it for now. This system makes some sense but it's a bit pricey, don't you think?

F451

Watching this thread too.

Bleeding my brakes today after replacing lines, painting calipers, new pads, rotors, etc. Lots of air in the system now. Keeping fingers crossed that I get good pedal pressure with the Power Bleeder, but will see.

Bill Ball

I got the consumer level kit for under $100. I don't expect to use it often. I think as long as you don't allow the brake system to sit open and drain, common bleeding and flushing techniques should work fine.

dr bob

It would seem that one of our pressure bleeders, with the addition of valve and some adapters for different-sized bleeder screws, could be used the same way push fluid from the caliper end.

For those of us with calipers with the bleed screws up high (that would be all of us...) I still have a concern about getting all the air out of the tops of both chambers. I'm thinking that you'd really want to do a normal forward-direction bleed and flush to make sure ther's no air in the calipers, then push backwards as this system does to clear any air from the ABS high spots where it might accumulate. I'm note sure the order you do the directions would be critical, but open that to discussion.

A while back I proposed doing a 'reverse bleed' on the clutch system, but search isn't doing well with my search terms I guess. I guess that's why they don't call it 'find'.

Anyway, we are looking forward to the results. My pedal has been higher and harder in the past, and it would be cool to have a good way to make sure all the ABS hardware and stuff air free of any bubbles.


Also--

I wonder if it would make sense to add a drain/vent line from the MC bleeder fitting, and reduce the risk of spilling fluid from the reservoir at the same time that you are getting the air out. The drain can would need to be close to the same altitude as the MC reservoir, I suspect.