I have the condition where the brake pedal is too low when used, others have reported the same condition here before. The brakes stop the car very well but when I got the car, an SRT, I noticed at once than the pedal movement was not the same as the NA that I had before.
I have bled the brakes many times and there has been no improvement.
With the engine stationary the pedal moves the amount or almost the amount I would expect with the engine running. When I start the car with my foot on the pedal still, the pedal sinks towards the floor so that the gap under the pedal just lets me slip my toes under the pedal. As I said the brakes will work fine and the ABS works.
What I do not understand is that there is a series of rods and pistons that make a solid contact with each other when the pedal is fully depressed and each piston will move brake fluid to each calliper piston.
My question is why is it that when there is a vacuum in the system the pedal moves more when it should be the almost same amount as when there is no vacuum in the system?
The pedal is not spongy at all so l have discounted air in the lines.
There is no leakage of brake fluid to be seen anywhere.
The pedal does not drop when a constant pressure is applied to it with the engine running or not.
With the engine running or not the same amount of fluid is displaced to move the pads against the rotors.
With the engine running there is a negligible effort to move the pedal to the point that the braking effect can be felt.
The car has the wire wrapped brake lines, even though I think this has a minimal effect on braking feel, I think the wrapping is more for hose protection and looks than anything.
I see only three things that could be wrong, the ABS unit with air in it or with sticky valves, a faulty brake booster or a faulty master cylinder which I replaced it with no improvement so I discount this as a problem.
From what I see the brake fluid bypasses a lot of the valves when the engine is not running and goes straight to the calipers pistons. I surmised that with the engine running the ABS would is active and the brake fluid enters areas where there are reservoirs that have sprung loaded pistons in them and the brake pressure compresses the springs and the reservoirs are filled and this caused the extra fluid to be required before the caliper pistons see enough pressure to move them. From this I reasoned that the ABS unit had some valves stuck and allowed the brake fluid into areas where it would not normally go unless the ABS feature was activated.
I am hesitant to replace the ABS unit as then it will definitely require bleeding.
I have the DRBII setup but I have not found the ABS bleeding program on it, I have had the pump on the ABS unit run for a second or so but apart from some readings that have no bearing on my issue that is all I found.
At the moment I believe the ABS unit valves are my problem.
Does anyone have any other ideas. The ABS unit is made by Teves and is model number MK20 ABS ESP, (Electronic Stability Program). The Crossfire one has the #
193 545 05 32, the ABS motor is #A
004 431 74 12 Q02.
I will add a schematic of half of the hydraulic circuit of this unit a little later, the other half is identical and is for the other side of the car.
So, anyone with other ideas or think my ABS unit is the cause?
Electronic Stability Control
https://www.aa1car.com/library/stability_control.htm
Teves Mk20 ABS
https://www.aa1car.com/library/abs_teves_mk20.htm
ESP explained in French.
https://www.vag-technique.fr/ext_fil...20_ABS-ESP.pdf