What can I do to get Stopping Power???
I have a 99 expedition 4wd, I have changed all the rotors, pads severe duty, master cylinder, have manually & power bled the lines & still feel there is not much stopping power. I have done the checks on power booster & it checks out. 21 " of vacuum to booster. I tow a boat with this so the brakes have to be good. Does anyone think it could be the booster still? Or please give me your input, it would be very much appreciated!!!!
Have you checked the ABS? Rubber brake hoses?
Yes changed all lines & hoses. Have not checked abs, where should I start on abs?
Codes first even though the light may not be on. Fords are noted for RABS valve trouble, make sure the RABS valve doesn’t have any air in it, most have a bleeder on the side. Check the rear brake fluid control valve for proper operation, seen some that have broken linkage so very little braking on rear axle. I’ve had a few that I had to reverse bleed to get the brakes to work properly. Do you have a scanner capable of activating the ABS during the bleeding process?
Answer not posting
No codes have popped up on my scanner. I'm assuming the valve is on the abs unit, & that there is a physical linkage also. I have a ford workshop manual that I will try to look that up. My scanner does not activate the abs. Thank you very much on the info, if you think of anything else I am all ears, you can never learn enough!
No. The RABS valve is in the drivers side frame rail usually just before the upward bend, it has a bunch of brake lines attached and a electric plug. If the ABS unit is leaking you maybe getting air back into the system, everything has to be sealed for it to work right.
So the rabs valve is just the big abs unit? My big workshop manual says nothing about the rear brake fluid control valve & linkage. It does say to perform a leaking dump valve test. Do you know where the bleeder would be on the abs unit? Thanks
ABS unit will not have a bleeder but the RABS valve will. The load sensor will be back above the rear differential.
The load sensor is mounted on top of rear differential & is electrical. But in my ford workshop manual it does not mention anything about a RABS valve. I don't want to be a pain in the butt, I am trying to understand this. Where again would this valve be located in an expedition? Again thank you for helping me with this, I hope it helps someone else also!
RABS valve picture. Drivers side inside frame rail.
Hi GA, A picture is worth a million words! Now I know what to look for! The bleeder is in plain view. I wonder why ford manual does not mention this valve. I will check out on vehicle later on today. thank you!
Hi GA. I do not have a RABS valve, that is for a 98 expedition & previous years before that. What I have is 4WABS consisting of control module, hydraulic control unit, & the various control sensors. If everything is bleeded right there should be no problem, which leads me to the power booster still being my possible problem.
How much vacuum is the engine capable of? You should be able to get two pedal pushes on the brakes after the engine is shut off before the brakes become hard, if not then you have a leaking booster. Have you checked the boosters check valve for leakage? You've done everything right you should have good braking power. Can you get the anti-lock system to pulse when you drive it and then hit the brakes hard? If not there could be a problem with EBCM even if it doesn't show any codes.
