Wilwood bbk bleed procedure

[MRX430]

I am relaying what Joe@2J Racing told me. He has the same Wilwood kit on his track FiST and has said this procedure is essential for having the brakes work properly and he’s installed many Wilwood kits soooo. I was just wondering if anyone knew what it was

 

[D1JL]

I don't wish to contradict Joe as he must have a reason for his statement.
However, ABS is a safety system and it is designed to reset itself upon start up and all the related sensors working.
There should be no reason to have the dearer reset the ABS unless there is a failure that would be indicated by an ABS or Brake failure dash light.

 

[MRX430]

I have no dog in this fight. I’ll ask him when he updates me on delivery for the kit.

 

[maestromaestro]

I had the front and back BBK from Wilwood done by 2JR. I am guessing that they have reset the ABS - but I have since replaced the brake fluid with the Castro’s SRF. That didn’t require resetting anything - so long as you don’t drain the master cylinder, you shouldn’t need the reset. But, yeah - FORSCAN, I believe, can reset it as well.

 

[MRX430]

I had the front and back BBK from Wilwood done by 2JR. I am guessing that they have reset the ABS - but I have since replaced the brake fluid with the Castro’s SRF. That didn’t require resetting anything - so long as you don’t drain the master cylinder, you shouldn’t need the reset. But, yeah - FORSCAN, I believe, can reset it as well.

I am just following the orders of an expert in the FiST world and Mitch is doing all the installation and tuning.

 

[shouldbeasy]

When I changed my brake lines I was trying to be quick and limit the amount of fluid lost so the reservoir never dropped enough to allow air in. If you do that and keep it full, bleeding the brakes is very simple.

The issue is whether or not Mitch has had the entire system apart long enough for air bubbles to form. If that's the case, well then I think the ForSCAN is your best option as new age ABS modules can be very temperamental from my experience.

 

[maestromaestro]

I am just following the orders of an expert in the FiST world and Mitch is doing all the installation and tuning.

Well, why didn't you say so... If Mitch is on the job, then you have nothing to worry about. [emoji23]

But - when Mitch is not available, and you're going to attempt bleeding brakes yourself, heed the swarm knowledge of the forum. It's not difficult - so long as you don't drain the master cylinder. Thus, this "resetting" business is once in a lifetime.

I had the BBK calipers off a number of times (before I figured out that the only way to retract those Dynapro pistons is with channel locks - as Wilwood for some reason had changed the shape of the calipers and no common spreaders would fit [emoji35]). So, you just need to be careful - or use a power bleeder and fill the pressurized reservoir with enough fluid...

 

[MRX430]

Well, why didn't you say so... If Mitch is on the job, then you have nothing to worry about. [emoji23]

But - when Mitch is not available, and you're going to attempt bleeding brakes yourself, heed the swarm knowledge of the forum. It's not difficult - so long as you don't drain the master cylinder. Thus, this "resetting" business is once in a lifetime.

I had the BBK calipers off a number of times (before I figured out that the only way to retract those Dynapro pistons is with channel locks - as Wilwood for some reason had changed the shape of the calipers and no common spreaders would fit [emoji35]). So, you just need to be careful - or use a power bleeder and fill the pressurized reservoir with enough fluid...

I did but no one reads

 

[kevinatfms]

I may be missing something, but I have done literally hundreds of brake jobs on ABS systems.
From what I have been told, taught, and or seen, all ABS valving is in the open state when not powered up.
This is to allow that when there is an ABS failure the system works as a normal brake system.
This simply means that all fluid will flow from the master through the ABS valve body to the calipers.
No matter what method you use, pressure, vacuum, or gravity, fluid flows the same.

Chances are that if you don’t have an ABS problem before you start, you will not have a problem after if you did the job correctly.
The most common error is that many force the caliper pistons back in without opening the bleed valves.
This forces dirty fluid back up into the ABS valve body allowing debris to get in and cause the valves to stick.

When flushing a system, it is best to remove all the fluid from the master and start with new fluid.
There is however, one thing that most forget.
That there no way to get all the old fluid out of the calipers without physically removing and emptying them.
This is because the inlet tube and bleed valve are both at the top of the caliper.
Although the bleed valve will allow the air at the top of the caliper out, it will not force out the dirty fluid within at the bottom of the caliper.

Please correct me if I am wrong.

The ABS HCU has high and low side pressure chambers. Each pressure chamber has two sets of valves. One is normally open, one closed. When the ABS ECU detects a difference in wheel speed during braking the module will pulse the low side solenoids to force the caliper to progressively stop the wheel speed difference. During this time the high side chamber is usually closed off.

With that, if you pull a brake line and the open line has enough time to gravity bleed the system you will introduce air into the closed side of the system. This is where the ABS bleed procedure comes into play as it will hold the low side solenoids open for a determined amount of time to allow the tech to ensure flow through each chamber of the HCU and to eliminate air pockets.

So while you are correct you are missing the fact that there are two chambers. The secondary chamber can introduce air into the system if the line is left open long enough for a gravity bleed to introduce air to the low side chamber.


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[D1JL]

The secondary chamber can introduce air into the system if the line is left open long enough for a gravity bleed to introduce air to the low side chamber.

Thank you.

As it has been stated before a gravity bleed is done by opening a bleed valve on a caliper one at a time but not removing or opening a line.
So, if you do not let the master go empty, how will air get back into a caliper with fluid flowing.

If the car is not turned on, I still do not see how air can get into the other chamber of the ABS HCU.
That being said, I personally removed all four of the calipers on my ST at the same time to paint them and never had an issue.
I do however, suggest that the lines should be capped when the calipers are removed for repair or replacement.

As a Certified Ford Tech. you should agree with this.
I was just a lowly ASE Master Tech. and Ca. State Licensed Brake Inspector so I will bow to your Factory Training.
Please don't take this wrong, I really do respect your training and I am always willing to learn.

 

[AZSP33D]

Air goes up, fluid down, gravity. If the ABS is above the caliper brake line connection that's opened up, fluid will come out, and after a while air bubbles may find themselves traveling upwards through the system. Keeping the res full and the cap off when changing lines is helpful to prevent this, and it can take a lot of fluid to run through it while changing the lines if not capping off at the caliper area..

 

[kevinatfms]

Thank you.

As it has been stated before a gravity bleed is done by opening a bleed valve on a caliper one at a time but not removing or opening a line.
So, if you do not let the master go empty, how will air get back into a caliper with fluid flowing.

If the car is not turned on, I still do not see how air can get into the other chamber of the ABS HCU.
That being said, I personally removed all four of the calipers on my ST at the same time to paint them and never had an issue.
I do however, suggest that the lines should be capped when the calipers are removed for repair or replacement.

As a Certified Ford Tech. you should agree with this.
I was just a lowly ASE Master Tech. and Ca. State Licensed Brake Inspector so I will bow to your Factory Training.
Please don't take this wrong, I really do respect your training and I am always willing to learn.

Anytime you open the system and allow the system to drain fluid off is a gravity bleed if you have no vacuum on the master. The system is theoretically open even with the cap on the master as the cap does not fully seal the system. The line still “bleeds” when open and cap on. So opening a line at the wheel end gives a flow path for the fluid to exit the system which then gets displaced by the air entering at that line.

Whether the air gets back to the ABS HCU is dependent on how long the line is open for and how much fluid is removed out of the system.

Ford adds the ABS service bleed to the service manual after any major brake system work to cover the tech, the dealer and Ford corporate of any liability. That’s the basics of it.

So will the OP get air into the HCU? No clue. Is there a chance? Yes always.

Does he need to ABS Service Bleed the system after? Not necessarily if no air was introduced into the system but if he likes to go through the Ford recommended service requirements for a major brake service he should complete the ABS service bleed after repairs are completed.

So again, it’s not required by anyone but Ford corporate for techs to follow to ensure the system is functioning at its original parameters after a major service.

And I was not trying to sound like you knew less or were incapable of providing information.
I was just stating from my knowledge that Ford uses the ABS Service Bleed procedure as a catch all when any major brake service is being completed to ensure the safety of the owner of the vehicle after the repair is complete.




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[MagnetiseST]

And I was not trying to sound like you knew less or were incapable of providing information.
I was just stating from my knowledge that Ford uses the ABS Service Bleed procedure as a catch all when any major brake service is being completed to ensure the safety of the owner of the vehicle after the repair is complete.

This, its good practice but likely unecessary.

I just installed my kit last night, love it so far. I did not reset the ABS module, but I did vacuum bleed the system.

Word of warning: the fittings that thread into the caliper for the hoses need some type of thread sealant applied to the end in the caliper. We thought all was good with the install, but the brakes weeped very slowly from those locations. After sealing the threads 0 issues.

 

[D1JL]

This, its good practice but likely unnecessary.

I agree it would be a good practice as stated above by @kevinatfms

.
Here is what the service manual says.

1. NOTE: The HCU bleeding procedure is necessary if the HCU or any components upstream of the HCU are installed new.

 

[MagnetiseST]

I agree it would be a good practice as stated above by @kevinatfms.
Here is what the service manual says.

1. NOTE: The HCU bleeding procedure is necessary if the HCU or any components upstream of the HCU are installed new.

Do we consider the brake master "upstream" of the HCU?

I do not think the calipers are "upstream" of the HCU though

 

[D1JL]

Do we consider the brake master "upstream" of the HCU?

YES

I do not think the calipers are "upstream" of the HCU though

You are correct.

 

[kevinatfms]

I agree it would be a good practice as stated above by @kevinatfms

.
Here is what the service manual says.

1. NOTE: The HCU bleeding procedure is necessary if the HCU or any components upstream of the HCU are installed new.

Its also stated as items 18 and 19 of the Brake System Pressure Bleeding procedure. Although they do state HCU replacement in bold at steps 18 and 19 in the bleed procedure.

Warranty time is 1.2hrs(for caliper replacement) which would indicate it includes more than just a regular bleed. This is obviously only for warranty purposes.

Here is what it states for Master Cylinder replacement which alludes that you reference the full 1-19 step system bleed which includes the ABS service bleed. This is also stated under caliper replacement.



And if anyone wants to know where air gets trapped.... Right as the lines come up and out of the ABS HCU(in blue).


Again, this is for by the book workshop manual steps and does not indicate what others have tried and completed without the ABS bleed.

 

[Ford ST]

Ford has issues with their abs units. If you ever look up squishy brake pedal from a malfunctioning ABS unit most likely it's a Ford product. Lots of videos out there. I guess the valves get stuck open or whatever so fluid is not going where it's supposed to go. One of the tricks people do to get it working again temporary is to go do some panic stops to get the unit to activate that seems to firm the pedal back up for a while. This also helps push air out of the unit downward so you can bleed it out of the lines after let's say a master cylinder replacement.
I have the factory service manual and you do not need to do a ABS unit bleed for the caliper. If I had a scan tool to do it would I sure.