ABS Master Cylinder / Pump Assembly

[brokencase]

Suggest you use Brad's parts Scorpio as the mule for your retrofit experiment.

You don't seem to understand. If your ABS is broken then you really don't have the option of a test mule. It's do or die on what you got.

If I have any problem on my Scorpio ABS going forward that I can't address with the MC rebuild kit or swapping out a front sensor then I'll be swapping in the power brake substitution faster than you can say "Ed don't like Helms or inbred Amish/Ammonite"

Seriously though Ed, where did the inbred Amish/Ammonite thing come from? That is so impolite...almost embarrassed to repeat.

Do you think I am Amish/Ammonite? Wrong again!

But what was it? Did one of their horse and buggies pull out in front of you at some point and you could not stop the Scorpio fast enough?
Was that an Amish guy who flat-bedded you away from Carisle 2021?

Do tell...Do tell...

Hahahahha...!

[brokencase]

Here's a thought. The 2003 vintage Crown Vics had ABS with traction control.
This would basically provide limited slip behavior on an open differential by using the rear brakes.

I've driven this vehicle in the snow and it works very well. Although if you drive it aggressively in the snow you can heat up the rear brakes.
As I recall it had a timeout on the traction control to limit overheating.

That would be a nice upgrade for the Scorpio.

In this case you would have to run new and separate brake lines to the rear calipers.

[brokencase]

Another thought...

I was wondering why the Scorpio master cylinder lasts so long. The high pressure pump and accumulator feed into the master cylinder (2650 psi).

Perhaps it is the case that the seals inside the Scorpio master cylinder are of a more robust design as a consequence of this higher pressure.

[Ed Lijewski]

Suggest you use Brad's parts Scorpio as the mule for your retrofit experiment.

You don't seem to understand. If your ABS is broken then you really don't have the option of a test mule. It's do or die on what you got.

If I have any problem on my Scorpio ABS going forward that I can't address with the MC rebuild kit or swapping out a front sensor then I'll be swapping in the power brake substitution faster than you can say...

I do understand. Your ABS MC isn't broken/inoperable. You assume it will so be. You assume it may/will happen imminently. Without warning. That most likely won't occur. And for most ABS MC issues or symptoms a new/good used accumulator should resolve those, or maybe also a new pressure switch and pump relay.

So I understand being prepared mentally and formulating a complete plan for a likely far in the future event.

You didn't understand the value of installing whatever mod (MC in this case) on a test bed, or mule, to assure all kinks or unexpected issues are resolved, before doing the mod on your more valuable Scorpio.

And if Brad agreed, you two could collaborate, benefitting from each other's strengths and available time. Brad seems to enjoy experimenting with parts swaps and retrofits

Maybe the distance between your homes makes it unfeasible.

But the thought and concept is valid.

YMMV

Interesting that you haven't demanded that Brad edit his post ti read "Helms" in place of the existing nomenclature.

Screenshot_20211124-160632_Firefox.jpg (93.62 KiB) Viewed 5636 times

[brokencase]

I guess we differ in that I don't see it as a high risk swap.

[brokencase]

Interesting...
https://www.ebay.com/itm/223779066569

I'll have to do some research and see if I can find what the pinout is on the connector to this animal.

The computer is integrated, so I believe just power and wheel sensor inputs are required.

Note that to implement traction control it has separate lines to the rear brakes. It would be worth running new and separate lines to the rear of the Scorpio in order to get the traction control.

I'd rather pay $25-30 for a used modern ABS unit instead what people are asking for the primitive and much older Scorpio ABS unit.

Also note you still have to convert to a conventional Booster/Master to implement this.

Ahhh...here we go...
https://www.crownvic.net/drock96marquis/TRACdisable.htm

[brokencase]

Here is a discussion regarding the retro-fit of modern ABS to earlier fox body Mustang.
https://community.drivenasa.com/topic/4 ... ationquot/

[andyofcolumbusmerkur]

Hello All,

I've been through a number of threads and found the 'theories' somewhat confusing.

Background
When I bought our Scorpio the brake / ABS light took awhile to extinguish (~25 seconds), after start up (after sitting overnight). After about a month of driving the brake / ABS light would come on occasionally when the brakes were applied. This became a regular occurrence soon afterwards. During this time I also noticed that the brake fluid reservoir would 'fill up' about 4cm (1.75"), above the Max line whenever the car was parked overnight. I assumed this is normal when the system is shut down.

I took a gamble and replaced the Accumulator with a good used one. This solved the brake / ABS light issue while braking. The brake fluid reservoir filling up overnight remained the same.

Current Situation
A few days ago I noticed the pump relay under the dash 'chattering' when stopped with my foot on the brake pedal. This morning I did a few tests and it still takes ~25 seconds to extinguish both lights after start up (sitting overnight). I can push on the brake pedal 3 or 4 times before the pump relay kicks in. If I keep my foot on the brake pedal the pump relay will begin to chatter.

I'm debating whether to replace the Accumulator with a new one or replace the complete master cylinder / pump assembly with a 'remanufactured unit? I know it is an expensive part but brakes are a critical component that shouldn't create questions.

Has anyone ever converted a Scorpio to a 'standard' brake servo / master cylinder set like the European 'non-ABS' cars? I recognize that this will negate the ABS system but to me that is a small price to pay for a significantly less complex brake system.

Looking forward to the feedback.

I read someplace that the Cossie racing teams disabled the ABS somehow. At least when racing on gravel roads. Maybe you could find out exactly how they did that. Since it seems like you don't care about having ABS.

[Ed Lijewski]

FWIW: Three part YouTube series on "Teves Mark II to Hydroboost" retrofit on TBird Super Coupe. (Painful watching as the Tuber is sloooow moving.)

YMMV

[brokencase]

FWIW: Three part YouTube series on "Teves Mark II to Hydroboost" retrofit on TBird Super Coupe. (Painful watching as the Tuber is sloooow moving.)

YMMV

Replacing one nightmare for another.

[brokencase]

Plenty of ABS delete projects on youtube. Not too many about ABS conversions or upgrades.

[andyofcolumbusmerkur]

Since the Merkur platforms are similar in many ways and people have used Scorpio non-vacuum assist power brakes on the XR (just like they did on Sierra Cosworth) it would be possible to go the opposite direction and use XR items on the Scorpio. Of course the Scorpio is a heavier car so you would need to take that into consideration. Along with brake bias and use of a proportioning valve. Some XR people have used the Scorpio 5 lug hubs/wheels and brakes. So you could look into what they did when combining these different cars. My 89 XR came with the stock booster and an adapter that allows use of the easy to find thunderbird master cylinder. It's the type found on supercharged V6 and 302 V8 Thunderbirds. Also there was another adapter for using single or dual piston Mustang brake calipers. Never had any problems with those items, they work great.

[brokencase]

Interesting about your adapter. Was this a commercial item?

I am still intrigued by the later and simpler ABS units. Looks like they are made by Bosch. As far as I can tell it is just a standard master cylinder and booster. Pressure/flow from the standard master is allowed to control braking normally until the ABS computer detects a locked-up wheel (or a spinning wheel, in the case of traction control). Then the computer and the pump on the ABS unit takes over.

One problem I see is the differences in the number of teeth on the rings. Particularly if the donor had different number of teeth front to back and that was somehow coded in the firmware of the unit.

This could be overcome with an Arduino board that would interface between the sensors and the ABS unit. It would require knowing what the Scorpio pulses per turn and what the donor vehicles pulses per turn are. It could then scale accordingly.

The other issue is with regards to error reporting. The later Mustang units had a CAN bus interface. But I don't know how the Crown Vic units reported errors other than a light on the dash.

I am also having trouble finding what the pinout is on the connector of the Crown Vic ABS unit.

It is a mystery to me that outfits like Wilwood and others don't offer a universal aftermarket ABS\Traction control kit.
In the case of traction control, It is far easier to replace rear brake pads then to replace clutch discs inside a limited slip differential.

[andyofcolumbusmerkur]

I think the adapter was made by David Godfrey. Or possibly Sun Valley Performance copied that design and then made it themselves. I can't seem to find any pictures of the MC adapter (a flat plate and a short length of pushrod) but here's a picture of the caliper adapter.

found some more info about the swaps
http://forum.merkurclub.net/forum/viewt ... er#p297676
http://forum.merkurclub.net/forum/viewt ... er#p295747

[brokencase]

If we forego the traction control then the 1994-97 Mustang ABS pump could be a candidate as it has the output fittings for the two fronts and the single rear. However, I can't tell if this unit has the controller built into it like the later units do.

Here is what it looks like...
https://www.ebay.com/itm/184973041880

It seems the units thereafter have four separate output fittings, one for each wheel.