[Greg_M]

You are welcome. That goes for everyone who responded.

Good luck and enjoy the benefits of ABS,
Greg

 

[Greg_M]

Rich,
That's great news. You got lucky.

Greg

 

[Greg_M]

JJ,
Yes I had/have hydroboost brakes. Two words best describe the brakes; safe and predicable. I never worry about sliding the front tires and with the computer controlled variable F/R proportioning, the rears work harder than they did before ABS. I can apply more brake to the more heavily loaded outside tire in a turn, which increases the overall braking ability in a turn. In this case, ABS is a dynamic side-to-side proportioning system which you can't achieve with a front/rear proportioning valve or balance bar.

It's the best mod I have done.

Greg

 

[Greg_M]

Whatever works for you. I didn't have a magnetic base for the DI so I made a fixture, which also helped me mock up changes to the design. The objective is to spin the axle with the ring loose so it can be true'd to center within 3-5 thousandths run-out and then locked into place with the SS allen bolts on the ring to the aluminum adpater plate and the adpter plate to the axle flange. It's a two-step process.

Greg

 

[Greg_M]

David,
It works to the same extent as a daily driver. The modulation is not affected by the ABS. It's really transparent and corrects things so fast you are saved from a slide before you even know what's happening. The sensation is like the tires grow Velcro. It does not pulse back into the brake pedal like some cars do. The only sensation is the brake pedal gets firmer.

In a straight line normally you would not nail the power brakes all the way to the floor except in the most dire panic stop. But if you do in this case, the ABS prevents any wheel from locking. As you know, my car tends to lock the fronts too easily under hard braking so the ABS is a lifesaver. Without it, using aggressive braking would require constant modulation to prevent a front skid. The ABS does that when the limits are reached and does it much faster than I ever could. Watch the video posted where Dave Smith drove his car against a real Cobra in the braking tests. Dave's car locked the front tires repeatedly and skid over 2 car lengths several times in the same stop.

On my car I noted it activated one time when one front tire wanted to slide as I was braking to enter a hard right turn. It prevented the slide thus I was able to continue hard braking and maintain controlled steering and my line through the corner.

The question of dual MCs and the balance bar is an interesting one. In my tandem setup both brake circuits experience the same foot pressure. In a dual adjustable system when ABS activates in one circuit the pressure will build in that circuit and the balance will shift to the other circuit applying more foot pressure to the circuit not operating in ABS (yet). I suppose that would be OK.

I included an ABS OFF switch under the dash so if you want to slide it around, turn off the ABS.

Greg

 

[Greg_M]

One issue that would have to be overcome with that sort of a system is that the ABS system pumps the "dumped" fluid back to a reservoir - which one are you going to go back to? Actually, you'd have to come up with some sort of a connection between the two MCs to equalize the fluid levels. Maybe that would be Ok.
Mike

I'm not sure about this statement. When the controller decides stopping additional fluid flow to the caliper is not sufficient to unlock it, the pump motor activates and withdraws fluid from the caliper storing it in the internal accumulator. There are 2 pumps, one for the front and one for the rear. The question I can't answer sitting here is whether the accumulator is common or divided between the F/R circuits. I want to say it is divided because even in a tandem system, there are two reservoirs, inside a common bottle.

If the the accumulator is indeed divided, the fluid would be returned to the correct MC when the ABS operation is over and the accumulator is drained.

See pump pistons:

The accumulator has an end cap on both sides of the controller body which makes me think it's divided. I believe there's an accumulator piston and spring under each of those caps

Greg

 

[Greg_M]

There's no hose going back. The fluid returns though the brake lines.

Greg

 

[Greg_M]

Another question - with the MC sizes typically used for manual brakes on these cars (3/4" + 5/8"), can you even keep the brake pedal off the floor once the ABS starts dumping fluid off? I've done two CNC manual systems now, and I'm pretty sure as soon as the ABS starts dumping fluid the brake pedal is going to head for the floorboard. I could be wrong, but there's not much excess fluid capacity there.
Mike

I was thinking more about this and the brake pedal should not head to the floor. When the pump removes fluid from the caliper, the valves close the path to the MC so the pedal should stay right where it is. The fluid is removed from between the isolation valve and the caliper not from the MC to the caliper.

When my ABS runs, the pedal position stays right where it is when the skid started and does no drop, just feels harder than usual.

Greg

 

[Greg_M]

As long as the tooth count is the same on all wheels, it should work. Another consideration is make sure the resistance of the sensors is close to the same and near 1,650 ohms. I don't think it's that critical however because the self test passes with any resistance between 0 and about 10,000 ohms.

The ABS can tolerate a 5% difference in wheel speed relative to the others before it will throw a code. This allows for some tire wear or slightly different tire sizes F-R.

HTH,
Greg

 

[Greg_M]

50 teeth is correct for 94-95 rings. Looks like you had a great idea that Ford messed up for ya. If the Mark VII ring count was a multiple of 50 we could use a fairly simple frequency divider circuit and make it work. What we need is a programmable divide-by-N frequency divider to adjust its effective ring count to the 50 tooth ring.

Frequency divider - Wikipedia, the free encyclopedia

Way too complicated.

Greg

 

[Greg_M]

Greg,

So If I can just attach an exciter ring to each wheel and they are all the same the system should work? Like these on Ebay?

http://thumbs3.ebaystatic.com/d/l225/m/mdAbY12t4oy9aHk8ycwBRDg.jpg

Theoretically, maybe. A couple of factors effect the operation. The material, size, and shape of the rings has a bearing on the pulse size produced from the sensor. Tooth count might be a consideration if it gets too high. The computer may have a window in which it considers pulses/second for the 50 tooth ring at say 130 mph. If you double the tooth count per wheel rotation it might exceed what the computer considers acceptable. By its interpretation you are driving 260 mph.

I counted the teeth on your photo and I get 45. If the ring has enough mass to make a good pulse, this could work. We could also pre-amplify it if needed. The sensors operate in the analog world and are changed to digital at the computer.

Greg

 

[Greg_M]

The computer needs all 4 sensors connected or it will fail self test. It doesn't know if you use one on each of four wheels or two on each front wheel. I suppose you could only use the front two ABS channels on the front wheels and plump the rear brake line to bypass the controller.

If you only want the front ABS, you could use two sensors for a single ring on each front spindle. That would satisfy the self test and provide 4 channels of data to the controller.

You can buy the rear rings by themselves on ebay or from the source I linked to in the article.
http://www.mustangmagicparts.com/motorcraft-f4zz2c189a-abs-p42189.html

Greg

 

[Greg_M]

Sorry David. I only studied the one I have.

Greg

 

[Greg_M]

My hosted buildsite (ABS pics) is partially down. I emailed the admin this morning.

1. You need about 10A to run the valves and the motor. A riding lawn mower battery would be fine, a car battery as well. It's wise to place a 20A in-line fuse in the power source to protect things during testing.

2. I thought FFR supplied SN95 front spindles with tone rings. Is this not the case?

3. I carefully cleaned (with a rag not water) the entire unit with 409. Then with lacquer thinner. That removed the grease and organic crap. I polished the metal parts by hand with a rag and Metal Polish - Polish Metal, Chrome, Aluminum, Brass, Plastic | California Custom Products Inc. the best metal polish out there IMO.

4. I cut off the connectors and stripped the insulation on the wires to receive an in-line crimp splice to the 18ga twisted pair wire (I made) that will extend the sensors all the way to the control unit. Polarity does not matter so don't worry about which of the two wires goes to the channel +/- connections.

5. You are welcome!

Greg

 

[Greg_M]

This one clearly has the holes for the sensors to mount. Can't tell from the photo if those are tone rings on the back of those spindles or not. Are they on there?

Front Spindle Set - Factory Five Parts Catalog

Greg

 

[Greg_M]

The web dude recovered the photos.

Here's an SN95 spindle. Simply put the sensor in the big hole and use the mounting bolt to hold it in place threaded into the smaller hole. No adjustment needed.

Greg

 

[Greg_M]

Rick,
Remember the codes you read have been stored in memory for who knows how long. They will not clear until ABS passes self test and the car is driven above 35 mph for a short distance.

The fact it won't pass self test is the first issue to address. It might just be the battery voltage is too low. Charge the battery up and try the test again. Are you sure you have all the sensors bypassed with resistors and the wiring otherwise correct.

Code 19 is a concern. It would suggest there's an internal fault in the ABS controller. The code 63 comes from removing the constant 12V supply (light blu/pink) before turning off the switched supply (BRN).

If you want, send it to me and I will figure out what's going on. I have some spare parts to test with.

Greg

 

[Greg_M]

No way to clear the codes wihout first passing a self test and then driving the car. Your sensors are fine. You can use your truck battery.

Greg

 

[Greg_M]

If they won't take it back, send it to me and I will see what I can do. If you want...

Greg