TEVES ABS help needed...still

[2Shelbys]

I have a hugely frustrating ABS problem. When braking, just before I roll to a stop, it seems like a valve opens or something as you hear a click and the pedal drops a little, then the pedal pulses and goes to the floor. It only does this when moving forward, never in reverse. Since the car has never had anything replaced but the accumulator, I decided to go the shotgun route. I pulled the complete ABS unit and installed a freshly rebuilt unit with a brand new accumulator. Same issue. There are no fluid leaks and neither the Brake nor Anti-Lock lights ever come on. Has anyone ever experienced this? Any help is much appreciated. (No, I don't want to go to a vacuum system. Yet.)

[Hemi Dude]

That is a strange result, goes to show how good those ”rebuilt” units are. When I asked a rebuilder many years ago if they used NEW parts to rebuild the ABS units, he told me “We use the best used parts we can find.” 

What do you think of such a statement? That is why I did the swap on my TC which now has 297,000 miles on it and the vacuum booster/4 wheel disc brake master cylinder “conversion” is doing real fine. Of course I don’t encounter snow and ice here in Arizona, but WHO would take his TC out in that kind of weather?

As for the particular result after replacement, the problem cannot be in anything beyond the ABS unit, such as in the hydraulic system.

Better get another unit or your money back!  Or you could decide to ‘re-decide’.

I do wonder where you got the ‘rebuilt’ unit from?

[2Shelbys]

I am pretty certain that it’s not the ABS unit since the old one and the new one had the exact same problem. I did the replacement because I thought there may be an issue in the valve block and I I figured replacing it would get rid of the problem. Now I’m wondering if it has a bad ABS sensor or maybe there’s corrosion on one of the the rings or something. Probably should’ve checked that first instead of assuming I had a valve block problem.

[Hemi Dude]

3 hours ago, 2Shelbys said:

 When braking, just before I roll to a stop, it seems like a valve opens or something as you hear a click and the pedal drops a little, then the pedal pulses and goes to the floor. 

That is not caused externally. That is a hydraulic loss in the hydraulic assembly, AKA master cylinder. No tone wheel or ring or sensor would cause this condition. When the pedal goes to the floor, which is an indication of the piston seal in the hydraulic unit failing or it could be valve body related, but it will be within the assembly, not outside of it. There is no place for the fluid to escape to unless there is a sizable leak at some location you should be able to see.

[2Shelbys]

12 hours ago, Hemi Dude said:

That is not caused externally. That is a hydraulic loss in the hydraulic assembly, AKA master cylinder. No tone wheel or ring or sensor would cause this condition. When the pedal goes to the floor, which is an indication of the piston seal in the hydraulic unit failing or it could be valve body related, but it will be within the assembly, not outside of it. There is no place for the fluid to escape to unless there is a sizable leak at some location you should be able to see.

That makes sense, but I can’t imagine two ABS units having the exact same issue. The pedal pulses as though the ABS has kicked in before the pedal drops. I have one of the Miller Tools test units coming. 

[Hemi Dude]

When you have your test equipment, you should be able to test and find the problem. It could possibly be an intermittent power relay, and that is just a wild guess. The fact that it is the same symptom from both units is unusual. Keep us posted.

[demco32]

On 9/5/2023 at 1:10 AM, 2Shelbys said:

I have a hugely frustrating ABS problem. When braking, just before I roll to a stop, it seems like a valve opens or something as you hear a click and the pedal drops a little, then the pedal pulses and goes to the floor. It only does this when moving forward, never in reverse. Since the car has never had anything replaced but the accumulator, I decided to go the shotgun route. I pulled the complete ABS unit and installed a freshly rebuilt unit with a brand new accumulator. Same issue. There are no fluid leaks and neither the Brake nor Anti-Lock lights ever come on. Has anyone ever experienced this? Any help is much appreciated. (No, I don't want to go to a vacuum system. Yet.)

Type of car? We have Teves on Jaguar too.

 

[Hemi Dude]

His car 1989 Chrysler’s TC by Maserati

[2Shelbys]

20 hours ago, Hemi Dude said:

His car 1989 Chrysler’s TC by Maserati

Mine is a ‘91. 

[Hemi Dude]

Same ABS system. 

[2Shelbys]

13 hours ago, Hemi Dude said:

Same ABS system. 

Yes it is. 

[Roger Frazee]

Not to hijack this thread, but there is a 1992 LeBaron in the local Pull-A-Part.  Can I use the parts from that car to convert the brakes on my '89 TC?

[Hemi Dude]

2 hours ago, Roger Frazee said:

Not to hijack this thread, but there is a 1992 LeBaron in the local Pull-A-Part.  Can I use the parts from that car to convert the brakes on my '89 TC?

Yes, if it has rear disc brakes