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Is my accumulator bad?


DAVES89

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Sorry Ronnie I never checked. It seemed the same but if I wasn't looking for it I wouldn't pay attention to it. I will say that this morning when I backed out of my driveway the Black's warning lights went out before I got to the street. My drive way is about 60 feet long. I didn't sit long in the garage before moving either as I like to watch the "show" as I get ready to go.

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You're a trusting soul Dave. I never move until the warning lights go out but I'm usually not in a hurry either.

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Now that would make an interesting survey question. If I had always waited for the lights to go out before backing I would never experience my first shift no shift into second. So in reality my swapping the engine/transmission prematurely is now all your fault! lol!

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I really wish someone else would do the test below and post your results. That  might give a better picture of how the average Reatta brake system performs.

 


KEY ON

Seconds until red warning light goes off - Mine=30 - Hydac=38  - Dave's Black car=35

Seconds until pump motor shuts off - Mine=46 - Hydac=59  - Dave's Blackcar= 54

 

Pumps until pump motor starts again - Mine=2 - Hydac=3  - Dave's Black car=8

Pumps until red light comes on again - Mine=12 - Hydac=14 - Dave's Black car=16

 

KEY OFF

Pumps until pedal gets hard - Mine=12 - Hydac=15 Dave's Black car= 14

 


 

 

 

 

Sorry Ronnie,

It has been raining here the past week and cold temps so I haven't been able to uncover my Girl so I could do those tests. I really want to because I am really curious also.

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I finally figured out the pin combinations in the five pin switch and made an LED indicator for when the various combinations make and break contact. Each combination was tested at least twice. As can be seen even if the pump pressures are in the proper range, the indicator lights may be off by some amount. There are three sets of contacts in the switch, two normally closed, the pump power switch and the red light and one normally open, the yellow light for anti-lock which looks for open as the proper pressure so the results appear backwards. This what I found on the one old switch I have:

 

Function     Pin combo   Test light on-off        FSM on-off

 

Pump         A > D         2050-2650            1980/2100-2500/2750

 

Red light     B > D         1475-1700            1450/1550-1850/1990

 

Amber        C > E          1675-1475            1850/1990-1450/1550

 

 

       It appears the FSM has a fairly wide range for the set points, although the three switches I have tested, two on my cars and the one spare all operate the pump in a very close range to what is noted above. I have only tested this one switch for the indicator light set points so a very small sample size. As noted, the amber and red light turn on points are just within the book value range on the low side, so when pumping down, the lights would come on as late as possible. On the other side of the coin, the indicator lights would turn off way early as the set points are out of range low. The results don't explain the difference in the number of pumps when checking the pump starting, as I have found mine to be very consistent, but the indicator lights may have larger fudge factor.

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It doesn't appear there is a wide gap between the pressure when the pump cuts off and when it cuts back on. I don't think the pressure switch or the the accumulator (assuming it is up to specs) is causing the pump to start quickly. There is something we are missing here.

 

On some cars the rod between the master cylinder and the brake pedal is adjustable. Does anyone know if that is true with the Teves system? If it is perhaps a difference in how it is adjusted would allow more back travel and cause the master cylinder to dump more fluid after each pedal press? Just throwing things out for discussion...

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I have removed a number of these units and I don't remember seeing adjustments. Although I was only interested in getting them out and wasn't paying attention. I have yet to need to install one.

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It doesn't appear there is a wide gap between the pressure when the pump cuts off and when it cuts back on. I don't think the pressure switch or the the accumulator (assuming it is up to specs) is causing the pump to start quickly. There is something we are missing here.

 

 

    The pump on and off pressure has always had about a 600psi spread and has been consistent on both my cars and the test rig. Somewhere more fluid is used from one vehicle to another. When I was going through the FSM I didn't find any reference to the reserve capacity of how many pedal applications are available. Granted, I was looking primarily for electrical information and may have missed it.

 

     Also, according to the FSM, my pressure switch failed because the warning lights turn off too early.  That doesn't have any effect on the quality of the braking since the pressure available is within spec. What I was trying to illustrate is the timing of the warning lights going on and off may not be reliable guide to the quality of the pump and accumulator system.

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Hal I have 2 NOS pressure switches as well as several good used ones if you want to compare. I also have a 3 accumulator balls [one is known good, two are untested]. Let me know if you want to meet sometime.

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I might be stressing too much over the pump coming on quickly. I drove my car to a small car show last night about 30 miles away and the brakes performed flawlessly. The car stops good and the brakes feel great. Unless we think of something else to test I'm just going to drive and not worry any more. Thanks for all the help trying to figure out what is going on.

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I might be stressing too much over the pump coming on quickly. I drove my car to a small car show last night about 30 miles away and the brakes performed flawlessly. The car stops good and the brakes feel great. Unless we think of something else to test I'm just going to drive and not worry any more. Thanks for all the help trying to figure out what is going on.

    I agree, drive it. I am more curious than concerned, and I will get together with Dave in the near future but I don't anticipate any big changes in what I have found so far. One note; with a helper to watch the warning lights in the car, the light test could be done from under the hood with the pressure gauge setup too. If the weather would cooperate I could do the level tests and pretty much conclude the investigation. A flush and brake hose change will not require must testing, it will either get better or not.



Hal I have 2 NOS pressure switches as well as several good used ones if you want to compare. I also have a 3 accumulator balls [one is known good, two are untested]. Let me know if you want to meet sometime.

 

Yes, definitely. You have such a large supply, it should help get a good average.

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What would really help would be Reatta owners reporting the results of the simple test to see how many pedal pumps it takes for their brake pump to start after the accumulator has been charged and the pump has cut off. I get about 2 pumps, Dave gets 8, others have posted on other forums that they get 6, and another Reatta website says 2-1/2 to 3 is average. The numbers seem to be all over the place and not many people want to give their input by doing the simple test on their brakes.

 

Perhaps our time would be better spent figuring out how to rebuild the pump motor instead of trying to figure out how to prevent it from failing. We need to find part numbers for brushes and bearing we know will fit. If I knew that I would go ahead and rebuild my spare pump motor and install it on my master cylinder. I would feel more confident if I knew the motor had been recently rebuilt with new brushes and bearings and I wouldn't worry about the pump coming on quickly. The unknowns are what scare me. I know the motor has lasted 26 years on my car - that tells me it is very durable - but I don't know how may years (or days) it has left before it quits.

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So I finally was able to uncover the Reatta and try the tests, but I don't know if I am going deaf or if the pump is really quiet because I can't hear it turn on or off even with the hood open. This is definitely a two person job - For Me ?  LOL

 

When I get another person to help me I will post my results.


On 4/26/2017 at 5:53 PM, Ronnie said:

 

KEY ON

Seconds until red warning light goes off - Mine=30 - Hydac=38  - Dave's Black car=35

Seconds until pump motor shuts off - Mine=46 - Hydac=59  - Dave's Blackcar= 54

 

Pumps until pump motor starts again - Mine=2 - Hydac=3  - Dave's Black car=8

Pumps until red light comes on again - Mine=12 - Hydac=14 - Dave's Black car=16

 

KEY OFF

Pumps until pedal gets hard - Mine=12 - Hydac=15 Dave's Black car= 14

 

 

I have some results, but I am confused - How hard of a pump are we talking about; mine were about a second apart and with a medium foot pressure as compared to a heavy foot when in panic mode.

 

[uPDATED]

 

KEY ON

 

Seconds until red warning light goes off = 11.95

Seconds until pump motor shuts off = 32

 

Pumps until pump mother starts again = 2

Pumps until red light comes on again = 17

 

 

KEY OFF

 

Pumps until pedal gets hard = 18

 

 

My pump and Accumulator was replaced a few years ago at least that is what the guy told me before I bought it.

 

unnamed.jpg

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Probably later this week or next I will try to do the test with my other Reatta with 60,000 miles. The one I did the test on has 178,000 miles on it, the pump and accumulator were replaced around 120,000 miles.

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Thanks for doing the tests. Looks like your results of the pedal pumps until the pump restarts were about the same as mine. I just pump the pedal at the speed I would if I were pumping the brakes to bleed them. I don't think the speed is too important as long as you press the pedal until it stops.

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Yeah I did notice some similarities.

Okay that is what I thought about the pumping pressure.

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  • 4 weeks later...

This is a copy and drop of my last post in the AACA forum. It is related but still need to do the brake flush and new flex lines.

 

      I am bringing this thread back as I finally got my car home to complete this run of testing. I moved the first three accumulator observations to this post and added three others. Accumulator "D" is from my beater '89,  "E" is Ron's Hydac which is almost new on loan to me in transit to its new home and then "F" is my two year old Hydac. I added the number of "pumps" required for pump restart and the observed fluid drop for each accumulator.

 

Fluid capacity at various pressures                          pre-charge       Fluid drop   Pumps to restart   Working pressure fluid

 

A: 170ml @ 1500psi, 190 @ 2000 and 200 @ 2600      425#             .698"               1 pump                              10ml 

B: 155ml @ 1500psi, 175 @ 2000 and 192 @ 2600      500#             .670"                1 pump                             17ml

C: 60ml  @ 1500psi, 102 @ 2000 and 135 @ 2600       1050#           .475"                2 +                                   33ml

D: 170ml @ 1500psi, 190 @ 2000 and 200 @ 2600      425#             .698"                1 pump                             10ml

E: 107ml @ 1500psi, 155 @ 2000 and 192 @ 2600       950#              N/A                 N/A                                  37ml

F: 107ml @ 1500psi, 155 @ 2000 and 193 @ 2600        925#            .682"                3 pump                             38ml

 

The observed fluid drop closely mimics the accumulator capacities noted in the pressure testing. While the Hydac units are larger, the two I have tested appear to have a somewhat lower gas pre-charge than a new standard style resulting in greater useful working fluid capacity, but not as much as indicated by the size. I have never been able to pass the "pump" test, so next on the agenda is a fluid change and all new flex brake hoses to see if that makes any difference.

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I wanted to post this before I finished the hose replacement, if indeed the rears get changed, because of the deterioration I found on the front ones. As can be seen in the photo, they had impending failure just above where the intermediate support surrounds the hose. I am sure others have seen the same sort of issue but is related to the possibility of the hoses expanding and the number of pumps available. They actually look even worse installed as they have a tighter bend than in the photo. The car did not exhibit any poor behavior and the brakes worked just fine.

 

0601171944-00.jpg

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Maybe that is why I am getting good test results on my Reattas as I have already replaced my front hoses. Mine were bad as well. BTW if you want to test switches and accumulators I have 3 of each that are untested.

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Ten-four Dave. I still have that testing in mind but everything I do seems to take longer than I intended. I have the youngest grandson for the weekend at the cottage so this weekend is full already, but in a good way. I probably won't get to flushing the rear brakes until next week, but at least the fronts are done.

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