HYDAC vs WABCO accumulator test

[ski.dive]

I just removed my almost new HYDAC and installed a new WABCO accumulator.

 

NO DIFFERENCE in number of brake pumps!!!

 

The pump still comes ON every 4th time I hit the brakes in my Reatta with either accumulator.

[2seater]

Good information to know. The total capacity on both units is the same. .33liter, but it appeared the Wabco "might" have a slightly higher gas charge, which may have been advantageous, but it seems they are equivalent. The Wabco seems to be more readily available, and it's nice to have two sources. Thanks for the update. By the way, my Hydac is good for four pumps too and the brakes work great. I also just replaced both front brake hoses where the outer casing was cracked near the clamp in the center. That seemed to make a marginal difference and brakes feel firmer. Of course it got a fresh fluid flush at the same time.

[ski.dive]

I always wondered how many brake pumps, the Reatta was supposed to get when the car was new? :huh:

[Ronnie]

I just removed my almost new HYDAC and installed a new WABCO accumulator.

 

NO DIFFERENCE in number of brake pumps!!!

 

The pump still comes ON every 4th time I hit the brakes in my Reatta with either accumulator.

 

I'm not surprised at that actually. You are doing better than me. I have tried two good ACDelco accumulators and the Hydac I sold you. No matter which on is on the car I only get 2 brake pumps before the pump starts running. I have also tried two different pressure switches and I get the same result.

 

I've added a new accumulator test (thanks Jim Finn) to the Accumulator Testing Instructions here on ROJ that I think is just as important as the number of pedal pumps before the pump starts. When I do that test I get 10-11 pedal pumps before the red warning light comes on. Do the test below and see how many pumps you get before the red light comes on.

 

Test number 1

The purpose of this test is to see how many pumps of the brake pedal it takes to get the red brake warning light to come on. The higher the number the better. A new accumulator will be about 7 pumps and a shot accumulator would be 1 pump.

1. Turn on the key (don't start the engine).
   
2. Wait for the red and yellow brake warning lights to go out and a few seconds later you will hear the pump stop running.
   
3. Rapidly pump the brake pedal about 4 times while watching to see if the red brake warning light comes on.  If it does, wait for the pump to build up pressure again. The light will go out and the pump will stop.
   
4. Then pump the brake pedal 3 times to see if the red light comes on.
   

-Jim Finn

[2seater]

I always wondered how many brake pumps, the Reatta was supposed to get when the car was new? :huh:

 

We are sort of left to our own devices regarding the amount of reserve capacity the system has. There is no standard in the FSM so we only have tribal knowledge to come up with tests and averages, which is a little flexible since there is no common test bed to work with.