Brake not functioning properly after rebuild

[Guest whytshdo]

Good morning gentlemen & ladies,

 

last week-end I replaced  all four Brake calipers, rotors and pads. I followed the bleeding procedures and had clear fluid/no air for all four wheels. After doing this, I went for a test ride. The brake pedal seems to go all the way down before engaging. however if I let off and pump it again it seems to work more properly. The car stops fine but the pedal feel is very odd. Also it seems that one off the brakes(front left) maybe be locked, even though it is brand new.

 

Also, while taking the test drive, I started getting a message on the CRT that the ECM detected and electrical problem. I'm wondering if these two issues are connected and if anyone else has experienced this and solved it.

 

I check the ECM codes and the only code list was E026 History. I have a manual and will be looking into this also.

 

Thanks in advance and any help/advise is appreciated.

 

Mike

[89RedDarkGrey]

2 hours ago, whytshdo said:

I check the ECM codes and the only code list was E026 History

 

QDM FAULT= (Quad Driver Module) The ECM is on it's way out. The really poor choice of placement of our ECM doesn't allow much airflow around the unit, and it gets very warm during normal operation as it is. Heat + computers is not good.

 

As for the brakes- I'd go over the rubber line, caliper pins, etc. to see what's up (or take it to a reputable Brake Shop. These days- "new" doesn't always mean "correctly manufactured".

[DAVES89]

I just brought up a series of posts called "Starts then stalls" that deals with quad driver. You may want to read it.

[Guest whytshdo]

Thanks Dave, that was a good read. I'll keep that all in mind as I progress.

 

And yes RedDarkGrey, I'm planning on pulling off the one brake and checking it over well for what might be a problem.

 

Thanks and I'll let y'all know if I solve

 

[Guest whytshdo]

Update: Thanks to a great tutorial on The ROJ site, I was able to diagnose the E026 code error to being a faulty Cooling fan relay. I also had a blown dash light. Replaced the relay and all 7 dash bulbs for the idiot lights and everything seems to be good to go.

 

I still need to tackle the brake issue. hopefully next week. I did check the accumulator by measuring the difference between full under pressure and pressure relieved; There was a 3/4 inch difference so this seems OK.

 

Mike

[padgett]

Usually a need to pump the brakes particularly if once pumped up it holds and does not sink to the floor slowly is air in the MC, I'd bleed them again.

[2seater]

On ‎8‎/‎9‎/‎2017 at 11:18 AM, whytshdo said:

Update: Thanks to a great tutorial on The ROJ site, I was able to diagnose the E026 code error to being a faulty Cooling fan relay. I also had a blown dash light. Replaced the relay and all 7 dash bulbs for the idiot lights and everything seems to be good to go.

 

I still need to tackle the brake issue. hopefully next week. I did check the accumulator by measuring the difference between full under pressure and pressure relieved; There was a 3/4 inch difference so this seems OK.

 

Mike

3/4" fluid drop is excessive and the accumulator should be replaced. In the case of the accumulator, less drop is desirable, slightly under 1/2" would be normal for a new standard style accumulator. Does the pump run every time the pedal is applied? If so, you need a new accumulator or as mentioned above, there is air in the system.

[Guest whytshdo]

On ‎8‎/‎10‎/‎2017 at 6:16 PM, 2seater said:

3/4" fluid drop is excessive and the accumulator should be replaced. In the case of the accumulator, less drop is desirable, slightly under 1/2" would be normal for a new standard style accumulator. Does the pump run every time the pedal is applied? If so, you need a new accumulator or as mentioned above, there is air in the system.

This doesn't sound right. On the ROJ site, the accumulator test states that 1/2" or less is bad. (If the fluid level change is 1/2 inch or less, your accumulator is on its last legs.) Basically the less difference in displacement the worse it is. So now I'm confused. Can someone else help to clarify this?

[2seater]

This is the thread on the accumulator testing I did a few months ago. Hopefully it will answer your concerns. In short, accumulator systems, such as home well pumps or our brakes, the amount of gas charge is supposed to be close to 1/2 the minimum working pressure. In our case, the working range for the brakes is between 2000-2650psi, so the gas charge should be around 1000psi. Low gas charge allows more fluid to be stored but the stored pressure bleeds down much more quickly.

 

I don't know why this displayed like this but it will get to the thread and you need to scroll back to the beginning.

 

 

Edited August 15, 2017 by 2seater (see edit history)

[Guest whytshdo]

Thank you for your response 2Seater.

 

Perhaps I'm Not understanding this properly so please bear with me.

Please understand, I'm not trying to argue. I truly only know about these systems what I've read/learned here. I'm just trying to reconcile 2 seemingly opposite answers.

 

From what I've read throughout this site and on ROJ, is that when you turn on the ignition, the Accumulator fills with fluid. Then, when you pump the brakes 25 times to release the pressure the fluid is expelled back to the reservoir. The amount pushed back to the reservoir is dependent on the amount of pressure behind the bladder in the accumulator. Therefore, a low pressure(read bad accumulator) would not be able to return as much fluid. Whereas a good accumulator with higher pressure behind the bladder would be able to return almost all fluid.

This would present itself as showing a higher difference between depressurized and pressurized in the Resevoir.

 

The following is quoted from the article "Accumulator function explained" on ROJ by Barney Eaton

"This sketch represents the other extreme... an accumulator with most or all of the nitrogen charge depleted.
This happens with age and there is presently no way of measuring the actual condition other than the brake test that have been developed.
This sketch shows the bladder completely compressed at the top of the accumulator. As the nitrogen charge diminishes, it is much easier for the boost pump to force brake fluid into the accumulator.
The pressure switch that turn on the pump comes on at 2000 psi and shut off at 2600. The ABS light comes on at 1500 psi and the Red Brake lamp comes on at 1300 psi.
Since there is no nitrogen reserve, the accumulator is always full of brake fluid and since you cannot compress a solid, the pressure will fall and climb very quickly, this is what happens when you push the pedal once and the pump comes on.

Also in this condition, the fluid level in the reservoir will hardly budge."

 

What I read throughout your testing, was how much difference there was from each pressure point to next, not change in reservoir level. So I'm thinking we're comparing apples and oranges on these 2 different types of tests

 

Again, Thank you for your response and further assistance

 

Mike

 

[2seater]

I know I had some difficulty with the concepts myself and was the primary reason I made a test rig to put some numbers to what many owners have observed over the years. There were standardized brake tests developed many years ago and are generally valid, but I guess I wanted more detail as to why. One thing to note is the accumulator will expel all of the fluid it contains as long as the diaphragm is intact and there is even 10psi of pressure remaining. The only way I can measure the volume of the fluid in the accumulator is to use a bench test with a calibrated container to measure the fluid used and compare this to the observed system pressure. I ran all tests multiple times, a total of nine accumulators were tested, including the ones @ Daves89. Additionally six total pressure switches were tested.

 

It is true that the fluid drop tests I did were conducted using my car as the test bed, so it is using a different pump but the accuracy of the pressure switch on my car has been verified more than once with my test gauge. Even if there may be a small difference in the test bed, the trends observed on the test bench were absolutely confirmed. I know the red and yellow dash warning lights are part of the previous test medium but they have zero influence on the actual system pressure and I have found a fair amount of variation in the pressure points for the lights to turn on and off. While it is important the lights work, they are only useful in a peripheral way in diagnosing the system.

 

I encourage everyone to make the simple test gauge and all of the tests (except the actual volume) I did can be performed right on the car without any disassembly except for removing the steel pressure line from the pump and installing the gauge. A helper would be beneficial observing the lights if desired but do not use the brake pedal.

 

For those that have seen this before, I did reconfigure to more easily bleed air from the gauge.

[Barney Eaton]

Mike.........can you give me the link to the ROJ (is that the Riviera owners site?)

This doesn't sound right. On the ROJ site, the accumulator test states that 1/2" or less is bad. (If the fluid level change is 1/2 inch or less, your accumulator is on its last legs.) Basically the less difference in displacement the worse it is. So now I'm confused. Can someone else help to clarify this?

The above is wrong and needs to be corrected....if it is on the Riviera site I will contact Ray but I need to know where it is...............it should read 1/2 inch or more.

 

Edited August 16, 2017 by Barney Eaton (see edit history)

[Guest whytshdo]

Barney...I'm sure I copied/pasted that line from the Reatta site. However now it reads differently. this is what is there now.

If the fluid level change is 1/2 inch or less, your accumulator is probably in good working order. If the fluid drops 5/8 inch or greater your accumulator may be on its last legs.

 

That's Strange. The only thing I can think is perhaps I printed that page before it was corrected and copied/pasted from what I had saved.

So all said, a good accumulator should be drawing less fluid from the reservoir than a poor one thereby creating less fluid level variation.

 

Luckily I have a new accumulator I can install. (Now where did that get stored after the move???)

 

Thanks for the help explaining this to me 2seater and Barney

 

After bleeding off the pressure from the accumulator; when removing it should I expect much fluid leakage from remaining fluid in ball?

[89RedDarkGrey]

59 minutes ago, Barney Eaton said:

Mike.........can you give me the link to the ROJ (is that the Riviera owners site?)

 

WOW. You don't know what ROJ is? Reatta Owners Journal (Ronnies' website) http://reattaowner.com/roj/

 

1 hour ago, Barney Eaton said:

The above is wrong and needs to be corrected

 

With 2seaters help- Ronnie already did last night- check this link: http://reattaowner.com/forum/showthread.php?tid=293&pid=2670#pid2670

 

Lots of miscommunication here

 

 

[Guest whytshdo]

Ok..so just for the record. After reading the Accumulator replacement instructions, it doesn't say that the Brakes will need bleeding. Is this correct that the brakes should not need to be bled if they are properly bled prior to installing the new accumulator?

 

Thanks again, the help is much appreciated.

 

Mike

[2seater]

If the brake accumulator is depleted as per the instructions, by pumping the pedal 25+ times with the key off, there should be essentially zero fluid leakage when the accumulator is removed. There is no need to bleed the brakes after replacement either. The accumulator is sealed by an o-ring, so be sure the original stays with accumulator when removed and there is one in place with the new one. The seal only requires hand tightening of the ball, no need to gorilla it in place.

 

Regarding ROJ: Yes, Ronnie noticed the incorrect wording, which I admit I never picked up on, and corrected it after your concern that there was a conflict.

[Barney Eaton]

Plus the accumulator is not part of the lines going to the wheels......it is in the booster circuit so even if air got in that line it would not put air in the brake lines.

[Guest whytshdo]

Ok great.. Thanks once again for the help, advice and new knowledge.

 It's also good to know that I'm not going senile about what had been copied from ROJ. It was changed after I had read it. Whew...thought I was losing it.

 

Y'all have a great day and I'll update after repairs are completed.

 

Mike

[89RedDarkGrey]

4 hours ago, whytshdo said:

 It's also good to know that I'm not going senile

 

You own a Buick Reatta... You're journey has begun

[Guest whytshdo]

ok...so here my latest update and question.

I installed a NOS accumulator I had in stock. It appears to have made a difference. Brakes feel a little better an my fluid drop in reservoir is down to just shy of 1/2 inch.

However, I need to know how to adjust the emergency brake. It won't hold the car. I looked in the service manual, but the process listed there did not seem to help.

Also, it now feels like the brakes are stuck engaged. When I put the car in gear and let off the brake, I have to give it a fair amount of throttle to move the car.

I have to take the car for emissons test and I think they'll want the E-brake working properly.

 

Thanks in advance.

[89RedDarkGrey]

Other than the turnbuckle adjuster under the drivers seat area of frame rail- you could jack it up, off all 4 wheels, and rotate each by hand to check for drag. Engine idling, foot on brake- select R & D a few times, check for drag. The RIGHT FRONT wheel is the only "powered" drive wheel. The TH440-T4 4T60 ME9 is a "limited slip" drive unit (in neutral front wheels counter rotate).

 

If the rear caliper pistons are binding, or adjusted too tightly (screw in with tool to loosen) it will seem as if the parking brake is engaged, at will easily hold the car.

 

I would strongly advise to not drive it in this condition- at all. You will quickly burn up pads & rotors, possibly damage a bearing, burn the fluid, and greatly increase the stopping distance.