6SpeedTL

This all started about three weeks ago in my 2010 RDX, during a hard stop or just sitting the pedal will go straight to the floor. Below is a list of everything done to correct with no luck.


1. Checked for leaks, nothing.
2. All fours pads replaced.
3. Brake fluid flushed and replaced.
4. Master cylinder replaced and booster inspected.
5. All four rotors replaced. Acura recommended this as they advised its possible my pads aren't making full contact with the rotor because its warped.

All this done and nothing has changed.

Any idea guys ?

Thanks

GSJake

Wow. I was going to say Master Cylinder.. but looks like you have replaced almost everything break related. No codes?
I doubt its the issue but maybe add braided steel brake lines as this will help with brake feedback immensely!

Tomtwtwtw

I'd think you would feel warped rotors if they're THAT bad. Have to assume the brakes were bled properly, but maybe worth checking again? Squishy pedal usually means air in the system...or if you're getting nothing at all from the brakes, maybe check the linkage of the pedal itself? Maybe also double check all your vacuum lines. Maybe new booster wasn't connected properly, or a leak (vacuum, not fluid) that caused the initial problem wasn't found and / or addressed. Good luck!

justnspace

iTrader: (1)

the service manual gives testing procedures on MC and brake booster.

I seriously would question on how some determined how the booster or MC are still good, if pedal is sinking to floor.

pedal sinking to floor is a symptom of failing MC or Booster


or it could be a loose vacuum hose

6SpeedTL

Thanks guys.

The Acura dealership is who flushed and replaced the brake fluid and also replaced master cylinder. Also, they advised of "checking" the booster.

The car stops just fine, actually much better than before since the new pads and rotors. The dealership also advised they checked to pedal itself and didn't see any issues. Fact is, pedal shouldn't go to the floor so something is wrong they just didn't seem to care.

Where are the vacuum lines and booster located ?

XLR8R

Your dealer did all that work and says it is ok. You need to go back, show them your complaint and work it out with them.

Kaputnik

Curious as to what the pedal is doing? Does the pedal pressure fade after initially being firm, or just easily pressed all the way to the floor? Does the pedal pump up rock solid when the engine is off?

When I am parked and engine running, with moderate force I can make my pedal go all the way to the floor. But there is no fade and the brakes seem to perform very well.

6SpeedTL

When first started its firm and fades as driven. Upon further testing I've found the following:

Slow steady braking - Pedal is fine, doesn't go to floor.

Moderate braking (70 mph to 20) - Strong bite, doesn't go to floor, unless I come to complete stop.

Aggressive braking (45 mph to 0) - Straight to floor, ABS kicks on. I'm thinking this is suppose to happen.

Car brakes great, especially since I upgraded to ceramic pads but I know when we purchased the vehicle the pedal did not go to the floor.

Kaputnik

^^ Seems like if things have changed and you really notice it going to floor, your dealer needs to address it.

Even though I mentioned mine can reach the floor with a bit of effort when not moving, it just seems like a normal pedal when driving; I don't notice anything different or unusual. I've been paying extra attention since I did a gravity bleed and pad change about a month ago.

Mr Marco

ABS Pump

57111STKA01

IIDXholic

iTrader: (5)

You should still feel pressure even with aggressive braking and the ABS comes on. On my Prelude SH, I know the ABS doesn't work, and even the light is on, code thrown indicates its "stuck", and the brakes lock. I would think if the ABS is out or stuck, and being the SH Prelude and SH AWD are similar, it would do the same as well. I bet when you find it out its going to be something stupid as a loose cable or something, it always is.

Kaputnik

Yep. Maybe just a fatigued brake hose or something. Try new or stainless steel brake lines, OP?

TheWrench116

iTrader: (1)

look for the obvious:
1 any puddles?
2 any wet spots on the rims or the chassis?
3 is the master cylinder ok?
4 is the brake booster ok?
if you find nothing then you need to start looking at ABS components.

hope this helps

pnoi521

I had this problem with my 06 TL. If you pump the break pedal do you start to get pressure? When we were trying to fix it on my car, first we replaced my master cylinder, but i think we had to bleed the break lines 3 times because it would go back to just going straight to the floor.
Finally, we replaced the VSA modulator and it solved the problem. Apparently it was pumping air into my brake lines. Hopefully your dealership will be like mine and apply the amount we paid for master cylinder ($350) towards the cost of the VSA modulator ($1,200)

6SpeedTL

Thanks for all the replies.

The car is at the dealership for a fourth time. Their now blaming the ceramic pads I put on, saying they get too hot. They dont seem to understand this issue started well before I put pads on.

All they want to do is replace the pads and re-surface the brand new rotors! They are completely dismissing any other possible cause. I mentioned the ABS pump and they advised it only works when ABS is engaged so that wouldnt be a cause.

Not sure where to go at this point other than a different dealership.

GSJake

THIS!!!!!!

TheWrench116

iTrader: (1)

give them this ultimatum. if your proposed solution doesn't fix this problem not only am I not going to pay you, your going to put in the pump for free. but make damn sure you know that your brakes were done right otherwise you'll look like an ass

csargemg

I had exactly this issue and it went away with a proper 4 inch brakes bleed. It is probably the booster pumping air into it

csargemg

Or as suggested above, the VSA modulator

juster

Hello guys.
Almost the same problem. I have 4pistons front BBK. Brake pedal soft(with running engine). Easy to floor it. Overall brake perfomance somewhere about 50-60% from stock. I must push that pedal REALLY extremely hard on dry and clean road to get ABS kicks in. Normal city driving style braking achieved only at 50-70% of the way to floor.
Pedal pressure does not fade after initial press. It`s just easy to floor it. Of course, there is no empty brakes feeling, it has resistance, but not like before.
If the engine is off - pedal become rock solid after few pumps and does not fade.

All brake lines and hoses - no leakage, no damage.
BBK changed back to stock for few months, then changed back to BBK, replaced EBC Redstuff with Ferodo dS2500.
Brake lines bleeded many times.
Replaced Master Cylinder, completely changed brake fluid.

I did not use diagnostics scanner yet
ABS pump not bleeded(people discuss it in other Acura`s threads), i had no information about that.

Hope this is not ABS pump damage.


Any suggestions?

05tortsx

I'm having the same problem on my 2010 RDX. Took it to dealer and they probably bled the brakes about 4 times (including gravity bleed). Even had another shop bleed the brakes and no improvement.

Dealer ruled out master cylinder and booster. They replaced the VSA Modulator under warranty and while a very minor improvement, pedal is very soft.

Car does stop ok it seems but the brakes don't grab and I feel when I really need to brake I might take the pedal to the floor and not get the braking power i need.

Car has been at the dealer many times and they even kept it for a week. They want to change pads and rotors at my cost to rule out any aftermarket parts causing the issue. Currently have Hawk HPS pads installed. Doubt that would cause the issue.

juster

UPD.
When i just started engine - brake pedal feels like it`s OK. And i can`t get it to the floor. Right after ABS pump starts (bzzzzz sound for couple of seconds) brake pedal soft again and it`s easy to floor it.

05tortsx
looks like we have similar problems. Please check how your brake pedal works right after you start engine.

wspy

Check this as Marco said long ago.

JasonK

Could be either they didn't bleed the system properly or there is air in the abs pump or the abs pump is no good now.

juster

i`ve found a guy with HDS scanner. We did ABS valve test many times. And a test drive with hard braking few times. Brake pedal feels better now. I feel better brake perfomance. It`s not like it should be - but much better. I will buy a barrel of brake fluid and ask mechanics to bleed everything to hell.

P.S.
when i reach 60-70km\h, shut engine off and press brake pedal - brake perfomance is amazing(there is no abs, but overall brake perfomance very good before wheels lock)

ljcolomacks

Did you ever find your solution to this problem? I am dealing with the exact same thing right now.
Replaced my my brakes with EBC rotors and pads and noticed the issues during break in.
Since then I have been back and forth to the dealer and have replaced my Master and Booster which hasn't helped.
They have been bled multiple times. I then switched pads and rotors to stoptech without any improvement.
Now I am back to stock everything and the braking is horrendous.
I literally just had to do an emergency stop at about 65mph and literally my pedal went straight to the floor.
The RDX slowed down but no ABS and not even close to locking up.

Has anyone resolved their braking problem surrounding this?

Tomtwtwtw

Had you added fluid or topped off the master cylinder anytime prior to doing your brakes, when pads were very worn? And if so, did you open the bleeder screw when compressing the pistons to make room for the new pads? Technically you're supposed to, although I honestly have never done that...I also only replace an axle at a time, and go very slowly when compressing the pistons.

That said, if you were topped off, and now you're forcing that fluid back into the system, there is added potential for damage. Very surprised that replacing both the master and booster didn't do the trick. Dealers aren't perfect...I'd honestly recommend bleeding the system yourself again if you haven't done it since the last dealer visit. Also check for vacuum leaks.

ljcolomacks

Thanks for the response Tomtw. Initially I did not add any fluid to the system and just slowly compressed the piston (without opening the bleeder). I assumed it wasn't air in the system since I did not open anything. I did not have to top anything off at the time.

I've had it at the honda dealer about 4 times now and they said everything is fine. Also took it to another shop who said everything was fine. No errors were present or anything. At this point I think the system itself it working fine. For whatever reason the two sets of aftermarket pads and rotors have not played well with the rdx.
EBC Ultimax Rotors with Red stuff pads
Stoptech Cyro Slotted Rotors with Street pads

I did install the original oem rotors last night and could tell there was already a difference. I had all stock pads on there with the Stoptech Rotors previously.
Just gonna bleed the crap at of everything and be done with this! I know some people have had good luck with the EBC Yellow Stuff pads but I myself am done spending money.

DCS

I realize this is an older thread but I have to make a decision on buying a very expensive VSA modulator or try a used part first. My question is, if I go with a used VSA module from a salvage yard is there any dealer required programming for the used part? Thanks for any response to this question.

After studying the ABS module operation, I think what happens with these modules is a small leak occurs in one of the outlet solenoid valves, which allows fluid pressure from the master cylinder to bleed into the motor pump circuit and causes a spongy, long brake pedal travel condition. I might try to tear my old modulator apart if I get the problem fixed with a new or used one so I can find out what is really going on. It appears they are built to be non-serviceable so might have to get creative tearing the old part apart.

Nedar

I realize this is an old thread but wanted to answer your question. I replaced my VSA module(used from eBay for $180 or so.. dealer wanted to charge me $3800 or so). After I replaced the VSA it solved the problem but I had a whole bunch of engine lights related to brakes and VSA. Took it to dealer and apparently they have to calibrate the sensors after VSA replacement. They charged me $80 to recalibrate and the lights went away. Hope this helps.

DCS

Thanks for the feedback. I did replace my VSA unit with a used one and saw no improvement and I also purchased a Thexon 803p master cylinder plug kit to confirm the VSA unit wasn't the problem. In the kit you can plug the four brake lines coming out of the VSA unit and confirm the problem is after this unit or not. When I plugged the brake lines output ports on the VSA unit I had a rock hard pedal so the VSA unit wasn't the problem. Those VSA/ABS modules are insanely expensive so spending money on the plug kit made sense to me and it turned out to be a great troubleshooting aid and assured me the module wasn't the culprit. I also purchased a scanner to calibrate the sensors after the VSA module install, the Foxwell NT710 with Honda/Acura specific software. The scanner also enabled activating the ABS module for brake bleeding.
In my case what ended up helping me the most were Techno Fit stainless steel braided brake on all four wheels. These lines replaced the rubber ones, which I had already replaced with original OEM parts with no success. With the Techno Fit stainless steel lines there was an immediate, noticeable difference in brake pedal feel, firmer and with more stopping power.