[Johnnynapalmsc2]

You're not getting an ABS warning light?

Nope no warning light, and the combined abs seems to be working properly (when pushing rear brake the front also engages)

 

[Johnnynapalmsc2]

Master cylinder might be going.

I will take it to a garage on the weekend, to see what they say. I read that putting a zip tie on the brake lever overnight could help to get rid of some air from the master cylinder, wonder if that's worth giving a shot

 

[Johnnynapalmsc2]

I do believe this is the dreaded Honda Bosch ABS brake system fucked up design in operation.

The exact behavior you describe is sadly part of the way Honda/Bosch say the early generation ABS operates.

This is an extract from the UK 1000RR forum dedicated thread to this very subject:

Important Notice - Please Read If You own an ABS 2009 Onwards Model

I know there has been a few post on this subject but after speaking to Honda Technical this morning again, after another episode at the weekend, those...

www.1000rr.co.uk

"
I know there has been a few post on this subject but after speaking to Honda Technical this morning again, after another episode at the weekend, those who are or have encountered this problem must do the following, before someone is hurt, as there appears to be some close calls.

I had a long chat with the guys at Honda Technical UK, about the brakes going to the bar intermittently, with reduced breaking! Honda UK claim no dealers are contacting them about this issue, which sounds ridiculous, considering the amount of posts I have read. Although there may only be a few of us encountering it, I still believe there is a problem. I did explain if the forum didn't exists, we would only think it's us individually who are having the problem, and not widespread.

Therefore I'm suggesting and Technical agreed with me, those having the problem MUST report it to Honda Technical or your dealer. Please ensure the dealer reports it to Honda this way Honda can react, other than that they are just looking at mine as an individual case.

Here are some numbers which you can you use.

Honda uk contact number: 0845 200 8000
"

Huh that’s a strange issue then. Just had a ride home from work and was paying extra attention at this issue, and after 40 minute ride not once did it occur. Also had a look at the abs light and it’s on until I started to move but then goes away which is what I assume is the standard. Tried to really slam on the brakes and the system seemed to kick in well too.

 

[Johnnynapalmsc2]

I am also a member of the UK forum and personally know of 2 owners who experienced the problems as posted by @RC45. The problem with the system is that it gives no warning. It might be great for months and then bang, just when you need good stopping power, the lever's right to the bar.

In UK, there are people who will specifically avoid purchasing the bikes with the Honda Combined System C-ABS. My belief was that the Bosch systems commenced with the 2014 bikes, but could be corrected on that.

So not really any solution for this issue? I would like to also take this bike on the track, but now I'm a bit hesitant. Also my warranty from the dealer is up, so that sucks. Might be still worth to try to bleed the brakes though.

 

[Johnnynapalmsc2]

Sorry, Johnny, that I didn't offer a solution. Problem is that no one has been able to.

Some bikes have been to the dealer for a full bleed (at a considerable cost) and had the problem resurface some months later. I am talking about normal road riders on non-modded bikes.

I am rarely negative about Honda, but this is one issue that has affected only a handful (I believe) of owners. Overriding problem is, as you say, living with the wonder of if/when the brakes will fail.

Certainly worth your while as a precaution to bleed the brakes with Dot 4 fluid. Not sure if you're aware, but the ABS system cannot be bled like the conventional system. There is a very lengthy and precise procedure required. The complexity is detailed in this link: C-ABS Bleed Notes V8.pdf

Thanks for your reply. Do you know any info on those owners with this problem? Would be interesting to see what their solution was. I’m assuming there is no way that the brakes would fail and I would actually have no brakes. For example I never noticed the brake levers going soft during hard braking, mostly when I release them after braking and engage again they go soft, and that’s like 1% of the time

Edit: Had a little research on other forums, looks like there is a considerable amount of people who experience similar issue. Except from what I've seen, everyone else who has it gets a flashing ABS light and then need to restart the bike to get rid of the issue. For me I don't get any flashing ABS light and the brakes go back to normal after releasing and re-engaging them. Will bring it to the dealer I've bought it from on the weekend, see what they say.

 

[Johnnynapalmsc2]

The few times this occured with my bike, I was coming off the track and heading back to the paddock at a slow speed when it occurred. The only thing you can do is to pump the brakes until it engages again, usually one pump was sufficient.

I also though about bleeding the brakes to solve the problem but Honda wanted to charge me 7 hours of labor times two technician just to bleed the brakes.lol. Eventually after my latest crash, I just removed the ABS system when rebuilding the bike.

Sent from my SM-G960W using Tapatalk

Now the big question is, did the ABS cause the crash or something unrelated? Thanks for the replies guys, so I'm assuming it's not worth at all to go to dealer and have the brakes bled, as the price like mentioned was pretty high

 

[Johnnynapalmsc2]

I have a 2009 ABS model and have some insight.

1. It is not a matter of properly bleeding the system. I did two full flush/bleed cycle including the power unit under the headers using a vacuum pump and did not notice a difference.

2. It is not the stock master cylinder. I replaced it with a brand new Brembo RCS19 and there was no difference.

3. It is not the stock rubber brake lines. I replaced them with a full Galfer stainless kit and there was no difference.

The problem is the caliper piston retraction by the power unit combined with the stock caliper piston extension/retraction distance.

Above a rolling speed, the master cylinder is disconnected from the calipers and goes instead to a pressure sensor. As a result, the "brakes" feel firm and the lever travel is great. Lets assume you apply the brakes and keep the brakes applied until you get below the ABS cutoff speed. As long as you keep the brake lever applied, the actual braking pressure is supplied by the power unit even though you are now in a situation where the ABS system normally would not engage. Now when you release the lever at below the ABS cutoff speed, the front power unit has to retract and the system must pull fluid away from the system.This is fine if your brake lever is fully released and fluid can flow from the master cylinder reservoir. The problem is if your lever is slightly squeezed (not fully released), the ABS power unit still has to retract and draw in fluid which means it will retract the caliper pistons more. Fluid cannot come from reservoir because master cylinder piston is past those fluid ports. Then, the calipers with pistons retracted more than usual are connected back to the front master cylinder, which is already partially compressed in this situation. When you go to apply the brake lever now, the lever travel is significantly greater than expected because the master cylinder is already partially compressed and the calipers are more retracted than normal by the power unit. This is why pumping the lever lets you regain pressure.

Replacing the stock calipers with a pair of Brembo GP4-RX was the very expensive solution. The GP4-RX calipers have less piston retraction by nature of the seal groove design and consequently also less fluid required to engage than the stock calipers. There is significantly less lever travel required to engage the pistons compared to stock calipers, which makes the ABS slop minimal because the power unit piston does not have to extend as much to engage the brakes and consequently does not have to retract as much to disengage the brakes.

Thanks very much for the info. Is the Brembo GP4-RX the calipers you recommend, or some other after market calipers could do the same fix?

 

[Johnnynapalmsc2]

Hey so finally my dealer said that they can have a look at the bike, and it will be on warranty still, is it worth for them to still have a look at this issue or there is no way it's the brake lines that need flushing? I think that's what they are willing to do, flush the brake lines. They obviously are not willing to cover these parts to solve the issue.
Also after speaking to them they told me it would only take 1.5hrs to do the brake flush on the bike, but it's with an ABS module, seems a bit quick