Hill start control issue

[Stu]

Had a nice ride yesterday 330+ miles around the Yorkshire Dales and Lake District and as you can imagine its a bit up and down in a lot of places

We stopped at some roadworks that was on an incline so naturally I engaged the Hill start control

I noticed that the bike wasn't holding as well as it has done in the past! I could rock the bike a bit and it would roll back

I have used this fully loaded up two up and it worked flawlessly but yesterday it didn't seem to play ball

Has anyone had this sort of issue before? is it a time for a call to the dealer before my warranty runs out

[exportman]

I would check the rear brake calliper make sure the brake pads are not worn out.

[Stu]

I would check the rear brake calliper make sure the brake pads are not worn out.

New pads at the end of last year so no issues there

[Stu]

Has anyone on here got GS-911 and a bike with hill hold?

If so I was wondering if you could check what pressures you get on the rear brake once hill hold is enabled

Also any pressures relating to the rear brake circuit with the brake on and off

[audibob2]

Twice I have had my hill start function throw a yellow warning , with the system not locking the rear brake. Once on a down slope. and then on my drive which is on a slight incline. Both times the "H" did not come on. As far as I remember, I kept my rear brake on as normal, and it seemed to
reset itself, and then it worked again.
You said you could rock the bike, and then it failed. What do you mean by "rocking".?
I will plug my gs911 in later tomorrow, and try and read any pressures etc. Have not tried this before , so bear with me.
Bob

[Stu]

Thanks for the reply Bob

Mine never failed it was still on but not holding as it should be

When I say rocking I mean back and forth and it will move where as other times it was solid as a rock

[audibob2]

Hi SAKM

First, my brake fluid is new. rear pads are half worn and braking is good on the rear.

The resting pressure showed 0.10 and pressure via the pedal, with normal type that would be used was 21.3

Hill start assist resting pressure showed 0.50 , then averaged 15.2 during several attempts.

You would expect the foot pressure to match the assist pressure, but BMW do state it is not a hand brake.

I hope this helps. I only use it on traffic stops with normal "level" roads, cannot be bothered or trust it on slopes.

They should have spent the money on a LOUD HORN THAT PEOPLE CAN HEAR, more useful.

let me know your outcome. Technology huh..

Bob

[Stu]

Thanks @audibob2

Those figures are different to mine! my holding pressure is lower!

I will take a trip to BMW and see what they say

[audibob2]

Why did the system not show a fault code for this. At least it would have alerted you prior to finding out when you least expected it.

There is no way I would buy a car with an electronic handbrake for the same reason.

Will be interesting to find the reason why.

How low was your pressure?

[Stu]

It won't show and error as according to the bike it's working

Mine shows in psi and it was 186psi ish yours works out at 220psi ish

[audibob2]

This is important info , although it is an annoyance for you.
At your lower pressure level ,irrespective of the cause, it is possible to suffer loss of "assist".
Perhaps it would be prudent for those with the gs911, or to have a dealer check it for you if you do not have access to one, to check their pressure at each service / rear pad / disc change/ brake fluid flush.
I certainly will.
perhaps those who have a gs911 and hill start assist , can give the forum their pressures, providing their rear brake is functioning as normal.
Then we can get an idea of the average pressure we can accept as normal.
Bob

[audibob2]

If anyone near to me needs access to a gs911, I am willing to let two others use mine to check their pressures.
Message me if you are interested.
Bob

[Stu]

If anyone near to me needs access to a gs911, I am willing to let two others use mine to check their pressures.
Message me if you are interested.
Bob

Thats good of you Bob

But if you are going to offer that service it might be wise to put you location in your profile

[Jggpossum]

Does anyone know the mechanics of how this Hill Assist works?

I have done about 1500Km on my 2023 1250RT and use this a lot as I live in a hilly suburb. On one occasion on a particularly steep slope at traffic lights I noticed that if I pushed ever so slightly with both feet on the ground, the bike moved slightly backwards. Wasn't a problem as it still held.

My "speculation" at the time was that the system is "charged" by the firm pressure on either front or rear brake levers. Hence why the system is not activated with the green H symbol unless you have applied a minimum amount of pressure. Minimum pressure might not be sufficient under all circumstances? Pull Harder?

I might be on the wrong track with this so would be good to learn how it actually works. Knowledge is power!

[Stu]

I believe it works off the ABS pump

I have logged the pressure through my GS-911 and I noted that no matter how hard I pulled with the front I got the same pressure

If I pressed the rear brake hard then pulled the front I got a bit more pressure but it then seemed to settle at a similar pressure as just pulling the front

I suspect that there is a pressure threshold set and it stays at the threshold