ABS performace

[luke2152]

Does anyone else get the feeling that the ABS is overly sensitive on this bike? I'm not talking about off road when it is switched off anyway. Until the T7 I'd never owned a bike with ABS and never felt I needed it but I thought it might be useful one day in a panic situation.

 

But when I'm pushing it a bit on the road I can feel the rear abs pulsing under normal braking into the corners. And recently had to do an urgent stop (not quite panic stop) for some animals on the road and both front and rear was operating. I'm pretty sure the ABS actually increased my stopping distance and whether it did or not, it took braking control away from me when I was still in control. Really not a nice feeling and all this was on dry tarmac. Anyone else experienced this?

 

I'm also not pretending to be some riding god who doesn't need safety features. To the contrary I'd quite like ABS which I never noticed day to day and came and saved me when things really went wrong. It's also possible that I just need to get used to the sensation of it.

 

[Canzvt]

1 hour ago, luke2152 said:

Does anyone else get the feeling that the ABS is overly sensitive on this bike? I'm not talking about off road when it is switched off anyway. Until the T7 I'd never owned a bike with ABS and never felt I needed it but I thought it might be useful one day in a panic situation.

 

But when I'm pushing it a bit on the road I can feel the rear abs pulsing under normal braking into the corners. And recently had to do an urgent stop (not quite panic stop) for some animals on the road and both front and rear was operating. I'm pretty sure the ABS actually increased my stopping distance and whether it did or not, it took braking control away from me when I was still in control. Really not a nice feeling and all this was on dry tarmac. Anyone else experienced this?

 

I'm also not pretending to be some riding god who doesn't need safety features. To the contrary I'd quite like ABS which I never noticed day to day and came and saved me when things really went wrong. It's also possible that I just need to get used to the sensation of it.

 

If you are on stock tires, and/or it is cold/wet/not perfect conditions and you are 'on it' hard, the ABS will be happy to help. The ABS is tuned to be quite conservative.

 

BTW, in a properly tuned ABS system, when activated during braking, attempts to keep the tires at or near their maximum traction threshold,  which on a firm surface likely equals the shortest stopping distance while in a straight line. It also allows the wheels to keep rolling, allowing you to maintain control and potentially steer around a situation (which may include steering into the ditch) and also likely to result in an increased stopping distance from OPTIMAL. On some of the higher spec bikes, this threshold of slip is tunable to increase the slip from a safe number (1-2%) to the ragged edge of safe (8-9%), thus decreasing the stopping distance, but asking more of the rider. I'm quite confident that I can stop faster than a standard ABS equipped bike - maybe 1 or 2 out of 10 times in controlled conditions. I'm 100% confident that I can out brake a standard ABS equipped bike 0 out of 10 times in a panic situation.

 

Most of the above goes out the window if you are riding on gravel/sand/etc.

[luke2152]

Yeah I agree with what you are saying and 8-9% slip sounds much more reasonable that 1-2%. Not that it changes my situation. I guess I'll stay in offroad mode for now and maybe try and disable it entirely.

[Doc Brown]

On 2/27/2021 at 11:25 PM, luke2152 said:

Does anyone else get the feeling that the ABS is overly sensitive on this bike? I'm not talking about off road when it is switched off anyway. Until the T7 I'd never owned a bike with ABS and never felt I needed it but I thought it might be useful one day in a panic situation.

 

But when I'm pushing it a bit on the road I can feel the rear abs pulsing under normal braking into the corners. And recently had to do an urgent stop (not quite panic stop) for some animals on the road and both front and rear was operating. I'm pretty sure the ABS actually increased my stopping distance and whether it did or not, it took braking control away from me when I was still in control. Really not a nice feeling and all this was on dry tarmac. Anyone else experienced this?

 

I'm also not pretending to be some riding god who doesn't need safety features. To the contrary I'd quite like ABS which I never noticed day to day and came and saved me when things really went wrong. It's also possible that I just need to get used to the sensation of it.

 

Compared to other bikes the ABS of the T7 is indeed conservative. It kicks in way earlier than on a street racer like a CBR 1000 RR or similar. That can be a bit annoying. First time I realized that was when I jumped from a Honda CBR 1000 onto a more or less basic Suzuki 650 and its ABS started so early, long time before I was out of control. But you always can switch it off, just don't forget that you probably will come into a situation where the ABS would save your life....

[luke2152]

I wonder if you could splice the rear abs sensor lead onto the front sensor. Then it would always see both wheels turning at the same speed (and be relatively easy to put back to stock later).

[Aleksandar13]

19 minutes ago, luke2152 said:

I wonder if you could splice the rear abs sensor lead onto the front sensor. Then it would always see both wheels turning at the same speed (and be relatively easy to put back to stock later).

I don't think this works as the ecu will ready back and front at a different ratio, hence the correction abs rings are the same slot and different size but the wheels are different. 

Aleks 

[Uncle M]

On 2/27/2021 at 3:17 PM, Hogan said:

I've noticed it tends to trigger with large suspension movements - riding over speed bumps, gutters etc, even if you are not using the brakes.

How would it be possible for the ABS to activate when the brakes have not been activated? I've no idea what sensors initiate ABS so I am curious about this. Thx.

[Canzvt]

4 hours ago, Uncle M said:

How would it be possible for the ABS to activate when the brakes have not been activated? I've no idea what sensors initiate ABS so I am curious about this. Thx.

I think this might be a misinterpretation of what is actually going on. Under normal circumstances ABS systems are designed to bleed/reapply pressure at high frequency into the brake system based upon measuring the pressure input (reference pressure) coming from the operator (ie: pre ABS module), taking an arming signal from a brake light switch and then monitoring wheel speed, all of which are fed into a specific ECU to calculate the actual braking pressure which in the case of the T7 will ALWAYS be equal to or less than the reference pressure. If the ABS system is not 'armed' as is the brakes aren't applied, then the system will not activate. If the wheel are not slipping, then the system will not activate. Having spent a number of years developing braking systems for N/A , EU and Asia Pacific markets, there are a significant number of fail safes mandated by the DOT/TUV/MOT etc that must be incorporated into the system design to prevent the ABS actuator from applying brakes outside of very specific operational conditions. If your brakes are being applied with large suspension movements, I would be taking it IMMEDIATELY to the dealer for repair.

[Uncle M]

@Canzvt makes good sense! I couldn't see how the ABS could be working when the brakes weren't being applied.  But makes total sense that what @luke2152 was describing was the ABS functioning not because of the suspension but because a hard application of the brakes that initiated the ABS was also causing the suspension to dive! Ha, of course!

[WalterT]

3 hours ago, Canzvt said:

taking an arming signal from a brake light switch and then monitoring wheel speed, all of which are fed into a specific ECU to calculate the actual braking pressure which in the case of the T7 will ALWAYS be equal to or less than the reference pressure. If the ABS system is not 'armed' as is the brakes aren't applied, then the system will not activate. If the wheel are not slipping, then the system will not activate. 

 

That would imply that the ABS could  permanently (or at least as long as you'd want) be disabled by switching off the arming signal from the rear light after ignition?! This is something that can realistically be hacked. Loosely thinking (depending a little on the timing of the ECU check cycle), by having a relay cutting off the break light switch arming signal a few seconds after the switched power comes on. Bike is turned on, ECU checks and see everything is in order,  then does not notice you've been riding for two hours without having used the brakes? Add a selector switch and presto? 

 

Or will it still throw a fit for other reasons?

Edited March 2, 2021 by WalterT
Typos

[luke2152]

7 hours ago, WalterT said:

 

That would imply that the ABS could  permanently (or at least as long as you'd want) be disabled by switching off the arming signal from the rear light after ignition?! This is something that can realistically be hacked. Loosely thinking (depending a little on the timing of the ECU check cycle), by having a relay cutting off the break light switch arming signal a few seconds after the switched power comes on. Bike is turned on, ECU checks and see everything is in order,  then does not notice you've been riding for two hours without having used the brakes? Add a selector switch and presto? 

 

Or will it still throw a fit for other reasons?

I suspect the trigger will be off a pressure sensor in the abs module rather than the brake light switch. Otherwise too easy for it to fail.

[Canzvt]

So the trigger can be from a number of sources. My explanation above is generic in nature as each manufacturer has their own specific interpretation of how they want their system to operate, what trigger they use, number of pulse counts on the wheel rings, system response time etc. As @WalterT suggested above, it is likely possible to hack the system although I have not studied the wiring diagram for this system nor do I know how the diagnostics sequence is designed to operate for this. This bike is equipped with full OBD2 diagnostics, which while familiar with how to obtain codes, and what they mean, I am not familiar with the diagnostic sequence/timing for this protocol.

Also, like @luke2152 stated above, the trigger is likely a pressure switch in the abs module, but a trigger is required to arm the system. 

[luke2152]

23 hours ago, Aleksandar13 said:

I don't think this works as the ecu will ready back and front at a different ratio, hence the correction abs rings are the same slot and different size but the wheels are different. 

Aleks 

I'm still not convinced it wouldn't work. The rings are the same front and back. 90/90/21 and 150/70/18 are very close in rolling circumference. They must leave some tolerance for whatever weird combination of front and rear tyres someone could reasonably choose (say a knobbly front and slick rear from different brands).

[Aleksandar13]

5 minutes ago, luke2152 said:

I'm still not convinced it wouldn't work. The rings are the same front and back. 90/90/21 and 150/70/18 are very close in rolling circumference. They must leave some tolerance for whatever weird combination of front and rear tyres someone could reasonably choose (say a knobbly front and slick rear from different brands).

Please have a read and see all the tests that have been done to find a solution for Speedo Correction.. You will find in that thread information on how much the ecu will tolerate in terms of difference between front and rear... 

Aleks 

 

 

[luke2152]

On 3/2/2021 at 6:23 PM, Aleksandar13 said:

Please have a read and see all the tests that have been done to find a solution for Speedo Correction.. You will find in that thread information on how much the ecu will tolerate in terms of difference between front and rear... 

Aleks 

 

 

Interesting read Aleks. Seems fairly tolerant. Makes me wonder if running two or even four bigger on the back would make rear abs less sensitive (while still working in emergency). Although of course it might make the front abs more sensitive!

[JohnfromDP]

I had my ABS come on during an urgent stop  as a car turned infront of me. I felt like I could of stopped a lot quicker had the ABS not engaged.

[Aleksandar13]

1 hour ago, JohnfromDP said:

I had my ABS come on during an urgent stop  as a car turned infront of me. I felt like I could of stopped a lot quicker had the ABS not engaged.

I am in the process of getting all parts ready for changing to braided lines with one single disc on the front and no abs...  

[Alan M]

4 hours ago, JohnfromDP said:

I had my ABS come on during an urgent stop  as a car turned infront of me. I felt like I could of stopped a lot quicker had the ABS not engaged.

You probably can stop in a shorter distance in ideal conditions but the benefit of ABS is to allow you to continue to steer the bike away from the danger whilst heavily braking. The other scenario is locking the front with a panic grab of the brake, the ABS comes in and increases the stopping distance but maybe it saved you tucking the front wheel.

[JohnfromDP]

I realize that, my problem is that I had nowhere to go, ditch, telephone pole or oncoming traffic.