17" Conversion ABS Problems

[SteveV]

After 5 years of ownership I recently decided to jazz up the GS instead of selling a kidney to buy a new one. So I converted my '01 1150GS to cast RT wheels using new pressed steel ABS rings.
I really love the way it now looks but...
My issue is that now the ABS cuts in really early and the brakes have a weird feeling. The sensor gaps are spot on at 0.45-0.55mm. Both ABS check lights go out when moving off, but the clunk, clunk noise sounds slightly different.
Not servo brakes.
I tried trawling the wealth of knowledge on this forum for ideas to no avail.
I did read that some on here had had ABS issues after conversion, but could find no reference to solutions.

Any ideas..............please.

Steve

 

[Paul Young]

Just a suggestion, with no guarantee of success but it can't do any harm... Have you tried an ABS reset? Once this is done, the ABS may "learn" the relative speeds of the new wheels. This also happened when I did the swap, but was due to loose spindle clamp bolts.

 

[KMD]

Steve, I've had the same problem. I did an alloy wheel conversion on my 1150 and had to fit new pressed steel abs rings. My abs lights flash but the brakes are fine, right until just about standstill, when the abs cuts in and releases the brakes slightly.

I understand the abs can be 're-programmed' to take the different wheel speeds into account but I think it's a very specialist job.

 

[Steptoe]

Changing wheel sizes often throws up similier ABS problems.

usually abs lights all flash up at higher speeds.

Never found a solution, but i've never tried really hard as it's never been my problem

 

[MattW]

I can sort of imagine what's causing the problem although a solution isn't so easy...

The ABS works by counting pulses and comparing the front and back wheel speeds against each other (and probably against another reference - road speed? - anyway it doesn't really matter).

Having changed the wheels to different (smaller) diameters you'll have upset the ABS controller's inbuilt calculations because it's expecting 'normal' to be a certain ratio of front to back wheel speeds (front wheel is larger than the back). It'll depend on the number of teeth on the ABS ring and rolling diameters etc but in any event you've changed 'normal' and the ABS unit is probably seeing a 'lock up' condition much earlier than it actually occurs.

I guess to restore 'normal', you've got two options:

Fool the unit by using different ABS ring(s) - you'll be able to work out the number of teeth / wheel rev by counting them on the old rings and working out the ratio between front and back - you need to get this exactly (or very close) to what the unit is expecting (this depends on other rings being available - you'd have to trawl through the specs / part numbers for different models).

Get the ABS controller reprogrammed by a dealer - I assume this is possible although a dealer might not want to do it for liability (or other) reasons. EDIT: Can a GS911 reprogram ABS function? - might be another option...

In any event I'd probably disable the ABS unit until it's sorted - at least you'll have full, predictable braking (albeit with no anti-lock).

Oh yes - third option - put your GS wheels back on....

 

[Sparky]

Hi,

Having just gone down a slightly different route, I've just changed the original 19" front wheel for a 21" front complete with TKC 80 tyre and pressed steel ABS ring. Where the original was the cast ring. This has been complemented with a new Karoo tyre on the rear.
The problem I found was that the ABS system started as normal with the warning lights going out as I started rolling, but as speed picked up as I rode downhill on the drive the front brake lever when applied became solid and started pulsing with no brake action. I presume the the ABS computer thought that the front wheel was locked and then kept releasing the brake, a slightly worrying moment as speed was building up. The quick fix was to disable the ABS and put up with the flashing red lights.
Would resetting the system enable the computer to relearn the changes or is it the new size front wheel causing the grief ?

 

[MattW]

I presume the the ABS computer thought that the front wheel was locked and then kept releasing the brake

As I said above, I think that this is what's happening due to the the measured and actual wheel speeds being different.

Would resetting the system enable the computer to relearn the changes or is it the new size front wheel causing the grief ?

From everything I've read about it, I think the ABS function is hard coded and I don't believe the ABS controller can 'learn' new wheel diameters (it's not something that would be required under normal operation - wheels don't change diameter - you don't introduce unnecessary variables and functions into safety critical systems). But there's no harm in trying a reset (well apart from potentially having no brakes after 'trying'....). I'm sure it could be reprogrammed by a dealer but you'd have to ask and see what they say - I doubt they'd be too keen.

But I've not tried to fix this myself - perhaps others may know better.

Edit: Might be worth posting a question on Adventure Rider - our American cousins like playing around with GS's

Edit #2: I had a look an ADV myself and ended up in the middle of a big pi**ing contest thread where some said that a reset would fix it, some said that not even a reset was necessary (as this is how the bike compensates for tyre wear) and some said that it wouldn't work whatever you do

I guess suck it and see (carefully) is the only way....

 

[SteveV]

Thanks Guys

I checked the bottom fork clamps were tight, I reset the ABS 2-3 times but the problem is still there.

I turned off the ABS and went for a nice long ride in the sunshine.
I guess that now my choices are:-
Try to get the system reprogrammed at a main dealer .
Live without the ABS
or
Put the proper wheels back in!!

I'll let you know what happens.

Steve

 

[dizzyrascal]

ABS

Steve

I bought my 1100 three years ago with the conversion already done, the previous owner had purchased a kit from Motorworks, suggest you give them a call. I believe that the ABS ring was changed to one that would normally be fitted to a 17 inch wheel
My breaks work as they should do so this is probably the answer.

 

[Myke Rocks]

Just an aside.

Steve

I bought my 1100 three years ago with the conversion already done, the previous owner had purchased a kit from Motorworks, suggest you give them a call. I believe that the ABS ring was changed to one that would normally be fitted to a 17 inch wheel
My breaks work as they should do so this is probably the answer.

The above is correct.
However, when designed, ABS systems are actually programmed with the inertia of the wheel.
As a consequence, they "know" just how suddenly a wheel can come to rest, and if the wheel stops quicker than this, they "Know" the wheel has locked, and release the brake automatically. If, therefore, you change the toothed ring for oen with a difecernt number of pulses, they think the wheel is stopping at a different rate, and may "cut in".
They also compare wheel pulses, & use this to provide same result.
Myke