08 ABS And Modifications


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On page 56 of the 08 touring models owners manual is a interesting bit of information all 08 ABS owners should read.
It says "ABS motorcycles must always use tires and wheels that are the same as the original equipment."

It further says if you change to different size tires or wheel diameters you can upset the ABS calibration and it will not work the way it was designed to work.

Read the entire section for yourself and possibly check it out with your dealer before you make any changes that might upset the ABS system.
I just spent the last 2 hrs browsing the net reading up on ABS Motorcycle brakes.
No doubt about it, under ideal conditions ABS beats regular brakes hands down unless one is a professional rider like a Nickey Hayden.

There are some issues:

1) As Mr. Data pointed out, you cannot change tire size or rim size unless the ABS controller has some sort of adjustment to compensate for that differance in size. I guess the Harley Davison engineers never thought of that one. There was no mention of a wider tire affecting ABS brakes that I could find.

2) ABS brakes do not allow you to stop on a dime. Is all about traction. So if its raining or snowing, allow at least a minimum of 3 seconds between yourself and the vehicle in front of you.

3) I got this artilce from a BMW site. I AM NOT AN EXPERT ON ABS OR ANY OTHER TYPE OF BRAKES , but this caught my attention !!
It may or may not apply to Harley ABS but if it does, its worth reading as it will make the rider aware of certain conditions where braking distance can increase.

A unique aspect of ABS controlled BMWs recently came up on motorcycle-usa.xxx, a website message board on which I am a moderator, specifically in the Motorcycle Safety section.

Everyone should be aware of a control aspect of your ABS system that some people may misjudge as a fault of the system, when atually it is done purposely to help maintain bike stability. The sequence is: when during NORMAL braking, the bike drops over a pronounced crack or edge in the pavement, in such a way that the rear tire is momentarily airborne, the ABS senses this as a rear wheel lockup event. Rather than simply limit braking to the rear wheel, the ABS system momentarily releases FRONT brake pressure in order to limit the time the rear tire is in the air. In essence, with this system it is not possible to do a stoppie on BMWs fitted with either the ABS-8M system (F800 series) or the I-ABSII system (R's and K's). The R-GS model has a ABS-OFF switch to depower the ABS system, but it is the only BWM with this feature. Do not simply depower the ABS on your Can-bus equipped bike as it will cause a fault.

Again, this is done to maintain bike stability, not to produce a shorter braking distance. In terms of bike stability, unless you are a praticed stunter or very experienced rider, a stoppie type event can VERY quickly become unstable with a crash as a result. But as with any rider assistance system, the rider STILL must be ware of how the system works and practice with it to know how it acts.

The real caution here though, is you do not have to engage an ABS type stop (as in High-Effort braking) to have the system produce this reaction. It can and DOES happen under normal braking. What you will sense, is under braking when the rear tire goes momentarily airborne, the front brake WILL release and the bike will seem to surge forward and then immediately reapply the front brake. This is very easy to produce even on a K1200LT.

Here's a for instance. You are braking at 20 mph on choppy pavement where each edge in the concrete is like a small 1" drop. The rear tire goes airborne after the front tire has dropped the 1" and is still braking. The ABS system engages, and even if for a 1/4 second you have NO brake action, and the bike will have gone 7 to 8 feet , or about a bit more than a bike length. Just be aware this DOES happen and you really should practice it to be familiar with it.

If this were to happen at 30 mph, in 1/4 second the bike could go 22 feet without braking action until the brakes re-engage. All the more reason not to follow too close behind other traffic!

When we sell a K1200LT at Nick's BMW we actually train the new owner about this action of the ABS system. It really should be done as training for all new BMW owners.
Interesting information Dan. I prefer to be in control of the brakes for just this reason and wouldn't buy the ABS on a bike. I have them in my car and they are great on 4 wheels but not for me on a bike.
I just lifted this from the HD website. It's from the 2007 press release.

"This advanced ABS is designed to work in conjunction with the Brembo-designed disc brakes on VRSC and Touring models. The ABS provides light lever feedback during ABS events to alert the rider to unstable braking conditions. Unlike many motorcycle anti-lock systems, Harley-Davidson ABS is a manual, independent system, meaning the rider maintains full, independent control of how much of each brake is applied. The components of the Harley-Davidson ABS have been designed and packaged to be virtually invisible, preserving the clean custom styling of the area around the wheels."

I've got them on my 2007 (older system) and found them fairly effective during a incident that occurred on a trip through Wyoming last month.