stupid brother in law

[Woody]

DS...you can still technically steer the vehicle with the ABS and in theory reduces the stopping distance. I find it extremely useful in our nasty ice and snow.

Lamron, if you are asking my opinion on how they work then I quite like them. The only hitch that we have reported to Harley is the following:
-We teach that in emergency braking now to hammer on both front and rear brakes at the same time as gearing down. When doing so between 2nd going down to 1st gear the brakes seem to disengage for a fraction of a second causing the bike to lurch a bit before reengaging. It happens very fast but enough for the rider to notice and could mean the difference between a serious collision/non collision.

Changing to ABS requires a change in riding philosophy as well. For instance, with non ABS, a rider is taught to not hammer on the brakes due to lockup (threshold braking) and if you do lock them up, then keep them locked up or you will high side (get chucked from the bike when the wheels free up from lockup. When I first took my motor officer course in 2000, a guy on the course did just that, locked em up and then released 60 km/hr, high sided, was thrown from the bike. He ended up with 2 broken arms with a cast up to his shoulders. He had 2 small children in diapers and his wife now had to wipe his butt for him! Thankfully he was OK, but man did we laugh at him the next day when he showed up with his wife.

Have a look here for more ABS info. The Harley ABS stuff is touched on at the bottom of the essay... bmwdean.home.att.net/abs.htm
www.policeone.com/police-products/vehicles/motorcycles/press-releases/107572/

For a detailed schematic of the Harley Brakes, I will have to talk to our mechanic and/or search the Internet if anyone is interested.

[Lamron]

That's interesting. It does say in case of failure you still have normal braking action, that's what I would be worried about. I wonder if you would learn bad habits that could hurt if you went back to a non-ABS bike afterwards. I know you have to keep the brakes locked and ride it out, but I hope I can remember that and resist the instinct to let off if I ever lock mine up. A high side doesn't look like any fun too me.

[daffy_duck]

a further note on braking on ice and or snow. put the car or truck in neutral if you are sliding, the reason for this is the engine is still turning the rear wheels by power of torque, if you have snow tires on, your rear wheels will grip more, pushing the vehicle further. puttiing the vehicle in neutral will stop this action, and then you only have to apply brake pressure adequatley enough to stop. i dont know about a motorcycle, i don't ride in the snow.

[Death's Shadow]

Yep put it in neutral or push the clutch in use the brakes sparingly. Most of the time just taking the power away from the drive tires is enough to stop the skid. If emergency braking is needed to avoid hitting some one else, I will take the ditch before hammering the brakes on ice. (if the ditch is available) Have done this once or twice before when some idiot pulls out in front of me out on country roads.

Other people may have good luck with the ABS Woody but I never have on the ice, I will stick to my old school brakes thanks. LOL

[Pvt._Michaels]

I now officially have cabin fever... I need to roll out the old cars and cruise!

ABS:

The biggest reason for ABS being superior on ice and snow is that it
modulates the brake pressure quickly so one can actually STEER the front wheels.
A locked tire does not steer..it slides in the direction of the skid.
So, you can actually :

a.) stop quicker
b.) while having a better shot at avoiding collision by steering out of a jam

A good all season tire like the Michelin HydroEdge or Pilot Sport AS series
REALLY helps on ice and snow

The Pvt.

[RedRock]

I'm told (Woody or Des can comment) that ABS technology has made some accident crash investigations difficult, as the ABS does not leave skid marks on pavement, the way old-school lock-em-up brakes do.

[Death's Shadow]

If it had worked for me as the abs was intended I would love em. I could not steer out of the situation and slid to the ditch anyway. Was only doing 30 mph at the time. Maybe I am just too old school. LOL

[Woody]

Redrock...ABS can still leave a skid pattern, but rather than one uninterrupted skid, they leave a hyphenated type pattern at the place the tires lock up for a fraction of a second as the ABS kicks in.

Traditional brakes leave this pattern: ______________________
ABS can leave this pattern: ___ ___ __ __ _


If anyone wants to get crazy and do a simple skid/slide to stop reconstruction to get the MINIMUM speed a vehicle was going try this:

1. Have someone leave a skid without you knowing their speed
2. Measure the length of a skid to determine DISTANCE (D)
3. Determine the drag factor/coefficient (F) of friction for the roadway. To do this properly you would use what we call a drag sled which is a tire cutout filled with cement that we know the weight of. The drag sled is then pulled across the surface 10 times to determine the drag factor/coefficient of friction of the roadway. For an average temperature asphalt roadway, the drag factor is usually around 0.70

Once you have all those, plug the numbers into a simple formula of the square root of 254(D)(F)

Example:

30 foot skid (d) with a drag factor of 0.70 (f)

1. =254(30)(0.70)
2. =254(21)
3. =5334
4. = square root of 5334...
5. =73 mph

The minimum speed the vehicle was going is 73 mph. The actual speed of the motor vehicle will be slightly higher though.

[daffy_duck]

i will need a calculator and a scientist. math never did too much for me,and where would one get a cement tire cut out i think i can't do with out one now that i know there available. heheheh

[RedRock]

Thanks, Woody.

[Death's Shadow]

so how do you do that with a car with abs.. do you have to measure each skid in the series and ad them up then do the math? Or do you measure the total distance, from the start of the skid to the end then apply some other formula in that allows for the "free roll" distance between the skids?

[vinsanity]

I believe that the free roll sections being inclusive are what makes for the calculated answer being the "minimum" speed that the vehicle was traveling.

[Death's Shadow]

was not sure if he was telling us the formula for the old braking system "pre abs" or the new applied formula. Was just curious.

[Woody]

Next I'll teach you how to determine speed from a point that the vehicle goes airborne...or maybe a vault calculation for how far a pedestrian gets punted! Fun stuff...

Oh, and the Crash Data Recorders (C.D.R.'s)(black boxes) in vehicles are now regularly downloaded as part of the investigation which tells us speeds, braking, seatbelts etc. Oh, and those of you with GPS systems such as "Onstar" are also utilized to corroborate crash reconstruction conclusions. Talk about big brother watching your every move!

[vinsanity]

LOL... The Sevier County Sheriff's department cannot SPELL GPS, let alone download information that would help them.