Squat for rear brakes B12

[2005B12S]

This is why transport aircraft have ground spoilers- the large panels on the upper wing that deploy automatically- they put maximum weight on the gear for effective breaking. That is their only function. Without them, stopping distances can increase by over 150%.

And all this time I thought they gave braking from increased wind resistance, too...  
Funny thing is they only automatically deploy when the thrust reversers are deployed - not the wheel brakes.
(And on Boeing commercial planes, they only do that if the pilot has pulled the speedbrake handle into the "Auto" detent. If it's in "Off" they won't come up.)

The ground spoilers are not tied to thrust reversers, but are deployed by a weight on wheels switch on the main gear. If properly armed, they will deploy when the mains touch down regardless of thrust reverser position. On some a/c thrust reversers are not even factored into landing performance, but ground spoilers are. They are essential for maximum braking.

The American MD-80 crash in Little Rock was a direct result of not arming the ground spoilers, without them on touchdown, the a/c hydroplaned off the runway unable to brake properly.

Didn't mean to get off on an aviation tangent, but the principles are the same- without full weight on the wheels, effective braking cannot be accomplished.

Ride On, Ed.
2005 GSF1200SZ
1983 GS750ED

[Daytona]

New user!


Joined: 25 Sep 2005
Posts: 4

 Posted: Fri Oct 21, 2005 11:53 pm    Post subject: Squat for rear brakes B12  

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I bought a B12 recently and noticed that I have very poor rear braking. I bled both nipples & checked the level of the fluid reservoir, and I'm 99% convinced that the problem isn't hydraulic -- at least up to the caliper.

I have a good firm pedal, and I do get a little braking, but very little. It wouldn't be possible to lock the rear, for example, even standing on the pedal. I don't see anything obvious wrong. The only thing that comes to mind would be a stuck piston.

I pulled the caliper and lowered it down (still attached to the torque link) and operated the pedal slowly. One piston extended, and one stayed put. Now, that doesn't really tell me much, other than one has a bit more friction than the other. Not much of a test, I guess...

How would I go about forcing the other piston to extend a bit? Has anyone else had this problem?
_________________
... and God said, "Let There Be Air Compressors!"
 


   Bet he won't do that again, ask!! Wonder if he got it fixed???  

[PeteSC]

Yeah, the old 'rear brake' myth has deep roots.....
  When I first started riding in the early 70's, common 'street' knowledge was the rear brake did all the work, the front was just to allow a little more braking, and keep the rear from breaking loose.  (or something bizarrely stupid like that...)
  If you remember, a lot of choppers had NO front brake, and some would put a bicycle brake on the front to meet state requirements.

  Be careful when switching to more aggressive pads.  I've heard even real experienced riders almost getting 'launched' when clamping down on more aggressive brakes the first time.
 (No names mentioned, but I still have my OEM pads on my B12, although a set of EBC HH is ready to go on, when I need them.)

[land_shark]

Have you tried cleaning the calipers and pistons?  Grit and residue in the fluid ports and elsewhere can cause issues.  This will give you a good chance to look at the seals as well.  Only takes about 1.5 hours to do.  How old is the bike?

[Daytona]

Yeah, the old 'rear brake' myth has deep roots.....
  When I first started riding in the early 70's, common 'street' knowledge was the rear brake did all the work, the front was just to allow a little more braking, and keep the rear from breaking loose.  (or something bizarrely stupid like that...)
  If you remember, a lot of choppers had NO front brake, and some would put a bicycle brake on the front to meet state requirements.

  Be careful when switching to more aggressive pads.  I've heard even real experienced riders almost getting 'launched' when clamping down on more aggressive brakes the first time.
 (No names mentioned, but I still have my OEM pads on my B12, although a set of EBC HH is ready to go on, when I need them.)

Hey Pete how many miles on your Bandit? You have a newer one don't you? I think they went to the sintered for the 2nd gen! I could only get about 10k on the other type pads. The use of my rear brakes must be why i get 5k miles on rear tires! The stinko's are still on after 7k though. Sintered pads last about 15k before they are close enough to change. 2/3rds worn. My front B-pads are still oem after 35k miles! Is there a posting on this that i can get more info? Seems to be a big diff on wear to tire/brakes between riders of the same bike.

[B12Teuton]

I had put HH pads on the front so the rear was moot anyway since the rear tire was off the ground every time I got after the brakes!

Seriously though, mine was weak as well and the better pads made it the way it should be.

[PeteSC]

I've got 21000 miles on the original brake pads, on my '99 1200.

[Red01]

I've got 40K on the OEM rear pads...

[Daytona]

Wow! I guess i need to start using the F-ones more! I figured they are lasting longer because ea pad has more surface than both rears. Must be why this 7k stinko f-tire looks like it was just put on! Oh well to late to teach a old dog new tricks! I never have touched the f-pads and they still look 1/2 worn! How about your front's?
 

[terrebandit]

If you're slowing down using the front brakes and the amount of traction available at the rear tire is minimal since weight transfer has lightened the contact patch and the engine braking is already taxing the contact patch.
Application of the rear brake could easily cause a skid in this kind of situation - and rear wheel skids can lead to low sides - or if you panic and let off the brake once the skid starts, a highside.

So, if you have available traction to use the rear brake, by all means, use it for the most effecient stop... but if traction is at a premium, don't.

Anyone who is fairly new to riding needs to read this and be a believer.

If you are on a wet road DO NOT apply the rear brake with the front brake.  You will induce a rear wheel skid.  This is exactly what caused me to highside and break my collar bone.  I was approaching a  easy corner at Deals on a wet road surface at about 55 mph.  I applied the front brake and then, out of character for me, decided to apply some rear brake too.  When I applied the front the front of the bike dipped robbing traction from the rear tire.  Then I applied the rear brake and the bike started to skid immediately, with VERY VERY little pressure.  Before you know it I was headed toward a barbwire fence, with bike out of shape from skidding, at about 50 mph (est) and decided to let off the rear brake in an effort to regain control of my bike and avoid a most certain collision with the fence.  Instead,  the bike highsided and SLAMMED me to the ground.  I still ended up in that fence and my bike was totalled.  Lesson learned!

Dave

[Red01]

This is why transport aircraft have ground spoilers- the large panels on the upper wing that deploy automatically- they put maximum weight on the gear for effective breaking. That is their only function. Without them, stopping distances can increase by over 150%.

And all this time I thought they gave braking from increased wind resistance, too...  
Funny thing is they only automatically deploy when the thrust reversers are deployed - not the wheel brakes.
(And on Boeing commercial planes, they only do that if the pilot has pulled the speedbrake handle into the "Auto" detent. If it's in "Off" they won't come up.)

The ground spoilers are not tied to thrust reversers, but are deployed by a weight on wheels switch on the main gear. If properly armed, they will deploy when the mains touch down regardless of thrust reverser position. On some a/c thrust reversers are not even factored into landing performance, but ground spoilers are. They are essential for maximum braking.

The American MD-80 crash in Little Rock was a direct result of not arming the ground spoilers, without them on touchdown, the a/c hydroplaned off the runway unable to brake properly.

Didn't mean to get off on an aviation tangent, but the principles are the same- without full weight on the wheels, effective braking cannot be accomplished.

Sorry - back on the aviation tangent... I need to correct myself and clarify.

I don't know much about MD-80's. My experience with them is limited to a couple of days as a structures mechanic 19 years ago. I do know a little about Boeing airplanes since I've been an Airworthiness Inspector on them for >16 years.

The way Boeing planes work is if the airplane is in the air mode and speed brake lever is in the armed detent, as soon as the main gear weight on wheels switches close (putting it in ground mode) and the throttles are pulled back to idle, the ground and flight spoilers all deploy.

If the pilot doesn't put the speed brake handle in the armed detent (Speed Brakes in "OFF" detent) and lands, as soon as the thrust reversers are applied, the system will automatically lift the lever up out of the OFF detent and deploy all ground and flight spoilers.

As soon as forward power is applied, the speed brakes will all return to their laydown position since the plane thinks it's going to takeoff again.

[2005B12S]

This is why transport aircraft have ground spoilers- the large panels on the upper wing that deploy automatically- they put maximum weight on the gear for effective breaking. That is their only function. Without them, stopping distances can increase by over 150%.

And all this time I thought they gave braking from increased wind resistance, too...  
Funny thing is they only automatically deploy when the thrust reversers are deployed - not the wheel brakes.
(And on Boeing commercial planes, they only do that if the pilot has pulled the speedbrake handle into the "Auto" detent. If it's in "Off" they won't come up.)

The ground spoilers are not tied to thrust reversers, but are deployed by a weight on wheels switch on the main gear. If properly armed, they will deploy when the mains touch down regardless of thrust reverser position. On some a/c thrust reversers are not even factored into landing performance, but ground spoilers are. They are essential for maximum braking.

The American MD-80 crash in Little Rock was a direct result of not arming the ground spoilers, without them on touchdown, the a/c hydroplaned off the runway unable to brake properly.

Didn't mean to get off on an aviation tangent, but the principles are the same- without full weight on the wheels, effective braking cannot be accomplished.

Sorry - back on the aviation tangent... I need to correct myself and clarify.

I don't know much about MD-80's. My experience with them is limited to a couple of days as a structures mechanic 19 years ago. I do know a little about Boeing airplanes since I've been an Airworthiness Inspector on them for >16 years.

The way Boeing planes work is if the airplane is in the air mode and speed brake lever is in the armed detent, as soon as the main gear weight on wheels switches close (putting it in ground mode) and the throttles are pulled back to idle, the ground and flight spoilers all deploy.

If the pilot doesn't put the speed brake handle in the armed detent (Speed Brakes in "OFF" detent) and lands, as soon as the thrust reversers are applied, the system will automatically lift the lever up out of the OFF detent and deploy all ground and flight spoilers.

As soon as forward power is applied, the speed brakes will all return to their laydown position since the plane thinks it's going to takeoff again.

I agree fully, it was your 'they only automatically deploy when the T/R's are deployed" statement that was incorrect. If ground spoilers are properly armed they are depolyed by weight on wheels. Under normal, everyday conditions, they are not controlled by T/R deployment.

As an Airline Transport Pilot with several type rating who has been flying transport category turbojet a/c for the past 10+ years, this statement stuck out like a sore thumb to me . It is possible to dispatch and fly an a/c with the T/R's deferred INOP, therefore their function cannot normally control another critical system such as ground spoilers.

Anyway, lets get back to motorcycles, this is starting to feel like work.

Peace and Ride On, Ed.
2005 GSF1200SZ
1983 GS750ED

[Bob Holland]

Riding Skills Series: The Basics of Hard Braking



By Jason Black
Photography: Wes Allison

1. Twenty years ago, you weren't even supposed to touch your front brake. You'd flip right over on your face, so the stories went. Five years ago, racers and riders were preaching the exact opposite: "Don't even bother with the rear brake; the front is all you need." So, in the pursuit of the ultimate braking performance provided by your average Bandit 600S, we hooked up our Stalker radar gun and the laptop computer and set out to solve the big braking question: What is the optimum braking procedure, and how do you do it?

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2. Keep your head up when riding, eyes always scanning what's going on around you. When applying the brakes, squeeze them smoothly, don't yank them. This gradually transfers weight to the front tire, increasing front tire traction and reducing the chance of locking the wheel, which eliminates the rider's control over the motorcycle. A hard stop using the front brake has the front tire howling on the verge of lock-up. The line between optimum braking and lock-up is a thin one, so make it a habit to go to an empty parking lot and practice hard braking. Our braking distance from 60-0 mph using only the front brake was 151 feet.

3. We didn't judge the distance correctly and nearly ran into the radar gun for the first rear-brake-only stop from 60 mph. Using the rear brake is useful when tightening turns, checking surface traction or settling the rear at corner entrances, but to use the rear brake exclusively in everyday situations is asking for a Volvo sandwich. Modulating the rear brake is tough to do without locking it at some point. Press down on the pedal firmly until you start to hear the tire howl; this is the point just before lock-up, and is the hardest you can brake without skidding. Impending lock-up is far more effective at stopping a motorcycle than a locked, skidding tire, so practice working up to it. If you're not accustomed to using the rear brake, lock-up is very easy to achieve, as shown in the photo. If lock-up occurs, keep the tire locked and countersteer in the direction you want to travel before you release pedal pressure. Braking distance from 60 mph using only the rear brake was a long 289 feet.

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4. Keep at least one finger on the brake lever at all times when riding. This cuts down on reaction time by eliminating the finger movement from the bar to the lever in the case of an emergency. Two fingers are generally all that is needed for hard stops on modern sport bikes.

For our final test, we modulated both the front and rear brakes simultaneously. Not surprisingly, we brought the motorcycle to a stop in the shortest distance of the three tests: 146 feet. Both brakes together undoubtedly provides the best braking performance.

If you're feeling confident, practice your braking over painted lines, through puddles and on bumpy surfaces, which further bring suspension forces into play. The more you practice hard braking, the better off you'll be next time you're forced into a panic-stop situation.
This article originally appeared in the October 1995 issue of Sport Rider.