Ironhead Bad break hypothesis

[IronHeadRon]

EDIT
You can ignore my first couple post, my ignorance of the mechanics of drum brakes bewildered even me. It gets ..... well worse, but descriptively and diagnostically more accurate. IT WILL GET BETTER with well documented pictures and procedures, I JUST HOPE IT'S SOON as I am still figuring this out) I changed the name to better reflect what a viewer might get from it (WHAT NOT TO DO IS COVERED QUITE WELL SO FAR)

Also, unless interested the debate about distribution of potential deceleration can be ignored unless interested, I was never trying to convince anyone, just shocked there isn't consensus. It is interesting but a moot point as WE ALL AGREE both brakes should work as well as possible.

At first we thought it was the throw (peg in way, but with that off it still doesn't work well.) Also put preload up to where we were dragging pad

About to rip her apart tomorrow (front is great but my pops has a big concern here carrying guilt from a wreck that put her down when I was 11 on the back, so you can see why it's a big deal to him ...... it should be to me but ...... geometry, idk I'm a front brake guy using rear I quick stops or for stabilization)

Anyways, I'm hoping something obvious is loose or worm, they used to work ..... until the day they didn't.

Pads not aligned with drum?
Worn pads not squeaky?

Well fond out soon but I'd anyone wants to guess have at it. Again not the throw or preload.

[BKB]

If you get to the point of "I just can't get this to work", I believe that Dennis Kirk may have replacement parts available. Some times old stuff is just so far gone that it needs new bits. I'm a cheap one my self, but at some point I know I have to throw $$ at a problem. Rear brakes are literally the most powerful force on a motorcycle. I've seen them nearly kill a friend because of a couple of loose/worn bits that caused a 60 mph high-side, when applied. Please, do it right.

[sportsterpaul]

Even worse when they apply themselves catching you by surprise!

[joe s]

Glazed linings?

[Doc308]

To start with something simple, have you centered the shoes in the drum after adjusting the throw? As already mentioned though, any persistent brake problems should involve a close internal inspection.

[IronHeadRon]

Originally Posted by BKB

.... Rear brakes are literally the most powerful force on a motorcycle.....

Even on a sportster (I am quite sure that is opposite with crotch rockets and dirt bikes with little rake, and am quite sure cruisers and hardtails are closer to 50/50; BUT YOU CLAIMS 50% IS SURPASSED, EVEN ON A 400LB BIKE?

ITS JUST A SPORTY ON A JAMMER?!, I am having a hard time believing this. (The logic, to my understanding, has been that the slight pivot forward during breaking puts more force on the front tire surpassing and siphoning the heavier loads induced normal force on the rear. Like Drag cars are rear wheel drive for maximum acceleration before slippage, the brakes on the front provide maximum deceleration before slippage)

Think about it, on an ideal road with a coefficient of friction = 1 (thus the tire would never slip) you could do a stopping or flip ass over elbows pulling the front brakes to hard (which obviously is not ideal, but won't really happen, just demonstrates that th we normal force could theoretically leave the rear completely)


Seems to me the only way to make your claim true would be if the back carried a lot of weight, which doesn't seem to be on a sporty.


Not saying I am right, just saying I think I am.


ANYWAYS, either way we plan on getting them 100% like I siad, please don't take the above as arguing that case above. I just disagree with the distribution of potential deceleration at the points of contact you claim.

Kids had a bunch of appointments and my dad is pretty wore out as well, so maybe tomorrow but maybe today.


What's a glazed lining and how the hell did dudes brakes engage without permission (I know your to smart to spring the crossbar backwards ....... how does that even happen?!

[IronHeadRon]

Originally Posted by Doc308

To start with something simple, have you centered the shoes in the drum after adjusting the throw? As already mentioned though, any persistent brake problems should involve a close internal inspection.

No, but we were thinking we were adjusting it back to where it was with the shorter linkage.also I embarrassingly did not realize there was a throw adjustment on the brake .... just preload and position of the arms on the spline and length of the linkage was what I meant by throw MY APOLOGIES IF BAD VOCABULARY.

Either way, I imagine that us easier with the tire off and the thing opened up, so that's the plan ....... I need to walk out to the shop, I am shocked I missed this......

OK I guess I need to study the book ...... I am usually able to figure this stuff out pretty quick but am embarrassed to admit I have no idea what you mean (besides maybe pulling it apart and checking, but I thought you were referring to an adjustment)[IMG][/IMG]

[BKB]

Maybe I should have said the most dangerous, rather than the most powerful. Still, the brakes, if working properly, will slow you down faster than the motor can speed you up. & if not working properly, will get you in trouble a lot faster, too.

[needspeed]

Your set up rotates the brake cam in the opposite direction from stock. When applying the brake the shoes should be spread by the radiused edges of the cam. Did you recontour the sharp edges of the cam so that happens?

Your forward controls may alter the amount of pedal leverage. Obviously I don't know, but I'm guessing it's less than stock.

Some reading. Post #4

http://xlforum.net/forums/showthread.php?t=1448695

[Ferrous Head]

None of the drum brakes on Sportsters are good.

The rear brake offers the advantage of higher leverage pressure (That long brake arm) and the generally larger contact patch the rear tire will give you. And compared to most sports bikes the weight bias is towards the rear, especially with the typical fat bast*rd that rids these things. My apologies to any skinny guys or women riding one.

The more effective you make the front brake, the less effective the rear becomes. You can see this demonstrated when someone does a "stoopy" getting on the front brakes hard enough to lift the rear wheel off the deck. I can do this with a Ducati with twin Brembo's but never on a Sportster.

The Sportster rear drum is better than the average rear drum braked bike.

But why on earth would anyone worry about brakes on a bike capable of 110+ MPH ?

Oh. And insurance companies rate your survival at 0% if ou hit an immovable object (tree or truck) at 60 mph or greater. That's zero per cent.