taller bars and cables

[nakedwaterskier]

but they maybe out of stock temporarily I am posting this info because we should all have oversize front rotor kits installed and cost could easily get in the way...If they are the cheapest, it should be dis sem i nat ed. It is a matter of life and death for street riding. Jeffrey 04 KLR (safety red) 79 RD400 Daytona Special (get out of my way) 62 Vespa VNB (don't run me over)

[Pat]

--- In DSN_KLR650@yahoogroups.com, "nakedwaterskier" wrote:

> but they maybe out of stock temporarily > > I am posting this info because we should all have oversize front rotor > kits installed and cost could easily get in the way...If they are the > cheapest, it should be dis sem i nat ed. It is a matter of life and > death for street riding. > > Jeffrey > 04 KLR (safety red) > 79 RD400 Daytona Special (get out of my way) > 62 Vespa VNB (don't run me over)

= = = Is a larger rotor the real answer to the weak KLR front brake? Seems to me the problem with KLR front stoppers is the weak mechanical advantage offered by only one piston, not necessarily the rotor diameter. I want it for that life-saving one-time 70 to zero stop, not for motard racing where a larger rotor is needed dissipate heat between frequent max braking aplications. I did upgrade to SS lines and and changed to better pads that Fred offers and it made a noticable difference. But the brake is still weaker than a friends DR650. Anyone out there know of any bolt-on dual-piston caliper units that can replace the OEM unit? Pat M A14

[Darren Clark]

The larger rotor will give you more of a mechanical advantage for braking. Note the pad size is still the same so the pad will not dissipate heat any better, so it's still not good for any competitive racing. The number of pistons is not that important on a small pad. If you have a long narrow pad multiple pistons will more or less evenly distribute the brake pressure across the entire pad. I have also upgraded to the SS lines, and it is a small improvement, but I'm planning on doing a rotor upgrade this winter and thin one looks good to me. Darren Clark 2004 KLR-650 A-18

> >

[Bill Benda MD]

From a non-engineer - if the contact area is the same size, how does a larger rotor give more of a mechanical advantage?

On 8/22/05 5:04 PM, "Darren Clark" wrote: > The larger rotor will give you more of a mechanical advantage for > braking. Note the pad size is still the same so the pad will not > dissipate heat any better, so it's still not good for any competitive > racing. The number of pistons is not that important on a small pad. If > you have a long narrow pad multiple pistons will more or less evenly > distribute the brake pressure across the entire pad. > > I have also upgraded to the SS lines, and it is a small improvement, but > I'm planning on doing a rotor upgrade this winter and thin one looks > good to me. > > Darren Clark > > 2004 KLR-650 A-18 > >> >> > > > Archive Quicksearch at: > http://www.angelfire.com/ut/moab/klr650_data_search.html > List sponsored by Dual Sport News at: www.dualsportnews.com > List FAQ courtesy of Chris Krok at: www.bigcee.com/klr650faq.html > > > Yahoo! Groups Links > > > > > >

[Alan L Henderson]

Bill Benda MD wrote:

>>From a non-engineer - if the contact area is the same size, how does a > larger rotor give more of a mechanical advantage? >

Think longer lever. When you increase the diameter of the rotor you are making the lever longer. You know what longer levers do for you when you tighten and loosen fasteners. Al A13 Iowa

[Darren Clark]

Imagine a big wheel made of stone that's 6 feet in diameter with a 1 foot in diameter stone shaft through the middle. To get it spinning with one hand it's easier to push against the outside diameter of the stone wheel and try to spin it than it is to try and spin it with one hand on the shaft (you have a mechanical advantage of 6 to 1). To get it to spin at 10 RPM will take the same amount of energy (power) at the shaft as the outside of the wheel. Only the force (or torque) is lower. Now let's try to stop it in 10 seconds. You'll need a good glove for this, it's the brake pad. If you push against the outside of the wheel it takes a little pressure to stop the wheel, also the glove will start getting hot. Spin it back up again and try to stop is by pressing against the shaft in the same amount of time. It'll take a lot of pressure to stop it now, and the glove will get just as hot as before (we're turning the same amount of energy into heat). The same thing applies to the front brake of a KLR. The amount of force required to stop the bike with a small rotor is greater than the force required to stop the bike with a bigger rotor. The amount of energy released as heat is the same though, since we're getting rid of the same amount of energy, so the stock little KLR pads will get just as hot as before (if we stop from the same speed and same distance). If we stop the bike faster now and in a shorter distance with the bigger rotors and the same pads we're releasing the same amount of energy into the pad in a shorter time so it will get hotter than before because it was not possible to stop the bike as fast with the smaller rotor (it's getting hotter because it doesn't have as much time to dissipate the heat). The rotor will act as a heat sink for the pads to help cool them, and unless you're racing I probably wouldn't worry about it. Darren Clark <- An Engineer that also builds race cars. 2004 KLR-650 A-18

[Bill Benda MD]

Great explanation, thanks. So with a larger rotor, will we need some sort of extension to place the caliper further from the fork so it will accommodate the increased diameter?

On 8/22/05 9:25 PM, "Darren Clark" wrote: > Imagine a big wheel made of stone that's 6 feet in diameter with a 1 > foot in diameter stone shaft through the middle. To get it spinning with > one hand it's easier to push against the outside diameter of the stone > wheel and try to spin it than it is to try and spin it with one hand on > the shaft (you have a mechanical advantage of 6 to 1). To get it to spin > at 10 RPM will take the same amount of energy (power) at the shaft as > the outside of the wheel. Only the force (or torque) is lower. > > Now let's try to stop it in 10 seconds. You'll need a good glove for > this, it's the brake pad. If you push against the outside of the wheel > it takes a little pressure to stop the wheel, also the glove will start > getting hot. Spin it back up again and try to stop is by pressing > against the shaft in the same amount of time. It'll take a lot of > pressure to stop it now, and the glove will get just as hot as before > (we're turning the same amount of energy into heat). > > The same thing applies to the front brake of a KLR. The amount of force > required to stop the bike with a small rotor is greater than the force > required to stop the bike with a bigger rotor. The amount of energy > released as heat is the same though, since we're getting rid of the same > amount of energy, so the stock little KLR pads will get just as hot as > before (if we stop from the same speed and same distance). If we stop > the bike faster now and in a shorter distance with the bigger rotors and > the same pads we're releasing the same amount of energy into the pad in > a shorter time so it will get hotter than before because it was not > possible to stop the bike as fast with the smaller rotor (it's getting > hotter because it doesn't have as much time to dissipate the heat). The > rotor will act as a heat sink for the pads to help cool them, and unless > you're racing I probably wouldn't worry about it. > > > Darren Clark > 2004 KLR-650 A-18 > > > > > Archive Quicksearch at: > http://www.angelfire.com/ut/moab/klr650_data_search.html > List sponsored by Dual Sport News at: www.dualsportnews.com > List FAQ courtesy of Chris Krok at: www.bigcee.com/klr650faq.html > > > Yahoo! Groups Links > > > > > > >

[Pat]

--- In DSN_KLR650@yahoogroups.com, Alan L Henderson wrote:

> Bill Benda MD wrote: > >>From a non-engineer - if the contact area is the same size, how does a > > larger rotor give more of a mechanical advantage? > > > > > Think longer lever. When you increase the diameter of the rotor you are > making the lever longer. You know what longer levers do for you when

you

> tighten and loosen fasteners. > > Al A13 Iowa

OK, good points all! I'll buy the lever mechanical advantage (i.e.; longer moment-arm) with the larger diameter rotor, my rusty old physics is slowly coming back. If I recall correctly, my buddies DR650 that stops so much better had nearly the same size rotor, but had 2 pistons on the caliper. I'll go check it out for sure tomorrow. I'm stuck on the thought that two pistons with suitably larger brake pads would make great sense if there is an OEM unit out there somewhere with similar bolt pattern & dimensions to the stock KLR caliper. Pat M A14 PacNW

[biggranger@direcway.com]

>Great explanation, thanks. So with a larger rotor, will we need some sort >of extension to place the caliper further from the fork so it will >accommodate the increased diameter? >Does tilting out the caliper with the adapter bracket change the >angle or dynamics and help anything? or does it only realign the >pads with the rotor?

Yes the caliper bracket must be changed to position the caliper and pads further out on the new rotor.

>I'm stuck on the thought that two pistons with suitably larger brake >pads would make great sense if there is an OEM unit out there >somewhere with similar bolt pattern & dimensions to the stock KLR >caliper.

Let's go back to the spinning stone wheel again. The glove is the brake pad, and your arm is the caliper piston. Let's say we apply 10 pounds of force to the glove to stop the wheel, so with one arm you're applying 10 pounds of force (this is the KLR caliper, one piston). Now we'll try a dual piston caliper with the same pads, use both arms and press on the same glove, but only apply a total of 10 pounds of force. You've divided the total force between 2 pistons so it's only 5 pounds per arm, but you're still putting 10 lbs of force into the glove. We didn't change anything by going from a one piston to 2 piston caliper (it just got more expensive). What we need to do is increase the braking area, and we do this by making the pads bigger. If the pad is still relatively square we could get away with just a bigger piston so the pressure is evenly distributed across the pad. But this is not always practical, the pads must fit the rotor and start to take on a semicircular shape and if the caliper had only one piston in the middle the pad would bend. When you apply the brakes only the middle part of the pad would be doing any work. This is where a multiple piston caliper starts to work good, 2 or more pistons will even out the pressure on the pad. But now we're turning energy into heat again, and if we're stopping faster, or braking downhill we only have a small rotor trying to dissipate more heat faster, and this will lead to brake fade and/or overheating the rotor and caliper. Ultimately is cheaper, easier, and better to reuse the existing caliper, and replace the rotor with a bigger one. You don't need to bleed anything, you get the mechanical advantage, and heat dissipation. Darren Clark

[David Farrell]

Below is a comparison of the two bars Renthal makes. Dimensions is in mm. The "Desert" bar is available in the US. I am looking at getting these "Dakar" bars from the U.K. if anyone is interested we can share shipping cost since you cannot get these in the U.S. From my understanding, the Desert bar is about the closest you can come to stock/original. The Dakar will give you a little more height and rise. Colors available are Blue ($53), Gold ($53), and Silver ($51). BAR Width Height Rise Clamp Area Sweep --- ----- ------ ---- ---------- ----- Desert 840 118 85 205 78 Dakar 830 130 95 210 75 --- Luc Legrain wrote:

> I would be strongly interested . How much hight gain > and sweep are we talking about ? What about color ( > black , chromed .. ) ? And what about cables and > such ? > Thanks. > > David Farrell wrote: > I know many on this group have recommended the > Renthal > "Desert Bend" bar. > I have a Honda Transalp in addition to my KLR. Many > on their list are recommending the Rentahl "Dakar" > bar. > The "Dakar" bar is about similar but about 1/2" to > 1" > taller than the "Desert" bar and I believe it even > has > a little more sweep. > The Problem: This "Dakar" bar is not offered in the > US. I have found a Renthal distibutor in the U.K. > who > will ship these to me. They are around $50 each but > shipping is about the same as the bar. He has > advised > that shipping is not that much more if he ships > several of these. > If anybody on the list is interested in this bar and > wants to share some of the shipping cost, Please let > me know and we can probably get a better deal. > Also, if anybody wants dimensions on this bar, I can > provide it also. > David Farrell > > --- agh19 wrote: > > > In the quest for more back comfort, I'd like to > fit > > some bars that are > > at least an inch or two taller. I'm sure others > > have made the same > > mod and I wonder if anyone has run into any > problems > > with throttle and > > clutch cable length. I'm sure my SS brake line > will > > be long enough as > > it's at least an inch or so longer than the stock > > item. > > > > Also seeking suggestions for good bar choices that > > might fit the bill. > > > > Alan > > A13 > > Raleigh, NC > > > > > > > > > > > > > > Archive Quicksearch at: > > >

http://www.angelfire.com/ut/moab/klr650_data_search.html

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