Drum vs. disc brakes?

[electric!sheep]

I have a 1984 TT600 (AHRMA classic BTW) and a 1986 XT600 with a Tenere tank. I'm not one into major restorations to have a garage queen of a TT, so I just want to take the nice suspension of the TT and toss it in the XT. The rear suspension looks like a drop-in swap (right?), and adds 1" of travel and a lot of adjustment.

The front also adds 1"...but I also would be forced to switch to drum brakes up front, instead of the fairly beefy front disk on the XT600. I'm hesitant to just swap the rear, because that would reduce trail, whereas a full suspension swap would increase it.

I can see the simplicity and reliability of the drum being a plus, but...will it stop me fast enough? I'm not doing any motard and typically run knobbies. Is it ok off-road? Is it safe around town or on the highway? Fully loaded with fuel the bike weighs 350lb, plus 150lb for me, with the possibility of another 50lb in gear.

[DougieB]

£13 buys you Motorcycle Roadcraft (it's a book!), which will explain how to plan your road riding better so you don't need to use the brakes much at all. Maybe less hassle? You would actually have to read it mind you, simply buying the book doesn't improve your forward planning.

drum brakes take longer to stop you, but if you're looking further up the road it's no big deal.

[electric!sheep]

Strangest response ever. Maybe I should remove the brakes entirely and rely on compression braking? Just need to look further up the road, right.

Seriously though, I have no idea how drum brakes differ from disc. Is it 25% more stopping distance? 50%? 100%? I want to be able to respond to emergency situations with confidence (not...OMG WHEN AM I GOING TO STOP???), but I don't need to do reverse wheelies either. That's the question. I might just end up doing the swap and seeing how it works out.

Looking up the road is fine and good, but sometimes you need to stop RIGHT NOW or slow the f- down because of a wash/barbed wire/chupacabra around a blind corner.

[electric!sheep]

How about an existentialist response: Does it matter if I stop? I could look further up the road, or I could use powerful brakes, but in a meaningless world, it is of no consequence whether I slow down or not; for to continue or to remain is an illusory distinction. If once, I saw stopping as the purpose in pressing the brake lever, I can now see the ultimate, inevitable finality of human existence in that simple motion--something that is far more poignant than merely coming to a halt at a red light. When the dark moment comes and I fly into the side of a car, this knowledge will provide me solace that no brakes could ever provide.

[DougieB]

drum brakes were standard before, and I suspect (though it's a wild guess) just the same amount of people crashed (cars and bikes) as they do now. nothing to do with being able to stop quickly, a lot to do with not looking further up the road!

seriously though, drum brakes overheat and then are useless till they cool down (same as disc fluid overheating). but I guess you're not headed to a track day. if you really don't know, then go with the drums and you'll learn the difference for yourself. new cables and new shoes make a difference, but the 'how quickly do they stop me' question is a bit subjective. try them.

but if you plan to run knobblies then you are already reducing the potential stopping power of your brakes (not enough rubber on the road). an utterly unscientific guess for drum effectiveness, for me, would be 75% of the power of discs. that would be comparing a like for like bike, not an old XT vs a new GS. On a decent drum setup you can lock the front. Do you use your disc brakes at 75% or more of their potential? Maybe not if you have knobblies on.

having said that I ploughed through a Nigerian road block because my drum brakes wouldn't stop me in time. I think disc brakes would have saved me an awful lot of hassle that day.

[brettsyoung]

Drum brakes fail when they get hot or wet. If there is lots of downhills, rain, puddles etc in your travels then go for the disks. Drums are ancient technology and can be really dangerous - you are going back 50 years to consider regressing to drums.

[DougieB]

50 year old technology? do you ever use a pencil, does it work? so why do aeroplanes still fly, because they recognised the bad technology of old, and re-invented the plane? age doesn't make technology bad.

The guy has an old TT and an old XT, and is happily talking about an inch of suspension difference not being an issue (which it ain't). I don't think modern technology (which obviously makes things easier for us) is overly important in this case, just being able to stop. Which drum brakes have been doing for at least 50 years, like you say...

[DougieB]

"How about an existentialist response: Does it matter if I stop? I could look further up the road, or I could use powerful brakes, but in a meaningless world, it is of no consequence whether I slow down or not; for to continue or to remain is an illusory distinction. If once, I saw stopping as the purpose in pressing the brake lever, I can now see the ultimate, inevitable finality of human existence in that simple motion--something that is far more poignant than merely coming to a halt at a red light. When the dark moment comes and I fly into the side of a car, this knowledge will provide me solace that no brakes could ever provide."

that's surely nonsense

[sipke]

Didn't really want to say this but 350lb fully loaded?

No way Mine is 157kg (bit less than 350lb if i'm not to much mistaken?) and it took me a year to get it there:
http://i10.tinypic.com/30rmwk1.jpg

Anyway, a drumbrake will get you in trouble. The extra inch will help it offroad, but only in the back and not that much. I would keep the TT as it is ( it's a classic dude ) and modify the XT: shorten the doglink so it wont hit the cases and fit a longer shock. Pick up an old WP4054-fork from an old KTM or TM at the breakers if you want to improve the front, cheap and a straight fit.

[DougieB]

what did you do? drums, discs or prayers?

[oldbmw]

Originally Posted by BrettUAE

Drum brakes fail when they get hot or wet. If there is lots of downhills, rain, puddles etc in your travels then go for the disks. Drums are ancient technology and can be really dangerous - you are going back 50 years to consider regressing to drums.

So are wheels, but they work well enough.

Drum brakes are easier to field repair in wild places...exactly the place where any more braking would likely lock the front. The twin ls front brake as fitted to 69 triumphs were better than any bike disk brake until 73-74. Now virtually all bike front brakes are better. BUT bikes have become much heavier, and are now able to ride on roads that allow/insist on much higher speeds.

[electric!sheep]

Originally Posted by DougieB

what did you do? drums, discs or prayers?

Nothing yet, got side-tracked with my Zodiac boat. I think I'll see about swapping the triples this weekend. I really want to see what the drum feels like, just so I know. The thing I really want out of the TT suspension is not so much the travel, but the cadillac-like plushness. My XT suspension is extremely stiff since the previous owner tried to (over)compensate for the 8 gal Tenere tank. I don't mind a little dive for a super-pliant ride over the rocks.

[electric!sheep]

Originally Posted by oldbmw

Drum brakes are easier to field repair in wild places...exactly the place where any more braking would likely lock the front.

That's one line of reasoning in favor. I LIKE simplicity on the principle of it. The less that can go wrong, and the easier it is to fix, the better.

[Mr. Ron]

Originally Posted by oldbmw

Drum brakes are easier to field repair in wild places...exactly the place where any more braking would likely lock the front. The twin ls front brake as fitted to 69 triumphs were better than any bike disk brake until 73-74. Now virtually all bike front brakes are better. BUT bikes have become much heavier, and are now able to ride on roads that allow/insist on much higher speeds.

I have to question this line of thinking. Drum brakes are far more complicated than disk brakes. Here's my case:
-Drum brakes activate on a cam, which must ride on either a bushing or bearing. Both are prone to wear.
-Drum brakes use springs, which are prone to breaking and possibly dificult to find a suitable replacement.
-When drums rust, your brakes will stick until everything is worn away.
-Drum brakes SUCK when they get wet!
-Drum brakes are dinosaur technology and were replaced with a simpler, more eficient disc system.
-Drum brakes need some form of adjustment, probably a cable. That being said, cable operated brakes are grosely ineficient with more parts to maintain.
-All cars all around the world operate with disk brakes. This means if you can find a mechanic that fixes brakes, they will most likely be able to help you.
-Almost all bikes in the world have disk brakes, so parts can be found or altered in a pinch.
Disc brakes are incredibly simple, self adjusting and efficient.They have a minimum amount of moving parts, and are all hydraulicly operated. They are very easy to maintain. It's your brakes and how you use them that will save your life in certain circumstances. Given the choice, i would never swap diacs for drum brakes.

[smokinrider]

whilst we are discussing this ill give my opinion.
drum brakes are sh*t. wet they dont work, muddy they dont work, worn slightly they dont work and when travelling at speed or load they dont work.
i think motorcycle manufacturers knew this so thats why they changed to disc brakes. simple and effective.
Anyone who considers going from disc to drum is a sandwich short of a picnic. the bike which has a disc has it for a reason. to stop the bike. clearly if drum brakes were better or even close to the same performance we would still be using them today on the front wheel.

If your going to retro fit a drum brake i would suggest taking the starter motor off of your car and replacing it with the trusty starting handle. same for the bike, junk the e start and fit a kick. hell whilst your at it remove all the light bulbs from your house and fit candles in their place. why not move into a cave and do away with 1000's of years of evolution all together.

DRUM brakes, i ask you. what next.