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I've only ever ridden sportbikes on the street and I am used to the stopping power of disc brakes. I have a 70cb 450 with drum brakes and I'm thinking of doing a front end conversion with a disc brake setup. I am wondering what ya'll think about the difference, whether its worth the trouble etc. My other motivation for doing the conversion is to lose the springer suspension to something with an internal spring more along the lines of a sportbike.
 

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Truth be told, stock for stock the drum has more stopping force than those early honda weak disc brakes. The disc brake however is more predictable, smoother, and requires less maintenance. The disc has a great weight advantage. Modified the disc swap would probably be worth it.

If you have ridden a street bike made within the last 20 years, these old braking systems wil feel like trying to stop a fully loaded 1970 chrysler newport with manual drum brakes.
 

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a well set up drum will indeed out perform an early disc conversion. they also (drums) stay descent for a long service life. new disc brakes truely are awsome in their ability to generate anti horsepower. but a lot of chassis, tire, and suspension capability goes into allowing it (big anti horse power) to happen. a cb 450 is missing more than a disc brake to slow it down like a gsxr.
-parks
 

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I just changed the front brake on my 73 CB350 from drum to disk. It looks and stops better than before. I used a later model CB front disk brake set up. My front forks already were set up to hold the caliper in place. I found that kind of weird in a way. Why set up drum brakes on a bike, but also have the brackets to hold a caliper for a disk brake.

Well I hope you decide to go with the change. You will enjoy the outcome. Maybe not so much having to need a master cylinder on your handle bars.


I did what last night !!!!
 

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Parks...interesting thing I discovered riding Mary's bike in the last race. I like her 305 brake better than my very aggressive T500 brake. Found the...technically weaker...305 brake to be more linear, smoother, and felt to have better feel/leverage at the lever. The T500 stops like a mo-fo, but feels kind of weird, sorta loose, imprecise, definately too grabby.
The T500 has the Vintage Brake compound. Mary's brake has the race compound shoes I have done up in the UK.
JohnnyB
 

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JohnnyB,
Do you think the difference in feel is only from the shoe compound difference or is it set up too? Does the 305 brake use the same length actuating arms as the T500 linkage? Is it an adjustment issue?
I am still using a stock CB350 brake on my race bike. All I did was sand and groove my best set of used shoes, totally disassembled lube and adjusted the stock linkage, and a new cable. I really don't have any complaints about the brakes. More would be better because I wouldn't have to squeeze so hard at times but fade has not been an issue over an 8 lap race.

Ken

AHRMA 412
Vintage racing - old guys on old bikes
 

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ok so I should go with disc or drum? I'm leaning toward drum... just because they are cheaper and cleaner looking. I have the dice set up on there but they are in a mess the whole system needs a complete overhaul

carpe diem.... seize the carp
 

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Ken, to tell the truth I think it's a bit of both. The 305 brake has a longer arm, so more leverage, but the compound is less agressive, so braking power at the lever feels about the same. Just behaves better on the 305.
The 305 drum is considerably more rigid than the T500, so there is less flexing and a more accurate feel to them. The T500 brakes really hard, but you can kind of feel at the lever that things get kind of tweaked when you brake hard....doesn't seem to effect stopping power, but does effect how delicately you can use it.
I've gone down in the rain at least twice after just barely touching the T500 to scrub off some speed, so I'm thinking it's initial grab is a bit too violent with the Vintage Brake compound.
I've got a set of shoes for it done up in the other compound that I'll try next year. If I don't like that I'll go to a 305 brake.

All the grab on the T500 felt like it was up front. Whereas the 305 with the UK compound felt linear, the harder you pull the more brake you have. On the T500 after pulling about 70% at the lever, it didn't feel like the last 30% was doing anything more. Both compounds didn't fade at all.
JohnnyB
 

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johnny
just curious...are the cable gauges identical btween bikes? brake levers the same? lead (as in champfer angle on leading edges)? drum diam./width? both dual leaders? and by the way, it's disadvantagious (and unneccessary) to use the front brake between 11 and 12 in the rain. take off more before 11 entry...
-parks
 

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Parks,
Same levers, same OD hub, T500 is wider...but shorter pads, 305 has longer brake arm, both DLS, T500 has a bit more chamfer. Probably about the same swept area, I'd guess the T500 has a bit more self actuation due to the wider, shorter shoe.

In the T11-12 area in the wet I tend to just touch the front brake at the exit of 11 before tilting it over for 12, soon as I hit that spot where the pavement goes from gray to black I lose the front. Typically I'm carring speed through 10 to keep Frank or Matt C. from passing me on the outside there..which they like to do.

When I mentioned my last crash to Tim Courts while in the bleachers he asked if I was on the brake at all over the pavement change...I said yeah. He said in the wet there is a huge traction change there and the sidecars will slide all over soon as they hit the black stuff. Usually I crash in the wet before I get there so this was unknown to me.
JohnnyB
 

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johnny,
as usual, i love your answers...don't know how to advise regarding the camels...seeing that they will read what ever i say and use it against you next time and that i'm an impartial while interested party anyway. but i'd rather someone beat me into twelve than fall down in front of them and give it to them. the one and only time (i hope) i did a "turn 12 throw it away in the rain while leading lap 1" (yes i've done it too) was the only time chris m got the better of me. turk (t-3) and then roper (in the bowl) fell in front of us on the first lap of the usvgp. after saying to myself "two good riders just fell down in front of you...take it easy...there's seven laps to go" i blew it. your comp throws it away enough for you to take it easier and wait to see if they gag...
-parks
 

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Good points. I've done the 1st lap leading thing twice in the wet approaching 12. And sure enough, last time Matt tossed it away about five laps later. I would have probably been good for a 2nd as I think Donelan was going to take me on the 2nd lap anyway.
I have a very tough time gauging speed in front in the rain, and usually my first indication I'm going to fast is being on the ground.
I'm not the smoothest rider out there, so that's certainly a factor in the wet. I depend a lot on hard cornering, hard on the brakes to stay in front in the dry rather than ideal lines...that method doesn't work for me in the wet.
JohnnyB
 
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