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Discussion Starter #1
I can't help but notice all the talk about front drum brakes. Didn't some of these bikes come equipped with hydraulic disc brakes from the factory?
Reason I ask is, I'm going to build a CB450 to race in whatever USCRA class I can enter it in, and both frames that I have came with hydraulic disc brakes. As I look at the rule book, it say's they're legal as long as I use the stock caliper.(I think)
I'd rather not convert to a drum brake, 'cause as much fun as it looks like to learn the black art of lacing a wheel, I don't think I'm up for it. Plus it would add quite a bit to the budget, vs rebuilding the caliper and m/c.
I realize I won't be racing against you guys in 200GP or the CB350 class, but wondering what the deal is with the emphasis on drum brakes...

FR
 

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FR,

Your CB450 is legal for both period 2 - the GP class and Period 2 - bikes up to 1972. If you race your bike in the GP class it must have a drum brake. And it should be competitive in period 1. If you keep the disk brake on it then you can only race in period 2 classes. And that means Heavyweight Supervintage, against bikes up to 850cc. So your best bet may be to watch ebay for an ealier CB450 front wheel. Then you can stay in the GP classes and you don't have to lace up a wheel.

So basic emphasis is GP bikes need drums to be legal. Period 2 and newer don't.

And on a completly different rule (and this may affect you)the only CB450s that are legal for the GP class are the ones that have the torsion bar heads. And I thought those ended before the disk brakes came out. So you may be forced into the Period 2 class.

Hope this helps.
Craig
 

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Discussion Starter #3
Thanks Craig, that 'splains it.

Both my '70 and '73 have the disc brake and torsion bar valve springs. I hadn't thought of just going with an earlier year drum. Don't even know whether the drum brakes are cable or hydraulic.
I also was looking at upgrading the front end, so I guess now that I think about it, unless I keep it stock, it's going to get complicated.

And the problem with going into heavyweight supervintage is, I don't imagine a stock CB450 will be competitive with anything other than another stock CB450...

Maybe I'll just get a good view of the first turn before everyone else disappears down the track.

FR
 

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FR,
I dunno if this is worth mentioning, but i believe the period 1 limit on forks is 35mm so you might not wanna go too trick. Also, a stock front end will probly be fine at first.
Just guessing but the drum brake is probably cable not hydraulic.

Z
 

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chris knows a guy and there were a bunch of pictures on the web of one i saw a while back. but there is a guy racing vintage stuff who has one setup.

jc
 

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Discussion Starter #7
Damn. I guess I was just dreaming when I said hydraulic. I just haven't paid attention to drum brakes, but I should've known, all the rear brakes are mechanical. It's just that with your foot you've got some leverage, as opposed to the 4 finger deal. Damn...
Anyway, thanks Zach, I thought there might be a limit to fork diameter, as there is in AHRMA for vintage dirttrack.

I'm still in the exploration mode to see what these things (CB450s) will do. Seems every time I look at modifying something, it's about a $grand, which should come as no surprise; cams/head work = $1,000 , front end, brake/Wheel = $1000 , seat/tank, tires = $1000

There may be another way to skin this cat though.

FR
 

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FR, did you ever sort out the brake issue? I'm tearing into my 450 and have a line on a 19" front(from a cl) drum... so that'll be legal in p1? And whats the deal with the torsion bar restriction?? I was considering the valve spring conversion... any input would be appreciated.

...and, not my bike but, with your flatrack/mx backround thought you'd enjoy it:


Edited by - ROSKO on Nov 30 2005 12:26:03 AM

Edited by - ROSKO on Nov 30 2005 12:28:03 AM
 

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roskos goin racing, roskos going racing!

yea, i'm definately excited!

(not about the deficit of gin though)

tex
 

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Discussion Starter #10
ROSKO,
Yeah, I saw that bike yesterday, while searching for 450 shit. Nice.

I wound up getting a CL front wheel too, so that I can race this lump in P1/GP500 instead of P2 against real bikes (no offense to anybody in GP500).
I'm still gonna get my ass handed to me in GP500, just not in the first 100 yards, I hope.

I can't remember if you're allowed to convert to valve springs in GP500/P1, I don't think so though. I'm not going to, 'cause I'm doing this on a pretty limited budget. I've been meaning to call someone to pick their brains about the torsion bars, don't know if there's a measurable wear limit, but I have a couple heads to borrow from if I need to.

More later...


FR
 

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Discussion Starter #11
A quick review of the rules in USCRA, the CB/CL450 is only legal in GP/P1 with the torsion bar valve springs and drum brakes (regardless of OEM),maximum 35mm forks, minimum 17" wheel diameter. I think WERA is essentially the same.

I haven't received my CL wheel, so I'm not sure about axle and brake stay fit...guess I'll need a CL brake cable too...

FR
 
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