Front disc brake

[dereborn]

OK, here it goes... Call me crazy, but: I'm going for a disc brake in the front next year. Plan is it's gonna be almost invisible. Original lever on handlebar, wire in under dash/btween tanks where cylinder is placed. Brake line out same way and into stock tube alongside fork. And - here's the thing - caliper and disc fitted INSIDE drum. Looks stock but will stop is the idea.
I shamelessly stole the idea with the hidden brake cylinder from a friend, but I haven't seen tha hidden disc trick yet... for a reason, maybe?...

Ouestion:
Will the stopping power of this small disc be no better than a proper adjusted stock drum brake? If so, it seems like a lot of work wasted for nothing.

IF possibly increasing the stopping power, and therefore worth hassling with, do you think one should ventilate the drum in some way? Drill a cpl of holes isn't too hard, and should make it cooler inside (YES - of course we're talking a repop drum! I'm not THAT silly...)

Any other thoughts, suggestions or warnings highly appreciated!

[DuoDave]

It would certainly make for a neat setup and sounds like the sort of project you should do just for the heck of it. BMW did the hidden master cylinder trick back in the seventies and Honda soon followed with a fully enclosed disc brake on the front of their CB 550. The enclosed brake never caught on because it was a real pain to work on. It will have to be a real small disc and caliper to fit in the drum. Try the rear brake on modern Jap sport bikes. Your main problem, though will be heat build up. The drum will have to be very well ventilated or, under heavy use, your brake will fade like crazy, the brake fluid will boil and you will end up with no front brake at all.

Oops, just noticed I missed the X out of Honda CBX 550. The CB 550 was an earlier Honda with a conventional front disc. Anyway, I've been out in the garage, and looking at the front brake on the Harley, normal size motorcycle disc brake components just aren't going to fit in there. Maybe you could find smaller parts from another application, but I seriously doubt that anything that small will give you effective stopping power. I've never understood why H-D went to so much trouble to fit a hydraulic brake to the back of the Duo-Glide, but left the feeble cable operated drum brake up front. Now you've got me wondering how hard it would be to convert the front drum to hydraulic operation.

[dereborn]

Now, that's another angle... Maybe one should look into the hydraulic drum idea! I was thinking of using a disc brake from a scooter o r something. Seen it used on choppers as rear brake. Also, one could let the top of the caliper pop up an inch or so through the drum, and that way get a little more disc diameter space. I think the ventilation issue is not that big a problem, i'm thinking 1 0mm (7/16?) holes all around the drum should keep it ok. and fading isn't really a new experience... the ol' drum fades pretty quick when you start using it! Let me know if you come up with anything more on the hydraulic drum!

[DuoDave]

I think you will be struggling to fit even a scooter brake in there. You will certainly stop effectively, though, if you have the caliper poking through the brake drum, as the drum revolves with the wheel. Maybe I,ve misundertood you on that?

[dereborn]

The shield...
I mean the shield of course!

Sorry.

[haggis]

Hey Dereborn,
I was thinking about your idea go check this out, forget the disc and go with a double cam shoe up front, Panhead tuned me into these guys a while back...it's a great idea! http://WWW.45partsdepot.com" onclick="window.open(this.href);return false;.

Haggis

[dereborn]

Yeah, haggis, I've seen that one, but it's only for springers I suppose? Ive got the ol' hydra you know...

[suicideshovel65]

Hi Dereborn,

I've seen some interesting parts on ebay that might work with what you are trying to do - it was a mini disk set up by Airheart (spelling?) I believe. Closed some time ago and I deleted the link so I can't send you a lot number I'm afraid.
Let me know if I can help you with scooter parts if that's the route you decide to take - I do live in Japan afterall!
Also, have you thought about using an early shovel wideglide? looks very similar to the pan front, but with a bracket for the old banana caliper. I know it isn't as tricky as what you're proposing, but it will get you a disk pretty easily. It's what I'm currently running on mine.
BTW what about running a disk and caliper behind the fixed shield only, and covering the other side with a hubcap? ie don't use the drum hub at all. That way you wouldn' t have the problem of heating, yet the parts would be mostly hidden from the sides. Not looking at the bike as I say this, so don't know if it would work.

cheers,

S.

[dereborn]

Yeah, I was thinking about the shield only and hub cap setup if I decide to go for double discs. But then I decided that if not hiding the disc totally, I don't have to hassle with hiding at all, and so I'm back to the drum path again!
I will try to find the airheart (airhurt?) things, and if you have info on scooter parts, pls let me know!

Thanx

/J

[panhead]

This link? http://www.prodorutti-supply.com" onclick="window.open(this.href);return false;

[dereborn]

5,5' discs seem 'bout the right size i think! Thanx panhead! I found this site http://www.sscycle.de/Main_e.htm" onclick="window.open(this.href);return false;
the mini setup looks real nice! I think a brembo caliper is the smallest I've seen so far, and these are not unusual in Sweden! Might be possible to make a reasonable deal on one.

Thanx for all your input so far! Please keep it up!

[relic]

Hello. Your idea did ring bell in my head, there is or was somekinda kit with brake disc and caliber integrated inside almost stock look shield.If you got Finish Kopteri-magazine 6/97-1/98,theres a pic of it,in for sale adds.
It is not mentioned who is the manufacturer,but in a foto it does not look bad at all,allthough I ain't never seen or noticed it alive....

[dereborn]

No, Relic, that magazine is not very common in Sweden... Have you got a copy of it? Maybe you could scan it and mail it to me? Or xerox it and snail-mail it? Would appreciate that!