Author Topic: adding another caliper for dual front brakes w/ pics on page 2 (Read 4063 times)

greenjeans · « **on:** March 20, 2008, 06:54:43 AM »

1972 CB750K project ***Pick up on page 2****

While it's titled as a '72, I've noticed that the engine is a bit farther away (serial number) than the frame so there's a good
chance that there are pieces of other bikes of different years on the bike. The air cleaner is from an "F" model, hopefully everything else is correct.

Question:

My front forks are mirror images of one another leading me to believe that I could add a second disc & calliper to it.
I'm guessing that all I need are another caliper, rotor, mounting bracket and longer bolts for the hub. Also will need a
valve/switch? for adding a additional brake line. Does anyone know if the bracket for the '72 model can be mounted on the other side with out modifying - or will I neeed to start looking for one of those?
If I need to start looking for replacements, does anybody know what year/model stuff I need to be looking for ?

I'd like them to be the same "looking" on each side.

Soos · « **Reply #1 on:** March 20, 2008, 07:03:15 AM »

So there is already a mounting point on the right leg as well?
You might have a set of forks off another bike.

Pictures are worth more than words here I think.

Don't forget the new longer rotor mount bolts along with the new rotor.
And to add the additional caliper to the hydraulic system, there are MANY ways to do it.
I rember a post asking members to post pics of the adaptor they are using for a 2 brake caliper system.
http://forums.sohc4.net/index.php?topic=21850.0

there it is.
It has quite a few options to think about, used off another bike, new, and the ingenious as well.

Any markings on the caliper you have?
Can you describe in detail the mount points on the brake caliper to the fork leg?

Could help ID the make year you can get a caliper off of.

l8r

Soos · « **Reply #2 on:** March 20, 2008, 07:05:36 AM »

Does your caliper look like the one in these pics in this thread?

http://forums.sohc4.net/index.php?topic=32240.0;topicseen

l8r

SteveD CB500F · « **Reply #3 on:** March 20, 2008, 07:18:52 AM »

There's a FAQ on the whole conversion process:

http://forums.sohc4.net/index.php?topic=259.msg47003#msg47003

bryanj · « **Reply #4 on:** March 20, 2008, 07:40:54 AM »

All things are possible, need a picture of the fork slider and caliper to say wether its very easy or needs a bit of work

Geeto67 · « **Reply #5 on:** March 20, 2008, 08:38:51 AM »

your air cleaner is not off an F bike. They are all stamped cb750 F.

lots of info out there about the brake conversion. The only real issue that comes up is what to do about a speedo drive.

greenjeans · « **Reply #6 on:** March 20, 2008, 10:43:27 AM »

I'll take some pics tonight and post them in the morning.

The link to the other thread.....those pics are so dark I can't make out what the calipers look like.

I'll scrounge around and see what else I can come up with.

Soos,

The caliper is mounted to the bracket which is mounted by three bolts to the fork leg. 2 bolts toward the rear of the fork,
and one in the front. The caliper and bracket look the same as the photos in the 750 manual that I downloaded off this site.

The fork lowers are identical mirror images...the one on the right just had mounts that aren't used for anything. Looking at the photos from the manual, it looks like I could get another caliper/bracket and flip the the part of the bracket that holds the caliper (it's 2 pieces - 1 mounts to the fork lower and the other is fixed to it by a large pin - it has the adjusting screw w/ spring) . )to use on the other side. Seems like I could use the same caliper. I can't tell from the photo if the part of the bracket that bolts to the fork tube is something that you could use on both sides or if it's "one side" only ie right or left only. Anybody have one hand to look at ?

greenjeans · « **Reply #7 on:** March 20, 2008, 11:29:00 AM »

here's a scan of the page

mystic_1 · « **Reply #8 on:** March 20, 2008, 12:11:33 PM »

If your brakes match that pic than you have the early-style 750 brakes. Here's the problem: the caliper arm bracket, which is the triangular piece that bolts to the fork leg, is not symmetrical. You will not be able to mount it to the opposite fork leg.

On the later models the caliper arm bracket, caliper arm, and caliper bracket were redesigned. The later ones work well with the dual disc mod but to do this on the early style brakes you'd almost need to have a new caliper mount bracket cast or machined.

mystic_1

greenjeans · « **Reply #9 on:** March 20, 2008, 12:26:41 PM »

That's what I was afraid of....

Basically what I'm trying to do is make a poorman's CR750 replica - with out the fairing...
most of the pics on those that I've seen, the brakes look like mine.

I'll have to look closely tonight and see how hard it would be for me to fabricate one of those.

I sure was hoping it would be symetrical.....would have made it a bunch easier. Guess I'm off to ebay

mystic_1 · « **Reply #10 on:** March 20, 2008, 12:33:28 PM »

Maybe upgrade to later-style forks legs and brakes? You'd need to do them all as a set because the fork legs changed when they redesigned the brakes.

If you look closely at the following pics from the Dual Disc Conversion tech article you can sort of make out the differences. Note the different mounting lugs on the backside of the lower fork tubes, and note that the brake caliper arm bracket has been much simplified. You can also see the redesigned caliper.

mystic_1

Geeto67 · « **Reply #11 on:** March 20, 2008, 01:07:23 PM »

what happened to the dual disc conversion article that used to be posted on this site? IIRC they did the conversion to an early bike (like a 71 or 72) and didn't have any problems.

Honda did produce an early triangular bracket for dual disc conversions. I have one in magnesium, came in that stash of parts I bought a while ago.

greenjeans · « **Reply #12 on:** March 20, 2008, 01:30:51 PM »

Quote from: Geeto67 on March 20, 2008, 01:07:23 PM

what happened to the dual disc conversion article that used to be posted on this site? IIRC they did the conversion to an early bike (like a 71 or 72) and didn't have any problems.

Honda did produce an early triangular bracket for dual disc conversions. I have one in magnesium, came in that stash of parts I bought a while ago.

Care to part with it ? (the bracket)

There's alot of conversion articles and links I'm finding within other posts but the links are dead...
Anybody else having that problem ?

mark · « **Reply #13 on:** March 20, 2008, 01:34:52 PM »

Some of the links may still be directed to the old sohc4.us address.

SteveD CB500F · « **Reply #14 on:** March 20, 2008, 02:13:35 PM »

The articles were moved from the forum to the Tech Library: www.sohc4.net/index.php?title=TechLibrary

There's one for 500/550:
www.sohc4.net/index.php?title=Dual_disc_550

and one for 750:
www.sohc4.net/index.php?title=Dual_disc_conversion

Geeto67 · « **Reply #15 on:** March 20, 2008, 02:16:23 PM »

There is no link of it on the .net site. There used to be a link for it on the old .us site but that is no longer there. The dual disc conversion article that is there now is not the one I am referring to, this was a scan of a magazine from the early 1970s.

Greenjeans, sorry mate, it is one of those things that I don't plan on parting with (not for what would be a considered a reasonable amount of money anyway).

if someone wanted to use it to make a casting though - might be something worth looking into.

mystic_1 · « **Reply #16 on:** March 20, 2008, 02:30:54 PM »

Quote from: Geeto67 on March 20, 2008, 02:16:23 PM

if someone wanted to use it to make a casting though - might be something worth looking into.

I was thinking how cool it would be to do that, wish I had the skills and facilities to do so.

A good machinist should be able to churn out a suitable piece from steel, yes?

mystic_1

greenjeans · « **Reply #17 on:** March 20, 2008, 02:41:09 PM »

Interesting......my pops probably has the equipment and knowhow to cast it. (jeweler/sculptor/metalsmith with more tools and machinery than any one man should have.) I'll give him a ring this evening and
see what he thinks.

mystic_1 · « **Reply #18 on:** March 20, 2008, 03:01:44 PM »

If that ends up happening, I'll take one too, please

mystic_1

greenjeans · « **Reply #19 on:** March 20, 2008, 04:05:28 PM »

Ok....these are what's on my bike:

Looking at piece number 1, it is symetrical. That leads me to believe that there was some thought to it.
Only have to cast one piece and it could be used for both sides......Part number 2 is not symetrical.
But....you would think that with my fork lowers being the same/mirror images, I should be able to find a
piece like #2 that is a mirror image to use for the right side - seem plausible ?

The calipers look exactly like the ones that were on my '76 cb550 that CBGhia now has. Rotors and hubs look the
same (from memory) The 550 and 750 use the same hub, rim and disc don't they ?
Did any of those come with dual discs ? Certainly some race bikes had them...

Off to the archives to see what I can dig up.

Anybody shed some light on that ?

Geeto67 · « **Reply #20 on:** March 20, 2008, 04:12:45 PM »

I don't think the calipers are any different, just the mounts.

greenjeans · « **Reply #21 on:** March 20, 2008, 04:31:57 PM »

That's what I'm thinking....just need to find a right side mount.

take a look at this: http://cgi.ebay.com/ebaymotors/Honda-CB-750-Brake-caliper-CB750-K-Brake-Hoses-02070_W0QQcmdZViewItemQQcategoryZ35592QQihZ019QQitemZ290216101616QQrdZ1QQsspagenameZWDVW

Doesn't that seem opposite/mirror of what I've posted ? Sure looks like it is or am I getting dizzy/turned around ?

edit: just noticed that the caliper has been mangled....could be installed backward - wrong bolts.
Yep it is.....that would have been too easy

mystic_1 · « **Reply #22 on:** March 20, 2008, 05:46:42 PM »

If you look closely at the part that you've correctly identified as being the critical one, your Part #2, you'll see that it is the same as the one you posted above. It does look like that caliper was simply installed on the bracket backwards.

mystic_1

greenjeans · « **Reply #23 on:** March 20, 2008, 06:26:02 PM »

Knew it was too easy.

Anybody know how to go about seeing if Honda actually made a right side bracket in '72 & getting a part number or something that could make searching for one a bit easier ?

kghost · « **Reply #24 on:** March 20, 2008, 09:33:21 PM »

I'm not sure the actual fork leg is different on the later models...

I think the mounting lugs are in the same place...its just a different bracket.

I'll compare some in the morning.

I have 2 K2's with the bracket you've pictured.

Along with a 73, 2 74's, and a 75.

I'll have a look if I get to the shop.

News:

Author Topic: adding another caliper for dual front brakes w/ pics on page 2 (Read 4063 times)