Topic: Dual Discs - lower pipe

[jaytee-nz]

So I'm gathering parts to fit a dual disc set up on my 1974 CB750. From what I can see others have fitted the standard metal lower pipe to the additional new right hand caliper. What I can't figure out is how it fits without changing its shape as the curved part that goes inside the fork leg needs to be a mirror image shape of the left hand one. Is it a simple heat it up and bend it job  ?

[mrfish2]

You could always run the brake hoses straight to the calipers and not have to fool with the hard lines. I'm gathering parts to do this as well and i don't plan on using the hard lines.

[Rookster]

I just used a new stock line but I bent it to fit the opposite side.  It has to be a mirror image like you said.  A standard brake line bender works. 



Scott

[martin_uk]

Brake pipes can usually be bent by hand without heating unless a tight radius, but can use an appropriate sized object to "lean" against to  form shape.

[Wobbly]

Why bother?

[jaytee-nz]

Wobbly - "why bother". Because my bike is completely stock and I want to keep that look rather than spoil it with non factory add ons.
Thanks for the other constructive replies.

[Wobbly]

Wobbly - "why bother". Because my bike is completely stock and I want to keep that look rather than spoil it with non factory add ons.
Thanks for the other constructive replies.

Since "completely stock" wouldn't have two brakes to begin with,  I have difficulties to follow your line of reasoning (i.e., "I want to keep that look rather than spoil it with non factory add ons" while adding a second front brake). Good luck anyhow.

[Rookster]

Hard lines are used where a flexible hose may come on contact with spinning things like wheels or rims.  Sure many people use a braided flexible line all the way to the caliper but some don't.  If you are the kind of person who wants a hard line around the fork leg, rim and wheel then the solution is to modify a stock hard line.  I bothered because that's what I wanted to do.

Scott

[Retro Rocket]

Wobbly - "why bother". Because my bike is completely stock and I want to keep that look rather than spoil it with non factory add ons.
Thanks for the other constructive replies.

Since "completely stock" wouldn't have two brakes to begin with,  I have difficulties to follow your line of reasoning (i.e., "I want to keep that look rather than spoil it with non factory add ons" while adding a second front brake). Good luck anyhow.

I'm sure Honda offered the twin disc set up as an option on these bikes, I don't think the forks would have been set up for twin discs otherwise, if so, that would make twin discs  a stock Honda accessory...

When the CB750 first came out, Honda had to keep the costs down to keep them competetive with the market, so steering dampers, twin front disc conversion kits, oil coolers etc were available, but only as optional extra's. Cheers, Terry.  

[Don R]

 My belief is the engineers wanted twin discs, they had to hold a price line and couldn't do it. But, they did leave us the option. I bought new power pipes and rebent the right one. I too, like the original appearance. Someone who didn't know, would think it came that way. To me that's the sign of an appropriate modification for an original appearing bike.

[wjustinleigh]

I've seen a lot of them, never a stock double disc.  Drilled rotors weren't stock either but seem like a pretty good idea.  Seems like the braided lines might a bit close to the wheel to me but other fittings could solve that.  My opinion either solution can look good on these old bikes, thanks for presenting the different options.  It's a beautiful bike, have to say the brake lines would be the last thing I noticed.

[Rocky2010]

Why dont you take the fork tubes out put left in the right & the right in the left side so then the calipers are at the rear of the fork legs remove the olive fitting in both calipers so you can screw the banjo bolt straight in the caliper and then use braided hoses straight down the back the forks. Much cleaner looking setup that is what we did in the early days.

[Wobbly]

I'm sure Honda offered the twin disc set up as an option on these bikes, I don't think the forks would have been set up for twin discs otherwise, if so, that would make twin discs  a stock Honda accessory...

Well, you are mistaken.

[flybox1]

@ the new caliper you are adding, stick a small sheet metal screw into the calipers hard line hole, and twist/pull out the tiny hard-line mating piece. 
insert it into the bleeder hole.
done.  symmetrical on both sides.

[martin_uk]

Why bother?
Which discs are these?

[flybox1]

If I read Wobbly's comment correctly "Why bother" is referring to the fact that you can run a braided line right to the caliper and totally omit the hard line. Easy and clean. He even adds supporting pictures. 

If you are using the earlier K calipers, the bleed hole and hard line holes are fore and aft of the caliper piston bore. As i suggested above, and pictured by Rookster, you can remove the internal fitting and insert it in the bleed hole on the 2nd caliper you are installing.  This will allow for symmetrical looking setups.  Bend the hard line to match.

Now, if you have the latter calipers, (see Wobbly's pictures) where the hard line and bleed holes are directly on top of the piston, the adjustment I mentioned is not needed.

[Wobbly]

Why bother?
Which discs are these?

EBCs from the U.K, because EBC USA wasn't capable of delivering the right hand one. EBC also made a neutral pattern which I initially got, but they couldn't track that one for me when I wanted to add the right hand disc. Again, only dealing with EBC in the U.K. got results as they made a right-hand bird wing pattern for me. It took two days--great service.
Here is the neutral pattern, that I had mounted first (bought from Amazon.com) although EBC USA tells me that it doesn't exist (I hope you can make it out):

[Wobbly]

As a side note: the neutral pattern and the left-hand bird-wing pattern had the same part number: MD 1062 LS. The right hand bird-wing pattern would thus be a MD 1062RS--but you cannot order it like that unless you talk to EBC U.K. directly.

[Wobbly]

Check out Jayhawks postings. He has been extremely helpful in all of this: http://forums.sohc4.net/index.php?topic=74547.msg1471732#msg1471732

This was also very helpful and is genuine Honda:


http://www.ebay.de/itm/Honda-CB-750-Four-K6-K7-F1-F2-Schrauben-Mutter-Tachoflansch-2-Bremsscheibe-/360623679324?pt=DE_Motorradteile&hash=item53f6d8a75c

[mrfish2]

Wobbly:  i see there is a speedo drive adapter there, but what purpose do the bolts serve? Are they simply longer to allow bolting 2 discs to the hub or just new bolts? I plan on mounting dual 750 discs and brakes on my 550.

[flybox1]

Wobbly:  i see there is a speedo drive adapter there, but what purpose do the bolts serve? Are they simply longer to allow bolting 2 discs to the hub or just new bolts? I plan on mounting dual 750 discs and brakes on my 550.

Yes, longer bolts for the added disc.
the posted adapter can be used instead of modifying the existing speedo drive plate, or routing out drive plate holes on the rotors carrier.

[Retro Rocket]

I'm sure Honda offered the twin disc set up as an option on these bikes, I don't think the forks would have been set up for twin discs otherwise, if so, that would make twin discs  a stock Honda accessory...

Well, you are mistaken.

I'm not mistaken Wobbly, , Honda had oil coolers, steering dampers and twin discs as options from the factory. Its been posted on the forum a few times, even the paperwork with the options listed and I quoted one above, I'll put it here for you again and i'll go look for the official document, its on the forum somewhere.....

When the CB750 first came out, Honda had to keep the costs down to keep them competetive with the market, so steering dampers, twin front disc conversion kits, oil coolers etc were available, but only as optional extra's. Cheers, Terry.  

Why are you so adamant they didn't, they wouldn't put the caliper hanger mount on the leg if they never intended a twin disc set up, I thought that would be pretty obvious....?

[Wobbly]

http://www.cmsnl.com/honda-cb750four_model14344/

Honda never "had oil coolers, steering dampers and twin discs as options from the factory." You won't find any of them in any Honda CB 750 Four Shop Manual. You won't find any of them in any of the parts lists (see above). I looked at CB 750 Fours as early as 1970, and never saw such options. I bought my current K7 new back in 1977. The only option was the color. I bought an F1 new before. Same thing. I probably have every book on the CB 750 Four in the English language and none show such options. I wish, such options would have existed because it would make the conversion so much easier. But they did not exist.

[Retro Rocket]

http://www.cmsnl.com/honda-cb750four_model14344/

Honda never "had oil coolers, steering dampers and twin discs as options from the factory." You won't find any of them in any Honda CB 750 Four Shop Manual. You won't find any of them in any of the parts lists (see above). I looked at CB 750 Fours as early as 1970, and never saw such options. I bought my current K7 new back in 1977. The only option was the color. I bought an F1 new before. Same thing. I probably have every book on the CB 750 Four in the English language and none show such options. I wish, such options would have existed because it would make the conversion so much easier. But they did not exist.

Wobbly, I'm sorry mate but they did exist, you aren't the only one thats had piles of these bikes either.  I think they probably weren't listed in all the manuals, which i have also, because they were listed as race parts for the CR750, I have the actual Honda part numbers for the Disc bolts, and the right hand caliper bracket parts somewhere, the oil cooler and damper were on that list too, when i dig them up i'll post them for you, anyone could buy these parts if you knew they were available, all the part numbers started with 300 and finished with 970.... I had friends that raced these bikes in the 70's and started buying race parts for the 750 in 1979, i still have some pretty trick parts, and have sold some as well, I was always more interested in the performance side of these bikes, I still have RC, action 4's and Yoshimura catalogs from the 1970's, some of the parts are also listed in the Yoshi catalog if my memory serves me well...

[mrfish2]

I for one would be interested to see those part numbers