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Discussion Starter #1 (Edited)
This last weekend I finally replaced the 36 year old hydraulic brake line on my CB400. It was cracking and routed funny because I had changed out the stock bars for superbike bars. It had been too long and I was beginning to really worry about it. So I ordered a custom stainless steel braided line from HEL (they come in many colors, though I stuck to the stock looking black line), installed and bled the fluid. I don't know why I didn't do this earlier! I guess I was a bit daunted by the task, but in the end it was extremely simple (as many of you surely know) and I feel much more secure with a modern line, and it's actually much thinner in diameter too.

Anyway, I spent a bunch of time searching specs which were scattered across the internet and mostly tucked away in this forum (thanks longdistancerider!), and I wanted to make a post that consolidates information in case someone (like I did a week ago) needs to know some more technical details about replacing their brake line on an old stock Hawk (1978 CB400). Some of this may be obvious, some less obvious:


  • The banjo bolt size is 10mm x 1.0
  • The fittings on HEL brand brake lines CAN be rotated
  • The stock angle for the fitting on the handlebar is 20°
  • the shorter (than stock) banjo bolts will work
  • DOT 3 OR DOT 4 brake fluid
  • It doesn't hurt to add 0.25"-0.5" in length to custom made cables.
  • Yes it's worth it
That's all! I just hope someone in the future finds this information useful!

-j
 

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Thank you i will surely make good use of this as i am looking to overhaul my front brake system ?


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Yes this kind of info is very useful, but just for clarity, do you know the pitch of the 10mm banjo bolts? there are 1.0 and 1.25 varieties.
 

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Is adding more length acceptable because the stainless steel cables are more stiff and "fitted" so a little slack will help? That's my guess.

You should mention something about crush washers and torque values. Crush washers SHOULD ALWAYS BE REPLACED. They are specifically called Banjo fitting crush washers, and you can find them anywhere (doesn't have to be Honda). Go to any motorcycle store and carry your old ones so you get the right size and buy a small handful from them. Copper or aluminum, doesn't make a damned difference.

Also, you cannot simply just take a wrench to the bolts to crush the washers. They need a specific torque value otherwise they will never seal and leak. Use what's in your manual; it's actually a pretty hefty torque value (somewhere between 30-50lbs if I remember correctly). I know this for sure because when I changed mine out, I was using a wrench to get them "tight". What I thought "tight" was not near enough!

Also, COVER YOUR PAINTED PARTS ALWAYS while working with brake fluid. Brake fluid will also mess up powder coated parts too. It's the only imperfection on my restoration is a faint "line" of discoloration that runs down my fork leg.
 

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Paint is one of brake fluid's favourite meals.
Water/moisture is brake fluid's worst enemy.
When working with the brakes, take care to not let it contact paint....it WILL destroy it.
Do not leave the reservoir open any longer than necessary....that includes the container the brake fluid came in.....ANY moisture will contaminate brake fluid.... quicker in high humidity.
Water has a lower boiling point than brake fluid....and if present, will affect the operation of the brake system.
 

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Thanks for this write up jbergen! Anyone have preferred vendor for these cables/parts? Know if these specs match the Cm400 also? I too just went to superbike style bars and would like to shorten my brake cable and might as well improve it in the process. I contacted common motor collective but they said they don't deal with the CM's.
 

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Bringing this back from the dead, anyone know the length of the stock hose and what size hose did you go with? I just purchased similar bars. Thanks
 
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