Front brake lever

[Ken4004]

Hi everyone I have a question about the the cb 400 four front brake , I know that the front brake on this model is not great but after fitting a new master cylinder a new set of hoses and fully bleeding the system the brake lever can be pulled back to within 15mm of the handle bar grips.

I believe it’s probably due to the hoses expanding under pressure as you can feel them expanding under pressure.
The answer would probably be to change the hoses for some stainless steel braided hoses to stop this flexing but how much difference does it really make to the effectiveness of the brakes by upgrading the hoses basically is it worth it ?

[TrickyMicky]

In October 2020, like yourself, I replaced evrything except the disc. These were all original type (NOT OE), fittings, so no braided steel hoses etc.  Even now, when I apply the front brake, it is a very firm, nearly hard feel, and I'm sure that if I felt brave or daft enough I could lock the front wheel. If your flexi hoses are new, and you can feel them expanding, then I would send them back and try another brand. Make doubly sure that you have bled the system properly, quick check is to rapidly pump the handlebar lever, if it firms up th en you have air in the system. Check with some blue workshop paper round every joint to see if there are any leaks. Finally, make sure that you have adjusted the caliper to give the accepted minimum clearance between pad and disc. Sorry, cannot remember the figure.  Get it sorted before you even think of taking it out on the road mate.
           PS Have just found my old purchase details, my pipework I bought from Legend

[Ken4004]

Hi Tricky thanks for the  advice , no I wasn’t going to take it on the road as it is but just wanted to know what is normal, I cannot pull the lever right up to the bars but within 15 mm and I am pretty sure all the air is out.
I bought the hoses from Wemoto in Brighton so would have thought they should be reasonable.
I will check out all the set up again and see if I can get any more air out and see where I am after that.

Thanks again regards Ken

[Mikep328]

"I know that the front brake on this model is not great "

Old wives tale courtesy of the internet.  Per road test data from then/now the 400F had the same stopping distance from speed as current middleweight standard Honda's.

more info... (you can take a look at the whole thread if interested)
https://www.sohc.co.uk/index.php/topic,29559.msg285797.html#msg285797

[Oddjob]

Quite possibly true Mike. Until it rains that is. Then it's pull and pray time. The other main difference is how it's setup. Brand new it would be ok, as it wore however it got worse, the new ones don't do that due to different design. For it's age it's a ok system, better with another disc fitted though.

[Bryanj]

Difficult to twin disc a 400 as no mountings on second slider, i believe there were some castings made years ago for it.

[Mikep328]

 My 400F is my primary ride in the UK so it's seen a lot of use.  I've ridden in the wet - though not pouring rain - and my best "statement" about the brakes overall is that I don't even think about them when riding.  After doing the re-work AND the break in procedure for new pads that you (OddJ) so kindly posted back then, it stops with no issue/concern when I need it to stop!     

[Oddjob]

Bedding new pads in correctly can dramatically improve these old systems. Whilst the 400 isn’t that easy to twin disc the 500/550/750 which use the same setup are. I could lock the front wheel on my 500 if I used it hard. I did find the stainless steel discs suffered with water film and severely impacted braking performance as a result. However this was 30 odd years ago and things might have improved since then.

Glad to hear it’s working well for you Mike.

[Laverda Dave]

As Mick says they do feel wooden with virtually no feel even when set UK correctly.
The last 400/4 I worked on had air trapped in the line that refused to budge. In the end I pull the lever back as far as I could and zip tied it to the handlebar, took the reservoir cap off and left it overnight, it worked.
As for the new rubber lines, I'm pretty sure genuine Honda items actually contain steel braiding sandwiched between two layers of rubber and they shouldn't expand.

[TrickyMicky]

One of the not uncommon features regarding older vehicles, (2 or 4 wheels),  is that nowadays they are being driven by people of all age groups, so there are differing expectations as to what is an acceptable level of performance. Being an old 'wrinkly git'  I was brought up with the idea of firm/hard braking required firm/hard input from the driver. This method, when used with a well set up hydraulic or mechanical system gave great feedback through the lever/pedal.  My first vehicle with a so-called powerful brake was a 1969 CB250 with a twin LS front brake, which I soon learnt not to apply too suddenly!! Bloody useless though when trying to stop the bike rolling backwards down a slope.  I never had a car licence until I took my test in 1969 on a London Transport bus. Very satisfying, but the early type air brakes felt peculiar at first, it was just like pressing your foot on a firm rubber ball. Because there was no mechanical connection between the pedal and the brake shoes, the only feedback you got was from the seat of your pants.  ABS had not been invented then, so I was taught the art of cadence braking on the skid patch in West London.  Moving on, my present car, a 14 year old Peugeot is the first car I have owned with ABS. The irony of this being that 3 days ago, the ABS warning light illuminated, and stayed on. To me this is not too much of a problem, as it still possesses a working brake system like I have been used to. BUT!!! it will not pass the MOT.  My GB250 is fitted with one of those 2 piston front calipers, which yes, is quite powerful, but has a vastly different lever feel to the 400, quite soft in fact. When I took it for its MOT, I queried it with the tester, and he replied that it was a perfectly set up brake. I realise that I have deviated somewhat from the original post, so, is there any progress on the offending front brake?  It'll soon be spring, when the dust sheets can be removed from the bikes and placed over the model railway!! Stay safe everyone.

[Bryanj]

Tricky, the abs light is frequently a wheel sensor covered in crap or failing, trouble is you may need an expensive scanner to tell you which one!

[Ken4004]

Thank you got everyone’s input, I will try pulling back the lever and leaving it overnight as suggested by Dave and see what difference that makes.
As I said previously and people have commented on is the fact that I am comparing a 50 year old bike with a modern bikes brakes , things have come along way in 50 years.

[Bryanj]

Oh yes, go and see if you can ride a Triumph T110 from 59 then you will never complain about the 400 again!

[Seabeowner]

To bleed the brakes I always remove the top of the reservoir and rubber diaphragm and just pull the lever back quite small amounts a few times in fairly quick succession. BUT you have to be be gentle to ensure the fluid does not shoot out. The bubbles will appear. Turn the handle bars full lock the other way and keep repeating. I didn't get any success with just pulling the lever right back. But did have one that still had what I thought was too much movement and fitted another spare M/C to improve it.

[Laverda Dave]

Thank you got everyone’s input, I will try pulling back the lever and leaving it overnight as suggested by Dave and see what difference that makes.
As I said previously and people have commented on is the fact that I am comparing a 50 year old bike with a modern bikes brakes , things have come along way in 50 years.

The best way will be to pull the lever back and whilst you do so open the bleed nipple and then close it whilst keeping the lever pulled back. Once the nipple is closed allow the lever to return and then pull it back to the handlebar, zip tie it overnight but make sure you wrap a cloth around the handgrip otherwise the zip tie will cut into it.