New to CB400 four and new here! Front brake improvement?

[Mikep328]

Hi all!  A few days ago I acquired a '76 CB400 four, took it out for my first ride.  Fun little bike...except for the front brake which I found totally inadequate. 

Subsequently I found this site and read all the posts I could find, seeing much re the "wooden" feel and generally mediocre stopping power.   On my bike the lever is firm, no sponginess.  It just doesn't apply any real stopping power, regardless of how much  pressure I apply on the lever.  The bike has 13,276 miles and is in excellent, well serviced condition with a lot of receipts for work done, to include replacing the cam chain tensioner as well as other engine "freshening."  The only modification to the bike from stock is an electronic ignition.

I contacted a well-known vintage Honda spares supplier, asking them for recommendations to improve the brake.  I was surprised that rather than trying to sell me a new rotor, new lines, new master cylinder, etc), the response was, "New pads may help but the brakes on a CB400F were never great." 

The front brake feels pretty much the same as the stock front brake did on my '73 Norton Commando - maybe even a bit worse - before I replaced the OEM master cylinder with a Brembo from Colorado Norton Works.  That, a set of braided SS lines, and some more aggressive pads in the OEM caliper transformed that brake.  It is now acts and feels like modern brakes.  Of course the down side is that the master cylinder does not look anything like the OEM version.

My general thought is to go down a similar path though from searching and the suppliers response, it doesn't sound like anything is going to make the sort of transformation I am looking for.

So...I'm wondering if anyone has done something similar (different master cylinder) or found some tricks/tweaks/mods to the OEM front brake that I have not managed to find via the search function.  Also, what are the most aggressive brake pads for street riding, including aggressive riding on narrow, twisty roads?  I don't care about rotor wear.  If I had to replace a rotor every 10,000 miles to get good brakes, that's fine.

Thanks!

[Trigger]

Welcome to the mad world of the SOHC 

It is a 70's bike and they don't have modern braking grip or stopping power. They were just a simple upgrade from a drum brake.

[davidcumbria]

Welcome Mike- great forum this.

I have exactly the same diagnosis about my 550k front brake which has a new master cylinder and caliper piston and pads. Pull as hard as I think reasonable with full hand not two fingers and retardation is pathetic- need to use rear brake all the time. Pads did not look especially glazed. My plan is to rebuild with braided lines and to clean the disc very thoroughly.

 Also need to check the master cylinder piston diameter which should be 14 mm. Some aftermarket units are 5/8 th inch which is 15.9 mm and that would increase the wooden feel. Also I have read that as a first disc brake effort Honda were worried about lock ups so made it intentionally weak.

A double disc conversion seems quite common on the 500/550  but I do wonder if a smaller diameter mc piston would help. The lever movement is very small so I could cope with more travel. Not seen any recommendations for smaller diameter  master cylinders. Agree that safety is a much more important priority than originality.

[Johnny4428]

Hi Mike, welcome to the forum, great place to be with very helpful people. I too have the pathetic front brake on my 550. But as advised going to give it a good toasting to bed it in properly. Nothing to lose.

[Bryanj]

Its easy to say you dont mind changing rotors but finding one isnt, no aftermarket to my knowledge.
Pads will make  difference, as will making sure the pivot is free and caliper adjusted, lines might make a small diffeence if yours are original.
Apart from that its just brake earlier!

[Trigger]

Its easy to say you dont mind changing rotors but finding one isnt, no aftermarket to my knowledge.
Pads will make  difference, as will making sure the pivot is free and caliper adjusted, lines might make a small diffeence if yours are original.
Apart from that its just brake earlier!

Aftermarket are available but, don't know if you can believe Slivers sales pitch >> https://www.davidsilverspares.co.uk/CB400F-SUPER-SPORT-FOUR/part_257875/ 

[Bryanj]

Thanks Graham, been a long time since i looked on his site, only when desperate now, sooner go to a mate in nashville!

[mickwinf]

i had a new repro caliper from silvers and the pads were terrible, dangerous in fact. Put some EBC ones on and much better but still not like modern stuff.

[Mikep328]

Interesting info guys, thanks.  I had ASSUMED (you know what they say about assumptions) that David Silver was THE place to go for CB400 replacement parts. 

[McCabe-Thiele (Ted)]

I've now fitted Brembo in mine - very pleased with them.

[Johnny4428]

Its easy to say you dont mind changing rotors but finding one isnt, no aftermarket to my knowledge.
Pads will make  difference, as will making sure the pivot is free and caliper adjusted, lines might make a small diffeence if yours are original.
Apart from that its just brake earlier!

Good point Bryan, I have been almost caught out riding along or behind others on modern machines.🥵🥵

[Bryanj]

Silver did have a lot of replica parts made when he "restored" a whole batch of 400's but some are, shall we say, not as good as others

[K2-K6]

Welcome Mike- great forum this.

I have exactly the same diagnosis about my 550k front brake which has a new master cylinder and caliper piston and pads. Pull as hard as I think reasonable with full hand not two fingers and retardation is pathetic- need to use rear brake all the time. Pads did not look especially glazed. My plan is to rebuild with braided lines and to clean the disc very thoroughly.

 Also need to check the master cylinder piston diameter which should be 14 mm. Some aftermarket units are 5/8 th inch which is 15.9 mm and that would increase the wooden feel. Also I have read that as a first disc brake effort Honda were worried about lock ups so made it intentionally weak.

A double disc conversion seems quite common on the 500/550  but I do wonder if a smaller diameter mc piston would help. The lever movement is very small so I could cope with more travel. Not seen any recommendations for smaller diameter  master cylinders. Agree that safety is a much more important priority than originality.

agree with your assessment here. Its primarily the hydraulic leverage ratio that makes them feel so wooden and inert.

Of their contemporary bikes the Yamaha RD400 had much more potent front brake with significant difference in hydraulic ratio in comparison to Honda's very conservstive approach
The Yamaha used a fixed and twin opposed piston caliper (making similar ratio to two Honda type in double arrangements) that would feel good even now.
Later they went to sliding caliper and single piston but with different master, still potent but lost that absolute rigid bite the old twin pot had.

Changing mastercylinder ratio of the 400 4 should yeald good results, but as pointed out, unlikely to be accomplished with std looking components.

[TrickyMicky]

Hi all!  A few days ago I acquired a '76 CB400 four, took it out for my first ride.  Fun little bike...except for the front brake which I found totally inadequate. 

Subsequently I found this site and read all the posts I could find, seeing much re the "wooden" feel and generally mediocre stopping power.   On my bike the lever is firm, no sponginess.  It just doesn't apply any real stopping power, regardless of how much  pressure I apply on the lever.  The bike has 13,276 miles and is in excellent, well serviced condition with a lot of receipts for work done, to include replacing the cam chain tensioner as well as other engine "freshening."  The only modification to the bike from stock is an electronic ignition.

I contacted a well-known vintage Honda spares supplier, asking them for recommendations to improve the brake.  I was surprised that rather than trying to sell me a new rotor, new lines, new master cylinder, etc), the response was, "New pads may help but the brakes on a CB400F were never great." 
   
The front brake feels pretty much the same as the stock front brake did on my '73 Norton Commando - maybe even a bit worse - before I replaced the OEM master cylinder with a Brembo from Colorado Norton Works.  That, a set of braided SS lines, and some more aggressive pads in the OEM caliper transformed that brake.  It is now acts and feels like modern brakes.  Of course the down side is that the master cylinder does not look anything like the OEM version.

My general thought is to go down a similar path though from searching and the suppliers response, it doesn't sound like anything is going to make the sort of transformation I am looking for.

So...I'm wondering if anyone has done something similar (different master cylinder) or found some tricks/tweaks/mods to the OEM front brake that I have not managed to find via the search function.  Also, what are the most aggressive brake pads for street riding, including aggressive riding on narrow, twisty roads?  I don't care about rotor wear.  If I had to replace a rotor every 10,000 miles to get good brakes, that's fine.

Thanks!

. Greetings, and welcome to the forum.  People that are brought up with these vehicles were used to the braking standards of the time. The braking power available was quite sufficient for the tyres and other ingredients that were the standard in the 70's, and this included many of the four wheeled vehicles as well. As time passed, engineering and tyre quality improved beyond belief, you had to be bloody brave to try and make rapid progress on a wet road whilst your bike was still wearing its factory fitted Sensitol lubricated tyres!!  Moving on to today,  you are still riding a historic vehicle, if you want to ride with your knees and arse scraping the floor, then use a modern vehicle. In fact if you want aggressive street riding, along with aggressive riding along narrow country roads, I hope we never meet.

[Trigger]

Interesting info guys, thanks.  I had ASSUMED (you know what they say about assumptions) that David Silver was THE place to go for CB400 replacement parts.

Some parts yes, but other a no.
Were are in the UK ? Maybe another member is close to you to compare, as i can get the lever sharp. Also look if it has a new aftermarket brake switch fitted, i have had problems with those recently