Topic: Better Front brake

[Artie]

My fully restored 1971 K1 is a dream to ride but although everything works as it should front brake lever effort is very high and stopping power poor compared to 2 finger modern bikes
 but I understand that is what was available in 1971 from Honda safety etc noobies locking up front wheel etc etc
I’ve replaced just front MCs on some of my other vintage bikes CB1100F / 79 CBXbikes with Kawi C 14 ZX type 14 MM piston 75-90$ on e bay
and now 2 finger power great feel
The front caliper on K1 is 38 mm and some suggesting useing 12MM front MC to get good feel
Anyone done it or how can you get better power by just changing MC for more bite
Would like to retain stock look to some degree as well
I know dual discs and major changes will get me what’s modern but I just want to change front MC only
I’ve also changed various front pads of w/ EBC pads but still wooden feel and need mucho lever effort for any stopping power
Ideas guys thanx in advance

[Stev-o]

Are you a very aggressive rider and/or track the bike?

[69cb750]

Using a master cylinder with a smaller piston or wheel cylinder with a larger piston will reduce hand effort.
If you pull hard enough you can skid front tire with original parts.

[BenelliSEI]

I have a stock K1 too. I recently changed over to the after market master that Vintagecb750.com sells. Didn’t really change anything. I also have a set of braided lines from Raymond at Apex. It all works pretty well. New steel line, and fresh caliper.

What I have noticed is that different pads make big differences. I didn’t like the last set of EBC pads at all. My favourite lately, are a few sets of old Honda NOS that came with other stuff. Scuffed them up, chamfered the leading edge, slipped them. They give terrific feel and great stopping.

New topic? “Your FAVOURITE CB750 BRKE PAD”

[Artie]

Using a master cylinder with a smaller piston or wheel cylinder with a larger piston will reduce hand effort.
If you pull hard enough you can skid front tire with original parts.

Reasonably aggressive but front brake lever is still way too  high

[Artie]

I have a stock K1 too. I recently changed over to the after market master that Vintagecb750.com sells. Didn’t really change anything. I also have a set of braided lines from Raymond at Apex. It all works pretty well. New steel line, and fresh caliper.

What I have noticed is that different pads make big differences. I didn’t like the last set of EBC pads at all. My favourite lately, are a few sets of old Honda NOS that came with other stuff. Scuffed them up, chamfered the leading edge, slipped them. They give terrific feel and great stopping.

New topic? “Your FAVOURITE CB750 BRKE PAD”


Did the MC itself reduce lever effort?

[Bankerdanny]

Randakk, the GoldWing guru, claimed that 14mm was the optimal piston size for single disk Hondas, while 5/8 was best for a 2 disk setup.

I followed his advice and bought a 5/8" Nissin radial master when I upgraded my 750F1 to an F2 twin disk setup. I have been very happy with the result.

[Artie]

I wish to stay with single disc but ONLY want to reduce lever effort and feel to std front end
Only wondering if anyone has changed only front MC to accomplish this

[Bankerdanny]

There are limits to how much better the brakes can get. My 550F had a stock master, but I sent the rotor to Godffery in Wisconsin to get thinned and drilled and also changed to a braided line. The performance was much improved and it handled my 240lbs plus bags and other luggage while riding through the Colorado and Arizona mountains with no issues.

I think that switching to a properly size modern radial style master will improve the braking, but for best results you should also reseurface the rotor, install modern pads, and upgrade the hose. Brakes are a system and for the best result you need to improve as a system, not just by replacing one single component. The cost of all these things on a single rotor bike is $350 - $400 and is in my experience well worth it.

[Artie]

Std mc bore is 14 mm
Vintage CB lists their replacement to be improved by going to 5/8” bore(15.8mm)
Has anyone used their MC only
I asked Vintage if it was less lever effort and they said probably about the same?
Again what MC only will give me less lever effort?
Seems to me that that a  larger piston pushes harder correct?

[754]

Its the  pads, the single brake in the 70,s seemed far better than today... and I am not riding any modern stuff, causing me to say that. Also braided lines help , and dual disc worked very well, the big drawback being weight.
 I lean in the direction of converting to one big modern brake, if you use the F forks or GL it's fairly easy to do..

[BenelliSEI]

Regarding your “effort question”. Smaller diameter M/C will have a longer stroke than a larger diameter, to displace the same amount of fluid. However, with the smaller diameter, you will deliver higher pressure, for the same applied force (assuming the same lever pivot dimensions).

As I said, I’m using the M/C that Vintagecb750 sells as a direct replacement for single caliper. It works well.

[70CB750]

Are you still using original rubber hoses?

[Artie]

Yes but hoses are decent and can’t feel any bulging anywhere in lines with static King Kong squeeze
I’m sure the right MC will make up the need but the question still is which one ,somebody must have been down this route???
Again this is typical of the day,high  lever effort but no feel not much confidence in front brakes by any standards of today’s brakes,
I ride this bike all the time and the brakes suck just trying to make it a little better and keep it stock looking.
1971 standards a disc was big time news and drumshoe brakes were even worse

[70CB750]

If you go to steel line, you will feel the difference.

[bryanj]

Go and ride a 1970 Triumph T120, you wont complain any more

[scottly]

Std mc bore is 14 mm
Vintage CB lists their replacement to be improved by going to 5/8” bore(15.8mm)
Has anyone used their MC only
I asked Vintage if it was less lever effort and they said probably about the same?

A 12mm MC will increase the hydraulic ratio with a 38mm caliper from about 7:1 to 10:1. Using a stock 14mm MC with two 38mm calipers, as was the common practice in the day, gave a ratio of about 14:1.
I would not use a 5/8" MC on anything less than two 38mm calipers.
Here is a helpful chart:
http://www.vintagebrake.com/mastercylinder.htm

[Artie]

Thanx your chart and info seems the correct path to follow
I think I will try a 12MM MC with my stock single 38mm caliper
Any recommendations for close to stock look

[Deltarider]

Are you still using original rubber hoses?

Well... I do. They're 45 years old, but on inspection I see no signs of wear whatsoever. Bike is parked in garage and so receives only a limited amount of UV light.

[slikwilli420]

Lines can look fine outside but degrade on the inside. Replace the line with an SS one, get an aftermarket caliper from AP, Grimeca or Brembo and build a simple adapter plate. Mate all that with the appropriate master cylinder and you will have brakes you can be very confident in.

[754]

The best rubber line, is not as firm as any stainless braided Teflon line.

[rotortiller]

I think I will try a 12MM MC with my stock single 38mm caliper

That's what I'd do. Most vintage masters have a similar mechanical lever gain and so the same stroke. That means the smaller piston will move less fluid  but at a higher pressure thus increasing  braking clamp force. The good thing is the stock master uses very little travel during braking being over sized and thus feels wooden, that allows ample margin for a smaller piston application resulting in better feel. The gains in braking while small will be there but are limited by the small brake pads and single piston caliper.

[Artie]

Ordered Bull blast MC which are 12MM thru flea bay and which post results, will probably change line too but MC first

[seanbarney41]

Ordered Bull blast MC which are 12MM thru flea bay and which post results, will probably change line too but MC first

will that clamp to 7/8" handlebar?  I would guess it was made to clamp to 1" bar.

[vik351]

Its the  pads, the single brake in the 70,s seemed far better than today... and I am not riding any modern stuff, causing me to say that. Also braided lines help , and dual disc worked very well, the big drawback being weight.
 I lean in the direction of converting to one big modern brake, if you use the F forks or GL it's fairly easy to do..

My Hondamatic 750A came from the states with raked pads (gaps in em) what the hell is that all about ... a wet weather thing...