Author Topic: Front Disc Performance Improvements - Bad Brakes (Read 12147 times)

RRRToolSolutions · « **on:** January 13, 2016, 05:53:25 PM »

Hi Guys,

I'll get my rusted oil tank sorted in the next week or so, then I'll be ok to crank and ride. I appreciate the inputs.

Now, problem #2 - my CB750 has never had good brakes. I rate the Honda at or near the bottom - that reserved for my 1974 GT750 dual-disc model (the worst). The CB's rear is fine, but the front needs dramatic improvements. I'm currently using new, OEM Honda pads that don't grap and hold the disc. My KZ900 has a fantastic single-disc brake, but this Honda will barely compress the forks in a hard pull. I've got drums that out-perform the Honda's disc system.

Are there some Sintered pads that will "bite" a lot harder than stock? I don't care about keeping the disc rotor shiny - I want to keep it out of the ditch or the back of the car in front in the event I need to shave speed fast. The rotor is in good shape, but I would replace it for something that stops - even something modern.

Help me solve this poor front disc brake issue. Stainless brake hoses will improve the feel and response time, but not the power so I'm looking for mechanical friction improvements.

Thanks, Gordon

Jerry Rxman Griffin aka MuthaF'er · « **Reply #1 on:** January 13, 2016, 06:39:10 PM »

Do you need to go through your caliper and master? Flush new fluid? Best place to start to ensure they are top notch.

And to think my thoughts were on another Gordon kit when I saw the title

NobleHops · « **Reply #2 on:** January 13, 2016, 07:59:16 PM »

Quote from: Jerry Rxman Griffin aka MuthaF'er on January 13, 2016, 06:39:10 PM

Do you need to go through your caliper and master? Flush new fluid? Best place to start to ensure they are top notch.

And to think my thoughts were on another Gordon kit when I saw the title

I agree with Jerry, go through the entire system. A single brake line is cheap, as is a caliper seal. If the master cylinder isn't leaking it's likely not the problem.

Don't neglect the disk itself. New pads on a nice flat disk need 60+ miles to bed into the disk, and that is properly done with a few hard stops from 60-0 with full cool down in between. But if the disk itself is glazed and grooved and not true, it may never come close to its potential.

My friend Tom Tokarz grinds stainless rotors to better than new, for something like $45 per rotor plus shipping. A great service.

www.truedisk.net

Drain the system, replace the line and seal, refill and install a reground disk and you'll be doing stoppies in no time.

N.

RRRToolSolutions · « **Reply #3 on:** January 13, 2016, 08:41:54 PM »

Are you guys telling me that you have good brakes on your CB750's? I want the same, but mine has never performed well. I thought it had something to do with the seaweed/organic pads they sold me - that's why I was talking bronze sintered pads.

I have a good friend that refinishes these stainless rotors on a flywheel machine. We learned years ago that you can't turn these on a lathe, they are just too hard and develop chatter marks and break tooling bars (we did that on one of my H2's). If you're able to lock your tire or even compress the forks, I'd love to do the same.

The fluid is clear and bled so no air or leaks. I'll have the rotor ground and see where I'm at.

Thanks Guys.

754 · « **Reply #4 on:** January 13, 2016, 08:48:15 PM »

I think the nowadays pads have a lot to do with it..
In the late seventies i had drilled dual stock discs, stock mc, braided -3 lines, and easy three finger braking and could howl the front tire stopping if I wanted too. Got to be the pad compound..

edwardmorris · « **Reply #5 on:** January 13, 2016, 08:52:47 PM »

I've got Daido pads with Blanchard ground rotor and new OE brake lines, stops quite well, but I have nothing to compare it to.

SOHC4 Cafe Racer Fan · « **Reply #6 on:** January 13, 2016, 09:50:22 PM »

I have dual GL1000 brakes on my CB750 and dual calipers on my CB550 -- both with modern pads, drilled rotors, rebuilt calipers, upgraded radial master cylinders and stainless steel braided lines. They are a big improvement over stock but not comparable to modern supersport bikes in terms of feel and outright stopping power. That said, my brakes can also howl the tire if necessary.

disco · « **Reply #7 on:** January 13, 2016, 09:58:20 PM »

Hi Gordon,
When I got my first CB750K6 the front brake was woeful. It felt "wooden". I could apply plenty of pressure...it just wouldn't bite. I went thru the whole system & replaced hoses, overhauled the master cylinder etc. I also scuffed up the rotor by placing some emery on a flat glass surface & rubbing the rotor over it. I found some Brembo pads from a UK seller quite cheap & installed those. Problem solved. Not up to modern bike standards, but I can lock the front wheel now.

PeWe · « **Reply #8 on:** January 13, 2016, 11:27:46 PM »

The brake disc is one important factor. My brakes need an upgrade.
I'll upgrade to dual front brakes this winter.

I have ordered new discs from David Silver. The disc is said to be much better. I could have updated the disc only, but I had already the right caliper and bracket so dual it will be.

A good start is to replace the disc and new pads. Make sure that the caliper is aligned and float as it should.
https://www.davidsilverspares.co.uk/CB750K6-FOUR-1976/part_273686/

They have a good master cylinder too if original is leaking. https://www.davidsilverspares.co.uk/CB750K6-FOUR-1976/part_123916/

becken · « **Reply #9 on:** January 14, 2016, 06:20:11 AM »

Contact Michael at Vintage Brake. He recommended a set of Ferodo pads (I can't remember which ones) for my 550. Though not like a modern set up, they did make a big difference.

flybox1 · « **Reply #10 on:** January 14, 2016, 06:50:38 AM »

I can stop quite aggressively with my dual disk setup.
Godferry's thinned and drilled 4mm rotors, stock calipers, EBC Kevlar pads, Slingshot SS lines, and an aftermarket 14mm MC.

greenjeans · « **Reply #11 on:** January 14, 2016, 06:54:37 AM »

New brake lines make a very noticeable difference vs 40 year old originals.

DaveBarbier · « **Reply #12 on:** January 14, 2016, 03:09:29 PM »

Quote from: flybox1 on January 14, 2016, 06:50:38 AM

I can stop quite aggressively with my dual disk setup.
Godferry's thinned and drilled 4mm rotors, stock calipers, EBC Kevlar pads, Slingshot SS lines, and an aftermarket 14mm MC.

Same exact setup. No where near sport bike stopping ability but I'd say my 550 can stop very well.

I'm comparing it to my brother's old Ninja and my buddies ugly Dyna.

Retro Rocket · « **Reply #13 on:** January 14, 2016, 03:14:37 PM »

I had a well set up 750 with twin discs, It braked very well, I sold it to a friend who was riding it when a car clipped a 44 gallon drum, spinning it out in front of him, he grabbed a big handful of front brake flipped the bike over forwards, the brakes had plenty of bite...

Garage_guy_chris · « **Reply #14 on:** January 14, 2016, 04:34:46 PM »

I have had similar problems with my brakes I have a CB450 that uses the same brake setup as the 750 with 38mm caliper, drilled disc, CBR600F3 master and 2 different sets of pads EBC and NOS Vesrah and it doesn't stop worth a damn.

On the other hand i have my 750 with dual front discs, drilled discs, 42mm 75-78 calipers, SBS pads, Braided lines, brake T and hydraulic switch delete, VFR800 14mm master and it stops comparable to lower end modern bike like my brothers Ninja 300 or friends CB500X

Im planning to do a dual disc conversion on the 450 with some SBS pads and hopefully it will stop good too.

scottly · « **Reply #15 on:** January 14, 2016, 05:31:53 PM »

Quote from: Garage_guy_chris on January 14, 2016, 04:34:46 PM

I have had similar problems with my brakes I have a CB450 that uses the same brake setup as the 750 with 38mm caliper, drilled disc, CBR600F3 master and 2 different sets of pads EBC and NOS Vesrah and it doesn't stop worth a damn.

What is the size of the CBR600F3 master?

sixthwisconsin · « **Reply #16 on:** January 14, 2016, 05:38:21 PM »

Quote from: flybox1 on January 14, 2016, 06:50:38 AM

I can stop quite aggressively with my dual disk setup.
Godferry's thinned and drilled 4mm rotors, stock calipers, EBC Kevlar pads, Slingshot SS lines, and an aftermarket 14mm MC.

+2 Same set up
Stops amazingly well compared to stock.

RRRToolSolutions · « **Reply #17 on:** January 14, 2016, 06:11:51 PM »

I have never had too much brake, when the need to stop comes - I want more than I need. I practice panic stops on each bike ride, so I welcome and really want the performance you guys have. I'm not a dual disc fan on these older bikes and I'm not convinced that duals are necessary. As mentioned, my 1974 GT750 Suzuki had all new components and I've ridden others to confirm they did not work. The rotor/disc material has a lot of stainless alloy and may never give the friction potential of steel or cast rotors. I've got modern bikes and while phenomenal, the 1976 KZ900 has amazing brakes using stock, factory components and a single disc. Perhaps the clamping load at the pads from the pressure generated by the master or the the material of the disc are the day/night difference.

The photo shows the disc as-is today. I've clearly got some grooving and surface issues - I'll start with a new surface and I'll come back here and report on my progress.

Thanks for all the inputs Guys! Gordon/RTS

seanbarney41 · « **Reply #18 on:** January 14, 2016, 06:17:36 PM »

the sohc4 pivoting caliper is never gonna be as good as a floating or opposed piston caliper. Props to Honda for first disc on a production bike, but the engineering is just not capable of what later designs are.

HondaMan · « **Reply #19 on:** January 14, 2016, 06:49:58 PM »

Gordon: the 750's front brake has always been less than the post-1980 bike's versions due to the stainless steel (18-8) disc. The things that improve it: you already know some of them.

Sintered pads are #1, and when you have them (like mine), you can lay a black streak on the pavement with the front brake (one disc). What I learned about this: don't use the sintered pads if you have 2 discs up front (don't ask!). That's how I ended up with 1 disc again, afterward...

The pad compound is #2. The ones I have found that work the best are a lighter color than the ones that don't work as well - or not at all when wet. The exception to this is one set of EBC "organic" pads I somehow got some 7 or 8 years ago: they don't stop, wet or dry, acting like something was wrong with the brake! It put my old worn-out sintered pads back in back then, just to be able to ride until I found some new ones.

Check around with the racing shop sellers online. This has been how I found some when I've needed them. They get it: one guy, some 9 years ago, sent me a set of ceramic ones (I didn't even know anyone ever made those for these bikes!) that took about 100 miles to break in, but then were almost as strong as the Fedora sintered pads I am running now.

Whichever pads you use, be sure they are sintered with bits of bronze in them. Honda's OEM pads used to be this way until about 8-9 years ago, at which point they seemed to become the same ones EBC was selling (junk).

BobbyR · « **Reply #20 on:** January 15, 2016, 05:40:45 AM »

I have often wondered if Honda was timid when they designed the front brake. It was new on production bikes at the time. The may have been afraid of stoppies and potential liability.

HondaMan · « **Reply #21 on:** January 15, 2016, 02:55:20 PM »

Quote from: BobbyR on January 15, 2016, 05:40:45 AM

I have often wondered if Honda was timid when they designed the front brake. It was new on production bikes at the time. The may have been afraid of stoppies and potential liability.

They were: the 2 things they didn't want to see was: rusty discs and people flying over handlebars.
They did 2 things to prevent this, which resulted in less brake. The stainless disc both reduced rust and, since it has a very finely-pored surface, brake grip. The second thing was the soft rubber brake hoses, similar to those used in the short flex sections of car brakes. The first thing I remember racers doing with the brakes was: hard pipe from the master to the lower stem, and braided lower flex hose. Both improved the braking, but still not letting the bike throw its rider! The latter started when the sintered pucks and dual-disc handmade setups started arriving.

Today we can get the nice Goodrich stiffy brake lines: I often use them on at least the upper section to improve the grip. They have nice chrome fittings, too.

2wheels · « **Reply #22 on:** January 15, 2016, 03:29:57 PM »

http://www.ebay.ca/itm/Honda-CB-750-K1-K5-70-76-Front-Brake-Pads-Sintered-/151202394109?hash=item23345d6ffd:g:OoAAAMXQVERSxtjr&vxp=mtr

Are these the good ones that will make my brakes better. Will they fit my ko?

HondaMan · « **Reply #23 on:** January 15, 2016, 06:46:18 PM »

Quote from: 2wheels on January 15, 2016, 03:29:57 PM

http://www.ebay.ca/itm/Honda-CB-750-K1-K5-70-76-Front-Brake-Pads-Sintered-/151202394109?hash=item23345d6ffd:g:OoAAAMXQVERSxtjr&vxp=mtr

Are these the good ones that will make my brakes better. Will they fit my ko?

They will fit the K0 caliper, although you may find that the little screw nub on the fixed pad needs to be either filed down a bit (might be too tall) or if it is a screw, you can pull the one out of your K0 puck and install it instead.

It would be real interesting to see these in real life: maybe I'll get a set?

RRRToolSolutions · « **Reply #24 on:** January 15, 2016, 10:26:03 PM »

I would prefer the Bronze sintered ones, I'm not sure what metal these have.

Friction and braking come from the pad material "biting" on the rotor - that would mean more wear and tear on the rotor. This seller states the opposite. I ran Bronze sintered pads on my 750 Kaw turbo and those made a huge difference in stopping power. I'm going to find me some vintage Bronze style pads and I'll report the progress.

Thanks Mark, All - I appreciate the inputs.

Regards, Gordon

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Author Topic: Front Disc Performance Improvements - Bad Brakes (Read 12147 times)