Topic: 72 750 front disc upgrade not helping

[gmet]

Hi all,
I restored my 72 750 and went with a drilled cast iron front disc from a firm in Australia, I had the disc machined down slightly so I could use it with my oem caliper setup.  This was said to be a great upgrade from the stock chromed disc. Anyway I rebuilt my original master cylinder and installed SS hoses where I could.  Everything is fully bled and the lever is firm. Also went with the orange colored EBC "soft" pucks.  The stopping power is horrible, I've had better results with an old single action front drum brake! Am I missing something? This is worse then stock.
Thanks.

[robvangulik]

Maybe try other brakepads?

[MauiK3]

Agreed, try OEM pads.

[CycleRanger]

Howdy! Welcome! 

[dave500]

i have a cast disc aswell,i used a smaller bore master and it stops really well,it gets better when its hot.

[BenelliSEI]

Agreed, try OEM pads.

+2. Will be interested to hear if there is improvement. I was about to try one!

[gmet]

So I originally tried the oem pucks and it was worse. What master cylinder did you use with a smaller bore that improved your braking? Anyone gone with somthing from the 80"s or 90's?

[Shtonecb500]

you said you restored this bike, do you have experience riding it prior to the restoration or is this your first experience with the 750?

[newday777]

Hi all,
I restored my 72 750 and went with a drilled cast iron front disc from a firm in Australia, I had the disc machined down slightly so I could use it with my oem caliper setup.  This was said to be a great upgrade from the stock chromed disc. Anyway I rebuilt my original master cylinder and installed SS hoses where I could.  Everything is fully bled and the lever is firm. Also went with the orange colored EBC "soft" pucks.  The stopping power is horrible, I've had better results with an old single action front drum brake! Am I missing something? This is worse then stock.
Thanks.

Welcome aboard the forum.
I'm interested in the results you end up with. Been thinking of ordering one of those cast iron discs.

As you are new here, go to the new members introduction section and introduce yourself and your history with your bike so all can see it and know what you have done with it since you got it. And as was asked how much you have riden it before this swap of the disc is important information.

[fizzlebottom]

With any new brake pad or rotor, you need to bed the pads in to the rotors: essentially breaking in brakes. If you expecting the highest performing parts right out of the box then you'll be surely disappointed.

[Doobie]

For anyone interested in a new rotor, take a look at the EBC Pro-lite, stainless steel and floating. https://www.amazon.com/dp/B0073DV9L6/?coliid=I29ITVM6EEWJYB&colid=8XQ3V5TXE3YB&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

[grcamna2]

Going from the stock OEM Honda SS rotor to a cast iron rotor is Always an upgrade.
The problem is not the rotor but something else.

[Don R]

 Be sure to follow the bedding in instructions with new pads and check the contact area to be sure the entire pad is contacting the rotor. The removal of asbestos hasn't always helped with pad material.

[gmet]

Thanks for the replies and the welcome that you have sent me. I have had 4 cb 350s a CB 500 four, and 2- 72 CB 750s over the past forty years. I did the cast iron rotor swap after reading about the upgrade on here four years ago.  I bought this 72 and sent the motor to a friend of mine Bob Moschinske who is now in TN, he did all the motor work while I laced up new rims, did the frame work, upgraded all bearings and bushings, electrical etc..
Bike runs great but the rear drum stops harder then the disc. It feels like the pucks are made of wood.  I'll try going back to an oem set and see if that helps, I'll also inspect the EBC units and see how they are wearing across the surface.
I will also go the  introduction page.
Thanks

[bryanj]

I put a cast iron one on a 500 many years ago and the only extra thing it did was lock in the wet which was not desirble, went to twin discs with gl1000 master and it stoppef super well

[grcamna2]

Thanks for the replies and the welcome that you have sent me. I have had 4 cb 350s a CB 500 four, and 2- 72 CB 750s over the past forty years. I did the cast iron rotor swap after reading about the upgrade on here four years ago.  I bought this 72 and sent the motor to a friend of mine Bob Moschinske who is now in TN, he did all the motor work while I laced up new rims, did the frame work, upgraded all bearings and bushings, electrical etc..
Bike runs great but the rear drum stops harder then the disc. It feels like the pucks are made of wood.  I'll try going back to an oem set and see if that helps, I'll also inspect the EBC units and see how they are wearing across the surface.
I will also go the  introduction page.
Thanks

Have you considered locating a set of Ferodo brake pads ?  I like them Much better than EBC's

[fizzlebottom]

Bike runs great but the rear drum stops harder then the disc. It feels like the pucks are made of wood.  I'll try going back to an oem set and see if that helps, I'll also inspect the EBC units and see how they are wearing across the surface.
Thanks

You still haven't mentioned whether you bedded the pads to the rotors. Confirm that before replacing anymore parts. It is a crucial step when replacing either rotor or pads.

[gmet]

I m not sure what you mean by "bedding the pads into the rotor" ? I have done a fair amount of slow steady braking to seat them a bit.  Please tell me more or direct me to the info.
Thanks, any info is a help

[calj737]

The issue is the master cylinder, not the pads, not the rotors, not the bedding process. When you swap from a single to dual caliper, the master cylinder needs to be appropriately sized for the proportioning. Dave500 gave you the hint: swap to a smaller bored master and the feel and stopping will improve immediately.

[gmet]

Im running a single caliper but I do understand the concept of a smaller bore MC so as to increase the pressure of the fluid delivered to the caliper. I was wondering if there was a common MC folks are using to achieve this.
Thanks and I agree with your response

[robvangulik]

Im running a single caliper but I do understand the concept of a smaller bore MC so as to increase the pressure of the fluid delivered to the caliper. I was wondering if there was a common MC folks are using to achieve this.
Thanks and I agree with your response

CBR600f

[MauiK3]

When I added the second disc to my K3 750 I kept the stock MC, I think they are 12mm. I read reviews that jumping up to a 14mm MC makes it feel “wooden”. My stock MC has a little more stroke but works great.
In your case, make sure your MC is stock size, not bigger.
If you came to this bike from a more modern bike you will likely never like the brake.

[calj737]

Im running a single caliper but I do understand the concept of a smaller bore MC so as to increase the pressure of the fluid delivered to the caliper. I was wondering if there was a common MC folks are using to achieve this.
Thanks and I agree with your response

Apologies, wrong response to wrong thread. Had a “dual disc upgrade” thread in my mind.

[gmet]

Robvangulik  thanks for the CBR 600 tip, I'll look into that.  Ive owned a bunch of single disc CB's over the years so I know how they should stop and this isnt even to that point so somthing is amiss, I'll check some different pads and look into the CBR MC.
Thanks guys!

[scottly]

When I added the second disc to my K3 750 I kept the stock MC, I think they are 12mm.

The stock MC is 14mm.