Author Topic: 750 dual disc vs. 550 dual disc  (Read 5113 times)

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Offline scottly

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Re: 750 dual disc vs. 550 dual disc
« Reply #25 on: April 01, 2015, 07:34:32 PM »
There is only about .002" difference between 5/16' and 8mm. The holes in the rotor hubs and the wheel hub are a sloppy fit with the 8mm bolts, and .002" won't make any difference. The main issue is that the heads of the bolts are thin enough to clear the speedo drive housing.
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Re: 750 dual disc vs. 550 dual disc
« Reply #26 on: April 01, 2015, 08:45:19 PM »
There is only about .002" difference between 5/16' and 8mm. The holes in the rotor hubs and the wheel hub are a sloppy fit with the 8mm bolts, and .002" won't make any difference. The main issue is that the heads of the bolts are thin enough to clear the speedo drive housing.


thank you sir. I noticed the bolt heads were close too, but look like they have enough clearance. I have a K0 speedo drive to use
on a k5. I did notice the chrome drive cover will not fit when a second disc is fitted, but all else looks good.

Offline jdenz

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Re: 750 dual disc vs. 550 dual disc
« Reply #27 on: April 21, 2015, 08:11:51 PM »
Hi Guys,

I know this might sound like a stupid question, but can anyone tell me where the front brake disc should be on a cb750k6. on the left or right side of the wheel? when i got the bike it was on the right ( looking over the handle bar). but Ive been looking around at pictures and i see most are on the left side ( looking at over the bars).
Thank you

Offline seanbarney41

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Re: 750 dual disc vs. 550 dual disc
« Reply #28 on: April 21, 2015, 08:33:55 PM »
yes. stock is on left
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Offline jdenz

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Re: 750 dual disc vs. 550 dual disc
« Reply #29 on: April 22, 2015, 06:55:09 PM »
Thank you sean,

Should I move it back to the left or leave it as it is? I have new tires on and I guess if I swapped the brake disc I would have to rotate the tire. Is that correct? what would you do?
Thank you
Denis

Offline seanbarney41

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Re: 750 dual disc vs. 550 dual disc
« Reply #30 on: April 22, 2015, 06:59:05 PM »
Does everything work alright?...I can think of all kinds of wrong possibilities, but need pics.
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Offline SOHC Digger

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Re: 750 dual disc vs. 550 dual disc
« Reply #31 on: August 18, 2015, 09:42:34 AM »
For you guys who had your rotors thinned, what was the final thickness? I am mounting 750K wheels on my 78 750F and want to use the F brakes. The 550 rotors have the same diameter, but are 7mm thick compared to the 750F rotors which are 5mm.

Offline 754

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Re: 750 dual disc vs. 550 dual disc
« Reply #32 on: August 18, 2015, 09:52:14 AM »
IMO the brake looks better on the right,  and you can runaway shorter straighter braided line for cleaner looks (if you can live without brakelight switch)
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Offline flybox1

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Re: 750 dual disc vs. 550 dual disc
« Reply #33 on: August 18, 2015, 09:55:20 AM »
For you guys who had your rotors thinned, what was the final thickness? I am mounting 750K wheels on my 78 750F and want to use the F brakes. The 550 rotors have the same diameter, but are 7mm thick compared to the 750F rotors which are 5mm.
Mine are from Godfferey @ 4mm.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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Offline Retro Rocket

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Re: 750 dual disc vs. 550 dual disc
« Reply #34 on: August 18, 2015, 04:13:35 PM »
My personal opinion on weight and brakes is I would rather have the added benefit of the safety in braking performance than the loss of handling performance I may not even notice in the weight savings of a few parts.

This says it all ^^. You will only notice the added weight, if any, at the absolute top end of the handling spectrum, {how many ever get there..?}, on the other hand, you'll notice the benefit of better brakes every time you ride... ;)
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Offline Cabilao

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Re: 750 dual disc vs. 550 dual disc
« Reply #35 on: August 18, 2015, 07:04:38 PM »
Im very happy with mine,awesome stopping power with an aftermarket MC from DS. And all factory made by Honda ;D
« Last Edit: August 18, 2015, 07:06:13 PM by Cabilao »
before:
Kreidler RMC(50cc)
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XS850(great bike)
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FZR1000(too fast)
Rickman CR900(sold for a good price)
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Rusi 125
CB 125 CL(just for fun)
Yamaha XTZ 125
CB750P7(mystery bike)
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Offline scottly

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Re: 750 dual disc vs. 550 dual disc
« Reply #36 on: August 18, 2015, 07:55:17 PM »
For you guys who had your rotors thinned, what was the final thickness? I am mounting 750K wheels on my 78 750F and want to use the F brakes. The 550 rotors have the same diameter, but are 7mm thick compared to the 750F rotors which are 5mm.
Digger, thinned 550 rotors are probably your best option for fitting 6 bolt wheel hubs to the factory dual disc F3 fork. Before you have rotors ground, check the offset compared to either a 550 rotor or a 750K rotor. If the offset is different, it may possibly be corrected during the thinning process?
Mick, the Yami rotors I'm running are about 4 pounds lighter than stock 750 rotors. That's four pounds of flywheel mass, as well as four pounds of un-sprung weight. You can have your cake and eat it, too. ;D
Don't fix it if it ain't broke!
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Offline SOHC Digger

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Re: 750 dual disc vs. 550 dual disc
« Reply #37 on: August 18, 2015, 07:55:51 PM »
Im very happy with mine,awesome stopping power with an aftermarket MC from DS. And all factory made by Honda ;D

What hub are you running? Those look like the 5-bolt discs I have on my 750F.

Offline SOHC Digger

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Re: 750 dual disc vs. 550 dual disc
« Reply #38 on: August 18, 2015, 08:00:07 PM »
Digger, thinned 550 rotors are probably your best option for fitting 6 bolt wheel hubs to the factory dual disc F3 fork. Before you have rotors ground, check the offset compared to either a 550 rotor or a 750K rotor. If the offset is different, it may possibly be corrected during the thinning process.

That's what I was thinking. I already have one rotor and I've pm'd a member selling another. I know they will sit closer to the center of the wheel than the stock ones did, so I would try and get them thinned out more on the inside so I don't have to shim the caliper bracket so much. But I'm curious what setup Cabilao has here. It looks like the 5-bolt discs but I've never seen a 5-bolt spoke hub.

Offline 754

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Re: 750 dual disc vs. 550 dual disc
« Reply #39 on: August 18, 2015, 08:56:15 PM »
It's the elusive 5 bolt wire wheel came on an F Fork. Rare..his is a cop bike.
I at one time offered to make some, but not enough  interest.
 I helped a member on here put bigger redrilled floaters..maybe VFR..calipers, onto a six bolt hub...the calibers were mounted to an F Fork.... Think I have an extra set of caliper mounts for that..If I can find them..
Maker of the WELDLESS 750 Frame Kit
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Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Lostboy Steve

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Re: 750 dual disc vs. 550 dual disc
« Reply #40 on: August 19, 2015, 05:31:44 AM »
Has anyone done a dual disc conversion where they banjo bolted a line off of one caliper over to the other like on newer bikes? or do you always split it off the switch?

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Offline Rookster

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Re: 750 dual disc vs. 550 dual disc
« Reply #41 on: August 19, 2015, 08:36:50 AM »
MCRider has done that on his build.  It looks good but I would think it would be hard to bleed unless you were pushing fluid through the bleeder screws up to the master cylinder.  Even then if you get a bubble stuck in that looped line it will be hard to dislodge without unbolting the caliper and straightening the line.

Scott

Offline 754

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Re: 750 dual disc vs. 550 dual disc
« Reply #42 on: August 19, 2015, 08:41:01 AM »
I don't like the line looped over the top,  two lines routed the same looks more balanced.
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Lostboy Steve

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Re: 750 dual disc vs. 550 dual disc
« Reply #43 on: August 19, 2015, 10:34:18 AM »
Ah, fair enough. Just thought Id ask.
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Offline Loctite77

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Re: 750 dual disc vs. 550 dual disc
« Reply #44 on: June 20, 2016, 05:40:42 AM »
Resurrecting this old thread to ask... What about stacking two banjo bolts on top of each other at the master cylinder?


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