Author Topic: Rear disc convention cb750 k  (Read 13392 times)

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Offline bluemouse1006

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Rear disc convention cb750 k
« on: July 05, 2012, 10:38:02 am »
Hi
I'm new to this forum but have been a member on the UK one for ages
I'm looking at doing a rear disc conversion on my CB 750 k5 , I have the rear swinging arm ,wheel ( comstar) rear brake master and slave etc . Looks like I will have to cut off the pillion peg bracket and the rear brake tube on the frame so that the alloy brackets from the F 2 can fit .
Anyone had any experience of doing this ? No one on the UK site has done it !!!
Any advice photos etc would help

Thanks Amos

Offline Don R

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Re: Rear disc convention cb750 k
« Reply #1 on: July 05, 2012, 02:15:55 pm »
I had thought of welding the needed frame sections from the F1 onto  the K frame. Instead I bought another F that wasn't wrecked.
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Offline Duke McDukiedook

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Re: Rear disc convention cb750 k
« Reply #2 on: July 05, 2012, 02:19:41 pm »
Sounds like an awful amount of work to convert to disc to me IMHO.
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Offline MCRider

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Re: Rear disc convention cb750 k
« Reply #3 on: July 05, 2012, 03:10:26 pm »
Sounds like an awful amount of work to convert to disc to me IMHO.
Agreed too much work for 10-20% of your braking. Money better spent fixing the drum, (arcing) and upgrading the fronts and the suspension.

Sorry to throw cold water. It would look cool.
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Offline Roach Carver

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Re: Rear disc convention cb750 k
« Reply #4 on: July 05, 2012, 06:18:04 pm »
I.have a bike this was done to. The passenger pegs are removed. F2 brackets will replace passenger pegs. Brake tube has to be ground back but can remain. Will have to weld a bracket for the brake fluid resevoir. Also the driver pegs are different for the f. You will need them also.

Offline MRieck

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Re: Rear disc convention cb750 k
« Reply #5 on: July 05, 2012, 06:37:02 pm »
If I went through all that I'd at least use Brembo stuff. ;D
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Offline Rookster

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Re: Rear disc convention cb750 k
« Reply #6 on: July 05, 2012, 08:06:21 pm »
Hallcraft offered a drum to disk conversion in the 70s using a Hurst Airheart caliper and master cylinder.  Look at how the master cylinder is mounted.  Seems pretty easy to replicate with some flat stock.  There is a ton of room behind the right passenger triangle for a master cylinder.  I agree with Mike.  If your going to a disk rear why use the F parts when you can upgrade to much better components.



Scott

Offline bluemouse1006

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Re: Rear disc convention cb750 k
« Reply #7 on: July 06, 2012, 12:47:22 pm »
Thanks for the replys
I have all the foot pegs etc and am happy some one else out there has one done,I thought that I would have to cut the brake tube a bit . Can I leave the pillion brackets in place or do I need to cut them off as well ..

The last photos look great but as I have all the bits I'll be using them ,with a rear comstar disc wheel included ..

Any photos with this conversion done would be much appreciated

Thanks again

Amos

Offline MCRider

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Re: Rear disc convention cb750 k
« Reply #8 on: July 06, 2012, 12:52:18 pm »
Hallcraft offered a drum to disk conversion in the 70s using a Hurst Airheart caliper and master cylinder.  Look at how the master cylinder is mounted.  Seems pretty easy to replicate with some flat stock.  There is a ton of room behind the right passenger triangle for a master cylinder.  I agree with Mike.  If your going to a disk rear why use the F parts when you can upgrade to much better components.



Scott
Somewhere on this dusty old planet there is a box never opened, with that kit in it. Somebody bot it for their baby but life got in the way and it was never installed.  Sigh   :'(  The bike it was intended for, low mileage, may be parked nearby.
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Offline Really?

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Re: Rear disc convention cb750 k
« Reply #9 on: July 06, 2012, 02:08:52 pm »
Scroll down the page a bit - http://www.cyclexchange.net/Wheel%20Page.htm

I don't have a motorcycle, sold it ('85 Yamaha Venture Royale).  Haven't had a CB750 for over 40 years.

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Re: Rear disc convention cb750 k
« Reply #10 on: July 06, 2012, 04:01:15 pm »
I was tempted to go the Cycle X route but man that's expensive and I'd rather spend the coin on a dual AP caliper front set up.
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Offline bluemouse1006

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Re: Rear disc convention cb750 k
« Reply #11 on: July 07, 2012, 09:42:53 am »
Flip that looks good but expensive !!! If I had the cash to splash that would be the way to go
Amos

Offline SoyBoySigh

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Re: Rear disc convention cb750 k
« Reply #12 on: April 22, 2015, 12:36:38 pm »
As for welding stuff on, I've got some SOHC 'K type passenger peg brackets which I scored from a guy doing a hard-tail chop - I'm planning to weld 'em onto my DOHC 'F, I have a CB900F right now that I wanna stuff into my old 750 frame (for the hard engine mounts vs the 900's heavier rubber mount system) and I'll probably only do it after doing all of the recommended frame bracing, close up the loop on the right hand side, all of that stuff. But THEN I wanna weld on the passenger peg brackets from the SOHC, then add some steel plate rear-set mounts to the space just below 'em.

Incidentally, there are some nice splined pivot lugs similar to the Tarozzi linkage system, available from the VF Interceptor series. Check out their brake pedals, the pivot shaft is on the pedal and the lug fits on the inside. I know they fit the GL1200 pedal spline, so I figure they'll probably fit the DOHC CB750K sport-kit version that I'm sticking on the 900 here. The U.K. spec Sport-Kit rear-sets for the CB750K, the brackets have the most rear-ward located pedal pivot. But I suppose that doesn't matter if you use the linkages. TONS of ways to fudge together the 'F type alloy brackets. Meanwhile my 900 sports some DIY plate rear-sets with Tarozzi non-folding pegs which the P.O. fitted. The master cylinder is stuck to a thin hunk of angle Iron which is welded to the frame. Very crappy weld, but it's welded. Sucks that he ground off the right-hand side third bolt hole (the one just behind the frame rail) 'cause it means I'll have to weld something back ON in order to properly mount the brackets I'm gonna use. It's all such a hassle, I figure it's worth welding a couple of solid lugs back there, or a drilled plate etc, and mount the rider pegs to another small alloy plate like the P.O. did (only not with the swinger pivot bolt & engine mount bolt running through it 'cause that's just butt-fugly, if you've got another option!) Just a simple plate or angle-iron mount, or a triangulation of three lugs to hold a plate in all three axes - And as for the PASSENGER pegs, I'm thinking a couple of lugs somewhere up the subframe for some CBR type passenger peg hangers. Heck you could store 'em with your spare helmet ha-ha. I'd probably keep 'em on the bike. I PREFER to keep the pillion available for any sexy hitchhikers I meet along the side of the road. Ha-ha.

I'm on a lot of painkillers, and people would have to be NUTS to jump on the back of my bike. (Back surgery that went awry....) But I wanna pass the bike down to my teenaged Ex-Daughter, and let her haul her friends around for passengers. So for that reason alone, or heck somebody could wind up driving ME around back there, I dunno - I'm restoring the passenger pegs to this bike!

And what a hassle, after what the P.O. did. Cut down the swinger pivot and engine bolts, but not short enough to run the bike without the DIY peg plates, AND not long enough to run the rear-set plates either! BAH. So with the CB900F's rubber-mount engine which uses thinner bolts than the CB750F, I think I can use bolts from a CB750C or CB750KZ or some such. The U.K. CB750K sport-kit rear-set brackets I scored use the smaller hole size. Too small for the CB750F bolts I've got, so I guess that makes 'em appropriate to the 900 - but yeah, if I'm gonna use these through-bolts I'll have to mill the plates down a lot thinner, which will weaken 'em, OR find some bolts to match this. Or longer bolts AND have 'em cut down & threaded. Ugh. If I'm gonna run 'em without any plates at all - which I'd much prefer to be honest, 'cause I feel that the alloy plates block a rather lovely area of the chassis which really shows off the bike's SOHC heritage - Then I'm gonna have to figure out which of the non-sport-kit CB750K or CB750C bolts would fit.

Of all the DOHC frames, I'd much rather screw around with the CB750C or North American CB750K versions, with the integral steel triangular passenger peg mounts. I'd just drill the hell out of 'em - reinforce 'em with an over-laid plate if needed, maybe a hollow steel tube to brace the pivot point - and use 'em for the rider pegs. As for passenger pegs, I'd wanna mount something else back there, a stand-off so the passenger pegs are ALSO rear-set. That way they don't bump your feet and screw up a panic stop or some other vital foot movement.

When I got back surgery, my left leg was pretty much numb to sensation up to the knee & beyond. Oh, it still had massive PAIN, like a phantom limb pain from the crushed spinal cord etc. But as for feeling what my toes were doing, I couldn't feel #$%*. You know how your doctor will drag a paper clip down the length of the sole of your foot? Yeah - nothing. At one point I was working at this aqua-culture research station, in the summer after my surgery, and I was in the water a lot so it wasn't so hard on my back. But yeah at one point my glasses fell off in the water, so I grabbed a long clear hose hooked up to a tank of welding oxygen and clenched it between my teeth, put a good sized rock into an aluminum boat, and made myself sink really far down. It's a good thing I brought the oxygen hose, even though when I unclenched my teeth it blew my lungs up like a balloon to the point of bursting and I lost grip of the hose - but that one breath of pure oxygen definitely saved my life. 'Cause way down at the bottom of the fish-farm dug-out (about the size of two city blocks, straight steep walls down to 20-30ft, etc) there were some remains of a wooden retaining fence of some sort. I got my leg tangled in some barbed wire which cut so deep it took a couple of years to heal properly, and apparently I got a nail-head caught on either my big toe or my heel, and dragged it through the sole of my foot from one end to the other, I know it must've been a nail-head 'cause it cut a T-shaped channel the whole way along, and left a lot of rust along the way. So yeah, I tore myself free of all that #$%* by kicking & feeling behind myself to untangle the wire, got back to the surface, stepped up into the truck, whereupon my co-worker asked me WTF all of the blood was from. I was like "Huh?" Yeah - my lower leg was NUMB. At least, to external stimuli.

The reason I mention it, is this was right around the time I moved up to the 1982 CB750F - How in the hell was I supposed to switch gears?

I took a heel-toe gear changer from my old C70 Passport "Underbone" scooter, and popped it onto the 750's gear-shift spline. This way I could bounce my foot up and down on either the front toe lever or the rear heel lever. No need to fudge around and squint at my left shoe while riding. Made it easier to ride around in flip-flops too, which matched with my outfit when I rode around naked in the middle of the night, pushing the newly rebuilt 750 past it's limits, in some deranged belief that if I went fast enough then the pain in my back wouldn't be able to reach to my brain. What with all the new meds in my system, I was totally unable to elicit a flow of adrenaline, and my life had basically taken a turn for the worse let's just say, so there was some kind of subliminal death-wish #$%* going on. Nevertheless, I remained a very proficient technical rider.

I parked the bike for more than ten years there, once it occurred to me that I could wind up hurting somebody ELSE - but it wasn't so much about the drugs as it was about my head-space. I'm still on a lot of narcotics, a hell of a lot more than back then. But I've taken the 900 out for a few spins and my technical riding ability is still there after all these years. Even if most of the muscle tone is gone. Provided I don't take all of the crap that I take at bed-time, to deliberately knock myself unconscious, so long as I'm only taking short-acting pain-killers with a known half-life & perfectly predictable effects (and stay away from all of the "-Contin" formulations which are useless mass-marketed crap in the first place) then I shouldn't succumb to some type of Narcoleptic or rather, NARCO-leptic fit - and there's nothing to freak out about. So long as I don't jump up in the middle of the night and ride the bike in my underwear, it's pretty unlikely I'll be riding with the really bad #$%* in my system. And of course I'll have to face all sorts of tests over and above what the typical driver/rider faces. A buddy of mine (R.I.P.) who was a chronic pain patient, had all sorts of B.S. from his insurance company about this stuff - in the end the only caveat was that he had to have custom pedals made to accommodate his peg-leg. Which was the insurance company trying to throw a wrench in the works, 'cause they knew he shared the truck with his wife, that they switched off when she worked nights at the post office. They figured it would be impossible, that he'd have to give it up. But a genius who worked on this prosthesis & stuff like that, built him this really trick system which was a plate that popped in and out of the space under the pedals, took five seconds to switch back & forth, which moved the gas pedal to the other side. Ridiculous really, they were telling a one-legged guy that he had to have the pedal on the other side so that his dominant leg had the gas on the outside edge and the brake pedal opposite that. As though he hadn't already adapted his driving style when driving with his prosthesis off to get some air on his stump etc. Or driving during the six month stretches when he couldn't wear his prosthesis for one reason or another. It was complete bull#$%*. But yeah, as for the drugs that had him practically drooling, had him talking around in circles, had him typing incessantly on internet forums - there was no effect on his reaction time. Kinda like that episode of "WKRP in Cincinnati" - where "Doctor Johnny Fever" agrees to do a public service announcement for drunk driving awareness, and his reaction time got better & better with each drink he took. Pretty irresponsible television. Probably held the vehicular-homicide rates up in the red-line for another decade at least, considering how long that show lasted in the re-runs....

So on the one hand, the bike's not gonna see everyday use, it's gonna be used on days when I'm feeling well enough to take less pills. My "light days" as I like to put it. When I'm using the thinner panty-liners. Otherwise, if I'm forced to take less and suffer through worse pain, I'll be prompted to ride twice as fast in order to get it over with faster. But it'll improve things immeasurably.

When I went for a follow up with my surgeon, I wasn't able to travel in the car without puking 'cause the lateral movements caused so much pain it made me that nauseous. I even tried laying down on a futon in the back of a van, and wound up rolling side-to-side. So we were running out of time, not only was it a six month waiting list and $500 penalty for missing an appointment, my surgeon was about to retire. (Though I guess it was his STUDENT ASSISTANT'S fault that somebody's cigarette butt fell into my spinal cord - they had to reef on my spinal cord & stretch it with some #$%*ing kitchen tongs or some such #$%* - I didn't find out about this until several years later, when functioning as a courier to deliver my files to a specialist aka a specialist's appointment - when I opened my file and read it - Meanwhile the surgeon and later on the pain specialists, would lay their hands on my shoulder or upper arm, look me in the eyes and very slowly say "You're going to get all better now. No more pain." See - this is what you call a "psychosomatic wellness". If it's possible to have a psychosomatic ILLNESS, then it must also be technically feasible to have a psychosomatic WELLNESS. Yes? "Free your mind and your ass will follow" as they say. Apparently not for me. But what must it be like, for your body to be spasming all over the place, doing all sorts of damage to itself when you push past the reasonable limits set by normal pain responses, #$%* just not working like it's supposed to, but you've got some type of half-cracked smile on your face as you repeat "All better now... No more pain...." It's #$%*ing mental. I mean, you can't even SUE these people up here, so it's not like there's some ulterior motive. Well, other than the cut-backs they did right around when I got hurt, when 3/4 of the neuro-surgeons who did my procedure promptly packed their bags & moved South of the border. Other than THAT subtle cash-grab, which was meted out to the oil companies who paid no royalties let alone penalties for all the smoke they're belching out of the tar-sands......

COUGH - yes. As I was saying. The BIKE - Yeah I wasn't able to travel as a passenger in a car, couldn't lay down in the back of a van. And the appointment was looming. So I got the missus to turn the car around and head back home. I took a few minutes to flip my superbike bar upside down and reverse the throttle & switch pots to suit the new Clubman-esque ergonomics, bent over the seat & tank laying flat as I got the missus to help throw my leg over the side of the bike, and stuck my feet up onto the passenger pegs.

I made the 250km+ journey in something like one hour. Made it to the appointment on time. What did they say when they saw me hobble in with a helmet in hand? "Ah - he's back on the bike! What a miraculous recovery!" Ha-ha. Gotta wonder if that's something to do with why they hung me out to dry. Pissed the guy off in the initial consultation, shook hands with him and when he asked what's wrong I said "Well my chiropractor sez....." This was the only word I got in edgewise prior to my surgery. Right before I went under the gas (six-seven months later, would've been more than a year if it wasn't slated as "emergency surgery" - that's how bad the artificial/deliberate healthcare cut-backs screwed SOME of us here in Alberta!) right before going under I said "What do you mean, gas? I didn't know I had to go under for this procedure!" He gets all nervous he looks at the rest of the crew and says "Now now, we talked all about this during our consultation...." Uh - NO. He spent the entire hour ranting and raving about the Chiropractors about what a bunch of #$%*ing quacks they are. Not like I was arguing with the man, I mean how the #$%* did I GET to that state in the first place? From people crunching my bones and sending me back out into the fray! Don't get me wrong, I got ten more years of walking like a normal person thanks to the bone crunchers. The one guy cancelled an entire day's worth of appointments just to keep hammering away on my back trying to get things back into place. After a high-school gym class "accident" which would've been a ridiculous windfall lawsuit if I'd actually seen a proper doctor and been apprised of the damage done. Ah, but I was too much of a hippie granola-head, vegetarian/vagitarian, didn't TRUST "Western Medicine".... But yeah, it's entirely possible that I pissed off the surgeon.

Truly though, if there's ever been a misinterpretation of a guy getting "back on the bike" - I mean, that day the 750 was more like a rocket powered hospital gurney than a proper motorcycle. Mostly navigated by memory while tracking my progress from viewing the white line to the right and the yellow line to my left of my field of vision. It's a good thing there are only so many turns on that highway, that I might've got 'em confused with one another and sailed into the ditch. Probably would've drowned if I'd landed in a lake, that's how #$%*ed up I was. IIRC there were points along the way where my sense of SMELL told me when I was passing through which crops being grown, to help me predict when the town of Clairesholm was coming up by the whiff of the huge pig farm to the South of it.....

You'd THINK it would be more sensible to adopt a more laid-back chopper-esque seating position with a back-rest & some "forward controls" etc. But THAT'S precisely the type of thing that will screw up your back. The tendency is to SLOUCH which gets worse & worse with longer distances. Far better to forgoe the BACK rest & create a "CHEST-REST" IMHO - & as such, I've been committed from that first uneventful yet dangerous trip, to create my "handi-bike" in the vein of a proper café/endurance-racer. For COMFORT'S sake. No joke though, it's gonna need support on top of the tank, rather than just hovering there perched on one's crotch & one's wrists in that well known masochistic yoga pose in repose. I mean, the booze-belly & the man-boobies are gonna help the situation, but there's still gonna have to be a proper pillow in the gap.

Ever see pics of those older Italian 50cc & 125cc endurance racers? The ones they raced up in the mountains on - some of 'em have a huge leather wrapped PILLOW on top of the tank. I guess they'd have used bigger tanks but those bikes really sipped the fuel slow so they didn't need it. Would've been heavier besides. But yeah, only in later years, on bigger bikes, did they fill in that gap with a bigger gas tank. Like this here CB1100R alloy tank, that I've polished up for my "CB900K0 Bol Bomber", the '82 CB900F Bol D'Or homage to the '65 CB450K0 Black Bomber - I've got a bit of a beer gut going, but figure I'll still add some type of tank bag ... hmmm without magnets this time though, 'cause the tank's not made of steel! Hmmm ... maybe epoxy on some rare-earth magnets? Dunno - Some type of tank bag full of clean underwear, just drop my chest right onto the pillow & take the weight right off my waist altogether.

Gotta bubble fairing here, re-pop of the Duck 900SS bubble. Gonna have to fit that really carefully, if my helmet's gonna be on the tank I don't wanna get my head stuck under the wind-screen!

Yanno what would be better though, far better than a tank bag: A "CB902" homage to the CB92 Benly Super-Sport, with the knee pads that reach up and around (reach-around?) the back of the tank to merge becoming a BELLY-PAD - then I'd need a Tony Foale leading-link fork like he used to make for the CB900F it's very own self - no question it would work. And then a faux-drum front brake, with GL1500 & PC800 parts, discs wrapped under shrouds like the CBX550F hub only bigger. A "CB902" with a CB1100R tail section/seat/cowl/side-cover but one that fits really tight to the frame with a down-turned rear fender, skirted even - to make the subframe of the bike look like a pressed-steel frame of a '60s Honda twin! OHHH yeah. Now THAT would be one hell of a bike. A CB92 scaled up for somebody who's not 16yrs-old anymore.....

Okay so I'm sorry for going off on a tangent. But it just goes to show that there's a whole RANGE of things you might wanna do with rear-sets. You might laugh at the kids who use the passenger pegs but there are practical reasons for that stuff. Like if you're half dead and need to lie down flat on the bike like you're Ollie Free or something. Might even be sensible to put STIRRUPS on the pegs to keep a gamey leg from falling off & getting chewed up in the chain. I could even see FLOOR-BOARDS I mean WTF. Definitely on a cruiser. Maybe even on a sportbike too.

-Sigh.

JWExperience

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Re: Rear disc convention cb750 k
« Reply #13 on: April 22, 2015, 12:56:45 pm »
WOW! That was like some Will Farrell blackout #$%* on steroids and meth.

Offline madmtnmotors

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Re: Rear disc convention cb750 k
« Reply #14 on: April 22, 2015, 02:26:44 pm »
A "vagitarian"? Gonna be difficult to forget that!
TAMTF...


Wilbur



Projects:
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Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

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Offline calj737

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Re: Rear disc convention cb750 k
« Reply #15 on: April 22, 2015, 02:32:57 pm »
Needs to change his avatar to Stephen King. And people accuse me of being verbose! Any Cliff notes for that last post?
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'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline Retro Rocket

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Re: Rear disc convention cb750 k
« Reply #16 on: April 22, 2015, 05:00:20 pm »
All his posts are this long, :o  I want some of what he's smoking, but with the verbal diarrhea part removed.... ;D
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
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Offline RainCityRider

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Re: Rear disc convention cb750 k
« Reply #17 on: September 07, 2017, 06:00:29 pm »
So I too am putting a rear disc on a cb750 K8 and need a little beta on mounting the master cylinder and reservoir as well as the brake linkage (how I actuate the master cylinder.
78 CB750K
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Offline Rookster

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Re: Rear disc convention cb750 k
« Reply #18 on: September 07, 2017, 06:29:02 pm »




I am using the stock spindle with a custom brake rod to actuate the pull master cylinder.  The master cylinder is mounted on a bracket on the inside of the rear peg mount and one of the rear set brackets.

Scott

Offline slikwilli420

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Re: Rear disc convention cb750 k
« Reply #19 on: September 07, 2017, 06:38:26 pm »
Ask yourself why you are doing it. If for a period racer look use stock parts of the period. If for actual performance gain, switch the hub to something much lighter than an F hub, use a small disc and light caliper. That would be a useful mod because you are reducing unsprung weight on the rear making it more compliant for spirited riding. Switching from one braking type to another with no weight loss is money foolishly spent in my eyes.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline HondaMan

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Re: Rear disc convention cb750 k
« Reply #20 on: September 07, 2017, 06:44:29 pm »
Ask yourself why you are doing it.

...what he said...the rear discs all drag a bit, making for lost HP. They also weigh a bunch, causing the same thing. And, I have never seen the rear drum brake fade from heat, even when I raced. Begs the question?
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Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

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Offline JBCB500

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Re: Rear disc convention cb750 k
« Reply #21 on: September 07, 2017, 09:53:38 pm »
I thought this solution looked pretty straightforward (page 11).  http://forums.sohc4.net/index.php/topic,115305.250.html

I'm planning to do the same.

Offline scottly

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Re: Rear disc convention cb750 k
« Reply #22 on: September 07, 2017, 10:06:30 pm »
Drum brakes have at least one, and sometimes as many as four, self-energizing, or leading, brake shoes. Self-energizing means as soon as the shoe contacts the drum, it is pulled into tighter contact with the drum without additional pressure from the brake lever/pedal, which can lead to a sudden lock-up of the wheel. Disc brakes do not have this action; braking force is proportional to the pressure applied to the lever/pedal.
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Offline Rookster

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Re: Rear disc convention cb750 k
« Reply #23 on: September 08, 2017, 09:37:14 am »
Another consideration is with rearsets the leverage available to actuate the shoes is greatly reduced.  The stock brake pedal is long and gives the rider a real leverage advantage.  With rearsets there is no way to make up the difference in leverage with a shorter pedal unless you elongated the brake arm.  With the disc conversion all the leverage issues go away. 

Scott

Offline 754

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Re: Rear disc convention cb750 k
« Reply #24 on: September 08, 2017, 09:40:44 am »
Good point.
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