Topic: Phaedrus: CB750 RestoMod - Update: 09/23/21 w/ new video

[Ecosse]

and let that be a lesson to all the egg-head shrinks: disorders are our friend. 

good news mc!

[MCRider]

here's the pics of the front end to be:

In the foreground is the "stack" that goes inside the tube/leg combo. Left to rt: spacer for the 2" over tubes, spacer that came with the springs, springs, spring stand, and its Allen screw.
Behind is the tube and lower leg at its extended length.

Here is the closeup of the spring stand. It looks very much like the damper tube in the later forks. That's what i thought it was, though the label said "use for phaedrusII". It does not appear in any K0-K1 microfiche i could find. So I thought it wasn't for this bike. I may be the first person that has ever removed it from the leg. nevertheless, including it, it obvious I have everything I need.

Truth be told, knowing what I know now about the later forks, i would have used a later fork with an emulator. The earlier forks won't take the emulator. i already have an investment in this fork, tubes from Franks, springs, all new bushings with industrial Teflon coating. I'll have the lowers Cryo treated. So I'll have the best that the old fork can be.

I don't think emulators were available pre-78 and I'm trying to stick to that theme, anyway. The next project will have them.

[MCRider]

Brenda at BikeBoneyard.com said I could return the forks for store credit. That's all I ask, so I'm happy. Live and learn.

PS: Service with her was always prompt and courteous. Seems like she processes a lot of salvage especially figuring she's in Montana.

[HondaMan]

MC:
Is there a (missing) rod in the center of that spring holder thingie? Reason I ask...this is the picture of the CB450K4 front fork that used the CB750 disc...

[mystic_1]

Most recent pics are of a early (pre-K2) fork, you can see the rectangular mounting boss with two bolt holes, as opposed to the earlier pics where the mounting boss is triangular.  The caliper hanger brackets and arms are not interchangeable on these two setups.

In the earlier setup, the rod is just a guide, the fork upper runs on it as it moves up and down.  Damping valve action is provided by the sliding collars that slide between the retaining rings to open/close the ports you see on the fork upper.  Later setup omits these valves and relies strictly on ports in the damper tube to control fluid.

mystic_1

[MCRider]

MC:
Is there a (missing) rod in the center of that spring holder thingie? Reason I ask...this is the picture of the CB450K4 front fork that used the CB750 disc...

Nope. There is no reason I would ever expect that. Never had a 450 or a 450 parts bike. When i bot the tubes from Frank, i had to have had something in hand, that caused me to buy those tubes, my intent was to assemble them quickly, I mean everything I would have needed was in my garage. Then it just didn't happen.

It was essentially the K1 fork i was running. The chrome on my tubes had worn out I trashed them bot new ones, got the guts teflon coated, repolished the lowers, then bagged and tagged and set it aside. What i have is what i had, exception being the new tubes.

[MCRider]

Most recent pics are of a early (pre-K2) fork, you can see the rectangular mounting boss with two bolt holes, as opposed to the earlier pics where the mounting boss is triangular.  The caliper hanger brackets and arms are not interchangeable on these two setups.

In the earlier setup, the rod is just a guide, the fork upper runs on it as it moves up and down.  Damping valve action is provided by the sliding collars that slide between the retaining rings to open/close the ports you see on the fork upper.  Later setup omits these valves and relies strictly on ports in the damper tube to control fluid.

mystic_1

Yup.

[MCRider]

So, another week...

High point was picking up the powder Coated frame and bits. Many pics already. So after cleaning some parts, and brainstrorming the next moves, we got to the bushings on the shocks. Previously reported the top bushings had truned to stone and crumbled out. These are new in the box, never used S&W shocks, found at a swap meet.  S&W was a premier shock back in the 70s and the company was bought by Progressive Suspension. Progressive sent me a bag of pairs of bushings for free, not knowing which these shocks would take. One pair fit perfectly, We armoralled them and pushed them in with the vice. Went better than i thought. Agfter getting them started, used some slipjaw pliars to encourage them in and sure enough, pop they were in.








The Powder on the frame lug interefered with the install a tad, but we encouraged them on for mock up. I'll likely grind that off for final install.

So then I offered the swingarm to the frame and ... no way. There was powder on the inside of the flange which i removed with the dremel and flat file. But even that was not enough. So I backed away, had a converse with hondaMan in which the point came up that the motor mounts will often affect the SA install. So a light clicked on, if I install and tighten down the front lower motormount, maybe the rear will open up. Sure enough it did. I took the opportuiity to mock up the engine guards too.



And here's the SA installed, at least for now.



Tired and time for bed. Will be a busy week as i hope to keep at it.

[MCRider]

Time to give credit where credit is due. I have a buddy, going on 25 years now. He was around with Phaedrus I, and saw the project languish in my garage for nearly 10 years. One day, over a year ago he said, Ron, why don't we just commit to every Sunday morning, working on Phaedrus for 3 hours for a couple of months and see what happens? I said OK. I told him look, a couple of months is nice but I don't want to get you excited, it will take a lot longer than that to do what i'm thinking, you may not be happy. And I can't ask you to hang around longer than that.  He said, lets just get started and see...

So here it is almost a year later. Haven't missed hardly a Sunday, just a few for Holidays, or family things. And he's still on board. I don't see any way I would've stuck to this discipline without him. Knowing every Sunday he'd be knocking on the door, kept me from sleeping in, and kept me working thru the week acquiring parts etc, for the Sunday session. Heck of a guy. He'll never read this, he's not on line. But it needed to be said.

Oh yeah, did I mention, he paid for the powder coating?

[bgfootball67]

Love the frame color!  Keep up the good work!  Can not wait to see this one finished!

[DollarBill]

You have a true friend indeed.  You are a lucky man. 

The progress is looking good and that mockup is making me long for that day with my own project!  The attention to detail you are putting into this is certainly going to pay off in the end.

[Ecosse]

real friends are a true blessing. as years roll by ya tend to value the worth of friendship all the more; it helps when you share passions too.

your frame, sa, and dampeners look stunning! this thing is gonna be a jaw dropper.



no pressure though. 

[Terry in Australia]

here's the pics of the front end to be:

G'Day Ron, looking good mate, I love the gold frame and those S&W shocks, I've had S&W "Street Strokers" on two of my bikes, they're great.

The forks you bought from the wreckers are definitely not CB750 forks from any model, but that shiny leg in the foreground is a K0 item, just like the ones on my K0. Not sure about the short springs and long damper rod though, I bought my K0 legs from a member here (mine had K1 forks on it when I bought it) and to save on shipping he stripped them and I just swapped the guts from my K1 forks into my K0 lowers.

I'm looking forward to seeing the continued evolution of this beauty! Cheers, Terry.

[MCRider]

Aah "Street Strokers" I rememeber those! Don't know if mine are such, they just have S&W engraved on the side of the bodies.

I seem to have a consensus from several sources that there was a brief run of CB750s that did not have dual disc adaptability. They were pre-Daytona homologation. I can't use them and I'm getting no interest from classifieds, so back to bikeboneyard for credit.

The new tube makes the spring look short as the tube is 2" over stock length. I had Franks make them that way to make up for loss of ride height going to the 17" wheel, and to hold a little more air for the air fork.

Yes it is K0-1. My bike is a K2 but at some point in its many rebuilds I retrofitted a K1 front end, gauges and all. What look like damper rods merely hold the spring.

Thanks it will continue to be painstakingly slow, but it will continue.

[MCRider]

Thanks everyone for kind words. Feeling good about it. We will march on.

[moham]

Wow, now I have to go look up what "homologation" means...

[MCRider]

Wow, now I have to go look up what "homologation" means...

http://en.wikipedia.org/wiki/Homologation

In order for the CR750 to be approved for racing, there had to be a rough equivalent in their street bike lineup. THe CR750 had twin brakes so that had to be an option for the streetbike.

There were 200 CR kits supposedly available for sale to the public, to convert a CB to a CR.  The kits were hugely expensive, there was no real intent by Honda for the parts to get in the hands of the retail public. But many did and survive today.

THese things satisfied the homologation rules.

Thanks for reading!

[HondaMan]

Wow, now I have to go look up what "homologation" means...

http://en.wikipedia.org/wiki/Homologation

In order for the CR750 to be approved for racing, there had to be a rough equivalent in their street bike lineup. THe CR750 had twin brakes so that had to be an option for the streetbike.

There were 200 CR kits supposedly available for sale to the public, to convert a CB to a CR.  The kits were hugely expensive, there was no real intent by Honda for the parts to get in the hands of the retail public. But many did and survive today.

THese things satisfied the homologation rules.

Thanks for reading!

Sadly, a side effect of the 'conversion' of the street CB750 front end to accept 2 discs was the same change that introduced the famous slow speed headshake of these bikes: the front wheel was laced 3mm over toward the existing brake to make room for the new one. On the CR, there were other accommodations for this clearance: on the streeters, the difference showed up between the 1-brake K0 front end and the 2-brake style, as the headshake appears with the 2-brake design.

Happily, retruing the wheel 3mm away from the disc will also stop it, and will make that funny-looking spacing of the tire and front fender look normal again. 

[MCRider]

There was sure some obscure history back then of which I was not aware.

I bought my K1 new in 1971 and it had that headshake. i worked in a shop at the time, and we tried everything. It only happened on decel with hands off the bars, so we could tell customers, why are you taking your hands off the bars?

But for me, we looked at the tire, the rim, fork oil, blah blah. Then I had one of my many crashes and had to replace the front rim. Laced it with no offset and no more headshake. So we blamed the old rim even though it tested true.

[HondaMan]

There was sure some obscure history back then of which I was not aware.

I bought my K1 new in 1971 and it had that headshake. i worked in a shop at the time, and we tried everything. It only happened on decel with hands off the bars, so we could tell customers, why are you taking your hands off the bars?

But for me, we looked at the tire, the rim, fork oil, blah blah. Then I had one of my many crashes and had to replace the front rim. Laced it with no offset and no more headshake. So we blamed the old rim even though it tested true.

Our first discovery of this was similar: my friend (and Honda mentor, then) Jim Chamberlain had a sandcast, but wanted the dual front discs. One of his friends bought a K1 at the shop, and Jim bought & swapped front ends with him to get the new style legs. Suddenly, Jim's bike developed the shake. Thinking it was the tire, he changed that, to no avail. We checked the whole bike, no discovery. When the K1 came back for its 500 mile checkup, Jim "borrowed" his old front end back and went for a test ride: shake gone.

But, he wanted the extra disc and had already ordered the Yosh parts, so we swapped back again, and the shake immediately reappeared. We knew it was in the dual-disc-enabled front end, but it took me another 10 years to look into the 'why' and figure out it was the relacing movement. I had dual discs on mine during the time, and could not 'afford' the 3mm move because it causes too-close tolerances for the other caliper. Now, years later, and back to one disc, I'm finally going to retrue mine to center. I really won't miss that shake. 

[Terry in Australia]

Geez I'm confused now Mark, I've got K0, K1 and K2 fork lowers at home and they're almost identical externally and internally, and both have tabs on each leg for dual disc mounting?

SteveK0's sandcast forks on all of his sandcast bikes (Japanese/American imports) are the same as mine, so I went thru my factory parts manual, my May 1969 copy of Cycle World, my copy of the CB750 Gold Portfolio and Great Bikes of the 70's, and every pic I've seen shows mounting tabs on both legs, right back to the (slightly different again) "pre-K0" prototype models?

I'm certainly no expert, but I'm wondering why Honda would have gone from dual disc capable forks from the earliest built CB750 to a short run of single disc capable forks for Daytona "Homologation", then apparently back to dual disc capable again? It just doesn't make any sense to me, have you got a pic you can post to clear this up?

I went to the CMSL site and looked at the parts fische pages for both the CB750 (all models) and the CB450, and guess what? Those "mystery legs" are identical to CB450K4 forks! Now I know that the "prototype" CB750 model used some CB450 "Black Bomber" parts, but those "Black Bomber" forks look nothing like the ones in Ron's pic, (the later CB750 forks that are similar weren't used until 1973 with the late K3 CB750) so I don't think those forks could possibly have been from a CB750, but more likely, the guy at the wrecking yard just misidentified them? Fascinating, eh?
 

[MCRider]

Geez I'm confused now Mark, I've got K0, K1 and K2 fork lowers at home and they're almost identical externally and internally, and both have tabs on each leg for dual disc mounting?

SteveK0's sandcast forks on all of his sandcast bikes (Japanese/American imports) are the same as mine, so I went thru my factory parts manual, my May 1969 copy of Cycle World, my copy of the CB750 Gold Portfolio and Great Bikes of the 70's, and every pic I've seen shows mounting tabs on both legs, right back to the (slightly different again) "pre-K0" prototype models?

I'm certainly no expert, but I'm wondering why Honda would have gone from dual disc capable forks from the earliest built CB750 to a short run of single disc capable forks for Daytona "Homologation", then apparently back to dual disc capable again? It just doesn't make any sense to me, have you got a pic you can post to clear this up?

I went to the CMSL site and looked at the parts fische pages for both the CB750 (all models) and the CB450, and guess what? Those "mystery legs" are identical to CB450K4 forks! Now I know that the "prototype" CB750 model used some CB450 "Black Bomber" parts, but those "Black Bomber" forks look nothing like the ones in Ron's pic, (the later CB750 forks that are similar weren't used until 1973 with the late K3 CB750) so I don't think those forks could possibly have been from a CB750, but more likely, the guy at the wrecking yard just misidentified them? Fascinating, eh?
 

Certainly nothing to lose sleep over, but what i got from Mark was that the single disc fork was first, for a short production, then still in K0 model run, they went to the duals for homologation and just stayed there.

As far as Brenda at BikeBoneyard, I tend to give the benefit of the doubt, the way they list their parts, but they could have goofed.  They've offered full yard credit, which is all I would ask from a boneyard, as they maintain they were pulled off a CB750.

Perhaps a mystery best filed with oil threads, and hypothetical airplanes on conveyor belts. 

Can't wait to actually get to the assembly stage and see that what i've got will actually end up being a CB750 front end. 

[voxonda]

In my 'replica' I found that, although the legs are virtually identical, the cast piece in one leg where the 6 mm adjusting bolt for the caliper alignment is going thru, is off center about 5-6 mm. So I need a longer bolt. In my memory this was never the case. Am I getting old or missing something?

Rob

[MCRider]

In my 'replica' I found that, although the legs are virtually identical, the cast piece in one leg where the 6 mm adjusting bolt for the caliper alignment is going thru, is off center about 5-6 mm. So I need a longer bolt. In my memory this was never the case. Am I getting old or missing something?

Rob

I think we have a situation where no one single person knows the whole story, kind of like the kennedy assassination. 

Luckily I don't need the full answer. Just enough to get me back together. Hoping to work on the rear wheel assembly this weekend, get it mounted and lookin pretty. Fender taillight assy if time permits.

[HondaMan]

In my 'replica' I found that, although the legs are virtually identical, the cast piece in one leg where the 6 mm adjusting bolt for the caliper alignment is going thru, is off center about 5-6 mm. So I need a longer bolt. In my memory this was never the case. Am I getting old or missing something?

Rob

That sounds like the replica of the CR "kit" legs from Yoshimura. They had a special mirrored casting to support the other disc, and it nested closer to the fork leg than the ones on the other side.