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

[Brown Bomber]

Worked hard, mostly cleaning parts, dang that takes forever. Brake calipers:

Looking back through this thread I found this picture of the caliper. From this picture I can see the groove where the piston seal resides has been hogged out to the point that the small ridge that runs down the middle is gone, being a square profile seal, it is supposed to rock back and forth on that ridge so it can release the piston from the disc. This happens a lot, moisture gets under the seal and corrosion eats up the soft aluminum, then once it's all clean there isn't enough aluminum there to do the job. Looks like you need a new caliper.

[MCRider]

Dang BB! That's observant. I will take a close look when I get it apart, but you could be right. They are very old and high mileage calipers. Maybe I'll buy some low mileage calipers too. 

I never knew that about the inside of the caliper. I remember vaguely, I think it was HondaMan (maybe it was you) posting something about how the ORing worked on pulling back the piston, but i couldn't remember what the trick was. Now I know and I'll check it up. I may need a low mileage caliper just to compare. If nothing else.

Off to eBay! Thanks.

[MCRider]

Dang again! You should see what calipers are going for on eBay!

[Brown Bomber]

Sorry, I hope I didn't sound like a jerk by pointing that out. I ran into that problem before and the problems you were having just sounded too familiar. Those things are stupid expensive too, that's why my 500T has a CL drum on the front.

[MCRider]

Sorry, I hope I didn't sound like a jerk by pointing that out. I ran into that problem before and the problems you were having just sounded too familiar. Those things are stupid expensive too, that's why my 500T has a CL drum on the front.

Not at all, I'm very glad to hear what you said. Gives me an option to explore, and likely solution!  These brakes worked when I parked it (famous last words) but with all new parts, except the caliper body, and the passage of time the great debilitator who knows?

I'm hoping Cycle Recycle Part II will have some reasonable. His is the CB750 black hole of parts.

[grcamna2]

That place Cycle Recycle Pt. II are they there in Indianapolis..& is it a type of place that just has piles of stuff that you need to take a bright flashlight and go digging through w/o anybody to help you ? 

[MCRider]

That place Cycle Recycle Pt. II are they there in Indianapolis..& is it a type of place that just has piles of stuff that you need to take a bright flashlight and go digging through w/o anybody to help you ? 

Yes its here in Indy. They have a "showroom" where you can just about walk around in, with only a passing fear of being crushed to death by literally tons of parts stacked and boxed on "shelves" that are hugely overloaded, pipes hanging on the walls, sidecovers hanging from the ceilings, and engine parts my GOD. Boxes of CB750 rocker arms, cams, trans parts. That
s why i say its a black hole (to be) where it will collapse into itself from its own gravitational pull.

Yes mostly he'll just point to a "place" and say they are over there (Everything is inside) And it is dark, a flashlight or miners hat would help. Used to be you could go upstairs but only employees are allowed now. I know what's up there. Its like an old ballroom or meeting room with rows of forks and a big pile literally of gas tanks in the middle of the floor. The people in the showroom downstairs would never stand still for a minute if they knew what was above their heads.

Bruce and i went to the fender rack last year looking for a fender for Phaedrus. And in about 2 hours, we found not 1 but 2 CB350F front fenders. One complete with stays and no dents, one that has been bobbed (currently on P. Being that it is identical to a CB750 except that it is for an 18 instead of a 19 (which is how mine is now) they are perfect. $10 for the full, $5 for the bobbed. (The center mount is different, but I was doing something else for that)

If it were more organized he'd have to charge more. he does sell a lot of new stuff too.

He's got some calipers...somewhere.   

[grcamna2]

Where I presently live(PA. until May 14...then GA.  yeaaah !) E.PA the Lehigh Valley there is only one Salvage "shop" next to Quakertown where there is a place called Larry's.He has the the small repair shop,salvage bikes outside rotting away and the indoor "Catacombs" that I've waded through on a few dark days w/o a flashlight and 1 or 2 times w/ a small flashlight...but His prices always seem to be HIGH.I sold him some parts from a former stock of items I had and he doesn't pay much.
The only choice I've had has been Ebay..CL is kind of a dead end around here.
I hope you bring a GOOD flashlight & maybe a caliper piston to check for fit. I need to buy one of those Special new type of "Blue-ish" powerful flashlights.

[RAFster122s]

David Silvers Spares has had someone remanufacture the piston bodies for the front cb550 so you might want to check there as well...

[MCRider]

David Silvers Spares has had someone remanufacture the piston bodies for the front cb550 so you might want to check there as well...

I always forget about them.

I did find 2 early style calipers in a box, one gray, one black. Appear identical, I guess the gray one is a pre-K1? and the black one is K1.  But boy are they grungy! Spider webs packed up in one of them. And corrosion build up under the ORings.  I'll need to disassemble and soda blast. One has a broken bleeder valve, par for the course. IIRC, from where these came, they are low mileage, so if I need them I've got them.

[Ecosse]

OT: don't look now but your avatar picture/bike showed up on facebook. 

https://www.facebook.com/pages/Honda-Cafe-Racers/320118184678336

[MCRider]

OT: don't look now but your avatar picture/bike showed up on facebook. 

https://www.facebook.com/pages/Honda-Cafe-Racers/320118184678336

Cool. But they got the one with me sitting on it (18yo). Do they have the avatar one sans me? I didn't find it.

Oh yeah, can i sue?     I guess once its on the internet its always on the internet.

[Ecosse]

i haven't checked on that. do you have any good sized copies of the bike only? i thought you did.

suing? come on ron.. you're perpetuating the ugly american stereotype and them uropeeins are watching. 

btw: looking at that shot made me think how cool it would be to make a bikini fairing with two rectangular lights like yours instead of the typical round unit. very 70's!

[MCRider]

i haven't checked on that. do you have any good sized copies of the bike only? i thought you did.

suing? come on ron.. you're perpetuating the ugly american stereotype and them uropeeins are watching. 

btw: looking at that shot made me think how cool it would be to make a bikini fairing with two rectangular lights like yours instead of the typical round unit. very 70's!

Yeah i have an 8.5 x 11 of the avatar picture. The facebook picture is buried in my thread. Or, I think i gave it to Carpy for his "Owner's Bikes" section of his site. I'll bet that's where they got it.

In the avatar if you look close you can see the keys/ignition switch hanging down from the frame, between the fr wheel and the frame. Its not quite finished.

OK, I won't sue.

I always wanted a fairing of sorts for that bike, but the lights won out. They make a bracket to mount these, but its for a bike with extended forks. On a stock front end the lower light was too low and the wheel would hit it. So I crossed two pieces of aluminum strap, bolted at the cross, horiz across the tree clamps, vertical with a perch at either end for the lights. It would never stay tight, would've needed welding had the bad guys not stolen it from me before i got to it.

They were Cibie Airport lights, still available, 100w each. A fog for low beam and a spot for high. Before i knew anything about alternator output, relays and buzkills like that. They were bright when they worked. Intermittent grounds.

Modern stuff is probably better but I'd like to try those one more time. On another bike.

[MCRider]

Received new caliper pistons from Yamiya. They are amazing. 5 orders now, placed on Sunday PM, received by next Thur or Fri!. Better than some outfits I ordered from in IL! Also got a rally nice faux or real leather key fob from Yamiya.

Also got one of the lazer cut ones from member Ray:
http://forums.sohc4.net/index.php?topic=56226.0

Too bad for the glare, but the engraving is very small and clear, really cool as well. I'll use one for the main key and one for the spare key. Maybe alternate them.

So we disassembled the spare calipers i found, in case we needed them for the current project. Here's a blow by blow on the grease gun piston removal trick. First get a grease gun. I use the type with a hose.

Unthread the end, leaving a male thread.

thread it into the open port of the caliper. I've been saying it would catch a few threads, but in fact, it caught less than one thread. That is enough.

After about 10 pumps the pad isout this far.

Another 10 and you're here

A few more and its done. Here's how much grease thre is to scoop out.

Easy peasy. Other things work, but now that i know this one I go here first. No danger from a flying piston as with air.
The other caliper only had one bolt holding it together and it is seriously compromised. No way its coming out without some really sharp drill bits or other implement of destruction.

So on to the calipers on the bike. They aren't releasing. I am 99.9% sure its not the MC return. The MC has been thoroughly gone thru. Turns out the rt caliper is returning. Its only the left that is hanging up. One firm tap with a rubber mallet will relaese it. So we removed the left caliper to see if the pheolic piston/ORing interface may be at fault. Brown Bomber suggested it may be the ORing channel in the caliper may be at fault.

We got it off and much to my surprise I couldn't get the puck out. It should have pulled out easily as it was new and (I thought) properly fitted. After much pulling and huffing, it came out and lo and behold, the edges of the puck were nasty not only with rust but with some sort of grunge.

In the caliper wsa also a bunch of this grunge, enough to feed the interference of the puck with the caliper walls. Beats me. We spent an hour cleaning, polishing, sanding to where the puck has a nice slippery fit in the caliper. I'm thinking this is all it was.  We'll find out later as time was up.

Bleeding is a PITA, but now that I know what it takes, I ought to get to it one day this week.

[RAFster122s]

What kind of grease did you use on the puck, piston and seal?

TwoTired recommend a 3M high vacumn grease that doesnt propagated even under very high temps.

Looks to me like you had some fluid get past the seal on that side to form part of the grunge.

[MCRider]

What kind of grease did you use on the puck, piston and seal?

TwoTired recommend a 3M high vacumn grease that doesnt propagated even under very high temps.

Looks to me like you had some fluid get past the seal on that side to form part of the grunge.

No grease on anything. never have.

Agreed. Thought occurred to me that maybe at the first, some fluid seaped by, and maybe the puck periphery had some paint on it as many new pucks do, and the fluid turned the paint into grunge gumming up the works.  Definitely no brake fluid where it didn't belong at this point though. Mystery.

I do think 99.9% sure this was the problem.

The right side seems to work properly, but I'll take it apart just to be sure before bleeding.

[CBJoe]

Hey Ron,

Get crackin' and you could almost unveil Phaedrus at The Rockers Reunion on the 19th!

Unfortunately I cant make it this year as my work has be flying to and from Germany once a month for the foreseeable future and I'll be gone at that time   

later, Joe

[MCRider]

Hey Ron,

Get crackin' and you could almost unveil Phaedrus at The Rockers Reunion on the 19th!

Unfortunately I cant make it this year as my work has be flying to and from Germany once a month for the foreseeable future and I'll be gone at that time   

later, Joe

Not quite, tank's at the painters, not due back till end of May. Might have it running by then (19th) though no one will know. Except the forum.

[Really?]

I am looking forward to this being completed soon and I want to read your review on your tire/rim setup.  Wondering what you find with regards to your front rim height.

[MCRider]

I am looking forward to this being completed soon and I want to read your review on your tire/rim setup.  Wondering what you find with regards to your front rim height.

Me too. The first revision was a 17x2.5 rim. (If you go way back in the thread). This interfered with installing the brakes and i couldn't use it. I possibly could've gotten by with a 17x2.15. But by then i had realized a 17' was probably too much of a change and went with a 18x2.15, to make sure I didn't have another problem meshing with the brakes. In fact the 18x2.15 looks like a much better fit. The caliper bolts just barely clear the rim, but barely is good enough. It has a 110/80 tire now. it looks very natural with the 18" front fender from a CB350F.

I used to ride Phaedrus I with my sport and sport touring bike buddies. I remember one ride in particular when we were really hustling down some twisties along the Ohio river.  I had a 19x 2.15 Borrani on it then with a 110/90 tire. What a hunk of meat, and I was sure this was holding me back from a handling standpoint. That was the impetus for a smaller wheel.

I realize the smaller wheel may not work well with an antiquated front fork, though I have made some upgrades there as well. I did use longer fork tubes to restore the ride height and (I think) rake, but maybe not trail? I'm not an expert on such matters, just an experimenter.

[Really?]

Yup, found that part of your thread last night when I was searching rims and tire width.  I wish there were more tire options with the 19".  I want to do a 110/80-18 up front and a 140/70-18 on the rear on the '76.

So you reckon the 2.5-18 rim would hit the caliper bolts aye.  That shows to be the recommended size for that tire according to Bridgestone.  2.15 they say is minimum.

Yea, that trail rake stuff, no expert here either.  Gotta figure that into it all too.

[MCRider]

Yup, found that part of your thread last night when I was searching rims and tire width.  I wish there were more tire options with the 19".  I want to do a 110/80-18 up front and a 140/70-18 on the rear on the '76.

So you reckon the 2.5-18 rim would hit the caliper bolts aye.  That shows to be the recommended size for that tire according to Bridgestone.  2.15 they say is minimum.

Yea, that trail rake stuff, no expert here either.  Gotta figure that into it all too.

Its not that it hits the caliper bolts. But it keeps you from removing them without removing the wheel. And if you have dual brakes, one caliper has to come off, then the wheel then the second caliper. If you just have one brake and you put it on first, you can probably get by with the 2.50. And since I already had to eat one wheel (Excel rim, Buchanan's spokes, Time and Effort lacing, balancing, mounting a tire) In actuality I got a good price for the hardware on eBay and was out mostly the time.

I wanted to get it right on the second throw. I didn't want the compromise of having to pull the wheel to service the brakes.  The 2.15 does the job, which it does. looks real good. Not pinching the tire at all. A Bridgestone Battleax BT45f.

I have 2 charts and both say the 2.15 is OK with the 110/80, but a 2.5 is probably more OK.

With one brake you can probably use the 2.50, but not on my advice.  .

The old 19 x 2.15 with the 110/90, the tire was so fat it wouldn't pull thru the brakes, one had to come off. Or let all the air out of the tire and squeeze it real hard. PITA.

PS: If you noticed i dropped my rear to a 17", with a 140/17 tire. Bear to get up on the centerstand. Got a spare i may have shortened or get some longer shocks.

[MCRider]

Cripes.    Thought it was going to be a great session and it just went downhill. First i thought I'd pull the remaining rt side caliper and see if it had the grunge in it that the left did. it did not. That was good. Pulled the puck seat and piston. Well I thought. The seat was IN the piston and would not come out. Heat, ice, channel locks. Finally tapped it like a jar lid with a hammer and broke the phenolic piston. The seat came off. As for braking the phenolic, i was about ready to not use it anyway, or at least use the OEM ones until we can be sure the brakes work.

Difficult to put the chronology in print.  Tried to reassemble the left side caliper but the piston would not move. We went to blow it out, air no good. Went to use the grease gun. Ran out of grease before it popped the piston. Probably OK as the hose broke, though it didn't leak. Oh well, that gun's gotta be 25 years old. Nothing lasts blah blah.

Tried to reassemble the other caliper with an OEM piston and got it wedged crooked and with no grease...

So I ordered 4 caliper ORings to be ready for what ever I decide to do. And a new grease gun. Hit it again next weekend if not sooner.

[Tintop]

Wow! you and brakes just don't seem to want to get along.   I do applaud your patience though, assuming you didn't create some new ventilation holes in your shop space.