The brake arm is attached to the Swing arm on the CL77 and suspect it the same on the other versions. So there is no relative movement between the brake backing plate and the swingarm when the SA moves relative to the frame. The brace is not fixed only to allow chain adjustment.
The brace on the front fork forms a triangle. The points of the triangle are the axel and the two mounting points of the brace. Anyone who passed trig in high school knows that the sides of a triangle are fixed. Hence the reason for angle braces in construction. It adds rigidity.
Not trying to argue or prove anyone wrong here. Just stating the facts. I would suspect that a number of folks may envision the rear brace being attached to the frame, and it might be on some bikes. Does not make sense to do so, but sense does not necessarily apply in all designs. Front brace is a perfect example because it is designed to move, but will never actually do so.
Today, I fired up the heaters and took a closer look at the front brake plate, bolts, etc. Here's what I found.
First, both the upper and lower brace bolts are cut threads, not formed/rolled. So shank diameter of the unthreaded portion of the bolt is slightly larger than the major diameter of the threads. The threaded hole in the brake plate is counter bored to allow the shank portion of an 8mm bolt to enter and just about bottom out. What the problem with my specific bike was, I suspect that the bolt had been over-torqued at some point with a nut and was later used to secure the brace. . The thread pitch was stretched a bit towards the head when checked with a pitch gauge. I found another bolt of the same size (length and pitch) on the rear fender and it worked like a champ. I also measured both the shank on the bolt and the hole in the brace and the clearance was not overly large. I doubt that the original bolt was shouldered for the lower hole in the brace where it bolts to the brake plate.
Yes, there is a unique part number for both the lower and upper bolt. Upper bolt has a head that is not as tall as a standard bolt. That I believe is the reason for the special part number. Cannot speak to the lower and need to research a bit more. But it appears that a standard 8mm bolt with that goofy 8 on the head is what belongs there. Anyone with an unmolested bike might be able to help confirm that.
regards,
Rob
'67 CL77 front brake brace bolts
I agree that I was incorrect earlier.
I was recalling a race bike with the front attachment to the frame. A good reason this arm floats is ya can remove the axle, 2 spacers, lift the chain from the sprocket, move the brake assy and take the wheel out the back. Install it and ya don't need to adjust anything. These bikes didn't come with anything other than a smooth top bolt anywhere. Ya want that goofy bolt I have plenty I've gathered over the years. .........lm
I'll make you a deal, LM. Send me the goofy bolts with the funky 8 on the head, I'll replate them and sell them on eBay and we'll split the proceeds.
All seriousness aside, I was under the impression that the bolts with the 8 on the head were very collectible. I know squat about what is collectible when it comes to Japanese bikes so I'm just repeating what I hear. Maybe it's urban legend. I found quite a few on my bike. That certainly does not mean they are correct when you consider it is over 40 years old. I have to admit, that I wonder why 8mm bolts have 14mm, 13mm and 12mm heads. Can anyone shed some light on that one?? regards, Rob
Rob, it seems to hinge on from where the fixing originated. Por ejemplo: European hex-head M8 (ISO-Metric 8mm) bolts (partially-threaded) and machine screws (threaded to the head -- 'setscrews' in UK-speak) mostly -- if not all -- come with a 13mm a/f head. Some of the M8s from Asian manufacturers -- particularly China, Taiwan & Thailand (i.e. the 'cheaper' markets) -- have a 14mm a/f head; there is possibly an engineering reason behind the rationale -- or perhaps the production method is less expensive(?). So far, in my 20 years of marine electronics installation, maintenance and problem solving, I've yet to come across a Japanese manufacturer who supplies their equipment with an M8 screw that doesn't have a 13mm hex-head. Japanese Radio Company (JRC), Furuno, Tokimek, et al all provide s/s or BZP screws in this category. Now, I've usually found that the Japanese automotive industry, since my first tinkerings with mates' cars in the '70s (Datsuns, Toyotas and, in the '80s>, Hondas) used M8 fixings that had 12mm heads BUT with a bearing flange (a 'built-in' washer arrangement), usually barbed to prevent any shaking loose, and of 13mm diameter or so. Another 'but' is where Jap cars were built in European factories and the fixings were locally sourced; in this instance anything goes: 12, 13 or 14, depending on in which country the screws were made! Further: some German and other northern-Euro '80s-builds had some 12mm-headed hex screws, although most Euroboxes have gradually moved to Torx, Triple-square or Spline-drive -- both internal and external headed -- since then..... The same seems to have been the case with the French and southern-European factories, but Renault & Peugeot went the Torx route (mainly for tooling reasons) very early in the '80s. I'm waffling now.........! And the reason Brits originally called a 'wrench' a 'spanner'? Derived because the jaw spans the head. BTW, our screws' heads started life as square, not hex. Steve,
Interesting. I have a lot of 14mm M8 nuts and bolts on the bike. Drove me nuts at first because I constantly had to make a second trip for the right sized wrench. Now I'm pretty good at spotting a 14 versus 13mm head. Tripple-square?? Is that Euro-speak for 12 point? Never heard that one before. regards, Rob
Rob, I forgot to mention that the Jap-bike manufacturers eventually moved over to 13mm-headed hex M8s. Yes, that would be the same thing, I s'pose. I Googled 'triple-square' and found this wiki; it's also known as XZN (?!), apparently, and is the last one on that linked page.
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