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Posted: Sun May 08, 2011 8:40 am Post subject: Re: brace mix of parts
jvandyke wrote:
Now reinstalling the tubes I find the spread between them to be significantly different.
If the spread is different, then wouldn't you have to use the same top bridge from another 750 and not be able to change the top and bottom bridge from a 500? That must be a complete front end off a 750 that you have on your bike. If it is then you can't change the top and bottom trees to a 500 without changing the whole front end, correct? I have a top bridge from a 750 if you need it. Here is a pic of the one I have.
Joined: Dec 29, 2009 Posts: 280 Location: Hudsonville, MI, USA
Posted: Sun May 08, 2011 9:14 am Post subject:
That's different than what I took off. What year is that one? I think as long as the top and bottom bridges are in a pair and the stem is the right size for the head and the tube holes are the right size..... _________________ recently acquired '72 CB500K Jeff
Not sure what year. I think it's a 74'. the distance from center to center of the fork tubes is 7 3/16 inch if that helps. Again, if your fork tubes are a set distance apart now and are 750 trees as you suspect, don't you have to use the same top bridge that has the same distance apart as the tubes?????? In other words, if you change the top and bottom bridge back to a 500 that has a different width or spread as you put it, you would have to change the axle width or spacers down at the wheel to match it too, wouldn't you since the fork tubes would ALSO have to be a different width or spread to match the 500 trees.????
Joined: Feb 15, 2007 Posts: 1357 Location: LaPorte, Indiana, USA
Posted: Sun May 08, 2011 9:44 am Post subject:
jvandyke wrote:
....... Not sure what to expect running cracked top brace (both sides) I assume that's pretty bad, although I never noticed any handling issues, I'd think the strength of the whole front end would be severly compromised and catastrophic failure is possible?
More like death is possible - get 'er fixed.
Lots of variation is possible. If you can swap the whole front end (forks/fender/brake/wheel), the variations are almost endless.
My DOHC CB450K4 has CB360 top and bottom clamps, a CB450K1 stem, and CB400T forks (33 mm)/fender/wheel/brake.
To make it worse, any 35 mm fork will slip into any 35 mm clamp, with other fitment issues ignored.
So it's hard to say what you're really dealing with here - too bad they don't stamp part numbers into stuff........
At any rate, the offset on a 500F is different than the offset on a 450 or 750 - meaning the distance of the fork tube forward from the stem. So there would be problems with fenders and calipers, etc.
The distance between the tubes is a different and equally important issue. _________________ Bill Lane - CB200-CM200-CB450-C70M-CL350
"When your only tool is a hammer,
everything starts to look like a nail."
Joined: Dec 29, 2009 Posts: 280 Location: Hudsonville, MI, USA
Posted: Sun May 08, 2011 10:48 am Post subject:
I'll just duct tape the old one......not.
Okay, here's pics. From my hasty rudimentay measurements (it's Mother's Day, I shouldn't wrench today) the spread between fork holes is awefully close to 7 1/4" center to center on both.
_________________ recently acquired '72 CB500K Jeff
Joined: Feb 15, 2007 Posts: 1357 Location: LaPorte, Indiana, USA
Posted: Sun May 08, 2011 1:23 pm Post subject:
Using your own photo, be sure to measure the "offset". The two clamps look different in the photo. Make sure it matches the offest in the bottom clamp or you'll never get the forks in.
The offset will radically affect your handling characteristics by changing the trail.
For a quick and easy method to determine your rake/trail visit my website - all you need is a tape measure and a level.....
Joined: Dec 29, 2009 Posts: 280 Location: Hudsonville, MI, USA
Posted: Sun May 08, 2011 2:55 pm Post subject:
Here's my hasty measurements, again, it's Mother's Day and I'm am REALLY busy......more time later.
I tried to measure the offset of the lower bridge and it "seemed" close to 2" tought to do on the bike with tubes half way in, and in a hurry.
_________________ recently acquired '72 CB500K Jeff
Joined: Dec 29, 2009 Posts: 280 Location: Hudsonville, MI, USA
Posted: Sun May 08, 2011 4:18 pm Post subject:
A guy over at SOHC4 sent me a pic of his top brace.
I took his picture, made is a bit transparent and superimposed it over my picture. I added the blue circles where his 500 four bridge tube holes are, red on the one I got from Butch that is supposed to be off a 500 four. Drastic offset difference. When his is placed over my broken one, they line up pretty good. Butch could the one you sent me be something different after all?
_________________ recently acquired '72 CB500K Jeff
Joined: Feb 15, 2007 Posts: 1357 Location: LaPorte, Indiana, USA
Posted: Sun May 08, 2011 4:53 pm Post subject:
I'd suspect that the 500 is the one with the shortest offset........ _________________ Bill Lane - CB200-CM200-CB450-C70M-CL350
"When your only tool is a hammer,
everything starts to look like a nail."
Joined: Mar 13, 2011 Posts: 169 Location: Ocala,fl
Posted: Sun May 08, 2011 6:38 pm Post subject:
[quote] At any rate, the offset on a 500F is different than the offset on a 450 or 750 [quote]. I have one from a 1977 cb750k with the same dimensions as your picture shows. BUT the gauge mount is different, it is 5 1/2" from hole to hole. I'm sorry to put you though all this trouble. Just trying to help. It is slso taller. _________________ MY BIKES: 1967 YAMAHA YL1E, 1980 HONDA CB900C, 1982 SUZUKI GS1100GL(project bike), 1975 KAWASAKI Z-1 903 .
Joined: Dec 29, 2009 Posts: 280 Location: Hudsonville, MI, USA
Posted: Fri May 13, 2011 4:24 am Post subject:
Got another top bridge off a 500k, just like my broken one. Fit perfectly. Almost done buttoning it all up. Hope to have it done tonight after work. Of course the weather turns to crap tomorrow but it'll be nice again someday....... _________________ recently acquired '72 CB500K Jeff
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