Topic: Dual disc cb750 spacer question?

[88blkiroc]

Can anyone show me a picture of how you spaced out the caliper arm pivot mounts from the fork on the right side of a CB750 dual disc conversion? My bike had dual discs on it when I got it but I dont think they installed them correctly as the right side was binding hard. I rebuilt the calipers already and mounted them up yesterday but when I snug up the bolts on the right side the wheel binds. After looking at it I can see the caliper arm isnt parallel to the disc as it is on the left side of the bike. Any pics you have would be very helpful. I was going to just space it out with washers but I need an idea of how many or if there are any alternatives to the washers that work better.

[HondaMan]

This installation depends on whether you're using the mirrored "C"-shaped hanger, or the "T"-shaped one. Both will interchange. If you have my book, or know someone who does, there's a section in the Front Brake chapter that shows the details. If you use the post-1972 "T" shaped pivot hanger, it is easier to install the right side disc.

[88blkiroc]

Im assuming its the T type. The bike is a 74 CB750K4 and both side caliper assemblies look the same so I assume its whatever is stock for that year. The pivot consists of a pin that takes one bolt at the bottom, goes through the caliper arm and then into a bracket at the top with a hole in the center for the top of the pin and a bolt hole to secure it to the fork on either side. I dont have your book nor do I know anyone with it unfortunately.



That's the only pic I have at the moment that shows the caliper at all.

[MCRider]

Trial and error. I used old nasty washers.

Then I used a chrome spacer from ACE Hardware (they had them in Metric in the Chrome drawers) with a chrome washer to make up the dif.

Yoshimura made them (whole brackets) from scratch out of magnesium, IIRC. A little pricey.   

[george]

I had this stashed back, never did it though, I'm in the process of switching to a DOHC front end.
Hope it helps, good pics .
http://www.salocal.com/sohc/tech/dual_disks/dual_disks.htm

[70CB750]

I copied this from the forum:


  Turn the adjuster screw until it draws the "B" pad (the "passive" pad that does not have the moving piston behind it) to within  5thou of the disc. Yes use a feeler gauge. Lock it in place with the nut. Now pump the brake until it is tight, then release. If the A pad is withdrawing properly, and the Master Cylinder is allowing it to withdraw as it should, you'll be able to measure your 5 thou clearance on the B pad once again. Smoothly, with no hitches.

Hope it helps

[spiritof67]

The Yoshimura/Checkered Flag Customs (CFC) magnesium brackets might be a little expensive but they are the way to go. But bear in mind, Honda had spacers for almost the whole mounting system, so even in normal use, there can be clearance problems....

Spirit

[scottly]

Im assuming its the T type. The bike is a 74 CB750K4 and both side caliper assemblies look the same so I assume its whatever is stock for that year. The pivot consists of a pin that takes one bolt at the bottom, goes through the caliper arm and then into a bracket at the top with a hole in the center for the top of the pin and a bolt hole to secure it to the fork on either side.

Yes, that sounds like a "T" bracket. To make it align vertically, you need to either add spacer washers under the top 2 "T" bracket mounts, or remove the same amount off the bottom fork-leg boss. If my memory is correct, the difference is something like .090".

If you have new pads, you might try mounting the caliper VERY loosely, and apply the brake; with pressure holding the pads square against the rotor, look at the mounting points. Any gaps need shims, any tight spots may need material removed. This will help make the pad faces parallel to the disc in both the horizontal and vertical axis. 

[cben750f0]

sweet that write up is still around, i wrote that up about 8-10 years ago...lol


yup, you either remove metal off the lower boss, lil, by lil, then use a straight edge to check the caliper arm mount surface is parallel with the disc face. once it is parallel , then you shim the top mount to suit.

hope this helps