Topic: Dual Disk on Early Forks with a Lester Wheel

[Rookster]

I know there are tons of How-To's on dual disks for the CB750 but they all usually use the stock hub and later forks.  Here's how I set mine up with a Lester wheel and early forks K0-K1:

The Lester Wheel does not have the flats in the hub to do the usual speedo drive modification so you have to come up with another way to anchor the speedo drive.


I chose to have a pocket machined into the extra disk to hold the speedo drive.






I used 4.1/2" long bolts and nylock nuts with blue locktite to bolt the disks together.  I shaved the heads of the nuts down to clear the speedo drive as well.

The early forks have a different caliper bracket that needs to be modified and spaced.  The lower mounting boss has to be filed down and the top 2 mounts have to be spaced 1/2" from the fork leg.






The caliper arm on the stock mount does not sit directly over the disk but is offset to cover approximately 1/3 of the disk.  The 1/2" spacers on the right caliper mount give the caliper arm the same orientation over the new disk.

The disks are not the same distance from the fork legs.  The 2nd disk sits about 1/4" further away from the fork leg as the original disk.  The 1/2" spacers solve any issues with having to shim the 2nd disk.


For brake lines I used slingshot cycles for the braided line and the stock Honda hard line.  I used a brake line bender and modified the hard line so it looks identical to the stock hard line.


I had the extra caliper powder coated gloss black to match the other one.  I used a new stainless piston, new OEM bolts, and bleed screw.


My goal was to get the extra caliper to look as stock as possible and match the other side.  I did remove the caliper bracket screws and springs and just let the calipers float.  The master cylinder is the stock one and I may change it out for a GL1000 master but I wanted to see how much feel the stocker gave me first.


I did get the disks drilled and thinned by Godfrey.




The stock master cylinder gives really good feel.  The only modification I did was to install a Magura dog leg lever.


HTH
Scott

[jaguar]

nice write up, just went through this on my lesters for my K1

What year is that speedo drive off of?

[Rookster]

I think the speedo drive is K1.  It was on the bike when I got it with the stock wheel and there was no reason to think it had been changed.
Scott

[Wavedancer]

Hi, I know this thread has been quiet for a while, but I have a question. I am converting my CB750 K4 to dual disc as in the posting above. I notice that on the right hand second caliper you have managed to switch the brake fluid line to the rear entry point to the caliper, to match alignment of the original caliper on the left side. I wondered how this can be done, because I am using a second caliper that was originally on the left of another bike, and it means in fluid  line has to attach to the forward thread (due to internal shape of the other thread to take the brake bleeder). Any help much appreciated.

Best regards
Graham

[Rookster]

There is a removable fitting/ferrule that seals the brake line into the caliper.  Here is a picture of it on my workbench:



You can remove the fitting by running a finish nail up through the hole from the piston bore out where the head will catch on the ferrule.  Clamp the nail in a vice and use a brass drift and a hammer to drive the caliper off the fitting.  Don't go crazy as you don't want to damage the caliper.  Heat will help.  You can then insert the ferrule into the traditional bleeder hole and then you can use the stock type line into the caliper on the other side.

Scott

[Whaleman]

It is a lot of work. I did mine about 6 years ago. Nice write up.

[Don R]

Nice work, I'm going to have another look at my K0 with Lesters, I'm pretty sure I've got enough parts around. I really like my triple disc F1. With the 836 in the K0 could probably use a brake upgrade. I'm still using the stock MC on the F1 It stops great, It will make the front tire beg for mercy.