Disc brake - general information about adding a second disc
Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models
Thanks to Steve Odell and Shaun Laughy and Charlie Mullendore of Antietam Classic Cycle for providing this information on the old Yahoo! Loopframe_Guzzi news group (which has now moved to Groups.io). Cam Conklin and Tom Halchuk also sent me some information via e-mail.
Some information from Charlie:
You need either two 39.5 mm thick disc/bearing carriers or a 10 mm thick spacer along with the 29.5 mm one.
I used 140 mm long bolts on Cam's Eldo when I added the second disc for him, but cut approximately 5 mm off of each as they stuck out too far.
Some information from Shaun:
The right bearing is retained with a circlip, but the left floats right about level with edge of the disc. There should be an internal spacer between the bearings of 76 mm in width (at least when stock components are used).
Some information from Cam:
The recessed bearing with circlip is on the right side with the external axle spacer. This gives a couple extra millimeters needed to fit the 41 mm spacer. Jim Carey confirmed same on his.
Reverse the bolts holding the fender stays in place as the nuts on the inside interfered with the new [floating] discs. [this should not be a problem if using the original style non-floating discs]
Some additional information from Steve regarding the bolts:
That's exactly what I did with the bolts but I used stainless grade 9 ARP bolts with stainless nylocks and cut them to size.
Tom Halchuk's dual disc conversion
I bought the new disc carriers from MG Cycle. I had some 10 mm spacers made AND a 1⁄4 inch axle spacer made.
The axle spacer pushed the axle out far enough so the axle nut wouldn't bottom out (run out of threads). I added the axle spacer and whole setup fits perfect.
This makes one part of the dual disk conversion (disc carriers) parts puzzle easier.