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Yes the CX with the dual disc setup stops very well. I will say though I also have a GL500 with twin disc and an '82 stock CX with single disc and two piston caliper. All bikes have a new master cylinder, braided lines and rebuilt calipers and they all stop very well. So I guess my point is rebuild it top to bottom and whether twin disc or single it should do the job well. But twin disc does look nice 馃榾
 

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I don't think I'm a spirited enough rider to notice a difference 馃榾

I will say my stock single disc CX is very predictable, and rides like a Cadillac on air suspension.

Rear tire is stock size 馃榾
 

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'84 CX650E that is evolving into a GL500
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I am unclear why you think the calipers with 32mm pistons would be better than the ones with 30mm pistons but the caliper bodies are identical except for the bore diameter and the left/right differences so if one will mount & work the other will.

The difference between 30 and 32mm calipers would be in the ratio of the area of the master cylinder's piston to the total area of all pistons in both calipers. The effect would be that you would need to move the lever a bit more to apply the same pressure with the larger pistons but you would need to squeeze the lever a bit harder with the smaller ones (think of it like leverage - changing the piston sizes is like moving the fulcrum). .
Having used a number of different calipers with different piston sizes over the years (winter & road salt is hard on them and I use whichever size I can get) the difference is more theoretical than practical and most of us wouldn't notice the difference.

Keep in mind that if you change from a single caliper to 2 calipers you will need to change to a master cylinder with a big enough piston to supply fluid to 2 calipers (you will feel the difference if you use the wrong size master cylinder for the number of calipers you have).

And as we discussed in another thread, if you change from the Custom's leading axle forks to the GL's centred axle forks you will increase the trail and the steering effort will increase noticeably.
 

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1982 CX500 C
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Discussion Starter · #26 ·
Somehow I figured that having 4 pistons vs 1 piston would result in better ability to stop the rotor from spinning, and hence slightly bigger pistons would increase that capability, although to your point, now realizing that the extra 2mm may be totally negligible (especially for the type of riding I plan to do, very chill/easy).

And yes I鈥檝e considered the change in trail due to the center mounted axle, and decided that I鈥檇 be okay with the increased steering effort (in exchange for better stopping), especially given that all of my other bikes have been center mounted forks, and the CX500 itself otherwise came with them.

I do wonder however what the trail/rake differences are between the CX with leading axle compared to the GL with center axle (yet longer fork tubes)鈥 Seems like the changes would work to cancel out the differences to work toward similar geometry, but wondering just similar (or different) they are both in stock form.
 

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'84 CX650E that is evolving into a GL500
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The advantage of 2 piston calipers over single piston ones is that they allow the use of long, narrow pads so that they grab the disc farther out from the hub so they have better mechanical advantage (the effect is basically the same as having a larger diameter disc).
The advantage of having 2 brakes is pretty obvious.

And yes I鈥檝e considered the change in trail due to the center mounted axle, and decided that I鈥檇 be okay with the increased steering effort (in exchange for better stopping), especially given that all of my other bikes have been center mounted forks, and the CX500 itself otherwise came with them.
Except for one detail: All of the bikes you have had that came with centred axle forks had frames that were designed to handle properly with centred axle forks. The same goes for the GL500 and all of the CX500 models except for the later model Customs.
The CX500 CUSTOM has a completely different frame from any of the other CX500s and they changed it again when they changed the forks. And the GL500's frame is different again. Your Custom's frame was designed to be used with leading axle forks so that it would have the kicked out chopper look that was popular at the time while still having a reasonable trail so that it didn't handle like the exaggerated front ends on choppers built by people who didn't understand how rake & trail affect handling.
The GL500's frame was designed to be used with centred axle forks so that it would have slightly more trail than the CX500s for stability for long distance touring on long, straight highways.

If you put the forks from a GL500 on your Custom you will end up with more trail than the same forks would have on a GL.
 

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Discussion Starter · #28 ·
Hmm you make some good points. I think I did see a leading axle CX500 fork with dual caliper mounts on eBay鈥 Perhaps I鈥檒l just grab one of those instead of the GL forks.

Regarding master cylinder, I was thinking of grabbing one from a Goldwing 1500, I believe those came with a 16mm bore, which should be just right for the dual disc setup, no?
 

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'84 CX650E that is evolving into a GL500
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The GL1500 has linked brakes so the rear caliper and one front caliper are connected to the rear master cylinder and the other front caliper is connected to the front master cylinder (my '83 GL1100 was like that too before I changed it). I am unsure about the diameters of the pistons in the calipers but unless they are much bigger than the ones used on the GL1100 and 1200 that would indicate a 13-14mm single caliper front master cylinder.

Note that it is not a great idea to install any used master cylinder without rebuilding it. There are lots of brand new master cylinders on the market for about what you would spend for a used one and a rebuild kit so why would you mess around with a used one?
 
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