Well, the rear master applies the front but like just in a first stage. It's intended to allow the rider to increase front braking at will with out risking a high side. If you simply remove the connection to the rear master cylinder, you'll also loose some front braking power as you'll loose the added pressure those pistons applied to the pads.
Right now the front brake master does give plenty of pressure to lock the front wheel. A wheel that is sliding or 'skidding' gives much less stopping power than one before lockup. So more clamping force, in this case, does not contribute to shorter stopping distance.
Just my thoughts … you miss a turn, you do a "go by" & turn around & come back.
VERY true. In this case, I had no traffic before or after, good safe runout area. and had yet to do a 'hard stop' or 'panic stop' type braking. This was done as a test. (Florida law even states 'U Turns are legal everywhere unless a sign prohibits' to encourage 'go by and come back'.)
I was gonna un-link the brakes on our's, it too has linked brakes, just slightly different. With the
GL1500, the rear brakes and left front are activated by the foot pedal, the right front is activated by the right hand lever. I know some have done an "un-linking", some like to be able to lock the rears if they want, but after long thought,
I decided not to un-link them. I don't think that a situation where the rears lock, the rear maybe side steps, and then if released could result in a flip … is something I want.
I think having a front brake apply too
reduces that possibility.
In my case, the front locks up before the rear even contributes significant braking. I will certainly replace the rear cylinders and test again before de-linking. If I find the rear cylinder continues to lock up the front, its a nogo.
My trike uses 9" Ford drum rear brakes, the wheel cylinders have two pistons opposite each other, I've
never known of or had a wheel cylinder only have one piston work. I've been well aquainted with drum brakes for over 50 years. I've had them leak & make a mess & need replacement or rebuild but not for a piston not working. Drum brakes are self energizing, the brake shoes get pressed against a post and the rotation action wedges the shoes against the drum. The one shoe gets wedged against the adjuster which wedges the other.
Got me beat, only 41 years turning wrenches for me. But I bet you got a head start... I know mine is a 7.5" ford rear, and according to Amazon the drum is 9.8" outside size, so we prolly have the same 9" drums. (Wagner 8952) When I test drove the trike, I pushed HARD on the rear brake pedal. This caused a shoe in back to stay partially extended, and give significant drag. I had to help the seller push the bike in the shop. He later messaged me that the fault was 'just an adjustment, and brake drums are tricky'. All he did was to back off the starwheel to allow the leading shoe to stop contacting the drum. When I had the drum off, and pressed the pedal, you can see the trailing shoe move but not the leading. I was being a dumbass, and so anxious to ride that I figured '1/2 should be OK for now' ...
Running a VW shop for 20 years, one sees a lot of drum brakes also. The front cylinders on a regular bug are oriented vertically (!) and must be bled before assembly to avoid the 'one pump then brakes work right' feel. I have even had people tell me that 'its how bug brakes work' Then I fix them, and tell them not to kiss the steering wheel...
The Bus front drums are even trickier - Double actuating/twin cylinder! They went to front disc in 71 though.
With the vertical orientation, I have seen several where the down piston is corroded/ frozen and the top still working. Not as common, but also seeing the leading shoe piston sticking while the trailing does not in the back. I was told this was because the trailing shoe is using the self actuating forces to press the piston back in, and the leading shoe relies only on the brake springs for return action. We have a lot of humidity here, might be a contributing factor. With a VW, I would do a HARD brake application in reverse to see if it freed up the drum, and suddenly gave much more pedal travel. That would be the 'smoking gun' leading me to a stuck piston diagnosis. Sometimes just adjusting the brakes after doing this things would be OK. With no reverse on the trike, this test isn't available.
Springs pull the shoes away from the drum so it is
important that the brakes be adjusted periodically to eliminate excess clearance or travel that will only lead to un-needed brake piston travel that uses up brake fluid capacity and delays brake application. I am convinced from your description and my own personal experience that what you are concerned about will be largely eased with a
proper adjustment of the rear brakes. I adjust mine every oil change or before any longer anticipated trips.