A very interesting question. One of the reasons for the wider disc spread, if I remember correctly, is for quicker heat dissipation to stop potential warping. If you look at drum brakes, then at disc brakes you will see several different design things that are different that can/could stop potential warping.
This is slightly off subject by you might want to look into this also especially if you are street riding your rig.
While I am running rear disc brakes in my black buggy (I forget where I got them now as it has been so long ago that I got them) off-road use, where parking brakes are not necessarily required, a lot of the newer cars/setups now have electric parking brakes which often require a separate mount for them. I am not sure... but I think the "P"-brake is electrically shut closed then, when you push the button, the brake is electrically unlocked not like a manual parking brake, where pulling and unlocking via, the handle so the cable does the locking, holding it in place, then unlocking. Not sure yet but based on the noises I have heard and starting requirements (I have to ask the question to a mechanic who knows for sure) but I think this is how they work now days. My new electro/hydraulic vehicle has this and some other things that I am having to learn how to deal with
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The last I heard (when I looked into it) was that
electro-hydraulic parking brakes (at least in the state I live in [unless big business had bought this rule out too]) are not legal as there has been a lot of problems with them in the past. My blue buggy came with drum brakes but had the electro-hydraulic setup which did let loose and did body damage to the buggy as it rolled backwards down an alley but (thank goodness for the front-end alignment causing it to turn when going backwards) luckily it did not roll down the hill and out into traffic. The rear brakes also locked up a couple of times on the dunes and I had to open the bleed valve to get the pressure reduced.
Lee
