^^^^
Now, it is of course possible that his use of the term "85%" is more to emphasise that the rear brakes do relatively little. "85%" possibly over emphasising? But "flippant"? - I very much doubt it. In our chat yesterday he also made the comment that the oem rears on the GTI were more designed for 'street' stopping as opposed to a workout on The Ring.
Now having said all that if that figure arrived from a conversation that took into account disc size, piston surface area,pad surface area, master cylinder piston stroke and surface area, pad material and piston rollback measurements then I stand to be corrected and please accept my apologies.
....I'm confident that his knowledge as AP's Senior Engineer will have taken such technical factors into account.
The question is whether his "85%" comment is to be taken literally or as emphasis - I would have to ask him when we next speak.
robin 85/15 would drive crap and thats the sort of split I would expect from a ford fiesta with rear drums.....
emphasis/flippant - tomayto/tomarto - its not 85/15 maybe it would be worthwhile asking your senior engineer mate to clarify.
Front end dive is not a good trait - wherever possible 60/40's ///// 70/30 is the figure
normally aspired to (depending on configuration) , mid engined cars can have 50/50 - I've had many pairs of Ferrari 360 calipers the psiton sizes are the same at 38/42 front and rear, discs sizes are 330mm front and rear, Audi R8 rears are big at 38/42 as examples
The rears should be encouraged to share the load, redistribute the forward energy in to heat front
and rear if you're brakes are really 85/15 then you should get it sorted you'll be amazed at what it'll do for your lap times.
I do a 300mm S4 conversion for 4WD mk4's which upgrade them from 256mm - we've had tangible positive results reported at the first stop, trackers and ringers also reported flatter braking, less weight transfer and better turn in and into corner confidence.
I think the 310mm R32 rears are a worthy upgrade, for a given (similar) pad area and piston size.... in easy terms its the difference between trying to move the rear ABS locking wheel with a ratchet as opposed to a breaker bar. If the rear ABS is kicking in then you need a bigger disc - think about it
One of the reasons for upgrading the pads to DS2500's on oem GTI rears is to reduce generated heat and its ramifications.
The pads reason d'etre is to deal with the heat generated - they dont reduce or increase the amount of heat generated you adjust that by hard you press and for how long, the generation of heat is a positive thing..... its how your setup deals with that through cooling, materials that gives you a good installation. As you probably know pads are classified by their reccomended operating ranges.
heat is a good thing - no heat no stopping the energy has to go somewhere!
Dont know whether its an installation issue but the 2500 compund has been getting a bit of a slating recently over on uk-mkivs, the pad of choice over there at the moment seems to be the pagid blues
Just my £0.02