LSP & BV design question?
all this talk about adusting the load sensing proportioning and bypass valve got me to thinking as i was driving the doublecab around town. can anybody help me to understand this a little better?
ok, so i agree, if you lift your truck or even if you have a slight misadjustment from factory specs, shifting some of the braking bias back to the rears should help you stop, assuming it wasn't adjusted right to begin with. it makes sense that all four wheels working together in the correct proportions should minimize your stopping distance in a panic or emergency stopping situation.
so, imagine i put 500 lbs in the bed of the truck and it lowers the bed by 1 inch (theoretically, substitue whatever weight you want) or i raise my truck with a lift kit in the rear. the result is that the valve mechanism adjusts the rear brake bias to compensate for the load it thinks is over the back wheels. the shorter the distance between bed and axles the more rear braking, more distance, less load (it perceives) and less braking in rear.
ok, now image the back wheels aren't getting enough brake pressue because the valve is misadjusted for whatever reason (lifted truck, not set correctly, etc.) this shifts more of the braking towards the front causing the truck to nosedive during a quick stop causing even less effective weight in the bed (ie, rear springs flex down and shocks extend causing even less brakeline pressure to go to the rear wheels). i know on my truck, i can visually see the front of the truck drop at least an inch even with good participation from the rear brakes.
now, take it a step further. the front wheels hit something slick and the abs kicks in on the front because the wheels start to skid. isn't this pretty dangerous? i mean, i can see a situation where you basically have no brakes because the abs sends the pressure to the back but the load sensor closes down the lines.
what do you all think (besides that i should have better things to think about while i'm driving around town!) ?
seriously, though, this seems like a dangerous misadjustment that multiplies itself. low rear brake line pressure causes front brakes to work harder causes front of truck to dip in stops with corresponding rise in rear of truck and even less brake line pressure sent to rears when back of truck lifts.
i could see this being the cause of some of the mysterious brake failures i've read about in other posts.
ok, flame away... maybe i'm missing something?
don't get me wrong, i think it's great that toyota gave us a way to adjust the brake bias on our vehicles. i really wish i had this option on some other cars i've owned. i just think the way it's done mechanically based on position of the rear of the vehicle relative to the axle could be pretty scary in some situations. any thoughts? experiences?
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