Existing Superduty trucks have "hydroboost" brakes, where hydraulic fluid is used as the pressure to boost the brakes and to power the steering. On 4x4 trucks at idle, where there is not a lot of excess pressure to go around, this often results in a feeling of "locked steering wheel" and has caused some frightening times for folks on occasion.
It sounds like the option is to go back to the OBS truck systems, where a separate vacuum pump supplies the vacuum that boosts the brakes, while the hydraulic pump is solely for power steering, meaning no more interaction between those two systems.
Sometimes more complicated is better?
Duncan
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Girls and other folks who don't know how to drive don't like the power brake system on our pickups. [img]/forums/images/%%GRAEMLIN_URL%%/wink.gif[/img] They want to be able to be stopped with the brakes crammed on and still turn the steering wheel at the same time. So they prefer the old power brake systems powered by vacuum. On gassers, the vacuum is free, but on a diesel you have to have a seperate vacuum pump. We have one for our HVAC controls and for the ESOF hubs on 4x4s, but it's a tiny one that doesn't cost much. When you go with a vacuum pump big enough to power the power brakes as well as HVAC and ESOF, it costs more. So expect to pay more for the optional vacuum power brake system than for the standard hydroboost system.
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My Sierra Blanca is a '99.5 PSD CrewCab hot-rod Towing Machine! BTS tranny; TurboRamAir intake and 4" stainless turbo-back exhaust; DP-Tuner tunes flashed into an Edge Evolution tuner; ISSPRO EV gauges and TTM; AIC; SP-Diesel exhaust brake and torque converter controller. I special-ordered it new and plan to drive it until it quits.
Also the vacuum boosted system (current) does not provide as much output as the hydroboost does, so you have to push harder to get to incipient skid or ABS activity.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SmokeyWren</div><div class="ubbcode-body">They want to be able to be stopped with the brakes crammed on and still turn the steering wheel at the same time.</div></div>
That's the situation the complaint generally comes up in, but the scary one you occasionally hear about has nothing to do with girly truck owners. Down a long incline where the engine is not much above idle (and only because of being driven by the wheels), and with an occasional application of the brakes, all of a sudden you have what feels like locked steering. Not so fun if, like most inclines, there's an occasional curve involved! Just because the engine is at idle doesn't mean the truck isn't hauling butt in some cases... so the lack of steering becomes a lot more than just an annoyance.
Duncan
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The 1997 F250HD Crewcab: Picture
The 2000 XLT Excursion <font color="red">(SOLD)</font>: Picture
The 2003 F250 Crewcab 6.0L: Web page
The 6.0L Bible: Web page
The 6.4L Bible: Web page
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: frobozz</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SmokeyWren</div><div class="ubbcode-body">They want to be able to be stopped with the brakes crammed on and still turn the steering wheel at the same time.</div></div>
That's the situation the complaint generally comes up in, but the scary one you occasionally hear about has nothing to do with girly truck owners. Down a long incline where the engine is not much above idle (and only because of being driven by the wheels), and with an occasional application of the brakes, all of a sudden you have what feels like locked steering. Not so fun if, like most inclines, there's an occasional curve involved! Just because the engine is at idle doesn't mean the truck isn't hauling butt in some cases... so the lack of steering becomes a lot more than just an annoyance.
Duncan </div></div>Also, while not in my SD, I have been in situations when off-roading in my Early Bronco that I HAD to be standing on the brakes (to prevent any movement that would have resulted in a nasty rollover) while at the same time cranking the wheel to get the tires pointed in the right direction to drive out of the situation.
Personally I don't care if the system is hydroboost or not as long as it has enough capacity to allow for BOTH maximum braking and steering at the same time. Anything less is an annoyance at best and a potential disaster at worst.
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Steve Urban
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2007 F350, Lariat High Line, SRW, SC, LB, 4x4, 6.0/auto, FX4, Camper Pkg, HD alt, Red w/custom black two-tone, Buckstop bumpers F&R, Warn 16.5ti winch, Line-X, F550 coils, 305/70R18 ProComp XtremeMTs
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