:I had this truck, with ABS on only 2 wheels. Believe it or not, it was the
:back two wheels that had ABS. The fronts did not. Why? You ask. Well,
:I'll tell you why. And how is this relevant to a car with 4-wheel ABS?. Also keep in mind a truck's weight bias (unloaded) will be more towards the front. The rear of the truck would tend to be more skittish to begin with anyway. Not a comparable theory here. If you have only ABS on the rears, the design of the system is intended so that you don't fishtail the vehicle (which trucks without any ABS are notoriously known for thanks to the front weight bias).
:1) Understeer is more desirable in a street car (from a manufacturing standpoint, it is "safer"). Understeer is indeed safer, and you are correct there... BUT that's from a suspension handling perspective. That's dialed in at the suspension and alignment level, NOT THE BRAKES. Studies have shown that an average driver will usually let off the gas than hit the brakes when the car starts sliding. On a car dialed for understeer, letting off the gas allows for the driver to bring the front back in control. On a car dialed for oversteer, depending on conditions, letting off the gas may cause disasterous results. Have you personally driven a car with just a larger front brake kit? I don't see a mention about brakes in your profile. I've driven a few and have noticed similar behavior under extreme braking conditions. I also developed the Supra big brake conversion kit that is currently being tested and is also a subject of discussion on numerous occasions on this board. But what what do I know... lol If you lock the fronts up on a normal car, then you can not turn to avoid a potential accident under that condition. It would be easy for you to say "well just pump the brakes and you'll be fine." But how many average drivers out there do you think would actually think to do that in an emergency? There's also the argument about the drivetrain layout of the vehicle... FR, FF, RR, MR, 4WD, AWD. Then there's also the front/rear weight distribution to consider as well. The Z32 is an almost 50/50 split... the truck on the other hand is probably somewhere around 70/30. Then take into accout weight tranfer during acceleration and braking. On an average car, approximately 70-80% of the braking duty is performed by the fronts. Now slap on just a front set of big brakes and you've suddenly changed the balance of bias. Now toss in the weight transfer to the front under hard braking you get the idea... :2) When wheels lock up, what happens? Well, if you're going straight, not a whole lot. If you're turning, locked wheels means sliding "end". Fronts locked, you push into understeer. Backs lock, you get your ass end passing you on the outside of your turn.
Right. Any moron knows that (I hope... otherwise we're all in a heap of trouble). :Your point of brake balance being upset has some validity. However, it would not be your tail end coming around, but your front end pushing out. Now, since the Z has 4-wheel ABS, and it should keep all wheels from locking up, I would say that the ABS (at the limit) will equal out things as much as it can. I never said the tail would come out, I said under track conditions, braking hard INTO a corner would make the rear end skittish. Can you whip the tail around? Sure you can if you really want to... I've make the car step out that way before. You speak of the ABS as being the equalizer. Perhaps it's true, but I do not totally agree that it will completely "fix" the bias issue. My reasoning is this: The ABS is computer controlled and the computer is pre-configured (or preprogrammed if you will) based on the orignal factory specs of the OEM brakes. Now when you suddenly increase the braking performance of the front by X% and the rears are left alone, the computer may try to learn and compensate for it but as with most computers, there is a range of acceptable values. Take the basic idea of sensors on a car for example. How does an ECU know a sensor is bad or faulty? Because it was programmed to notice these things. When a sensor falls out of its acceptable operating range, the computer knows something isn't right. The computer, if programmed for this, will try to compensate or go into safety or fail safe mode. I can't say if the Z32's ABS computer functions exactly the same way but using basic logic, deduction, and track experience, I would think it's a safe bet to assume it functions similar in the methods. The Z32 ABS computer have been known to not function correctly when using different diameter wheels and with different rolling circumferences (between the fronts and rears). So my arguement about the ABS not really "fixing" the new bias problem isn't totally unfounded. Generally speaking, if you were to do BOTH front and rear kits, then the bias issue wouldn't matter much as the difference in bias from front and rear would be virtually nullified and negligible. But we are discussing about a front only set up (NOT a front AND rear). How much good/bad this does... well, someone give me a
:wildwood set (front and back), and I'll test it out. :-) And just how would a front AND rear set up support or disprove the theories and assumptions put forth for a front only set up? As per my original post, I said under normal street driving conditions, a front only set will be fine to use. This is where 90+% of the Z-ers will be driving (very few people I know actually track a Z). The difference in the heavier front brake bias would only become apparent under track conditions. Oh, well, the wildwood set claims to keep stock brake bias (with stock back brake, I don't see how...), so I guess that'll be a set of wildwoods, plus some other front-only set... :-) If you also don't see how the front only set would not affect the stock brake bias then why are we having this discussion? My original post points out the fact that a front bias is expected with a front big brake set up only. Your skepticism to the Wilwood claim just supports what I said earlier.
Harry
1992 Z Twin Turbo - Stage "Who gives a sh!t, it's overated anyway."
2002 Subaru Impreza WRX
1993 Honda Prelude VTEC ICQ # 1553422  Check my site out!
 
"OMG! I'm going straight to HELL!!!!" - Wolf [Pittsburgh] Click to find out why... LOL "my girlfried is inside my dashboard....." Posted by: DeLL116 on April 14, 2002 at 04:59 pm
YugoBernie: i mena that in the best way
YugoBernie: my left ball wont fit on it
SpdDemon13: well you need to talk to spee about that
YugoBernie: thats not right
SpdDemon13: lol
SpdDemon13: sig quote... lol
YugoBernie: damn you
SpdDemon13: mwahahahahhahaha
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