cygnusx1

Very nice work. I like to see what people can do with "lackluster tools". I am in the same boat.

I have been thinking about this all night after I understood what you are seeing. What you are describing is the strut assembly trying to rotate forward in the direction of the wheels rotation from braking induced moments. With positive caster, this force does have a vertical component and will want to lift the front of the car under braking. However, this is a moment about the ball joint, produced by a force on the contact patch opposite the direction of travel of the car. This is not at all related to the clock position of the caliper. Whew. My brain hurts.

You are really close to understanding this. You are thinking that the strut is angled forward so that a horizontal force at the top will make it compress or extend because of the angle. That is correct. What is incorrect is the assumption that the force is horizontal. It's not, it's always perpendicular to the strut axis so the angle between the force and the strut is 90, cancelling any lift/droop.

I think you can and should mod the VbGarage to do it. The VbGarage needs fixin' anyhow.

Dave, Theoretically, no. Practically, it could flex/bow the strut piston shaft.

And that "twisting moment" will be there, cancelled by the same exact vector, no matter where the caliper is mounted on the clock.

I am only trying to explain. It is tough to explain obviously but when I know something, I wan't to pass on my knowledge. When I don't know something I listen. This time I am trying to make people understand. The main thing to understanding this is that the caliper AND the spindle are both the same body. The caliper is bolted to the strut housing and the spindle is welded to the strut housing. All of the forces applied to the brake pads are transferred to the strut housing through the bolts. The wheel wants to pivot around the brake pads when squeezed, but it can't because the spindle holds it in place. The force of the wheel against the spindle exactly counteracts the force of the caliper. This cancellation happens all inside the wheel-struthousing-caliper relationship. The strut itself (the piston) sees none of what is going on. I am not trying to be a d*ck. I just want to make it believable and understandable.

That movement in the suspension you saw JM, was force from the axles. They are an "outside" force and have nothing to do with the brake. It would do the exact same thing no matter where the caliper was mounted on the clock, or if you wedge a stick in the spokes of the wheel against the strut tube. I think people have a generaly difficult time mentally separating forces that are coming from the contact patch with the internal forces of the brakes. Yes, when you brake, the nose of the car dives, the TC rod gets compressed, a trailing arm would want to lift up, but NONE of these forces are coming from the caliper. They are from the contact patch loading.

My post has already explained what REALLY happens. I can even give you diagrams and actual force numbers but I don't have the time right now to put it together. I am a trained Mechanical Engineer and have worked on cars and designed automation machinery for over 12 (edit: 15..i am getting old) years. The caliper is not pushing up down or sideways on any strut or suspension member. It can't, the caliper is bolted to the strut. Here is an excersise that can help you understand: Hold one arm straight out in front of you. Take your other arm and push down on the arm that is straight out. Is it making you fall forwards? Answer: No. Why not?

bjhines, you are correct about the ABS being the culprit of this semi-myth. The ABS would be converting the wheels momentum into vector forces because of the fact in my point #1. Those "shudders" ARE effecting the way the tire meets the road. For agressive ABS especially, with racing suspension and very rigid tires, position of the caliper could become a factor. For the rest of us with soft suspensions and squishy tired commuter cars, the "shudder" is mostly absorbed by the soft tire and not transmitted to the contact patch.

No, No, No, No, squeezing the pads against the rotor produces a moment about the center of the pads. That moment is completely checked by the wheel bearings as a vector force radial to the spindle and perpendicular to a line between the spindle and pads. In summary, there are NO forces transmitted to the suspension from the interaction of the pads with the rotor no matter where the caliper is clocked on the rotor or how hard you hit the brakes. All the forces that the suspension sees and that are large enough to effect handling are from the tire contact patch and the cars center of gravity acting on the suspension, NOT the caliper. On the other hand a couple of very small, almost negligable forces to the suspension effected by caliper position do exist: 1) In a dynamic condition example with the wheel off the ground spinning fast, apply sudden braking, the suspension will shudder/jolt as the rotating momentum of the wheel is converted into vectors on the spindle. These sudden changes in wheel speed are not usually seen on the street or track unless you lock up a wheel. The "direction" of the jolt will be determined by the position of the caliper on the clock. 2)When the suspension hits a bump, the entire unsprung suspension, including caliper is accelerated upwards. If the caliper is at 9oclock or 3oclock (or trig fraction off either angle) it will impart a slight twisting force to the suspension due to momentum. It is a VERY small force compared to what the suspension is designed for. Go ahead and teach me something new if you think I am wrong.

There was a certain generation of Supra that had the black wing at the top of its hatch. Early 80's. Anyone old enough to remember these?

The 200SX transmissions and the truck series were all internally similar if not identical to the Z transmissions.

I just put you over the $1000 mark. She will liftoff at 185 mph I am betting.

The good thing about stock S30 "aerodynamics" is that it LOOKS fast. When you BS that you car goes 170mph at least you don't look like a total fool standing next to it. I think I'll go donate to the Wind Tunnel thread now...

I have used a GPS unit on the windsheild. My speedo is about 2% optimistic. I have been at 120mph with just a urethane airdam reinforced, and street performance suspension. It feels great but I have no desire to go any faster in a 30 year old car. I can't wait to see the results of the wind tunnel. My wager is lots of lift from underhood pressure and a little bit of vacuum on the hatch area pulling up and back on it.

Beautiful area you live in. The roads around here are twisty like that also. We have a bit steeper terrain locally. The only issue around here is population. You could never run something like that on the nice roads around here with all the traffic and hidden driveways. Were there any Z's? I didn't see any.

Check it out

Ill make it easy: Lower it 1"-1.5" with a kit that has Iluminas and matched springs. Add 1" bump steer spacers front Add front and rear camber bushings 1-1/8" front swaybar, 3/4" rear Poly bushings everywhere. use rubber on the backside of the T/C rods and steering coupler. Camber, have it aligned with -1.3 degrees front and -0.5 rear. front/rear toe set to ZERO. That will be a good street setup good for guessing .92-.96g's with good tires.

Get a suspension package if you can that has matched springs and struts. I doubt your sway bar is 1-7/8'. It's Probably 1-1/8". That is the biggest you would ever need up front. Try 1" front and 3/4" rear. Lower it as much as you want with the kit you pick. 1-2" is acceptable lowering. Dont get caught up with the Pros on this site. They are really good at getting the last split seconds out of a lap, but for the street, you can stick with more conventional "bolt on kits". LOL sorry about the laugh but you dont need bump steer spacers for rear wheels...they dont steer. My suspension geometry is not adjustable. It is totally stock except for the 1" Spacers and the front camber bushings, 1" lowering springs and Iluminas. Don't change too many things at once. One at a time. Street Suspension Importance: **Wheel Alignment after mods. 1 Springs and struts and tires 2 Sway bars (Poly bushings all over the car) 3 Camber adjustment (front and rear) eccentric Bushing type or Camber Plates 4 Bump steer spacers (front) matter of preference. I use em. 5 T/C rod bushings (Poly or aluminum) I like Poly/Stock combo (search) 6 Steering coupler (I like the stock one) Don't worry about what the pros are doing unless you are already deep into racing and you are on slicks.

I avoid rough roads but to tell you the truth the car seems to track fine. I am not sure if -1.3 is enough to notice but the tires are wearing much more evenly. The tramming is more of a function of tire design and toe.

Right Mike. Since we are way off the dangling mystery of the original post (no offense original poster)...My brother posed a question to me the other night about torque, gearing and top speed. He is a big fan of diesel. He touts the torque of them. He asked if it is better to have torque or HP for a top speed. I told him that HP makes top speed. He disagreed and said that with alot of torque you could just keep changing gears to keep in the torque band and keep increasing speed. He was dissapointed when I told him the torque gets divided through gears. The wheel torque would decrease with every up gear change. Was I correct? I think so.

I put the bump steer spacers in before I even knew what they were. As far as I can tell, they do keep the control arm more parallel with the tie rods when looking at them from the front. They also keep the roll center of the car above ground which I hear is a good thing. The camber bushings are fairly easy to adjust when the car is on jackstands and you have the right tools. Just loosen and adjust and lock.

Nice videos. IMHO, rally drivers are the best drivers...or at least the craziest. The navigators....are even crazier. Here is one of my favorite films. Hang on! Edited: to the higher quality link! http://www.youtube.com/watch?v=s9q845WtC5I

Generally, a taller gear with a turbo motor lets you stay "in the boost" longer. The added load from the tall gear spools the turbo that much harder. This is the same reason that my turbo Z loves climbing hills. I have a 3.54 but would love to go taller. In first gear, the tach goes by so quickly that the turbo can't catch up.