johnc

> So with proper suspension tuning, the FWD > weight distribution problem (nose heavy) can be > eliminated? The weight distribution on a FWD car doesn't have to be a "problem", its just something you have to account for in tuning. Porsche has done similar things with the rear weight bias on their 911, 993, and 996.

With modern cars the "feel" has more to do with suspension and chassis tuning than drive location. Under about 300hp a FWD race car can get around a track as fast as a RWD race car. Look at World Challenge Touring for the best example. Although the BMW's won the manufacturing championship Klienubing's Integra won the driver's championship (and Acura won the previous year.)

Pontiac fixed the rod bearing problem (heat buildup) with the 455 SD motor. They reduced the rod bearing journal size, forged the crank, and forged the rods. Had one in my 1966 GTO.

Having just completed yet another Skip Barber racing school I can emphatically state that the transmission is used only for acceleration in road racing.

Here in SoCal and in Arizone there's a Pro Truck series where the basic Winston West chassis design runs a 355" crate motor and a three speed automatic. These trucks run road racing tracks lots of times and they are very fast (somewhere between ITS/ITA and GT2). Something has been done to the transmissions so that downshifts are slow and smooth and upshifts are very hard and fast.

I have been told that the order of preference for the "weber design" carbs is: 1. Solex 2. Mikuni 3. Weber I have no experience with any of then, just passing along what an engine builder recommends.

Its hard to increase the track width of a strut suspension without creating horrible side effects. You basically have to move the entire strut assembly as a unit, retaining all the stock angles and relationships. A while ago I got to look at the front suspension of the BMW E36 GT3 and that's basically what they did to get 2" more track width in front. I have seen spindles offset outboard small amounts but I don't know how effective that is.

I'm not sure. My racing motor burned a quart of oil every couple hours of use yet had very little blow-by. The intake manifold and intake ports were spotless. I did run Mobil 1, changed the oil after every event, and ran the stock PCV system. The valve cover vent ran to a catch can (per the rules.) For some reason I'm thinking that intake deposits are mostly the result of fuel, not oil. But, I'm a suspension guy. Motors are just things that make the car go forward.

Actually, a PCV valve is supposed to purge the crankcase of oil vapors. Maybe there's an excessive amount of blow-by?

Normally a worn driveshaft is indicated by a vibration at speeds in excess of 50 mph. You'll feel and sometimes hear a rumble below your right shoulder that increases as vehicle speed increases. Replacing the trans and/or diff mount will make the sound go away for a short time, but it eventually comes back as the mount gets damaged by the vibration.

Compare wheel cylinder sizes. I think you'll find they are pretty close so you can probably just use the stock Z master cylinder.

Yes, you put a spacer under the shock insert.

The suspension of an automobile must provide the following: 1. Compliance allowing the tires to follow road imperfections. 2. Isolate the chassis from the vertical accelerations caused by road imperfections. 3. Control of the attitude of the tire to the road surface. Basically an automotive suspenstion must isolate the sprung mass from the unsprung mass to achieve the three main objectives above. The less mass the automotive suspension has to contend with (both unsprung and sprung) the faster it can respond (the suspension is said to work at a higher frequency.) Since the unsprung mass (wheels, tires, hubs, etc.) must respond to higher force and higher frequency accelerations than the sprung mass (because of spring isolation) then we can understand why reducing 1 pound of unsprung mass is the same as reducing 4 pounds of sprung mass from a handling/braking standpoint. If we look at bump compliance as just one aspect we can see how a suspension that reacts quicker will leave the tire more in contact with the road, thus affording more grip. As for a 240Z, I don't know the exact unsprung weight numbers but its fairly low compared to a number of other vehicles of the era. When calculating the number you need to include 1/2 of the weight of the strut, shock, and spring. The driveshaft and differential are sprung weight and 1/2 of the halfshafts are unsprung weight. The raw unsprung weight number is not as important as making efforts to reduce that number. To determine spring rates you can either ask someone or start with Carrol Smith's "Tune to Win", in particular, Chapter 6 - "Rates and Rate Control - Springs and Anti-Roll Bars."

The S03 series of tire you are looking at are not designed for drag racing. They are an autocross (A compound) and road race (R compund) tire. As such, they should be mounted on rims that are as wide as the tread width. For your 9" wide rims, the optimum size is 245/45-16. And yes, you'll get less than 2,000 miles out of these tires and they are not designed (nor does Hoosier recommend) that they be driven on the street. These tires do not have steel belts in them, puncture very easily, and can be flat spotted quickly if you are clumsy with braking.

Go here first and learn about vehicle dynamics. If you understand this, then suspension mechanics becomes much easier. Physics of Racing

What's up with the Miva store plug in? The store is requiring an upgrade or the Miva engine the store uses has expired.

I think its a terminiology thing. When I see the the term "plastic deformation" I think of a single sustained stress that moves a material beyond its yield strength. As designed a suspension spring should never reach the point of plastic deformation. Springs are designed to work within the material's range of elastic deformation. I guess you could call spring sag plastic deformation, but I think its something else related to fatigue.

Well... There are advertised tire sizes and actual tire sizes. The DOT has certain rules for stating the various dimensions of a tire and standard rim widths that must be used. But, in the real world, things are not what they seem. For example: Hoosier's Sports Car DOT Radial (the S03 series) in size 245/45-16 only has a "245" section width on the DOT specific standard rim width of 8". Hoosier's recommended rim width range is 8.5" to 9.5" with 9" being ideal (because of the 9.2" tread width.) If you call Hoosier and talk with one of their product managers for this tire line (I talked with Jeff Speer) they do not recommend running this tire on an 8" rim. The actual tire size on the recommended 9" rim is 257/45-16.

Sounds possible. I would take a mule engine and test on it first.

I've read a number of posts from folks who run 5.5" or more backspace on their rims. For the life of me I can't figure out how they fit that much. I'm running 2.25" diameter coil overs and measured (repeatedly.) The most I can run in the rear (with a 9.5" section width tire) is 5" of backspace. Am I missing something? Are you folks raising the spring perch and running short springs?

> If you plastically deform the spring (take it > past yeild) If you do that to a suspension spring, chances are your entire car (and possibly you) has been plastically deformed as a result of the accident that occured right after you deformed the spring.

Air bags are constant rate springs just like regular coil springs. If they are sized and pressurized correctly they can work very well. Unfortunately, all the ones that I have seen are designed more for ride height control than performance. The Mother's 3.8L Supercharged V6 PT Cruiser displayed at the SEMA show had an air bag suspension on it. The night before it was to be shipped off to SEMA they brought it to us at EMI to "fix" the suspension because the car was basically undriveable over 30mph. We had to shim the bag mounts so the car could run low enough pressures and still have some ground clearance. It still handled like poop.

A better place for those jack stands are the frame rail junctions just inside of the front of the rear wheel wells.

Not knowing the ZX in detail, you're best bet would be to find one with manual steering (if such a beast existed) and get all the parts from the steering wheel on down. If there were no manual steering ZXs then you might be better off spending your weight saving effort and dollars elsewhere. I don't know if the previous gen steering rack and system can be used on a zx. If you figure it out, write it up for the FAQ.

Doesn't Rebco make both the Outlaw and the Wildwood caliper?