johnc

Those are good shocks for the money. You can also use the adjustments (to a very small degree) to help the car launch.

I've never spent time thinking about a raised 240Z but what you've listed above sounds correct. Also, I assume suspension alignment and setup is very different for low traction surfaces. I assume you're limited to about 6" in wheel width (for both dirt and tarmac) so some of the issues we face with 10" wide wheels is not relevant. Your plan to use two different sets of struts amkes sense. I would also run much stiffer anti-roll bars for the tarmac courses. You want to control roll as much as possible and keep the narrow tires square to the road.

Then it looks like you have the car setup well.

As Tim and 2126 said above, "No!" Pre-1976 model year cars are exempt from the bi-annual and sale testing but those cars still have to comply with all the smog requirements as of their date of manufacture. A police officer, a BAR offical or contractor, or the DMV can order a specific car to undergo testing essentially at any time and for any reason. I've seen BAR officials take down the license plates of modified vehicles at car shows with the intent of ordering a smog inspection. When I asked them why they were doing that, their reply was, "Random compliance checks."

By design, there shouldn't be any bumpsteer in the rear suspension of a 240/260/280Z. If parts (bushings, mounts, etc.) are flexing then you will see some bumpsteer from compliance, but that's nothing the can be measured on a rack.

Its not that bad. We're just doing some engineering masturbation here, arguing about very fine points of suspension and steering. Once ALL of the rubber is out of the steering and suspension then the little stuff we're discussing starts to apply.

And I'm of the opinion the Ackerman is of benefit to an autocross car but is of little value to a track car. With Ackerman steering geometry the first increments of steering angle show almost no Ackerman effect. Once larger amounts of steering angle are input the amount of Ackerman increases. That works great on the tight, slow speed corners of an autocross. On a race track where you rarely see steering angles greater then 10 degrees Ackerman has little effect. In the past, the NASCAR folks used a lot of Ackerman thinking that it would help turn the car but they ended up overworking their LF tire. Current thnking in NASCAR is for a more balanced front end setup so that the front tires don't fight each other and scrub speed.

Looks fine except, somehow, you slid over into the passenger seat! Do you drive this car on the street?

With all the talk about the bumpsteer problem on a a 240/260/280Z, most folks think that "bumpsteer" is a bad word and something that should be avoided at all costs. Well, that's wrong thinking. What is bumpsteer: Bumpsteer occurs when the toe angle of a wheel/tire changes when the wheel/tire moves up (bump) or down (droop) in its range of suspension travel. What causes bumpsteer (on a 240Z): The steering tie rod end and the LCA do not move through the same arc in the range of suspension travel. What is not bumpsteer: Bumpsteer is not and generally does not cause steering wheel kickback. Why is too much bumpsteer bad: Changing wheel/tire toe angles while a suspension moves through its range of travel causes constant changes in the tires slip angle. This makes precise control of the car's direction more difficult and reduces available grip by a small amount. To some degree the car becomes dynamically unstable over bumps and under braking. Why is a little bumpsteer good: Small amount of bumpsteer (specifically toe-out in bump for the front of a car and toe-in in bump in the rear of a car) can be used to alter the response of the car while cornering. In the front, small amounts of toe-out in bump effectively decreases the outside front tire slip angle during corner entry while load is being transferred. This reduces corner entry understeer. In the rear, small amounts of toe-in in bump reduces power oversteer by allowing the outside wheel/tire to point toward the inside of the corner. It also helps straight line acceleration by increasing rear stability under squat. The amount of beneficial bumpsteer we are talking about here is from 1/32 to 1/16" of change in the first couple inches of suspension bump from static ride height. So, as your mom always said, a little bit of something is good, a lot of something isn't.

Back in the 1970s I had a Q-Jet on the 1972 455 SD engine in my 1966 Pontiac GTO. Mailed the carb to a guy with a small shop back east named John Lingenfelter. When he sent the carb back he called me and said, "Don't ever replace this with a Holley. A well tuned Quadrajet is better then a well tuned Holley on any street driven car." After working his magic on the Q-jet, the GTO went from sporadic 14.5s to consistent 13.2s and I won more then my share of purses at OCIR during the Wednesday night brackets. Also won a number of street races because all the "experts" thought the Q-jet was bad carb and couldn't match a Holley equipped car.

Since swapping these spacers is a simple, trackside thing I suggest you make up 3 sizes and use part of a test day to determine what works best on your car. That's what I did and why I ended up with 25mm thick spacers on a front suspension that did not have the LCA pivot relocated. I even been known to run different thickness spacers on tracks that have significantly more important turns in one direction then another. Try increasing track width with wheel spacers.

Davy, Was that reply directed at me? If so, I'm not building the car, just offering some suggestions. If not, to quote Emily Lattella, "Never mind."

I feel so used...

Uuuummmmmmmmmm... Beeeeeeerrrrrr... [drool] Coors! Why? Because during my teens and early 20s I had more sex while drinking it (and watching women drink it) then any alcohol, drug, or sobriety since. Unfortunately, it doesn't have the same effect now...

Time to get on my soapbox again, and Chewievette, I'm not picking on you or your statement... Any 240Z longitudinal weight distribution in the range of 56F/44R or 44F/56R can be made to handle pretty well. Weight distribution is not the end-all that many magazines make it out to be, for example: an Acura Integra Type R is a very good handling vehicle and its weight distribution is 63F/37R. Don't focus on the numbers. Tire and wheel sizing, spring rates, anti-roll bar rates, shock adjustment, track width, alignement, etc. can all be used to tune even bizzarre weight distibutions.

And, unless you're installing an 8 to 12 point roll cage in the S30, the spring rates you mention will make it a very poor handling "track car." Use the search function on this site.

Mike Kelly, number 3 on Maximum Exposure's "What Were They Thinking?" Max X List! So, about a dozen HybridZers are watching TV a few months from now wondering about the dumbass going boating in the Chevy truck when the driver climbs on the roof... "Hey, that guy looks like Mike Kelly!" Didn't they teach you to steer into the current during driver's ed?

Yup. Because I never raced for more then 30 minutes at a time I didn't need the complexity of a pump, lines, cooler, etc. I changed the diff fluid after every race weekend (3 to 5 hours of running) and didn't have any problems. There's no way, regardless of horsepower, that a street driven car can generate much heat in the diff in a 30 minute drive. Quaifes do generate more heat the a clutch pack LSD, but they only generate significant heat when they are differentiating (going around a corner) under power. FYI... at the end of a 30 minute race session you couldn't put you hand on the outside case of my R180. Periodoc checking with a temp probe showed the case was about 190 degrees and the fluid was at 230 to 250. For a synthetic oil like Redline that temp was fine.

Synchros are not trashed by horsepower, synchros are trashed by the driver. Improper shifting will trash the synchros because they have to take a load that someone who is proficient at shifting doesn't place on the transmission.

Search... been discussed here at length many times. Quick answer: Nissan Motorsports.

The T56 in the Viper shares little with the T56s you guys are talking about purchasing. The gears are shot peened and receive special heat treatments, the synchros are stronger and of slightly different design, shift forks are strengthened, the input shaft is a stronger material with special heat treatments, etc. Even then, the T56 is a weak point in the Viper's driveline when road racing. Lots of folks who race basically stock Vipers, ACRs, and Comp Coupes in VRL have to go through their transmissions at least annually. Adding a pump and a cooler helps.

I suggest relocating the pivot point up .750". I've used .875" but my car was extremely lowerd at that time. To my knowledge the LCA pivot point is the same on the 240/260/280Z crossmembers but I haven't done a survey to be certain.

http://www.betamotorsports.com/services/cageandbars.html For a street and autox only car I would recommend a roll bar. - John

13.6 to 1. Sunoco Supreme - 112 (R+M/2).

Having raced a 240Z with a multi-disc clutch, I can tell you its not a simple swap and its not for a street car. You need the change to an annular clutch release mechanism, you'll need a different flywheel, and you'll need a different snout on the starter to move it inward to match the new flywheel. Also, multi-disc clutches don't like to be slipped. They are either in or out. Slipping them will cook the friction discs and blue the drive plates. On my 240Z the clutch friction discs lasted for 15 hours of track time and the drive plates lasted for 30 hours of track time. The friction discs were $102 each and the drive plates were $100 for two.