tube80z

On most hills it takes a third of the way for them to really start working. One trick for any street legal car is to drive around at legal speeds but use a lot of brake gas to build heat into the tires/brakes. As you sit in line that latent heat can make a huge difference. If you have a hill where you all drive to start make sure you do real work to get heat into the tires. Often that can make a second or two up in the bottom third of many hills. Driving at normal speeds on the course can help you at times. But many times the difference between legal and race speeds is so much that it seems completely different. Almost all hills have a required novice program where they often take all of you up the hill in a truck and talk about key areas (usually safety related) and show movies of the course. No matter how many times I've ran a hill I always go to these often taking crap for where I went off on what year and so and so. I'd look for vids on youtube and make sure to record your own. You can watch them at night to help memorize what it looks like at speed. Just make sure the car still drives after the event. At some point we all have a moment when pushing really hard.

I've done a number of hillclimbs in the Northwest. Assuming the roads are similar your setup sounds reasonable. One thing to make sure is that your alignment doesn't make the car follow ruts/lines and that road camber changes in the road aren't a major issue. In general you won't be using your brakes as hard as you might on a track/autox course for most hills. For us a lot of corners have apex speeds in the 45 to 60 range and only a few in the 75 to 80 range, which is usually major pucker when a tree or rock is very close to you. I lost a door mirror on a rock wall at Bogus Basin (Boise ID). At hills you'll probably see more suspension travel than anywhere you race. So make sure you don't hit bumpstops or that could make the car very nervous. My only other advice would be to drive the hill as you see it at about the 95% level. As you learn it you can know what areas you can really keep the throttle down. But be careful you don't try and gain too much time each run. Keep each run close and inch up. I've seen too many people do a few slow runs and then really go for it only to crash. Generally it takes 2 to 3 years before you know the hill well enough to start chasing records, at least for an amateur like myself. And then mother nature often has her say. Hillclimbs are probably the most fun thing I have done in a car. You may go faster on a track but the feel from a hill is something else. And when you're done and talking very quickly or foot won't stay still you'll know it was a good run. Cary

I think a lot of this depends on how high you rev your engine. In most of the cars I've ran we typically used a 3.70 to start with and launched in second and then used third for most of the course. I found that quicker for me than dropping to second and having to deal with managing a lot of torque at the rear wheels. It also depends on whether your willing to change diffs for track/street versus autox. If you don't want to change diffs then I'd look at a lower ratio 3:55 or 3:36. If you're willing to change then maybe lower than what you have and start in second and go for third. As many others have written you want a gear that's good for 75 to 80. I wouldn't use a 4.38 for track days as they generate a lot more heat than a 4.11 or at least that's been what I've seen.

The only thing I saw I might change would be to use safety washers that has a built in conical spacer so the rod ends have more clearance to their bodies. To keep from trying to move the top of the strut you need this extra degree of freedom. Dan did an excellent job in the sticky discussing all this. That's why the majority of the aftermarket arms for the back of the Z aren't really a very good design. I did a quick and dirty set for a friend's car where we wanted to try adding some antisquat. While we never went down that road we did notice the car seemed to put power down a little better. This was on a car with 15 inch FA rears and 436 WHP. I know that's anecdotal but the toe-link arms do remove some stiction from the suspension and any where you can do that it will help. I think another area of development we haven't looked at too close is the outer mount on the rear strut. It would seem to me that we can do this in a more adjustable way that's a lot lighter and mount the heims flat so we're not rotating the bearing in the housing.

I've had good luck with real hammerite. I put it on with a roller and it holds up pretty well. Cary

That rule of thumb doesn't apply to race/high performance cars. It's really intended for ride (flat ride) for not causing discomfort. For racing we are more concerned with balance in the corners and control. As long as the car doesn't hop off the ground in a straight line it's okay. It's also perfectly acceptable to have the same frequency front and rear or the front stiffer. In a high HP car that often is quicker. Cary

You have a really nice car. It would be a shame to try and hack it up to run in EM. As mentioned below you have two options for classes, XP and SM. SM doesn't allow for any chassis mods outside of strut bars and a basic cage as I understand it. XP allows more freedom on the chassis but you can't mess with the firewall. Your car could fit in either class and probably be fun to drive and locally competitive. To be nationally competitive is a whole another story and would require a completely different direction I'm afraid. If you like to drive your car on the street and do track days then I'd look at SM. If you have to put it on a trailer and run on slicks and do autox/track days then XP is probably a better match. EM will require that fabrication become your hobby and you'll most likely end up with a silhouette of a car. If you really want to run in EM I'd either fund a rusted out junker or just build from scratch and put a fiberglass funny car style body on. As mentioned below the best way to pick springs is by frequency. For a more streetable car I'd look at springs in the 2.5 to 2.75 Hz range (most likely 300 to 400 lbs/in). You'll also need inserts that can deal with this and ideally you'd want something custom valved. It's not as big of an expense as you might think and money spent up front is going to be better than buying three of the same part. I'm sure you already know that pain. For an XP car on slicks it really depends a little on the tires. I'd probably start at 3 Hz for a sedan/GT based tire and look at going stiffer. If you run the FA tires then I'd look at springs in the 3.3 to 4.5 Hz range (that's very stiff and requires very good shocks). And to run rates that high you really need to have a cage that ties the car together. So the easy route would be to start in SM and then progress up. But truth be told you won't be much faster in XP than in SM unless you do some serious work to make all the new bits work together. There are a lot of really smart people on this board that can help point you in the right direction to go faster. But the ROI quickly goes south. For bushings you really want to look for other options than poly. The stiction is way to high and that hurts grip. Where ever you can it would be good to change over to rod ends/monoballs. Again this all depends on class. We're all happy to share what we know around here. Hopefully this helps. Cary

One option I haven't seen discussed is to put an X in the floor. Very common in the pro touring car categories (BTCC, V8 supers, etc.) For about the same weight as the subframe connectors a lot of people put in you can increase the stiffness a lot. Ideally this should tie into the cage completing the bottom. The rocker reinforcement shown on Dave's car was at my prodding. We had a hillclimb accident where the driver was seriously injured because this area folded up and struck him. The door bars did their job but the rocker and floor gave up. He now has a limp and was off work for about a year. If you look at newer cars this area has been massively reinforced compared to the Z. Cary

A friend glued the window on his 280Z chump car. It worked great and we saved a nice gasket from being wasted. Oddly the car drove very different before and after. Gluing in the windshield makes the car stiffer and at least in this old clunker you can feel it. cary

You've already gotten a lot of good info so far. One thing I found is that my car worked much better when running stiffer springs and less bar on surfaces that had less grip and/or when it was damp. I would be looking at 100 to 150 more in spring rate and a much smaller front bar and possibly no rear bar. You can then tune it using rake (lower the end for more grip/raise the end to take more roll stiffness). That's a better way to balance the car than reducing traction on one end. For autox the quicker the car will transition the faster it will generally be. I'd look at how much droop you have with the spring seated and see about removing some of that with a limiter. I'm guess you have somewhere around 1.75 inches of droop presently. Try removing 3/4 of an inch and see what you think. It should be an easy and cheap thing to try. And another things most people don't understand when changing only one thing at a time is a change in springs requires a change in ride height or you have not changed one thing at a time. BTW, to go faster you really need to start looking at reducing friction on the suspension. That means getting rid of poly and any bind you may have. That's where the next big gains will come from. Cary

I would see a couple of advantages to this. It should keep the tires flatter on the ground and if done correctly would have a roll center that moved with the car in a 1:1 relationship. Unlike the strut that moves at a different rate. I could see this making the car feel more stable in corners when putting power down or when trail braking. And I could see that making the car quicker just because the driver feels more confident. Cary

We use toe plates at the track and can get within a 1/16th with them. That's measured on an alignment rack after the fact. I can't see how you need to be more accurate than that. My preferred method is to use parallel strings. Tom Holt had a good design I stole from his site (thanks again Tom!).

I'd read some of the stickies and do some searching much of what you're asking has been talked about many times. The spacers change the roll center height and where you are on the stock curve. My only criteria would be the thickness of the spacer and quality of the hardware.

I have the smartcamber and it works very well. It's been at the track for a number of years with no problems. It measures caster by checking the camber at a specific inner and outer steer angle. If you download their instructions you can see the procedure. You could probably do the same thing by using a carpenters square, a tape measure, and some basic trig. I' quite happy with mine. Cary

I think most people never make it past step one.

I don't really want to get into a FWD/RWD battle but BTCC is interesting. If you watch much of it you can see the BMWs often make up a ton a places on the start and then struggle until about mid race where they get strong again. The FWD cars are much harder to get off the line and then are often very quick but seem to lose pace towards the end of the race. And certain tracks are seem to favor certain configurations. At least in this series the different configs use the tires at different rates and that often has a lot to do with the outcome. And in single lap qualifying there's often very little difference between the two even when you figure in ballast. Cary

Rake is a powerful tuning tool. You can use it to balance different spring setups Generally you want to lower the end that isn't sticking but you mustn't overdo it. Most cars will respond to 2 to 3 turns on the spring mounts. For the understeer problem you've been given many things to think about. If you can get some pictures of your car under load in a corner where it is pushing that would really help us point you in the right direction. If you haven't noticed almost all the suggestions are around making sure the front tire has proper camber when loaded. On a Z roll is something you need to aggressively control or the tires will end up in a positive camber placement to the road and you will lose traction. Cary

It was a discussion we had some time ago about increasing installation stiffness. I tried searching but couldn't find it. This mod was quite common on many of the higher end Zs that raced in the 80s. I'll have to see if I can get you a picture of the rear mod they did. It was a bridge plate similar to the front. It might have been in the same discussions where the rear suspension braces were talked about (bridging tranverse link to the mustache mount).

25% underdrive balancer is 6.25 inches in diameter. I got mine from Scoggin Dickey and it's an Australian powerbond brand. I needed the extra clearance this gave the the stocker was almost touching the datsun rack I used as a mockup.

Cables will work but they are not always the easiest to adjust. In another post you were looking to be able to make changes to droop and see how that made the car handle. Your turnbuckle may have anywhere from 200 to 400 pounds of tension on it depending on your spring rate and the amount of droop you're allowing. And to adjust length you will need to hold one end or the entire limiter will try and twist on you. It can work but isn't a super quick I want to change from 3/4 inch of droop to half an inch and test. At an autox you typically don't have a lot of time and may find removing the wheel, adjusting the turnbuckle, putting the wheel back on, and measuring droop takes too long. My new car will have a mechanical system like a reverse bump stop. This should allow me to be able to set the droop based the stop clearance. And I could build a simple step gauge to try different amounts of droop quickly at the track. In my case I'm looking t integrate this into the front ARB. Cary

John's reply has a lot of good info. Maybe this will help too. The suspension movement really has little to nothing to do with the overall weight transfer. That's a function of CG height and wheelbase. But where it will make a lot of difference is on how the car is used. Using a RWD road race car as an example you may want it to squat when coming out of a corner. When the rear suspension drops the RC generally lowers, which would shift some of the roll stiffness forward. This would allow the rear tires to have more longitudinal traction if they are not fully utilized and help the car come of the corner harder. For a FWD car you might want to try the opposite of this. The other thing to keep in mind is the geometric changes cause load to transfer much quicker than spring/shock/arb changes. These can have an effect on a car over a longer run where they may heat up or overheat a tire by working it too hard. And an example where we may want to use a lot of antisquat is on a car that needs to keep a certain ride height (underbody aero). In this case the aero is more important than the mechanical traction. In a lot of the newer books and publications they are not looking at a single axle as much and talking about pitch centers. It's kind of the same thing but looking at what happens the car overall. Hope this helps, Cary

Attached is a pic of the bracing Jon/John have discussed.

From what I remember of the Roulle seminar the ackerman versus anti-ackerman argument depended on the tire construction. It had to do with how the peaks of force versus slip angle changed. So what works on one set of tires may not necessarily work or be right for the next set. Neil Roberts didn't think it was too important for road course work but also mentioned you might as well set it at 100% to make pushing the car in the pits easier. My personal feel is this will be more important for tracks with slower corners and more steering angle (more autox like).

I've had more experience with Kumho than Hoosier street radials. In watching a few local guys it seems like the Kumhos may not be as quick but they last much longer, often to the cords. For the GY slicks the new radials are light years faster than the older bias plies. I would not even consider bias slicks if you have the new option. In back to back tests the radials were three quarters of a second faster on a 46 second course. We only changed camber for the radials (similar to what a Kumho/Hoosier would run). The only downside is they are heavy and a ***** to mount. Compared to Hoosier/Avons the GYs are currently the quicker tire. Cary

Dave's running 436 WHP and 430 WTQ on the 36 with no problems. Neither he nor I were very kind to it this summer. The real downside is ratio choices compared to the 44. On the plus side the price is a lot less. Send me a PM and I can get in contact with Dave/Sonny. Cary