tube80z

I know you don't like my advice. But if you're going to use small chokes you should really put 40s on the car. It will work much better. If you decide to put a larger cam in this engine similar to the old datsun comp rally or slalom cam then you may find the larger chokes to work a lot better. We ran 32 mm chokes on a autox car for quite a few years. It wasn't until we started testing some of these pieces did we find these just don't work as well as you'd think in 45s. In our case the larger chokes were better across the board. This engne had a little over 11:1 compression. Cary

The 15 inch Atlantic tires are a good choice and readily available. For what it's worth I run the 13 inch Atlantics and have similar pressures (looking for 18 to 18.5 HOT). Make sure you get fronts if you go for the smaller tires all round. In the 13s there is the same size that is a rear and when you get them on the front the car won't turn for crap. Just something to watch out for. If you go to a pro Atlantic race you may be able to haul off some of the yokohama radials. They are designed to run on a 12 inch rim in the rear and you'll be in the 24 to 26 HOT pressure range. I've found it much easier to use two sets of wheels/tires. I keep notes on use and match them that way and flip each on the wheel after three events. The bias ply tires will grow as they are used you can use this as a guage on what tires to match up if you buy used. Each year I introduce a new set to replace those that are in the worst shape. This has allowed me to drastically reduce my tire budget. I have the tires on nitrogen and they are bagged when not in use. Cary

That's a really bad thing to do. 32 mm chokes on a 45 are not going to flow was much air as a similar choke on a 40. I did this test years ago on a flowbench. You need to stay above 35 mm to break even with 45s. For an agressive cam I'd think you'd be looking at 38 and still have decent mid and bottom. Cary

A friend of mine runs the goodyear 16 inch radial in a 250 compound with 550 springs and koni insterts. It works very well although many claim the shocks can't deal with this. There's nothing wrong with picking a known quantity and the 16s certainly are. You might be faster on 15s or even 13s. But you'll have to figure out how to make them work. If you're up for the challenge it can be fun. It can also be very frustrating when you start going backwards. Cary

If you run with a pavement temp under 95 degrees the 25A may be faster. It also depends on how long you run and how hard the car is on tires. If the temps are higher or your car is hard on tires then I'd opt for the 35. Cary

Yes' date=' kinematic changes (suspension geometry) will have more influence to the handling than what you can get with spring/bar/shock changes. If you're looking to really increase performance this is an area to focus on. A good DIY book is Race and Rally car sourcebook by Staniforth. For more of an engineering approach, Milliken's Race Car Vehicle Dynamics. And an even better option would be to invest in Claude Rouelle's seminars in data acquisistion. He spends a couple of days talking about vehicle dynamics. It's like having a book you can ask questions of and get answers (http://www.optimumg.com). And if you're really fortunate the seminars by ICP (Richard Pare and Steve Lathrop), which are aimed at club racers and have a ton of good info on them. Cary

Active suspension doesn't defy the laws of physics at the end of the day weight will still transfer. It does offer extraordinary control of how that transfer is proportioned and that is the key. I seriously doubt anyone will offer a retrofit kit ever. The software would need to be fine tuned to each application (car, tire, use, etc.). A basic Motec data logger that has the minimum amount of channels to do this will set you back at least $5k. So it is interesting but probably not of much use to us. Cary

It was nothing more than being able to make a quick change in a repeatable manner. Often when we have sub-minute runs I only have 4 to 5 minutes at most before I run again. So taking temps, pressures, and deciding what needs to happen is really compressed. The tube car will have a number of adjustments done with shims so I can make changes very quickly. I'm hoping for the limited amount of time I have to practice it will help with testing. Most times if I get out of line than I have a huge wait. So the theory goes that I need to make as many adjustments as I can in line with very basic tools. Cary

I have the GC plates and originally got them for a 280Z. When I test fit them they seemed to have room for caster adjustment. So it may be that the older 240 has a much smaller strut tower and that's something I'll have to take a look at as I have friends with just about all versions. The instructions I got were a joke. You'd think GC could supply some instructions drawn on CAD with an acutal size template for drilling and cutting. What I got looks like a fax of something someone drew on a napkin. What I do like about the plates is how the transfer load from the spring to the plate rather than the spherical bearing. I ended up changing how these mount on my car. I put them on top of the tower and made a plate the goes under. My toughts at the time were to come up with a shim arrangement to allow quick camber adjustments while autoxing. Cary

I should point out that 13s do take some work to get good brakes and steering arm clearance. For tires you can check e-bay, local race tracks, http://jbracingtires.net/index.htm, and other sources. I get most of mine from John and he's always treated me very well. Tires are bagged when not in use, mounted with nitrogen, flipped every three events, and treated with Formula V as needed. I start with two sets and after a year I rotate in a new set. I keep a running log of their use and match them by diameter. It's important to do this with bias ply slicks as they grow as they are ran and you can end up with weird handling if you don't adjust for this growth. I try to keep tires matched by diameter on each end. Radials needn't worry about this. And I get the car off hot tires as soon after a run as possible. It all helps to make them last longer. Cary

Yes' date=' that the idea. If you mount the heim in the right spot you should be able to the keep the installed height about the same as a normal bushing. Even if it ends up being taller it won't be enough to cause a major issue. Keep in mind this was a Rocketsports TA car and they have deep pockets. They appear to have used a 3/8 MS spec rod end. I'd opt for lager cheaper ends. I'm guessing a half inch would be overkill but you can get a cheap grade. Or a decent grade 7/16. What's really cool about this mounting method is that it lowers the friction of the swaybar mounts. Poly mounts can have quite a lot and what most people don't realize is the solid U-shaped bars bow in the middle when worked, which leads to more friction. The heim allows this to happen with no worries. And reduced friction always equals more grip. And if you don't want to do this you can always wrap teflon tape over the bar where the bushing is. Or make plastic bushings that have better lubricating properties. The teflon tape will help against squeaks for street cars. I guess the pic helped Cary

I picked 13 inch wheels for a smaller diameter to ge the car lower without messing up the geometry and have less rotating weight. After a lot of research I picked formula atlantic tires because of availability (cheap on the used market) and they had the latest in constructions. A lot of people have told me this won't work -- I didn't listen. I run Hoosier tires in R25A (when it is coler) and R35 when it is warmer. Just remember that different tires have different spring rates and this all has a major impact on your suspension tuning. Pick something and stick with it or you will be chasing your tail. Cary

I don't have pics at work of this. I'll try and find a pic tonight. The heim attaches to the car with the head hanging down. On the sway bar is a split clamp with ears. This is bolted to the bar and then this is bolted to the heim attached to the car. Maybe that helps? Cary

Nope, you make a bracket with ears that hooks to any bar that you have. Think of a split clamp with ears. Here's a pic In this case the heim hooks to the swaybar. Just think of this in reverse. Cary

So you effectively have studs if I get the gist of what you did. Should work. If you're going to weld things to the car I'd look at putting a boss either inside or outside for a heim joint and hang the swaybar from it. Much lower friction way to mount. Cary

Where's the spring going to go? It's trapped. It may not seat correctly and that may end up damaging parts but I've never seen an issue from running on the streer or autox/hillclimbing with coilovers. It usually only happens when you jack the car up. There are a couple of things you can do to help as well. You can wire the springs to the spring seats (some use zip ties) or you can use droop limiters to make sure the spring is always seated. Having enough droop so that the spring is completely unseated isn't going to get you anything. It also makes jacking the car off the ground a little easier. Cary

You basically have two options. Two classes you can run in and keep a semi-steetable car on DOT tires. Those are street prepared (BSP) and street mod (SM2). It sounds like you want to do a number of mods that would move you closer to the SM end. From the little that I have kept up with SM it sounds like bolt-in subframes are now legal and that means you can relocated all the suspension pickup points and make the amrs longer. The other option are the three slick tire classes. Those are FP, EM, and the new AP. With the exception of AP, which is a bit of an unknown, you will not have a very streetable car if you intend to be semi-competitive in these classes. Most creature comforts are thrown at right off the start. It's really up to you at this point. I'd opt for a semi-street legal car if I were to do this all over as it helps to get some mileage on certain parts. And if you can truly replace subframes then SM2 sounds as good as any and you're likely to have a few people to run against. Disregarding what PAX says, I think in an older car like the Z that prepared will be faster than SM. Mostly because of what you can do to reinforce the chassis. Cary

You have a few too many open ended questions to completely answer this one. I will offer that you don't want to mount the bar in needle bearings. As the car flexes they will bind as they are not designed to deal 2-axis misalignment. A better solution, commonly seen on Trans-Am cars these days is to hang the sway bar from two heim joints. This will allow for bending of the bar and mounts as well as rotation. Another option is the pillow ball mounts you can find for many of these bars. They have a spherical bearing the bar goes through. Coleman, SCP, speedway should have all these parts. Cary Cary