tube80z

Just to set the record straight. The tube80 has yet to run under its own power. Hopefully this coming year. But the old design of parts have been statically tested. And we ran this configuration on a modified stock-type arm (toe-control link) on our old yellow Z for three years with no issues. I don't have the means to meaure side load on the struts. And to be honest I'm not all that worried either. What we have here isn't really much different than the front end of a FWD vehicle. I'm sure those have side loads too but it doesn't seem to be too big of an issue. Cary

That's already been done in a Jame's Bond film If you hit the curbs wrong on Medford you can get a little air. And their have been times when that extra little tenth seemed like a good idea. Bent parts after the fact seemed to indicated it may not have been. Cary

Bending the J-bar isn't going to happen often. I did it once and changed things a bit by adding a piece of metal to the bottom. Regardless, the J-bar isn't as good as using a double shear bracket and solid rod end. I think what bends this part is heavy braking and then hitting a FIA style curb or getting the car into the air and coming down under brakes. At least that was my experience. If you look at a number of formula cars from the early 70s and even some trans-am cars from the 80s and 90s they have figured all this out. I was trying to go the easy route and discovered that it isn't always as easy as it looks. The rear arms pictured about from the first version of the back of my car were tested and worked just fine. I didn't see any issues of bending the clevice or the attachment point. But since I'd already seen a problem with the similar joint in the front all this is changing to solid ends in double shear on the inside especially since I was going to double the HP/TQ. And since I did read the Carrol Smith books I owe him that much. And I will probably change the aluminum toe adjuster to a swedged steel part because it makes me nervous too. Although I've used the tubing for TC rods and tie-rods for a long time. I usually build new ones every other year. I had three reasons for wanting to do the rear arms this way. The first, which will sound silly to most, is to be able to quickly change rear toe. And before Johnc rips me a new one for that being stupid I would like to point out that it is an autox thing. By changing toe I can get more heat into the tires when it is cold. The second reason was to increase the installation stiffness and a side benefit I'm hoping for is reduced stiction. And lastly was to have an easy way to change squat/lift and RC positions. On the second version of the car this all attaches to adjustable mounts. All of this is easy enough to test if you have a porta-power and a pull ram. You do what is called a parasitic compliance test. To do this test you push and pull across the axle and note deflections versus force. The second is you push and pull longitudinally (front to rear) again noting defelction changes per load. These kind of tests will tell you a lot and give you an idea of what will most likely be the first thing to fail. This simulates how the forces are actually fed into the pieces. Not a mathematical proof but a nice old fashioned low tech way of measuring this before you do something stupid in front of your friends. It's much better to find something out in the garage where your emabarassment can be contained Cary

There are other bars, you just need to look real close. I'm curious why it appears to have a lot of production car still left in it. Cary

I'm not following all this but I don't think you'll get much stiffness from the rocker stiffenning on top and bottom. Maybe stick to the bottom and build an X across the floor. The center would need to come out but then you could connect the four corners. In lieu of a cage that might be the next best thing you could do. The only other option I would see is to make the car more of a back bone design by enlarging the tunnel and integrating the front and rear suspension loads into this. Before you start any of this you may want to build some basic models and see what works best. Even crude balso designs can help you figure a lot out. Class rules, if you're worried about that, will probably get in the way of a lot of this. Cary

I raised them about a half inch. I don't really know why they look so low in the photos. Cary

It's not the easy. When you open the roof or put a smoke bomb up there it will effect flow. A long time ago some backyard aero was tried on the freeway early in the morning. One car had yarn tufts all over and a chase car was supposed to video and take still pictures of the tufts. What we noticed is the chase car needed to be a long ways away to keep from changing the flow pattern. Claude Rouelle recommended a distance of at least 50 feet in his seminar. Cary

No by pedal ratio I mean where you put the balance bar. On a car wtih a vacuum booster it needs to go a little higher up the arm. I looked at the tilton pedals and used there leverage ratio when I modded the stock arm (distance from pivot to balance bar and total length of pedal). I have driven a car with the balance bar in the stock location and it requires a lot higher pedal effort to get stopped. Cary

Take a look at this site, http://www.airtab.com/. I know one person that mounted these to their enclosed trailer and it does really work. If you look at people that have used them you'll find a link to a 914 that mounted them on the roof like the EVO. He reported that the car felt more stable at speed. Cary

There are a number of theories that also argue that momentum has a rather large effect in explaining how airplanes fly and spoilers work. Aero is an area of interest to me but I don't know enough to have an informed opinion. I can and do have data that tells me a spoiler is worth a large chunk of time even at autox speeds. And that's all I'm sharing Cary

I did option 4. Not that hard but you need to make sure you get the pedal ratio correct. You can see some shots at http://picasaweb.google.com/tube80z/BrakeUpgrade If these are a little small let me know and I can send you larger versions. Cary

We can start with the basics. The car is a FWD chassis. The cage looks to be built for a RWD car and doesn't hook to the front at all. How the legs of the cage hook into the chassis don't seem to make sense. The fabrication is top notch. I wish I could weld that good. Cary

Search the internet for Susprog3D. You can download a working demo and the cool thing is the extensive help files. They contain many excellent referrences. Cary

Not that I have any real experience, but with IRS you could do a number of things you can't with a live axle. Assymetric camber, toe, etc. And you could experiment with packers to adjust when the bump stops are engaged as well as ride height to try and even the weight distribution at the rear. In some ways you're wanting just the opposite of what road racers do. If your car has an automatic have someone power brake it while you watch the rear wheels. You may get quite and education from this and decide that toe can help to fix this (or look at heims or much stiffer bushings). Cary

I have his video and brought it up when I took the Motec seminar with Claude Rouelle. He spends a lot of time discussing suspension kinematics. What I got out of that class was the classical approach to thinking about RCs in general isn't really very good and we don't really have decent tools to work with them. What I mean by that is most software doesn't really roll the car realistically and how the points move (RC, IC, etc.) isn't real and tire and component deflections can cause large changes. You can analyze geometry and some decent cars show a lot of RC movement, which many books tell you is bad. But when you use the force based approach you will find that this isn't the case. Claude went on to say that movement isn't so bad as velocity. That's one item that really needs to be watched. I don't know if you get racetech magazine or not but they had a really good three part article on force based RCs from Andy Thorby. Like anything the more you know the more complex it gets but his explanations were very good and he provided a few tools to help. In the motec seminar Claude goes over pitch centers and how they work, which is exactly what you're seeing here. If you get a chance his class is really a good one to take and will shine a bright light down the mineshaft. Cary

Now if you're gonna tell stories let's get them straight. I cam up to drive as Mike was using my R200 diff from my race car. It just so happens you can't share a car in Woodburn, or maybe any drag strip since that was the and only time I've ever been on a drag strip. And Michael didn't break a halfshaft, he dropped my R200 onto the ground when the rear diff strap pulled apart. I remember everyone giving me crap the Michael broke my diff Then we got to push the car out into the parking lot, remove the numbers, and call tripple A. Then the tow truck driver managed to ding the car up on the way home, and Michael was less than amused. I think Paul's car was about the fastest car there other than a couple of real drag cars (supercharged rotary truck, something else, and a fool on a snowmobile). Yep, small world. There are also a number of stories related to the Medford track, Kelvin's garage, and a number of areas in between but those have been sworn to secrecy. Cary

In Medford an ex-Griggs Mustang took TTOD when the Datsun guys didn't show up this year. Other than that I've seem a demon fast Toyota Starlet, a killer B210 (actually was a GT-5 car), another that had an L20B, and a few older RX-7s that all at one time or another took TTOD. So it can be done but it's not something typically seen. I think you'll see more fast live axle cars at higher speed events. Autox generally seems to favor smaller cars and the deck is stacked. Oh, I did forget some FWD cars that have live rear axles. Do those count? Cary

I'd be careful on that one. What you'll find is that you can quickly screw things up with antisquat and too much will make a car that puts power down well when going straight but oversteers when you press the throttle in a corner. The same is true of antidive and too much of that will make a car have terminal understeer. The big one that you missed for an advantage is the a live axle is simple to setup. There are many pitfalls to be avoided with IRS and a poorly setup IRS will generally not functional as well. Cary

Not to get too far off topic here, but I believe the current theory is his tires lost heat behind a safety car and more importantly ride height. When he came to the next high speed corner the car bottomed and he lost control. I think the answer to why carbon wheels are not allowed in F1 has to do with rules. Last time I checked metal was required. I wouldn't use these on a street car of mine. Maybe a racer but I'd agree with the concern over bumps/potholes shattering them. Cary

should caster plates read camber plates?

These are generally thick enough for that not to be too big an issue. And on my balance bar sleave I used a hone to fix it. In the past I've used some pieces of aluminum round stock I have to control the warping. I don't know if any of this helps or not. Cary

Why would you turn it? Why not alter the front crossmember the bolt-on rear pieces to deal with the larger diameter? I think I'd be inclined to weld the collar to them anyway. That would seem a lot cheaper when you don't have access to a lathe. Good find BTW, I knew I saw them but I wasn't having luck without their catalog. My next trick would be to find these in my shop ... Cary

What I'm trying to find on their stupid site is a adapter for building your own lower control arm. It uses a spherical bearing with snap rings to hold it in. You weld these onto a tube and then you can make your own LCA. I even have a few of them but I can't seem to find them to measure them up. Argh, I'll keep looking. Cary

No, I was thinking it might be possible to use a spherical bearing holder in place of the stock rubber busing. And the stock arm would fit into this. I don't know if the sizes would work or not. Just a rough idea of a possible way this would work with little to no machining. Cary

I don't know the OD of the pieces but I've seen a machined sleave from stock car products that you might be able to use. If it really is one inch then you might not need any machining. Cary