tube80z

Here's an example from a friends car.

I can't count the times I've almost ran over another car towing and trying to get up to speed to merge on a short onramp only to have someone barely moving or stop at the end. Cary

I drove back from Alaska and found the drivers from BC nuts. Passing on blind corners, into tunnels, etc. This was all out in the middle of nowhere but it was always plates from BC. Cary

It's odd to hear fuel running out the throat. In my experience a high fuel level will cause problems with both barrels not just one. And generally you'll have fuel coming our the air vent hole too. If you run the car when it's stationary can you see this? Things I'd check are the acceleration pump circuit (make sure one isn't leaking after they squirt) and make sure the choke circuit is turned off (I seriously doubt this has anything to do with the problem). Check your gaskets as sometimes they do fail and cause leaks. Also make sure the venturi is properly seated. A loose grub screw will allow the barrel to rotate but you'll generally have an issue with the car missing if that happens. You didn't mention anything in our post about that. Everything works fine except for the leak? It also sounds like you have other things to look for too. Cary

The penultimate and ultimate crossmembers were something I did the design work on many years ago. We were racing 510s then and wanted to reduce the rear camber gain to try and keep the wider tires flatter to the ground. Almost all of the tech that was figured out is in this thread. The big thing we found was that you wanted to try and keep the rear trailing arm level or close to level so the camber and toe didn't change as much. The trailing arm angle changes both the toe and camber curves as well as RC position. At least on the 510 the suspension seemed less sensitive to camber being changed on the inner pickup. I would expect the 280ZX to be similar but that should really be verified. Cary

Please note I have deleted a number of posts from this thread that didn't appear to add any value to a really good thread. I would like to ask that we try and keep on topic so it ranks very well in search engine relevance.

Actually I had a similar problem and when I started running limiters and it helped to fix this. The pics Jon has shown plus a number of others were showing the car on the inside edges of the inner tires. The limiters helped keep the inner tire flatter to the road (look at the yellow car example, which was the original car wear all this was tried out). Up until that point I was continuing to de-camber chasing tire temps and was seeing similar wear issues. I would at least test this to see if it helps. Cary

Mine were flipped, turnbuckle mounted on top so it wouldn't move and the cable on the bottom. Nothing ever showed signs of touching anything rotating. Cary

Doh -- what a dumb ass thing to say All I can say is that with how Jon has them there's not been any issues on a number of cars setup similar. Even at full bump there's not much room for these to move. We're talking 400 to 600 pound spring rates. For softer cars that could be a problem. You could always use a small tension spring to keep them pulled a certain way, which is what I did on some brake lines I worried about. Cary

This will all be under tension so it won't rattle around. Cary

I think the issue with it for us is the RC would be way too high. Maybe good for a SUV not so good for a sports car. Cary

Looks good Jon. I used rod end spacers against the struts on mine and safety washers on the outer ends just in case. I hope you have better luck with the slot gap bearings but we needed to change to real three piece rod ends as the others were sloppy after one weekend of use. Cary

You can run cables or you can build a frame that pivots at the back and everything bolts to this. You can even use that idea to independently set ride height and splitter height. I have a really cool video somewhere of the tripple 8 Ford falcon's setup (aussie V8) and how it worked. The other car was Morgan Smith's. He also road raced his car and commented how much more planted the nose was in higher speed corners. It was solidly mounted and would occasionally rub the ground fairly hard. Cary

I have experience with two Z cars that ran splitters. Both were quicker with them than without and neither had problems with porpoising. The level of downforce that we generate is a lot less compared to a sports racer that has a flat bottom and front and rear diffuser sections. I think your idea will work but I'm not sure I'd spend too much effort on it based on my past experience. In both XP and EM you can't run a diffuser section on the splitter and this is what seems to increase the pressure gradient and cause the bouncing. I would recommend that you make the splitter so that it is hinged and can move up when it comes into contact with the ground. That will save a lot of wear and if you do it right you can even leave it on while loading on a trailer. Cary

I think you're right after looking at the larger pics. I just have no idea why someone wouldn't have put the plates next to the tubes. Cary

In looking at the detailed pics I'm not sure it was crossing a gap. I really think this was an attempt to strengthen the piece. In addition to closing the back of the tab I'd add gussets from where the clevice connects to the base of the triangle. That should stiffen up the area and reduce any bending of this section of tube. The rod ends used for his are very low quality. I can tell you from personal experience (having built a few sets of these myself) that these will quickly wear out if they are not quality three piece rod ends (no slot gaps either). I'm also not sure of the bolt is the correct length to have only the shank loaded. I would make sure of that too. Cary

Years ago Pirelli had something similar in F1. I remember reading about it in the old autoweek newspaper format. I also remember two compound tires and other odd things being tried. I also remember my early BFG autox tires had two different sidewall stiffnesses, which is sorta similar. Cary

Make sure to use a liberal amount of anti seize when you put it back together. Even a 5/8 bolt can get stuck over time. Cary

I really like Ortiz but I think his answer was way too short. There's a huge difference in the speed of the weight transfer between geometric/linkage changes versus those done with spring/shock/ARB changes. The tires will know the difference. CAry

The Rouelle info was for the TC2000 touring cars not the WRC car pictured. The TC2000 YPF Ford featured a duct that reintroduced the cooling air (now heated) behind the wheel in a low pressure area. I was watching DTM this weekend on speed and it appears they have a similar arrangement. Why this increased downforce wasn't discussed. It could have been that it helped to increase front diffuser flow are allowed a higher pressure in the front of the car. Sorry, Claude has a way of saying things to get your attention but then often doesn't completely elaborate.

Get a tilt hitch. Makes a world of difference. Cary

Try this http://www.wrc.com/jsp/index.jsp?lnk=300&featureid=1020&desc=Features:%20Aerodynamics. I think this has the movies but my browser refuses to play them for some reason. And the full text article and links here: http://www.wrc.com/jsp/index.jsp?lnk=221&featureid=1418&desc=WRC%20explained:%20Aerodynamics Cary

I have it and I'd say it's worth that much. It's aimed more at the club racer and how to measure and find improvements. It's somewhat like the aerobytes series in Racecar Engineering minus the wind tunnel. But it does have some practical advice. The quality of the book is horrible though. So if you can find it cheaper I would go that route. Cary

Some more cars to check for inspiration are the Argentinian touring cars. Search for TC2000 for some pics. The YPF Ford has a very advanced radiator ducting system that Claude Roulle talked about in his seminar. It was good for 25% reduction in drag and 30% more downforce. The Ford radiator setup is also featured on the WRC.com site in a video with the cars designer. There's also a really cool discovery video that features the prodrive cars and shows them being built. And this was the season they had major issues with water splashes so they feature the ducting and what was done to fix it. Cary

A friend of mine experienced in plastic welding says they aren't too bad. The issue is the tips that are used more than anything else. He has a number of custom ones and this welder was modified to use those. As far as heat source and air mixing it seems good enough. Cary