tube80z

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

I think you'll find in this day and age most things are measured the way they are because of convention. SAE has a standard set of definitions that are commonly used in the automotive world so people understand what each other are talking about. Cary

Canola oil works really well too. Just make sure to wash it off before it hardens. And a 5/8 bridge reamer does a really quick job of this if you have one. Cary

But the way the tested made weight much less of a factor. In a semi-steady state test the only factor would be an increase in rolling resistance. And from the results it appears that's a very minor factor. Now if the test would have been accelerating up to a certain speed then the 800 pounds of clay would have made a much larger difference. All that said I was pretty shocked with the result too. I'm still willing to bet you could have used a lot less dimples and gotten the same results. But it wouldn't have looked so cool. I wonder how many people are out there trying to figure out how to dimple their cars Cary

From what I saw in the water tank the dimples didn't seem to be any different than vortex generators on the roof line and back of the car. I'd be willing to bet you'd see a similar reduction using them in strategic places. Lexus already does this underneath their cars so at least one manufacture is on board. With regards to racing cars if it worked and was allowed by the rules it would probably be done. And usually drag is traded for downforce, which makes a much larger difference in lap times.

Yes. Years ago at the Fall endruo in Medford a guy showed up with a group B vega rally car. It had wings, 4wd, and a supercharged cosworth engine. It was the first car I ever saw that could drive over the old high curbs and shifted three times down the front straight. I only wish I had picture. Another time we had a Deacon Monza show up. A Lemans running Porsche 934 and Jose Garza's Indy car. There's been some really bizarre to really cool equipment show up over the years. BTW -- Enduro is this weekend. C

Try searching for bump steer spacers and you'll have a lot better luck.