TheNick

I've played with the OptimumG stuff - the user interface is much friendlier - both can get you the same answers - it is just a tad bit more work to get it out of WinGeo http://www.mitchellsoftware.com/prod01.htm

The software is a sample version of Bill Mitchell's WinGeo - you don't get the opportunity to actually model suspension from scratch but it does show you how the use the software. The excel sheets that it comes with are very useful - they are ugly as hell - but there are step by step instructions in the book. If you want 75% of the material and have a quick reference manual - pick up the Haney book instead.

http://www.amazon.com/Introduction-Race-Car-Engineering-Book/dp/0973432004 Better than any of the Smith books or the RCVD book. Shows actual application of the math and comes with suspension design software and load transfer worksheets. While you are at it check out Paul Haney's - The Racing and High Performance Tire - written by a journalist and not an engineer - very easy read - can be done in one sitting and the info is very easy to remember. My personal favorite book because it relates directly to the club racer who doesn't have the means to do all the testing in the world, or they have to work within a certain set of rules that doesn't allow mounting point relocation

There are a few other advantages that others haven't mentioned 3rd spring/damper that is only active in pitch/dive - this explains it better than I can: http://optimumg.com/OptimumGWebSite/Documents/TechTips/Springs&Dampers_Tech_Tip_3.pdf and http://optimumg.com/OptimumGWebSite/Documents/TechTips/Springs&Dampers_Tech_Tip_6.pdf You can also make your sway bar much much smaller/lighter. Also have the ability of using rising rate rocker arms. There is also the ability to change the motion ratio of the suspension very quickly if you use multiple holes in the rocker arms, this will give you a very easy change in wheel rates - you don't have to worry about taking multiple sets of springs with you to the track.

Those other EM cars were spewing crap everywhere - I guess that's pretty typical for them though right The Corvair was supercharged too The BM car was driven by a guy who's taken top 2 or 3 both of the past two years in Topeka and I think he ended up in the 35's raw time - he won PAX too - followed closely by a CM car and then myself and Geoff Chambers in a virtual tie for 3rd and 4th (he got me by .006 seconds!!!!!) I was pretty happy with how things went - that Honda leaves me with huge grins every time I drive it How come you run EM instead of XP? Too light for the 5.7liter? Our courses are significantly faster than what we saw there - last one I designed had an average speed of 45+ and I was hovering right under the rev limit at 55 for most of the course - here's an incar from an STS CRX that took 4th on PAX - no video from my car yet - we don't have the MaxQ hooked up yet with the two cameras (thats the co-driver's - I have a DL1 already in the car)

Got to see Cameron run on these today in Terre Haute - car looked very very good - put down power very well with the LS1 and Cameron seemed spot on with his patience - which was extremely important on this course. Great looking car Cam - what did you end up getting down to? I went over and started changing tires after your second run so I didn't get a chance to see the other 3.

I have a late 70's car titled as a 71. That makes me feel better about weight - I have basically the exact same setup in terms of motor - just need to get it in and running. But with autox season in full swing I don't see it happening till the fall. I made the mistake of typing in "5.0 supercharger" into Craigslist a couple weeks ago...DON'T do that You will see money disappear very very quickly from your bank account

They sell Rota wheels - Rota makes very good wheels for the price. 18racing are good people to deal with too - they were the first ones to get Rota to build a 15x7.5 Slipstream for the ST autoxers a few years ago.

Cool - I'm kinda surprised at how heavy the car is - do you still have a full interior and whatnot?

Still pretty left side heavy - any thoughts on trying to get more weight on the right rear to put power down better and deal with the chassis asymmetries that Cary spoke about above?

Talk to Marcus Meredith at Margrave Motorsports http://www.margravemotorsports.com He revalves Bilsteins on the side of his real job - I've ridden in his ESP Mustang that had 1200lb+ springs and you couldn't even feel the bumps on the course.

http://zzyzxmotorsports.com/library/roll-center-myths-and-reality.pdf Found an excerpt from the Bill Mitchell paper I was talking about Also some other good links if you are in the mood to pay for SAE papers Asymmetric Roll Centers http://www.sae.org/technical/papers/983085 Force Based Roll Centers http://www.sae.org/technical/papers/2006-01-3617 Good PDF File on FRC's and their application https://aerade.cranfield.ac.uk/bitstream/1826/2097/1/Allibert-2007.pdf

You aren't picking on me We're having a discussion And I didn't say that RC's don't matter - I just said their vertical position doesn't effect load transfer. That is actually incorrect - I went back and looked at my reference material and double checked the equations

Great thread discussing RC movement relative to CG height http://fsae.com/eve/forums/a/tpc/f/125607348/m/47110403711

Lateral load transfer is based solely on CG height and track width - the RC location doesn't have anything to do with it. If you are having issues with putting power down then you need to know what the dynamic alignment changes look like under bump. Does the outside rear toe out or in under bump? How much? Whats the anti-squat look like on these cars (I don't know but I have a feeling its a rather large percentage - but I could be wrong - its happened before ) Maybe you are running too much static camber? Try stiffer springs and run less static camber? Not as much roll so you won't need as much camber for lateral acceleration and the tire will be more upright when its time to get on the gas for exit. A large rear sway bar will also make it harder to put power down (what type of LSD? Clutch? 1.5 way - 2 way? Helical?) The LSD type will factor into what size of rear bar you need to run. In a higher HP car - I think it would be advantageous to find a way to not run a rear bar at all like 74_5.0L_Z.

What did you do to remove anti squat? I realize you are talking about a ZX model but the discussion probably is still worth it. Spacers under inner control arm pivots?

Technically - anytime the one wheel instant center is not exactly on the ground - there are jacking forces present. This is why the Kinematic Roll Center calculation has been proven to be more of a "internet engineering masturbation exercise" (I think I stole that from JohnC somewhere ) recently as Bill Mitchell has presented papers at a few recent SAE conventions detailing the benefits of the force based RC calculations (which you can't do with a CAD program or without knowing actual tire loading). His most recent versions of WinGeo has the capabilities to calculate the FRC - you just need to estimate tire loading based on the desired roll gradient, lateral acceleration and CG height. I could try to find the papers - but I'm not at my work computer and don't have access to the SAE library without it. Continue on with your regularly schedule thread

Yup you're right - the 3rd picture in the series is at a deceiving angle and makes it look like the heim mount is at the end of the 2x3 tube that is bolted to the stock locations.

Very similar - but with more of the stock underbelly removed and the inner pivots higher in the vertical axis. I'd think that keeping the CA the same length as stock would be pretty advantageous - the ones in the pics are what like 3" shorter than stock? You know why but for those that don't - the longer your CA's are, the less dynamic alignment change and roll center migration.

I bought a universal crossmember mount from Speedway Motors. I had to modify it slightly because there are differences in the block mounting holes for different 302's. With my 94 Cobra engine - I had to move the engine mount tabs closer together. Cost was about $60 with rubber mounts IIRC and took about half a day to setup and weld in.

Yeah sorry if my explanation wasn't clear - you'd also need to rethink the rear mount for the control arms too. I think its possible to do with some 2" square tube. Basically make a completely new rear subframe. Probably not too difficult if the car is on a rotisserie. Of course I don't know what the antisquat % and roll center locations are like with the stock locations, so maybe there isn't any need to consider it anyway.

I'm still waiting for someone with more patience than myself to come up with a way to adjust anti squat. In my head I see the inner CA pivots cut off and a nut welded in place (vertical/face of the nut pointing down towards the ground) and then an enormous rod end used to adjust the Y-axis/vertical axis height of the front and rear CA pivots. That also a pretty decent way to control the rear roll center too.

Thanks a lot Jon!

Downloaded. Yup I have no desire to go through that pain. I'll pay someone to do it. Thanks! Should any transmission shop have the proper tools to put it in?

Anybody have an good links to a website detailing setting backlash and whatnot for installing the diff in an R200? Rear end stuff is just about the only thing I've never done on a car and I'm hopefully going to be putting one of these in next week.