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Either above or below ground can be made to work. The are some subtle difference and some major ones. Geometry transfers forces quicker than springs/shocks/bars. This can be felt by the driver and a key tool in changing balance. Generally above ground RC will generate higher tire temps and raise the front of the car as it rolls. My advice would be to make this adjustable if you can because if you change tires or do more track days. If you can't I'd shoot for running the lower control arm level. If I had to be pinned down on a range I'd pick someting like -2 to +3. The rear RC definitely needs to be adjustable in my book. Lower to put power down and higher to get the car to turn. You have to manage the loading of the rear tires so that they don't get overheated but still let the car turn and put power down. While this isn't adjustable in a stock configuration I would make sure you take this into account on the C4 rear end. It will also let you experimentally determine what works best with the front suspension, in case you don't have time to make it adjustable. There's a good thread at corner carvers that shows a bunch of C4 geometry. It's listed under putting this into the rear of a Mustang. Dave and Sonny run this rear in different cars in Medford. From what I was able to gleam the C4 uses a ton of rear antisquat to keep the suspension from bottoming, which is a consequence of spring rates picked for a flat ride. Removing most of this makes them work better. On Dave's locost the difference between mounting stock and making the links adjustable made a large difference in how well the car put down power. Install with the halfshaft near level and build adjustable inner brackets (or buy the ones from vette brakes). This will let you change the rear RC. I'd also make sure you have some leeway in being able to raise or lower the batwing and the front mounts. We learned this the hard way. I'd run less than 20% antisquat in the back. Also get rid of the stock spring and go to coil overs. It's a lot easier to setup and work on. Cary

When you mention 1 inch of droop is that total or how much you reduced it by? On 550 Pound springs my car had a little less than 1 inch compression. In the rear I typically set the limiter so that I can slide a 0.040 feeler gauge between the spring and seat (like adjusting valves). In the front I was running around 5/8 to 3/4 total droop. On a really smooth track sometimes less and if really bumpy setup the same as the rear. I didn't have any of the jerkiness you describe. I'm guessing with your softer springs you need more droop in the rear. Try the procedure above for the rear and I think you'll find it helps. We accidentally eliminated droop from a friends car in and it behaved very similar to what you're seeing. So that's my long winded way of saying I think you're on the right track. Cary

Well we won't accuse you of not trying a few changes For tire temps you really need to get down in the rubber. I measured surface temps and they often were cooler and closer together than down in the rubber. As Jon mentioned the key is getting to them quickly after you've been loading the tires up.

Looking at your pressures shows me that you're working the front end much harder than the rear, which you would see as understeer. Ideally the front and rear will build pressure at a very similar rate if the setup is balanced. As a first step I'd go stiffer on the rear springs and add some rake. More camber won't hurt but the pressure rise should stay about the same. If/when you get a pyrometer and average temps you should see a similar trend. Hope this helps, C

I had a similar weight distribution on my 240Z when I ran the FA tires and that makes it very out of square. What I found was that I could tune the car to allow for extra cornering grip and still take a lot of throttle. This proved to be quicker than running the car square with four front tires. I was never able to get four rears to clear everything to see if that was faster. I'm not saying that one is better than the other but I think driving style plays a lot into this too. But if you look at a number of racing cars there are a lot that run staggered setups that don't necessarily have rear bias. But then again there's the acura LMP1 car that got a lot quicker by going square. Definitely something that will need to be tested this next year. Cary

Looking at your pic it appears you don't have enough camber on the loaded side. If you don't have a pyrometer you can also look at air pressure rise. The end that is being worked the hardest will show a larger increase in pressure. Did you track this at all? Your setup doesn't mention coilovers but if you have those I'd try raising the rear of the car (start with two to four turns). This should raise the rear RC up, which should shift balance towards the rear. You could also try lower the front but make sure you don't go too far or the turn-in will get lazy. Hope this helps, Cary

Lisle 55600 in case you need it.

I'll second that and mine was only 9.95

Since I'm posting I'll probably be wrong but I remember those a hot street grind. A lot of lift and short duration. I think somewhere in the 475 to 495 lift range but shorter than stock duration. I had one in a street car in the eighties and it was NOISY. The aggressive ramps seemed to about double the valvetrain noise. I'll have to see if I can find my original BRE book as they were listed in it. Cary

I have a 4x4 Titan and 15 to 16 on the freeway empty is normal for me. Towing runs in the 10 to 12 range depending on how fast I go and what trailer I have behind me.

The video really doesn't have much more than what he has explained in his newsletters. I wouldn't recommend purchasing it. I'd use the same money to buy Neil Roberts new book Think Fast. He has an example of using a FEA model of your suspension that does the same thing Ortiz is talking about but it also takes into account tire spring rate. It's a really good book if you haven't heard about it. Cary

It sounds like the basics are covered here. If you are starting to generate downforce and want to be able to run softer main springs you may look into a third spring. For our cars the easy way to do this is a Z-bar. I think I would focus on keeping the high pressure air in the engine compartment from dumping under the car any way you can. Take a look at pics of ALMS GT2 cars as they have a lot of ideas you can poach (splitters, full length floors, wheel vents, diffusers, etc). Cary

If you ever autocrossed at the fairgrounds in Salem or Redmond this would look very familiar. Cary

Not to be argumentative but you can increase caster and not increase trail. I also think you'll find that pneumatic trail's contribution to self centering is much smaller than that of caster or SIA. Cary

I think mostly what your seeing is a design that has less SAI (steering axis inclination) and a lot of caster. Where I think the magic is in new cars is the bushings. The can be very compliment in certain directions and very stiff in others. Cary

I used to have a severely bent race car and it always pushed in one direction and was loose in the other. When I measured the car I found the wheelbase was about 1.5 inches shorter on one side. Squaring the car made it work the same both ways so I would say this can be used. On a friends car pushing the wheels forward for more caster move the balance close to 1% to the rear. But you have to be careful with rules as a lot of sanctioning bodies require a specific wheel base. Cary

I asked Claude Rouelle in his seminar what he thought of the hyperco perches and he said there were no better than the torrington bearings and caused problems with frequency response in the suspension. He shared a few cool videos from Ohlins engineers that showed how much the spring would rotate and bend out of plan under load. I think Hyperco may have something similar on their site. In the ICP seminar (Richard was a presenter) he talked about the perches and how back in the days of IMSA GTP that they would often see shock shaft failures from the bending loads being placed on them. These perches remove most of that and allow everything to more with less friction. When I asked about struts he said that they tested in a dyno and it looked okay but on the track the side loads caused so much friction there was no real benefit to be gained. For a street car I wouldn't use these as they require frequent rebuilding unless the design has recently been changed. For Toby's BMW has you tried hanging the ARBs from heims as has been discussed before. It makes a similar contribution. Cary

Oddly I had a similar list I was thinking about. I talked to Richard Pare (he invented the hypercoil perches) and he said they offer no advantage on a strut suspension. Were you thinking about them to reduce NVH? I would add a few things. Woodward custom power rack and KRC pump to be able to adjust the steering feel to my liking. An upgraded HVAC system and a decent cruise control. I had a new 1978 280Z with factory air and it doesn't come close the to the system that was in my SER or my Titan. And for NVH I've often wondered if you could put some sand on a bare floor and run the car to see if there were wave patterns that formed (perhaps too low tech). Cary

Nothing. 14x7 is an oddball and you'd be better moving to a larger diameter that has a better tire offering. As OEMs keep going bigger the sixes for our older cars are getting much smaller. Cary

Years ago I got to watch this car at PIR (Portland) and it would outrun all the IMSA GTP cars down the straight and then get caught in the braking zone. Over and over this happened and it was very entertaining. Cary

One thing not mentioned is body size. Try them in your hand first. I bought an original Canon DLSR and won't switch because of lenses. If I could start over I might start with Nikon now and that's based on how it fits my hand. I'm not a fan of how both Nikon and Canon downsized the bodies for the lower end cameras.

MST3K

The pond is a lot bigger than you have here. Basically all the green after the straight is water. Too bad you can't see the big burn mark and tree I knocked over from a few years back. We're now entering the corner at the end of the straight in the low 90s. The last recovery should be on youtube judging from all the cell phone video I saw being taken.

3/16 like yours. These got made in a hurry and I had intended to add a gusset but ran out of time. They do flex some but seem to work okay. My tie downs aren't at a super steep angle so maybe that helps.

Sorry, I totally blew that one. They also work really well when pulling the car out of a certain pond at the end of certain track ... but I don't need to say anymore about that. Cary "three times is too many"