tube80z

Go the SCCA website and look at the current fasttrack. This is listed under items for the BOD to vote on. It's not a done deal but generally when they get this far it's a pretty good bet.

If you read some of the latest news coming from the SCCA they are allowing 200 pounds off the min weight by sticking with 275 or smaller tires. One of the issues I'd see trying to do SM2 in the Z is 18s are going to raise the car. And to take advantage of the narrow track I'd think you'd want to do all you can to lower the CG. SM2 cars are really fast from the results I saw from nationals. But I'd look at CSP for some inspiration of what can be done with a lot less power. The problem with a lot of the packages I've seen is they are difficult to drive to the limit. Have you driven a 400 to 500 HP S30 in an autox. It's a lot of fun but to get the last little bit is a real trick. And forget all the fancy shock stuff unless you have a datalogging system and know how to use it. I've seen plenty of Penskes on cars that would have been better off with non-adjustable Bilsteins. In the end there are probably four key things to keep in mind. You need to build the car and you need to remember what makes a car fast, not what everyone else is doing or how much horsepower someone has. You need to be able to drive the car, which means you need to be comfortable and the car needs to be easy to drive. You need to be able to tune the car and ideally this needs to be done to the track and to the conditions. I've been to a number of national tours and I rarely see this being done. And lastly the car needs to be easy to work on. It's probably going to eat a lot of parts to be competitive. I'd vote for XP personally. More room to work on the problem areas. Either way it sounds like a fun project. Cary

You could take a few clues from newer cars. Almost all have a stout bar running across the dash expanse tied into the door frames. And they have a bar across the car below the seats. I'd also think in a S30 a rear strut bar could serve some function in side impact, assuming it's a little bigger than normal. And the bars from the front of the rockers to the TC boxes would help some to spread load from a side hit. If you have a really old S30 consider some newer doors with door beams. Cary

These lasted about three events before pounding out the liners. We switched to Aurora bearings, AM series if I remember correctly, and they are doing better. But even these are taking a lot of abuse. They were very stiff when put on the car and now are very easy to move. I recommend the 3/4 rod ends to Jon because they have a lot more bearing surface area and the price difference isn't that much. I would have thought the front would take more of the load too. It was a 3/4 QA-1 part and it had no slop and was still pretty tight. The same batch of 5/8 QA-1s were used in the lower front control arms and for TC rods. These are holding up fine. So I do think there's a lot of stress back here. Of course this is a V8 car driven by a couple of immature adults that giggle everytime they see 14 inch black marks get laid down. Cary

Not that it matters on track days but if you autox some people get fairly pissy about wheel base changes. Given that I'd opt to do the change up front for more caster. Are you just wanting to center the wheels in the wheel well or is there some other reason driving this?

The arms I made ended up about 3/8 wider than stock to get the CV axles to work. We ended up modifying the arms to where they are maybe stock or an 1/8 wider. The axles still have some room to move. The rear arms are very close to flat (as in the pics I sent) and you have to watch droop or you'll start to loose free play in the axles. We moved the upper pickup point for the plate out to get camber in check. The hoosier radials don't seem to like a lot of negative camber (-1 in this case). The key as you mention is to find an axle and then build everything around that. And you have to decide if you want a narrow or wide car. Cary

Not sure, but I would at least make sure to keep the same front to rear distance. What I was looking at doing was moving both points back a little to make it possible to raise them up a bit. Cary

Another option is to shift the mounting points back a bit to gain clearance. You're still going to have to do some work in the sheet metal probably but you could change the inner mounts to rod ends and use custom arms as in a couple of the other threads. The benefit of doing all this is you have the ability to start playing with squat. You do need to be careful when you raise the inner point you don't foul the half shafts. The car above may look cool but that rear suspension isn't going to work very well. If you're flat statically you may find the having the arms drop a little as above helps to put the power down. At least that's one things we've seen from the cars setup this way. Another option is to change the outer as Terry did in yet another thread. Lots and lots of options -- pick wisely Cary

My vote is more rear percentage. What I've seen is the more power you have the more static weight on the rear helps. I had to run 200 lbs. of ballast to be legal in FP and when I moved it from the passenger side to hanging off the diff the car was quicker. But you're right that a number of things change and it's hard to pin it down to any one item. The other question I'd ask is whether the car performs transitions better with a passenger. That's also very important. And I agree that this is all really fun. I had a good weekend too and found out how well a splitter can work. Cary

In thinking about this some more I wonder if the wing is more about yaw moments rather than downforce. I could see that helping to make the car more stable in turns. Cary

Please keep this myth going. We've found that 35 MPH is about the point where you can start to see some aero advantage. At 45 MPH it's clear as day. Cary

That's pretty cool but I'm skeptical it works any better than when set at max downforce for autox. I'd like to see a back to back test showing speed and g traces. I could definitely see this working on road courses. Cary

We did a T10 conversion for a race car and used the quicktime bellhousing that sets the tranny forward and had to manufacture the special pilot bushing. Later found that the LS7 bearing is very similar. Now it looks like Mcleod has an offering too. I was pretty excited about the article when I got the magazine but that didn't last long. It read to me more like a advertisement for buying a Mcleod flywheel. If you want a light weight flywheel then you have to look at the above option using the LS style flywheel. They mostly glossed over the use of an annular throwout bearing info. It would have been nice if they would have discussed more options for clutch and pressure plates to use the lower cost chevy parts. Oh wait, if I buy the Mcleod flywheel I can do that too. I give it a half thumbs up. But most of the info already seems to be on this forum. Cary

For pressure we've been running 22 to 24 lbs. You may need to bump this a little for the track. Softer will heat up the tires more and maybe too much. If you run bias air pressure you'll probably lose the tire off the wheel (another oops that doesn't work moment). The camber has been used at hillclimbs and autox events. No track days yet. So take temps and make sure the tire looks good across the tread.

I totally agree, but what I was trying to get at and poorly worded as a flimsy chassis generally needs a lot more to see a change. Meaning you need to make larger jumps in bars or springs. Anyway, I think I'm digging a hole here .... Cary

The chassis torsion is just another spring. Even though you've stiffened the front it's hard to say if it really changed the overall chassis torsion. If that hasn't changed then you probably won't need a change. It's somewhat hard to say without some numbers to take a look at. But as a general guideline if the chassis becomes stiffer you can run softer wheel rates to get the same result. What you need to know is what is the lateral load transfer distribution on your car. In the spreadsheets at the top of this thread that's referred to as the magic number. One option that I've found that works for me is to setup the suspension to try and get equal roll angles front and rear. This minimizes the need for chassis torsion. It has a side benefit of making the tires last longer and that's a big plus for me. Cary

The hoosiers are a little bit of a different animal. What we've found playing with them this year is that they need similar levels of camber to the bias plies. But to make this work you really need to control roll. So I'd start out running what you have listed above and look for temps. They seem to like about 10 degrees hotter on the inside for us. These tires do not seem to like camber gain very much, which is a plus for us. We're taking care of roll and running the fronts at 1.5 degrees and the rears at 1 degree (all negative).

If it's an R180 you'll find it won't work.

Unless you change the rear control arms to a different design you can't change the angle of the rear struts without putting the suspension in a bind. Ideally you'd install everything to make sure you don't have a bind and then tack in the plates. Cary

So commander cheap is finally parting with that

How much of a change can you get in your magic number by changing chassis rake?

There's also the cross weight change that happens because of caster. Put a car on scales and turn pads and you can really see it all working. Cary

It's probably just semantics then. I'm thinking weight transfer based on wheel base and Cg height. I guess going to a lot lower spring rate will cause the front to rise and the rear to squat but the overall Cg height isn't going to change that much is it? This is more what I was thinking and I call this load transfer. So I'd agree stiffer springs will increase the load transfer. And I'd agree softer springs will slow it down. But at the rates mentioned I have a hard time believing there will be any advantage based on the suspension moving a lot more and having camber change that works against you. My thought would be that this would be better controlled using shocks since what it appears we're looking for is based on suspension movement. Maybe softer rear compression and less front rebound. My own experience shows a slight gain in performance when running 450 pound rear springs that when my car was running 175s. But these were not using drag tires (FA rears). It seems like there are some people on this forum that are going really fast with the independent rear. And if I recall correctly one of those cars was using bumpstops to limit the rear compression. That will increase the rear spring rate fairly quickly. So I think the rear tires can handle a lot more than we give them credit for.

Weight transfer has nothing to do with the springs. I'm not following how that's going to work. I'm not a drag racer so maybe I'm missing something. Cary

I've seen pictures of a number of the Dodge Vipers that had vortex generators on the underside of their splitters. These were in front of the tunnels that fed into the wheel wells.