JMortensen

If you didn't want to swap out the brakes, a wheel spacer should have roughly the same effect.

If the front diff mount is weak, then the diff can really twist the bar hard. I had a friend with an R180 (weaker mustache bar) and the U-joints from the driveshaft hit the ebrake linkage and trans tunnel. That's a lot of twist. The bars are spring steel, but they aren't indestructable. I suspect that most of the time that has a lot to do with the the front mount not doing its job. FWIW, I don't think the aluminum mustache bar is a good idea, especially if you're using a stock front mount. Aluminum is a poor substitute for spring steel if the part needs to bend and return to its original shape.

Obviously the straight one has more potential to make a lot more downforce. I think you need to duct the radiator though, otherwise you'll end up shoveling extra air into the grill which can result in net upforce as John Coffey has talked about in the past. If you go big on the splitter, you'll probably end up needing something in the back end, spoiler or wing, to balance it out. It's not just a one and done thing.

I did Zero Rust on the underside and Rustoleum primer inside and out.

I used it quite a bit on my car and on some of the metal that I used to make patches. Worked well so far as keeping surface rust down goes. I never painted directly over it, always wiped down panels with acetone and did a little scuffing with scotch brite or sand paper, haven't had any problems with paint peeling or anything. Still working on my build, but I painted some of the parts 6 or 7 years ago, and no sign of anything peeling off or any other issues.

AZC knuckles decrease the turning radius. The T3 tie rods say that you have to drill out the steer knuckles, so you'd have to do that with the AZC knuckles too. It would be A LOT easier to drill out the AZC knuckles than the stock steel ones.

I think you missed the point of my earlier post. You will continue to have travel after you hit the Koni bumpstop. It just effectively raises the spring rate. This is much preferable to the poly bumpstop, which doesn't compress as far and has a much much higher spring rate. If you have 25mm of travel before you hit a 40mm Koni bumpstop, you have probably 55 or 60mm of travel there. Those bumpstops compress A LOT by design.

Bilsteins are an easy fit in a 240 tube. It's the Konis that are tight.

1.5 x .095 tube is just the right size Leon.

There was an interesting discussion on rear control arms that I was kinda hoping you'd chime in on. Hopefully Dan is able to recover all the lost info.

No the one on the probe in your hand in the picture. The probe has a short nut built into it with exposed male threads and the probe sticks out from there. What you have is a 1.5" or 2" long hexagonal adapter for some other kind of vehicle screwed onto the probe. Or at least, that's how it looks compared to my Autometer probe. Here are the Autometer instructions if that helps: http://www.autometer.com/download_instruction/0318J.pdf

The imaginary line is drawn through the outer and inner joints, so if you moved them to the same angle and height, there is no practical difference whether the inner is lower or the outer is higher or both. The instantaneous center would move to the same place. If you moved the outer lower without changing the inner, the starting height of the line would be lower and the instant center would be further away than if you just moved the inner. I see the problem though. I thought you were talking about a bar which would bolt to the strut, but you were in fact talking about the inner pivot. You are correct. Moving the inner up would raise the RC.

The probe is brass if I recall. Yours already has an adapter on it. Unscrew the long hexagonal thingy off of it and throw it away or put it in a drawer.

If I'm understanding you correctly, you're confused about how roll center works. If the car is raised up a lot as an example, you have a steep downward angle from the inner pivot to the ball joint and a very high roll center. If the car is really low, you might have the control arms pointing up from the inner to the ball joint. This would have an underground roll center. "Bumpsteer spacers" raise the roll center by lowering the outer pivot. See this link for more: http://www.e30m3project.com/e30m3performance/myths/Weight_Transfer/weight_transfer2.htm Here's one instructive image: You cannot possibly align that toe link to have zero bumpsteer. Unpossible.

I ran mechanical on an L6. Was disappointed that I had to go electric with the LS motor. The mechanical was accurate enough that I could see the thermostat open and close. Get the adapter and use it. Just take the thermo housing to the hardware store. It's all NPT fittings IIRC. EDIT--Oh, and don't kink the tubing. You can bend it back and forth and zip tie it up if the line is too long, but don't kink it.

I think you'll find that you end up with a lot of bumpsteer with a toe link that short. Even if you can choose whether it's toe in or toe out, you don't want a lot of bumpsteer. You might mock it up real quick to see what it does in practice. The new end for the strut sounds like it might enable you to twist a rod end 90 degrees and then install it in double shear with the bolt going through vertically, which would be preferable to a single shear ball joint IMO. You could space out your mounts and then add spacers if roll center adjustability was the goal. If your ball joint was on the bottom, that would raise your RC and increase roll resistance. Help me out here. This relates to which design? I'm not saying that RCVD tells you how to build Z suspension, but I can't yet see where the info there isn't applicable to general suspension designs that you might put under a Z.

Would you like to clue us in?

My take: That front toe link, if jointed, now has a bumpsteer effect. The shorter the toe link the worse it's going to be. If not jointed, you have an H arm that isn't all one piece, so essentially a weaker H arm. Also the rear pivot on the control arm is bolted to those sheet metal uprights, and I'd be wary of disconnecting the front and rear inner pivots. RCVD has a "reversed A-arm and Trailing Link" in their book. I am pretty sure this design is used on a lot of Subarus, and is very similar to what you've drawn, except the trailing link is essentially straight longitudinally. If you were to do this on a Z, you'd have the trailing link pretty far inboard, which is not ideal. Anyway here's what they say about all of these variations:

The bolts screw into the ring gear, so you can't drill them out, unless you can drill and blind tap the ring gear. Just run the bushings.

Race Car Vehicle Dynamics by Milliken and Milliken. I think I typed out the section that talks about H arms in the "yet another control arm" thread. While we're at it though, your control arm design doesn't make a lot of sense to me. It looks like you've got a longitudinal pivot on the rear of the arm, but not the front. If the front joint is built onto the control arm itself as it appears to be in the drawing, then you have a pivoting, adjustable length "extra" link that you can never adjust and which can never pivot, assuming the rear part of the arm is welded together. You also have no front pivot for the arm. Would you run a stock bushing in front? If the extra link wasn't attached to the control arm but to the chassis, then the ball joint would swing straight up and down, but the extra link wouldn't. It would have to twist in relation to the rest of the arm. So as the control arm moves in your design, the rear part of the arm with the bj moves up and down, and then the link pivots on a different axis. This would cause toe changes (bumpsteer). What you need is pivots at the points of the one piece triangle, and the front and rear to be inline if you don't want bumpsteer.

A friend of mine used Kirkey Intermediates in his 510. He's a bigger guy, so when I drove the car I was pretty loose in the seat. Had BIG issues with hitting elbows on the bolsters. Ended up with the Ultra Shield RS 15" and I think I tweaked the outside wing in .5" or so to clear. I made a bracket really quickly to try that seat in my Miata. Drove 2 hours to an autox, raced, and on the way back I figured out I was about 2" off from straight behind the steering wheel. At least IME having everything lined up perfectly doesn't seem to matter.

Monoballs can take a pretty decent axial load with no problems, witness just about every camber plate you can buy and all the aftermarket arms running 5/8 rod ends with no trouble. I did bump up the size to 3/4 rod ends on my arms just for a little insurance, but apparently quite a few people are running around with A-arm toe link setups with 5/8" rod ends. The benefit to running an A-arm with toe link is that it doesn't side load the strut. Read in RCVD and it says that the problem with the stock H arm design is that it does. If the joints are strong enough, then the fact that you're putting more load into a single joint simply doesn't matter. The reason for the toe link in front is that the rear (fixed) pivot will be directly under the strut, so there won't be side loading on the strut from being loaded by the front pivot which is not directly under the strut. Agree with G-E, if you're going to change it, CHANGE IT. Do a different axle and hub, integrate better brakes, might as well do SLA suspension while you're at it. Why start modding the strut to take a ball joint? If you're going to that trouble, throw the whole strut in the garbage and start with something better.

After how many drag strip passes? What you were doing the last time might not matter so much as the history...

The Koni bumpstops are long and squishy, unlike poly bumpstops. You really don't want to touch your poly bumpstops, whereas if you hit the Koni bumpstop, it just increases your effective spring rate.

Good input here. I continue to believe that HLSDs are weak in terms of lockup. There is a tradeoff to a tighter diff, but that's the direction I'd go. Looking at Dan's pics, it really does look like the splitter's effectiveness will be compromised by running much softer rear springs.