tube80z

If you have the ground to bottom of the crossmember I can figure the rest out. I have measurements for the chassis assuming the strut towers haven't been moved. Thanks for the best wishes. She's doing fine but still has a lot of pain. Cary

One thing to keep in mind is locosts are mostly built from 1x1 0.065 tube. 0.125 at 2x2 will be strong, hugely overkill, and weigh a lot when you're done. You could easily get away with the 0.065 for most of the frame and if you need to add strength in certain areas then bump it up to 0.095. Good luck and have fun with this. Cary

What is the ride height? I also need to know the top strut location (where the mono ball is). I can fudge a lot of this if you want but ride height will be important. And to set expectations it may take a few weeks to get this for you as my wife is recovering from surgery. Susprog just gives you numbers and those will need to be plotted in excel. I'll overlay the two options so you can see if this is important. Cary

My advice having gone down this road is that if you want to make a tube chassis don't start with an actual car. Just measure out the big stuff on the floor or your build table and start from there. Ship in a bottle construction will take 3 to 4 times longer and you run the risk of copying issues from your base car (I would know, my first tube Z chassis is now hanging on my shop wall as an art project). If you really do want to do this you might consider a slightly different track. Cut off the front end and make it from tube. That will take less time and the car won't be down so long. Then when ready do the rear. If you're going to do this you need to have a plan on what it is that you want to change. You also need to be very careful that you don't fall into the trap of using too thick of tube or your tube car will weigh more than a unibody one. People may laugh at that but when you add up everything needed to complete the car you may find that is true. Cary

You could move it to mount on your k-member. That would be slightly forward of the TC mount but allow it to align. That said a long time ago a friend measured all this and used wingeo to see the curves. While it did change it wasn't some major issue. When you pushed the front wheels forward for more caster the curves were very close again. If you want to do the measurements I'll put it in susprog and then we can share the plots so you can decide.

You can't trail brake effectively that way. So when you put a big splitter on the car and need to keep it flat on the ground in entry that will become important. Dan did mention the car moving too much. Part of that may be too much suspension travel. From the second picture there's too much roll and that has decambered the outer tire. So even if the car feels great there's a higher level to be had. And these spring rates aren't stiff by any means. Starting points for slicks these days should be wheel rate equal to corner weight for no downforce and that can go up to 1.5 or higher. Add XP/EM downforce and numbers over 2 can be used. On radials .8 to .9 seem to be the norm. On track cars running at higher speeds other ideas could be used.

That's how they are supposed to feel. If you're trying to get them to feel like hoosier radials you'll need more pressure than where they make max grip. The slicks should be about half for your suspension travel when everything is working correctly. It took me a long time to figure that out even when told it was right. Your pressures are high but not completely out of the realm of reason. A good picture head on of the front at max load will show if you need camber or air pressure. I have a favorite place where we run to get these. I can point you to some examples if that would help. If there are properly inflated more camber or more caster might be needed. I would lower the rear of the car until the spring rattles and then bump up the rate to around 550. I ran rear limiters with just a small amount of drag on a 0.40 feeler gauge. If the track was smooth I ran less and less front droop often down to 0.25 inches to control roll and make the car turn in faster. If you have big bumps you may need to limit the same as the rear. I missed the second pick of your car. It looks like it's rolling too much in that photo. I think you tried the limiters in the past but can't recall. I would do that again and see if that helps with the rolling. I'd also be very tempted to increase the springs rather than add front bar. Springs will reduce the amount of pitch and roll compared to just the bar. Your spring rates look close for the car on radials.

How much weight do you have on front? Any tire temps? You're pressures look too much to me for Avons. Maybe you arrived there by experiment but we're usually down in the 19 to 22 range. As far as springs go for the Avons I'd be 100 to 200 lbs/in more. You're car is around 2500 to 2600 lbs. with you in it? Cary

I was saying from the picture it looks like the front is compressing (Dan's pic). From your info I'd go with more rear spring to keep it from coming up. And since you don't have a rear bar perhaps a Z bar instead. Another option would be more tire pressure. Until we see pics it's shooting in the dark. And then we have that issue of you running the wrong tires that won't work on the car If I can ever get you down to Medford we'll see what it's doing and get it fixed. Cary

I think the sharing isn't setup for public on your pics.

Drill out a large nut and weld that to the tube. Or buy a tube already setup with flats. Both are options. Cary

Interesting project. Keep up the good work. Cary

Raising the rear will help it turn better and should increase rear tire temp. But at the same time it will not put power down as well. Adding spring will do both but hopefully won't hurt forward traction as much. Add Avons and this will all probably change. At least it runs and doesn't have any issues that need to be addressed outside of tires and initial setup.

Dan has some good information about caster above. I don't think that is the problem here but it could be adding to it. I say that because we've had two cars running the FA rears all round that were setup very close to Jon's car and neither of them lifted tires when going into tight turns under braking or in transition. After thinking about this for a while the car is rolling on a diagonal on the inside front to the opposite rear. So we're already extending the inside rear tire. If we're on the brakes then the rear will be very close to fully extended before we start cornering. Now add roll mostly from the front end dipping on one side and steering induced ride height change and it's looking closer to what is described. So how to fix. I'm thinking we need to go stiffer. As the rear tires are not up to the same temp as the fronts I'd go with more rear spring and if there's a lot of rake reduce that at the same time. If that doesn't fix it then more front bar or stiffer front springs. This will help reduce front roll, dive, and rear lift. Cary

Nice run. What time you were hoping to get? Sorry to hear that PP is looking less likely to happen. It would be great to see it come together. Cary

It may be logger dependent too. I'm not completely sure what I was using corrected for roll, which would give higher numbers. Hopefully more data this next year to see how Hoosier and Avons compare. I created a math channel that looked at 1/4 seconds of cornering for continuous (autox) and then picked out the highest number for peak. On an EP car on GYs I would see similar numbers on a race technology DL1. But that was the best I ever saw and it could drop a lot depending on track conditions. For lateral acceleration (or longitudinal) are you thinking of comparison of cars or just as a gauge for your own car? Bob Knox recommends a 0.3 second moving average filter for acceleration data. Cary

You can also bolt angle iron to the ST bar and run the rod end from it. Heavy85 has a nice piece he built here, http://i1150.photobucket.com/albums/o618/ls240z/Mobile%20Uploads/image_zps6017f710.jpg Cary

On slicks you should see 1.6 continuous and spikes near 1.8. Tires keep getting better and better.

You need to reinforce the nut you used. A threaded bushing could have been used, which would have more weld area. And a rod end would give you much more room to raise the inner control arm if you need to. The large bearing you have looks like it would contact the top of the crossmember. Just a few things to think about. Cary

MSD box has a tach out option. I think it's a 5 volt square wave.

My guess is the bushing that's used to guide the shock rod at the top. Those can wear and you get that rattling. If you go with the larger Bilstein size you can use a different piston (COBB) that has more tuning options. (Digressive, linear, etc.). Option 3 use the strut rod and a linear bearing as the bushing but done have any piston or oil in it. It will be a control arm so to speak. Them mount a coil over shock inside of the strut. This used to be done years ago in IMSA before you could get good struts. Then you can use much cheaper shocks compared to struts. Option 4 like Jon mentions is convert to a 2 piece strut and use 240SX struts. They have built some really nice pieces. Option 5 go to a-arms and no more struts. Obviously rules may play into this. I'm doing option 5 myself after reviewing the other alternatives. More fab but cheaper running costs when done. Cary

Actually if you make two cuts to the centerline at angles it makes a cope. Lay a coped tube on a flat surface and you'll see. There are tables of what angles to use. The paper method is pretty cool too. Cary

Just underwear. That's all that's needed.

If you play with Kevlar you'll need carbide scissors. They will probably cut up the blanket. I really don't think you have anything to worry about. But your idea of bonding kevlar to the tunnel or the bellhousing should work. You can get a bellhousing that's rated to contain the flywheel clutch for your setup. It's very heavy. Cary

The QA-1s are called a slot bearing. They are a 2 piece design and not designed for the amount of vibration you'll see on the rear suspension. We used these first as they are low cost and they lasted one event and the liners pounded out. Then AM Auroras in 5/8 and they pounded out and then 3/4 X/Ms (not sure but their top lines) and they worked fine. I've done CMs on a street car and those seem to be working fine but it hasn't done a ton of mileage. It's your money but I don't think you need to spend $200 a rod end to get some that work. Hope this helps. Cary