tube80z

I wouldn't do it so big. I'd only do a 2x2 or 2x3 size area. I don't think any larger will buy you anything extra. You also have the door side that can be boxed from the door post to the fender liner insert. Cary

A couple of options I could see. One is to change the tube you currently have from the rocker to rail (TC connection). Remove this and add back in so that it forms a triangle with the cross tube you have from the rocker to the rail. Option two is to add folded sheet metal on the firewall where it bends and bring this straight down and fold back to the floor. Connect to both frame rail and rocker. Then add in the tubing. The benefit to this option is you don't have to remove the existing tube from the rocker to the rail. This will be stronger for not a lot more weight. On the side of the car (not shown) where you have the tube going up you can fill in the area where the fill panel to the fender is. This is covered back to the door post making another box. That's about it for easy. You may want to look at seeing if you can add in a crosspiece between the frame rails that would connect with this new crosspiece/torque box. With the exhaust on the side it should be opened up just behind the flywheel area. If you need some pictures let me know. And to finish use the BMW example. Your K-member could connect to the TC box and back to the rocker rails. And you can can have a skid plate that connects the crossmember/k-member, TC boxes and across the back of the engine. The more complicated mods involve taking the rails apart and adding metal/tubing inside and working that in. Hope this helps, Cary

Yes

Yeah, I think we all love project Blinky. I have learned a lot from those two guys even though they act like they don't know what they are doing half the time. It's definitely an act. I have been doing CAD for some time though so that's nothing new. I do think you should sue BMW for using your K-member I think adding a skid plate underneath that connects to all the points would add a good bit and it's not a bad idea to have that under the car anyway. One thing to remember when you build any prepared car, or your V8 supercar, is that you don't build that cage and bracing in the car. Those bits are built and the car is added on around it. I used to do the former and got much smarter on my new car. I have taken major sections off by removing the spot welds and then make whatever I want underneath and then add back only the bare minimum. It's also given me a lot of ideas for how to make a street Z much stiffer. But that's about the only way the welds can be done on some of those cages. The main tubes are the required thickness for safety and all the rest are as light as needed by FEA. There are a few videos on youtube that show the triple 8 cars being built and you can see that the newer cars have even more cage bracing. And the most amazing rear live axle I have ever seen. When you first look at these designs they seem silly. But the stiffer you can make the car and still make weight the better. The reason as I understand it is since the chassis is a spring it requires you to raise the rates on springs and dampers to meet the targets you want for axle stiffness. The floppier a chassis the worse this is or you need to have a completely different method for determining the chassis setups. When the V8 guys went to the new COTF it caused them a lot of headache because it isn't as stiff as the old car. A number of drivers also complained about the feel of the car as the stiffer chassis is more responsive. A lot of the rules of thumb have changed. I have heard you need 5 times the spring stiffness for the torsion, also 10, and 20. It's really related to the constant learning in racing. I think Jon has some good shots of his exhaust. That's the one area I forgot to document on Dave's car. He did a 90 at the bottom of the headers and came out though/under the lower frame rail behind the TC box. It was mostly the thin lower section but he also had to notch the main rail a little and added back in some structure. I wasn't too worried since this was also tied to the cage. From there the pipes came out and around the front of the rails and down the side of the car. How close you can go depends on the mufflers you use. There are two downsides to this mod. The noise goes up and you need to be careful when getting in/out. But working under the car is much easier. Transmission and diff swaps are a lot easier and can be done on a car when it comes in off the track if needed. Hope this helps, Cary

You need to put the bolts back in your struts where the e-brake bracket goes. Some people have had this crack when it's left open. Cary

I would agree. I saw all this after I had done the Nascar style door bars on my cage. I'm pretty happy to have three tubes pressed out to the door skin and hope I never hit anything with them but in case I do there's almost 12 inches to me. I moved the seat against the tunnel and will be mounting on tubes that are connected to the cage. Perhaps the following picture of a V8 Supercar might help. There's a lot to steal from this design. They have connected the sides of the cage to the main rails and the seats float on this. This is more or less what the inside of my car is starting to look like. The key is to always make triangles. As long as you do that you add strength. The Z car is missing structure that connects the front frame rails to the rockers as well as a triangulation to the strut tower from the outer rail. This is all standard on new cars. There are a few examples I've seen that may be of help. These are both for older Mustangs but the front structure is very similar, http://www.sn65.com/fire%20&%20ice%20unibody%20reinforcement.htm and http://www.stangnet.com/mustang-forums/threads/torsional-rigidity-test-67-coupe.723029/. On the Mustangs the export brace is a large contributor to torsional strength. And it's very similar to the bracing done by BMW. So I think that would be a good. There's also a series about modifying a Mini that's really good called project Blinky. They are building it like a real unibdy using folded sheet metal and spot welds. There's a lot of ideas I got from it. You can find it here, https://www.youtube.com/user/badobsessionmsport. Hopefully the V8 supercar pictures and the export brace idea help. On my car I have a bar that goes across the front of the unibody just behind the rocker horns and will be tied into the front frame rails. I have just enough room to run this under my transmission as I have moved the exhaust to run down the side of the car. This is something I just found I could add and is not shown in the first pics I posted. I will be connecting the structure above to this. Depending on your transmission you may or may not be able to do do this. But I would think you could make something similar to the skid plate brace the BMW used connected your crossmember to TC buckets and perhaps a few more attachment points. That would serve dual purpose as a skid plate and also connect all the lower suspension points to the frame rails and rockers. So would I.

So thought I'd try and upload some photos of the ideas I mentioned. I'm not sure this will work so well but here goes. This past season I saw a tire come in on an older car and the driver was lucky not to have their foot broken. I got to thinking about how to stiffen all this up. I wanted all the tubes to connect so that if the wheel/tire came back at me it needed to rip apart a lot of metal, which hopefully will stop it. This also serves to work as additional triangulation to make the car stiffer. I think you have something similar to this but for adding structure to the front of the rocker to the main frame rail I was thinking along these lines. My car was modified so the cowl is now removable. This allows me to add some more triangulated structure to replace what was there. I have been researching side impact and found that there's some research around the Prodrive mini that looks interesting. I don't think you'd want to redo your door bars but they found this setup to work very well, And In reading some papers about side impact strength it seemed like adding a cross beam to the floor that connected the subframe connectors to the rockers and lower door bar would make a lot of sense. There's some data in this report, http://www.dynalook.com/8th-european-ls-dyna-conference/session-1/Session1_Paper2.pdf. If you Google body in white topology studies you can find a lot of info about strength and accident testing from the auto manufacturers. I noticed there's definitely a trend in making the floor much stronger and connecting the sides. I did find a few interesting ideas on retrofitting from some rally sites. One idea that seemed very interesting was to mount DOW IMPAX foam between the seat and the and the side of the car. For my hillclimb car I'm using left and right nets along with a normal window net. I have a basic Kirkey road race seat and I'm building my own halo wings and a basic frame to stiffen the seat. I found some research that indicated the need for special padding to keep from getting lower back injuries. You can read about it here, http://www.802solutions.com/crash-pad-products/. I don't know if you're interested but I found some ideas on how to make the car stiffer. A lot of them come from a really cool tech talk from BMW around the new M4. I couldn't believe how stiff they were able to make a street car. http://youtu.be/8CJ6IwVzV-A I have another project for making a fun to drive streetable car and this looked like a good fit. For cooling there are a couple of options to look into. Evans cooling, which is essentially a zero pressure option or if you don't like that then retrofitting to a constant pressure system. I saw these on a lot of the cars at Pikes Peak when I was there, http://www.crracing.com/cr-designed-products/pressurized-cooling-systems. Hope this helps, Cary

Overall I like your car a lot. I do have some ideas on how you could do some of the detail work a little better. I'm not sure you want to hear that now as you'd need to redo some of what you have done. Specifically how you are protecting your feet. That could be turned into a pickup point for the suspension. The one area where these cars cars are weak is the floor. you have an extra tube along the rock, which helps a lot. I'd personally consider running a tube across the car about midpoint in the floor to connect both side. And something similar across the back. These can then be used to solidly mount the seat to the cage. And if you desired you could add more triangulation to make the car stiffer. You have connected the the entire side of the car from rear strut to lower rocker, which is really good. A lot of builds miss this. I can't tell if you welded the rear hoop into the roof. That's a similar mod to the dimple plates. Remember to glue in the windshield if you're doing glass. It will add to the shell's stiffness. Overall I think you did a really nice job. Pikes Peak would be a great place to run, I'm totally envious. The one thing I saw when there was you need a lot more cooling that anywhere else in the world as the air is so thin. You may want to think about water cooling brakes if legal and/or a larger radiator and oil cooler. Looking forward to seeing this happen, Cary

Sorry to hear about your back. I have been in your shoes (major back surgery) and can offer you need to be very careful in your recovery. I have all my lumbar and S1 fused and I can tell you that you need to look at some of the newer options out there. I think a fusion is a medieval surgery and often leads to needing more of the same in the future. I wish no one the level of complications and shit I have had to deal with. I really hope plan A works for you. And if not be very careful what plan B is. As you now well know your back isn't something to mess with. Cary

I was looking at that same image earlier and I think there's no easy way to separate the mains. I do have restricted pushrods and have been thinking about adding spring squirters rather than trying to flood the valve covers.

The windage tray info can be found at the same site as the scraper. Interestingly the latest issue of Engine Masters features a 436 CI LS running one of the teflon scrapers and windage trays from crankscrapers.com. They also did some very interesting things to control oil. They completely tubed the came and added external drains back to the pan. I'm thinking that's pretty high dollar stuff but depending on what you do perhaps an option. It looks like a scraper, external drains, a good, pan, and one of Vern Schumann's oil pumps might be all that's needed. Here's a link to the modified oil pickup tube, http://schumannsdynamicperformance.carshopinc.com/product_info.php/products_id/131438/LSPSF My comment about the accumulator is not that it won't work but if the block is not setup to send oil to the mains first and you inject at low pressure it will most likely end up going to the cam and heads first and then if there's any left to the cam bearings. Where is your pressure sensor port in all this? The block I have in my shop with the big hole in the side was running an accumulator. I don't know if there's an easy way to inject oil into the lower end and block that from the top but I think that's what's really needed when the pressure drops. Perhaps this was all really bad luck but I have too much money in my motor to take things to chance. And I'm also concerned because I expect my car to corner at a much higher level than the cars that were data logged, hence the dry sump. Hope this helps, Cary

I ran across an interesting article on how to upgrade the stock type LS pumps. Take a look here, http://ls1tech.com/forums/generation-iv-internal-engine/1366685-schumanns-sale-lsx-oil-pumps.html. One interesting item to note is that one issue noted causing problems is the screen on the oil pickup. This should be made much larger not to cause problems. I also found the external bypass interesting. Supposedly this solves the issue of running the pump at speeds higher than 6500 RPMs. Cary

I'm sorta late to your party and there's a lot of anecdotal evidence for LS oil issues. I've been told by a number of people that this isn't an issue at all and I'm more or less overthinking it. I have been a part of a few tracked LS engines and seen them die. From what I can tell the LS engines have a shit oiling system compared to what Datsun originally gave the Z. The first problem is the block is not set up to oil the main bearings first. This is done for a production engine so you don't have any rattles that drive warranty claims at cold startup. If you look at the aftermarket blocks the oiling is setup with what's called mains priority. I think there may be a few simple tricks to fix this but I haven't tried them so I won't add to speculation. I was thinking you might be able to plug the upper galley and then feed it via an external source you could restrict. For the more adventurous have at it. One the oil gets to the heads it's more or less dumped back onto the cam and the crank. If you haven't drilled holes in the lifter trays those will fill with oil too. I can only imagine how frothed up the oil will be from being dumped on all the rotating parts. I saw an interesting trick I wanted to copy on my engine where a baffle above the cam that directs the oil onto the cylinder block walls. This was in one of the Engine Masters magazines and was claimed to help with HP. It seemed like this would help to keep the oil from getting air into it in the first place. I took a good look at the ideas from Ishihara and Johnson (http://www.crank-scrapers.com/Chevrolet_LS.html) and bought there teflon scraper. For a little more than the IR piece you can get there laser cut scraper that is a lot better design in my opinion. And if you're handy (who here isn't?) you can copy the windage tray. From reading a lot of various articles it sounds like the oil gets wrapped up around the crank as windage and what doesn't goes up to the heads. And if you run them hard and long enough the quality and volume of lubrication gets to the point where these engines let go. I have a mockup block from one of these episodes that has a very large hole in the side. So here's what I do know. If you log the oil pressure and you go around a left hand corner for more than 2.5 to 3 seconds and you're pulling over 1.25 Gs then you'll probably end up with zero oil pressure. You can overfill all you want and run an accumulator but it won't do a lot of good giving the oil is headed upstairs first. I also found that if you run down a long straight and jump on the brakes the pressure can drop a lot. I got to help out at a circle track event and my friends LS powered car would completely fill the right side head until it came out the top. From reading and talking to a few other people I've been told that this is partly a oil drain back issue and partly related to too much oil going to the heads. Jon and Richard already mentioned external head drains. Ideally these need to be a number 8 fitting and hose (1/2 inch). The heads are drilled and tapped in the back in the valve spring pocket area. I've uploaded a picture of this done on a SBC to give provide a better idea. We tried unhooking the PCV hose on the circle track car and hooking it to the dipstick tube. This worked much better than you'd think. Up until that point the PCV system (one of the can systems) keep filling and we'd lose over a quart in a couple of laps. I think if you run a scraper and windage tray, drill the lifter holders, and have external cylinder head drains and do the overfill trick you can probably deal with corner under 1.25 Gs. Once past the 1.25 G cornering level I think you need to look at a real dry sump. If you can do some ebay shopping you can put together a good system with a new pump for under 2K and probably closer to 1500. I did mine using a used pump for around 1250. That wasn't too much more than an accusump, windage tray/scraper, special pan, and PCV system. The trick to making the dry sump cheap on the LS is the drive system and mounts. You don't have to spend the money for the ATI damper unless you want to. And a used tank and lines can save you a ton of money. You do need to be able to clean all this stuff and fab mounts, which isn't any more difficult than putting in a motor. Hope this helps, Cary

What I've found to work best is Neil Robert's recommendation. Find a constant corner and apply brakes medium hard. If it pushes you have too much front bias, if the rear steps out too much rear bias. If the cornering balance stays the same they you're set. Cary

I used cables and turnbuckles on my car. The top mounted with nothing more than a fender washer and a bolt. The connection was pretty much what Jon showed in his pictures. Nothing ever bent even with numerous off track excursions with wheels in the air. One nice side effect of running them is that you don't have to jack the car up as high to put wheels on. Version two for me was going to be a stop that was under the ARB arm. I saw a few older sports racers running something similar and owners said no issue running up against the limiter. The did say it was a ton easier to adjust these to keep abreast of ride height changes. Cary

And the Woodward spool valve has no damping built into it. So it allows for a lot of assist but you can still get good feel and treat it much more like manual steering. It's one of the few affordable solutions that lets you change t-bars in the spool valve to change the steering force curve. But to the original point I don't think there is a bolt-in solution that uses new parts anymore. All require some fab to use newer used or rebuilt parts.

Why are you using a 240Z? You're adding a frame that sounds more like it's built for a 3/4 ton truck. Why not go with the heavier 280 body and reinforce that. If you're using 2x2 why not thinner? I would think 0.65 would be more than enough and you can almost get two for the price of one weight wise. I'd personally have some sheet folded that mimicked the front rail to add in the back. Then up top do the same but tie into the seat mounts and tranny area boxing that in. Then complete an X rocker to rocker. Take a look at the maier reinforcement for the convertible 65 mustangs. The X will help with stiffness more than two parallel connectors. http://www.mustangdepot.com/OnLineCatalog/Suspension/images/PNMS2214B_App_650w.jpg Cary

On my new race car I have implemented a triangulated double cross tube front structure. There's the normal cross bar at the front of the doors and another that would be at the base of the cowl, which I have made removable. This structure gives the tubes coming from the strut towers a place to feed load into. This ended up being a lot stiffer than just using a single cross bar on the cage and provides a solid spot for tubes coming from the strut tower. I'd think on a street car a similar idea could be used and would make the a-pillar stiffer in case of a side impact. When taking these pieces out of the car I was surprised at light it all was.

Ken, Your wish is my command, at least for the merge. That last time, and it was a long time ago, I ran an autocross with the circle track to infield it felt like hitting a curb when going onto and off of the banking. I think you said that was the loaded side, which sounds like it's loaded up with a lot of lateral force and run across the junction it may be too much for the hub to hack. I don't know about your steel wheels but when I run my diamonds really hard I could see a wear pattern on the hub face. Do you see anything like that on yours? I'm thinking the easy solution is a 5-lug hub so there is more clamping against the wheel. If you have ARP or similar studs and upped the torque it might be harder on the hub with a flexible wheel. All conjecture but not sure how you really test this one out without a lot of fancy equipment and/or FEA on part models. Cary

If you're willing to do some work you can source used motorsports bilsteins cheaply and those can be revalved. That gets you a good shock with many valving options. I have picked up various shocks in very good condition from 35 to 50 dollars. These are rod end shocks and to work you'll need to fab mounts. On the strut side there is a lot of info on this site of various options that can be done. If you can't fab or don't want to do the work then you're looking at a kit of some kind. It all boils down to how much you value your time. On the 280ZX platform the rear suspension squats very easy and the camber will go negative quickly. It gets worse if you lower the car. You'll need to raise the pickups if you lower the car to help with the squat and for a street car I'd look at a Z-bar in the rear that acts like a third spring against squat. If you do any tricks like running packers against the bumpstops you'll probably shock the tires too much on launch and lose traction. I've played with z-bars on 510s, which are very similar and was able to run a much softer rear spring but not have so much squat. For a street car I'd think this would be a good way to go. Hope this helps, Cary

Old tires can be used to work on balancing your setup but when the grip goes the car still feels good but goes slower. If you run a data logger you should be able to compare your lateral acceleration from when it was working better. If you don't data log I would recommend adding that to the must have column of stuff. From what you're writing it's clear to me that you need to be stiffer. That will reduce rebound requirements and you'll need less bar and let you run with lower roll centers. As far as how to go faster that is all about first principles. That is what are the terms in the equations of motions and their various forms. That is mass, center of gravity height, and grip (force). One often overlooked area that pays big dividends we have talked about from time to time is friction. The more you can remove from the parts the move equals more grip. Hope that helps, Cary

From your picture and the following description it sounds like you want flexibility in being able to have a non-zero toe curve and the ability to tune it by using spacers on the toe-control link. The only downside I see is if you stick to something similar to the reverse a-arm design in your diagram you give up being able to also adjust anti-squat and lift. This assumes you keep the strut and don't add an upper a-arm. Is this going to be a strut or an a-arm? The other thing to check is if this design is not as stiff as using a reverse a-arm. To check that on the car you use some method of pulling the wheels together with the vertical position locked. Then repeat by pushing. Then switch to pulling/pushing the same side wheel pair. This is a poor mans K&C rig and you can see camber and toe changes from force at the contact patch. I think you could do something similar in a CAD package to at least see what the forces were in the members. If no difference that's great. If you end up putting a lot more load on a single member or joint then you might have problems. Happy to see a more technical thread in this section. Cary

Looks really nice. Very, very jealous

A friend with a performance oriented street Z had 305s on the front and 315s in the rear. It drove fine on the street. It had power steering and that's probably going to be a requirement unless you can leave with a high steering effort. Cary

Square (all the same) or wider rear work fine. It's all in the setup if you're not matching the contact patch area to the weight distribution. Wider rear generally allows more throttle in a corner sooner and that gives a knock on effect down the next straight. It also depends a lot on the type of event you're doing. If the reaction stuff is a copy of the original IMSA items the rear was setup for 14 inch wide wheels. Cary