tube80z

I have an easier solution for you (well maybe). If you're using heims on the inner ends of your control arms you can turn them to be up/down orientation instead of front/back. The bolt can come down from the top. You'll need to make the top flat and create a tab on the bottom of the crossmember to make this double shear. You get an additional bonus in that this is a lower friction way to mount the heim (also do the TC the same way). Just mind the total travel so you don't hit the bearing race. This would allow you to adjust the up and down a small amount for different RCs. I think if you move the inner pivot too muh you may need to move the inner tie-rod up or down as well. When you measure bumpsteer it will tell you what end needs to go up or down from the curve. Cary

When I did mine I made a piece that went on the rack end (inner tie-rod removed) and then I dropped a transfer punch through a hole in this piece to mark the crossmember. Seemed to work for me but you need to make some bits. For Jon's setup it sounds like a u-bracket that you could slide shims under would be the ticket. This would allow for precise adjustement and it would be mechanically solid. I've not had much luck with the slotted adjustments I've played with in the past. And to get really carried away with this topic why not make a new crossmember that allows the inner pivot points and steering to be moved as a unit. This would let you play with RC positions and camber change without messing up bumpsteer. Then you'd need to have the TC points adjustable and you could adjust anti-dive. Cary

I have some friends that run a GT4/5 cars (nasport champions, many track records, etc.) They use live axles and have tried all the types of linkage you can find info about. They settled on a 4-link with panhard. They thought it was the simplest that responded the best to adjustment. My personal choice would be a 4-link with a mumford linkage. About the only thing I can offer from personal experience is that a car that must corner will not put the power down with anti-squat in any great amount. It would be far better to use springs to control the body mass then geometry in this case. The gentleman on corner-carvers is in for a rude awakening when he gets his car running with 100 percent anti-squat in the back. Cary

The car in the pictures is Dave Kipperman's. I race with Dave and the plate is reinforced underneath. He thought it looked better on top and I'd agree. His 510 is done the same way. This is a really nice car built for to show off at track days and autoxs. Dave built the car in about 6 months. There are a lot of cool features hidden on the car. It features a lot of bracing in the bottom of the engine compartment, rocker panels, etc. Cary Cary

If you measure the car you'll find it will generally be stiffer if you spread the load out on the strut tower. It is easier to go to the tube but you can't spread the load out as much and this seems to make the structure less stiff. But then again, you have the rules to deal with. On a couple of my cars I haven't worried about the rules I welded a plate across the ribs top pf the tower and brough the down tube into this. Then the side tubes I brought into the front face of the rear tower. And then had a strut bar that was welded across the towers. I did something similar on my mod car after playing around with whether it was better to run the tubes together or spread the load out. Those simple experiements indicated that it would be better to spread the load. Hope this makes sense, Cary Cary

Some of us are burried at work and can't find the time to play as much as we might like. Another goup are probably headed to Shasta Is this going to be weld in or bolt in? I'm guessing bolt in. Does it need to be SCCA legal? I seem to recall you could only have a max of 180 gegrees of bend in the main hoop. It may not work to put holes in the floor and drop the bar down to weld the top. In this case I think You'll need to build up a base from the rocker to the raised section in the rear floor that fits under the bar. I think the SCCA has a rule regarding how much angle the rear stays can have from the car centerline. I don't have a rulebook handy to say for sure. So I would check that. If they don't I think you're fine connecting to the crossbar you have welded in the back. There are a host of solutions from here. I think you'll need a diagonal from the drivers side top of hoop down to the lower passenger side at minum. To make is stiffer you can put in a upper and lower X to the opposing struts. I'd also look at attaching to the roof section if this is weld in. This not only makes the structure stiffer but will help to keep the car together in a side impace. The lower X requires some creativity to get around the seat depending on how far back yours is. If you intend a bolt in solution that I have another idea for you. Sorry, work calls -- Cary

A local shop used to think 0.25 inch plate was the end all solution for everything. Somewhere I have a set of lower control arms with two quarter inch thick tabs for the sway bar mount. Never mind the arm is no where near that thick. They built a lot of dirt cars. Cary

I don't know if this will help or not. But when you make a tubeframe you don't preload it. I think a lot of the issue with subframe connectors is when you have the car up on a lift to install them. In that case the chassis may have some loading that isn't the same as if it were supported by the wheels. So if you just have a bare chassis I think you're fine. That's generally been how I've done this in the past. Cary

Looking at the photo you can definitely see a lot of extension on the inside, which is pretty common. If you limit this you'll find that the car won't roll out of its geometry window as easily. I currently use 0 mm rebound on the front and 15 mm in the rear. If you run on rough courses you may need a little more but generally not more than 5 mm front and 25 mm rear. You don't really need a lot of rebound. What you'll find is the car rolls less, turns in quicker, and puts the power down better. When I started doing this I started getting comments about how flat my car cornered. I found it was generally about 0.15 seconds faster on my standard referrence course. I also found the car more consistent and easier to drive. Easy to do with cables and turnbuckles. Worst case you throw it all away and call it a waste of time. This is a common setup crutch that's not too well documented. Cary

I'd agree. Pit wisdom often is not. John, on the ROD you ran it pretty much with the controls arm near horizontal didn't you? In that situation the ride height differences have a lot more to do with tire diameter. In my situation I'm running very short FA tires on 13 inch wheels. Did the ROD ever run against Vic Sias's BSP Z? I'd be curious how closely mathced they would have been. Cary

Totally agree. Machining always takes ten times longer than you'd think. I resort to machining when I have no other choice. And that's probably why I'm so slow at it. But I have a friend that is very good and anything machine still takes a long time. Even fancy CNC tools are not as quick as you might think. Cary

Sorry, I forget that some of this may not translate too well. A bridge reamer is probably best explained here http://www.nutty.com/reamer.html. It just so happens the standard 5/8 bridge reamers tapered section matches the Ford tie-rod end taper. So instead of heims at the end of the suspension you use tie-rod ends and tapered holes. Very similar to the front suspension on a BMW where they use balljoints for the inner pivots. Probably not as good as a heim but will last forever on the street. Just an option. Hopefully this helps. I have some pictures but I can't figure out how to make this forum post them. Maybe I'll put them in my gallery and give you a URL. Cary

Delrin is okay but not that great of a bushing material (poor impact strength and shatters when cold). Nylon expands and contracts a lot with humidity. A better choice would be one of the UHMW plastics. Very hard to machine. A couple of people used to make TC rod kits with steel cups and UHMW balls that lasted forever. It would be a good option for the rear bushings. Or if you decided to do something trick you could use Ford tie-rods instead of heims. A standard bridge reamer is the same taper. This will get you a solid joint that articulates and will hold up well to dirt and grime. It's an old streed rodders trick. Ford tie rod ends can be had for less than $10 a piece. Cary

Yep, tried it and it works. You need special structural closed cell foam. And you need to make sure you have no rust as you are basically screwed if you need to do a repair. The foam is toxic when melted and makes it nearly impossible to weld. Our old race car went to the JY because of this. It's a common thing to hear about with the japanese tuner crowd. http://www.sportcompactcarweb.com/p...6scc_proj300zx/ for more info. Cary

Check out the online machine shops. It may be an easy way to get your piece made. Cary

A safety washer is built this way. http://www.spidertrax.com/fabrication_msw.htm With these you can use a normal rod end. Cary

I guess the question would be how much travel would you have? That's going to be the key. For the steering arms you may want to consider having them cut out of structural steel rather than playing with the stock pieces anymore. I've used T1 and Formualoy 4040 (or something like that) with good results. You can bend the steering arm to have the correct alignment with the tierod. Somewhere I have some pics -- just need to figure out how to post pics here. The trick way would be to change the inner heim to have the bolt going vertical through it. It is lower friction and you could use spacers to set a specific RC. If you mount the outer heim in single shear you will want to use a safety washer on top and bottom. They allow more angle and if teh bearing falls out of the race will mechanically trap it. Cary

Here's what I did. I cut an old set of tierods apart and chucked the end in my lathe and turned it down to make a bushing. This was welded into some thick wall tube that was tapped for the 5/8 heim on the other end. Your way sounds easier on all honesty. I have a welder and seem to like to figure out how to make all my projects into welding projects. Maybe I need to by some hammers ... For the heim on the steering arm I'd recommend some safety washers/misalignment bushings. I got mine from spidertrax. These will allow about 22 degrees of motion before binding. To drill out the arm I used a 5/8 bridge reamer. These are for aligning rivet holes in buildings and are fairly cheap. Most people don't know the taper part is the same as a Ford tierod end. This is a cheap way to make effective linkages that don't use heims and can hold up to dirt a lot better in case you want to go that way. I think the Datsun taper is also the same as some international parts if that helps. Cary

Have you tried changing the rake to balance the car? Lower the end you want to stick more or raise the other -- keeping in mind where things work best on these cars. You might be surprised at the results. Cary

The aluminum arms can be bent if you anneal the aluminum. If you have some severe bends to do you may need to make completely new arms. I've seen a few where a new end was bolted to the splined bit. You can also make hollow bars and weld everything up. 4130 with proper heat treating is what you need to do to make them last. I've tried a few mild steel versions on my car and they will start cracking after a couple of years. I didn't think it would work at all and was surprised they lasted this long. There's a lot of weight that can be saved by going this route. If you're not concerned about the weight good ol' stressproof is hard to beat. Cary

It depends on what you can do in your stock class. In SCCA you can't do anything to the coils. Some local clubs allow a little more and you could try and use packers but I seriously doubt these would help. My experience with them is that they generally lead to unpredictable handling if you get into them on a corner. Another option would be to use droop limiting. Probably not legal either but can help to keep the car from rolling as much. And if you really want to use the stock springs you can limit droop and preload them with shims. But since you're going to have to pull all this apart why not just put in more appropriate springs? Cary