tube80z

I seem to recall a GT-2/3 Mazda that uses something like this at Portland (PIR). But they aren't wilwood. They are an expensive stacked and furnace brazed rotor. So in concept they work but I think the problem as John mentions is that the Wilwoods can't handle the heat. Now for an autocross car getting heat into the rotors quickly is good and would allow you to use a real race pad and keep unsprung weight down. Cary

71 240 Z (built for GT-2) Glass nose Glass doors Glass hatch lexan windows Basic cage 280Z engine (9 pound flywheel) 13 inch formula atlantic racing slicks 2 gallons gas 1850 before ballast 75 Tube80Z (built for SCCA soloII EM) Ford 5.0 Aluminum heads, manifold, etc. T5 with dog ring conversion most of above body work 13 inch formula atlantic racing slicks 2 gallons gas 1620

I've found that if you turn the key while working the wheel against the lock it will usually release. Very common on the Nissan line when they get older. Cary

I don't think you need to replace the rears. The balance bar should be setup so that when you press it all the way and have pressure on the cylinders it is straight across. At rest they will typically sit at an angle when you have different cylinders. They can handle a large range of adjustment. I prefer to run a slightly larger master and have less pedal movement. I ran the numbers you listed and I came up with needing 3/4 front and a 1 inch rear to get a range of .51 to 1.43 gs (and used the numbers of .58 for front mu and .4 for rear) With a proportioning valve I think this would work. I have a friend with a 510 than ran this same setup and it worked for him. He just used smaller MCs to have less pedal effort. You can also use different pad materials in back to help out. I run the PFC 01 material for my car. You might consider one of the aggressive fronts with a medium torque rear, like the 97 compound. Or what ever your favorite brand of brake pad is. Cary

Jon is right. You need to think about pressure and area for brakes. The pressure is fixed by the size of the master cylinder. If you have more area for it to work against then you have more force available. To increase brake force at one end you either need to go up in caliper piston size or down in master cylinder size. I have wilwood dynalite 4 pistons on front and 2 pistons on the rear. I use a 7/8 front master and a 3/4 rear. I have an adjustable balance bar and proportioning valve. This is adjusted to get the most ot of the rear until you really stand on it and then you get a little more front bias. It will take a bit of work to get it et right. A set of caliper bleed guages or a set of brake guages plumbed into the car can be a big help. For pads I'm using performance friction 01 material. If I can't get the heat then I switch to 97s. Cary

Why not use a stock pedal box modified for dual masters? There are a couple of people that will do that for you. I think DP products is one. Probably about the same cost as the entire pedal assembly but ti will be easier to mount. Cary

Yep, that was pretty much what I was thinking. I like it. The next step is a set of rear arms that connect to this and are adustable for toe. You really don't want to try and bind poly as it will develop a lot of friction and wear. The renderings are really cool. I don't know what you use but my hat is off to you. Cary

For cost that's a little hard to say as I had a lot of bits and pieces already. Speedway Motors has AN line kits for hotrods. I was converting over to Tilton masters and wilwood calipers and took the opportunity to convert all of it to AN. I ran a small section of braded line from the masters to hard line to make them easy to change and deal with any flex in the firewall. I'd have to say less than $200 including the flaring tool. You need a different flaring tool (37 degree flare) for the AN fittings. They use a compression sleeve and a nut to mount that compresses against the backside of the flared section on the tube. Another alternative is if you have a Parker hydraulic store in your town is to use their fittings. My local dealer quit stocking AN-3 because they didn't want people doing what I'm doing. The majority of the cost will be in the few metric to AN fittings that you need if you use stock masters and calipers. If you use aftermarket calipers that have pipe threads the fittings are less than $3 a piece. When I first did double flares I had a lot of leaks I had to chase down. My experience with AN fittings so far has been no leaks at all. It's all I use on my race cars. And if I had a street rod I'd do the same. Cary

Have you considered an X bracing for the verticals? It would need to be spaced out to clear the Diff but I think there is space. This should be stiffer. Cary

For chamering I used a small 6 fluted countersink tool on a battery operated drill. I then used a small file to prep the outer edge of the tube as well. Then I used one tube flaring tool to create the bell and another to finish it. It was a lot of work to get it to not leak. When I did the brake lines for my new brakes I threw all this stuff away and converted to AN. It didn't leak a drop and was much easier to do. You need a new flaring tool and different hardware for connections. Braided lines ar e a lot cheaper this way too. If you're looking at repacing everything you may want to do this. And if you use or are thinking of using Tilton pedals (or similar) they alread are setup for AN ends. Cary

If you're looking to put power down better than a smaller rear bar will be a better option. If you know all the data about your car you can determine how much roll resistance each axle pair has in total and you can use this to switch between spring and bar. One trick I've used that I think works quite well is the use of droop limiters. I started doing this to use less limited slip and trying to improve turn-in. What I found is that it also helps to put the power down. This isn't something you run on the street but can be quickly added (cables and turnbuckles) when you race. I use an 1/8 to 1/4 inch of droop in front and around 1.5 inches in the rear. This helps to keep the limited travel in the suspension being used for what we wanted, not overall body movement. It's a path to explore at least. You may find it doesn't work at all but you won't be out much trying. Cary

I think a lot of the difference has to do with how you use the car, tire type, weight, etc. In my case the car is an autoxer and I use really short 13 inch tires (20s or 22s). It may be that my RC isn't that much different than other cars on a lot taller tires. For the most part I have my lower control arms near level. I also make sure that the inner lower control points (TC rod and LCA) are level too. If not you'll introduct anti geometry and this will induce understeer, or at least that is what I have experimentally concluded. I also use spring rates very close to the corner weight supported. And I run the front with less than a 0.25 inches of droop and the rear around 1.25 to 1.5 inches of droop. I don't think you'd want to copy any of this for a street car. For softer rates you'll need a some anlge down towards the wheel. I think the sweet spot is close to level when cornering. I don't if this helps at all Cary

If you look in the newer version of the how to hotrod book you'll see something like this on the Bob Sharp 280Z racers. I think it's a good idea and you can go further by connecting the rocker to the TC box and forward to the crossmember. All this can help to triangulate the bottom of the engine compartment to make the car stiffer. Cary

If you don't want or have time to find a spindle tool you can do the same thing with a stack of washers and 3/4 inch nuts. It's slower but will remove the pin in the same manner. 12 AM the night before a race will make you resourceful Cary

Why don't you do what a lot of racers do. Convert the struts into uprights and make a top and bottom a-arm. May not be as good as a dedicated piece but you can use the stuff you already have. Unless you have nothing and then you're free to put what ever you want on the car. I'm with John on this. I don't know why you'd want to put Pinto pieces on your car and expect it to handle any better than a Pinto. To do this right you really need to design pieces to work with the rest of your car. Otherwise you end up with an expensive project that won't work any better than plain ol' struts. Cary

I thought VDP was velocity dependent pitson, learn something new everyday. I run the low buck ground control advance design shocks with custom valving. I would love to have been able to use Penskes or Ohlins T44s but they were well outside of my budget. Do you set those up with internal droop limiters? I'm currently running around just under a quarter inch in front and about one and a quarter in the back. Cary

Okay, I came to the game late. Is the 55/45 discussed above front to rear or rear to front? I was a little lost on that one. For what it's worth I ran at the Bogus Basin hillclimb with my car, which is L6 powered and 2 percent heavy with me in it to the rear. My first run up the hill was faster than any I've seen from previous results from Kim. While this doesn't mean anything it seems to be the argument that he uses for why rear weight isn't needed. Forward weight bias for hillclimbs is generall seen in Pikes Peak cars. If you look at the 4WD monsters this is how most of them are setup. I think it has to do with trying to get equall traction from the tires at a dynamic state. Not really something we'd see translate over to paved hillclimbing. Most of the fast EMOD cars autoxing are heavy to the rear. They do this to help with traction out of corners. They generally try and hit a 45 front to 55 rear target and work well. My tube frame car is built to try and hit this number and the back of the engine is 1.5 inches of the car centerline (completely behind the firewall with a 5.0 Ford). Good discussion though. It seems to validate my weird little view of the world. FP Z car using GT engine setback and little 13 inch wheels and tires. The only thing I saw missing here that relates to PMOI is gyroscopic forces from the rotating components. Which is why I think 16 inch wheels are wrong for an autox car. Cary

For the record that was the front roll center. I have never used a rear RC underground. I should also point out that my car was using 20 inch tall tires at the time. With the current 22 inchers the RC is actually above the ground. It seems to be a common notion that getting better camber compensation will solve a lot of problems with our cars. I have tried this numerous times and never seen the results it would indicate. What I have found is that you're better off not worrying about that and trying to keep the tire from laterally scrubbing. At least in my experience that did more for grip and overall driveability. If you can go with a longer link then you have a little more freedom to play with this. What ever you do in the back of a Z think really hard about making the outer strut pickups double shear. In the stock setup you can see a lot of flex that changes the toe setting. If you have an automatic car (stick would probably work too) try adusting your rearview mirror to watch the tire and powerbrake the car. What you see may surprise you. Instead of alternate holes make the design so that you mount it using spacers. This is a quick and easy way to make changes. Cary

The clevis is bolted down and is solid when tight. The difference is one bolt versus two on the stick TC rod. That can have a tolerance too, but when you tighten it it doesn't move around. I guess you forgot the rubber bushing that's usually at the end of all this that moves around a half inch or more. And even if you did install delrin or some other ball and socket option it will flex too. This is a proven and tested design, which in my opinion is a lot better than what Arizona Z offers.

650 was my upper limit. That would be 1.5 times the corner weigt on the EMOD car. To get there will require more development work on the shocks I think. Last year I ran 1 to 1.2 times the corner weight on the unibody car. Right now it has 400 lb springs all around from an event we ran late last year where it was cold. Cary