74_5.0L_Z

http://forums.hybridz.org/topic/83751-how-much-tubing-to-make-a-roll-bar/

How unfortunate about the loss of recent posts. I'll bet we lost at least a hundred useless "What tire size", "What backspacing", and "What Color should I paint this" topics. We need a sub-forum for useless, non-technical crap to go in.

Cameron, What are your other suspension settings? How big is your front sway bar? How much caster are you running? How high are your front and rear roll centers?

I have been battling a similar lack of rear traction on corner exit. This year in response to that problem I have done several things. First, I raised the front by 0.75" to raise my front roll center. That seemed to help, So I then began putting successively lighter springs in the rear. I began the year with 500 lb/in front and 450 lb/in rear and a 20mm front sway bar. I then switched the 450 lb/in rear for 425 lb/in. This change decreased my rear frequency, decreased the rear contribution to lateral load distribution, and also slight lowered my rear roll center. It was a noticeable improvement. Next, I replaced the 425 lb/in springs with 400 lb/in springs in the rear. Again, this made a noticeable improvement. However, again I changed several things by putting the lighter springs in the rear. Lower frequency, lower contribution to the lateral load distribution, and lower roll center. With the changes that I have made, I have made an extremely noticeable improvement to my corner exit traction. I have also not yet reached a push condition that can't be driven around. At the last autocross event, a friend captured video showing me lifting the inside front tire and carrying it for about ten feet. The car also now squats much more noticeably in the rear.

I have been getting the same errors.

The other thing that affects pedal effort is the relative size of the caliper piston area versus the master cylinder piston area. Contrary to what many people seem to think, reducing the size of the master cylinder piston lowers the required pedal effort and increases the pedal travel. Increasing the master cylinder piston size increases the required pedal effort and reduces the pedal travel.

I deleted my booster about thirteen years ago when I went to four wheel disc brakes. All the it takes is a plate that has the master cylinder bolt pattern superimposed on the firewall bolt pattern, and an appropriate pushrod/clevis going into the master cylinder. I used the stock 260Z master cylinder with my set-up. I believe that it has a 15/16 bore. I autocross the car frequently, and I love the feel of my brakes. So, can you delete the booster? The answer is yes. Should you use a single circuit master cylinder like used on the kit shown by the original poster? Hell No! My entire brake system is as follows: Front: 11.75 x 1.2 vented rotors Outlaw 2800 calipers with 1.75" pistons Hawk HB237N.625 Pads (HP Plus compound) Rear: 10.75 x 0.81" vented rotors Outlaw 2800 calipers with 1.375" pistons Hawk HB237N.625 Pads Wilwood proportioning valve Stock Pedal Assembly Stock Master Cylinder With good components front and rear and good brake balance, there is no need for a brake booster on our cars (IMHO). To me, the booster is only an extra source of weight and an extra item that can fail. The pictures below show the aluminum plate that I used to delete the booster. The first picture shows the plate on the firewall, and the second shows the master cylinder installed. Note: Edited my brake set-up inventory. I thought I had used the 1.25" pistons in the rear, but I was wrong. I installed the 1.375 pistons on the rear thirteen years ago. The memory just isn't what it used to be....

I just got back from there. My wife, daughter, and I had a great time. We did all of the touristy things while we were there, and we also did some hiking. Spend a whole day in Golden Gate Park if you can. Start at the museums and work your way to the beach. Eat at the Beach House. Hike the Lands End Trail. This is a cool hike with lots of cliffs. Go to Muir Woods. Get there early and take the Dipsea Trail instead of following the tourists (about 5 miles). You will have the place to yourself if you go against the grain.

My fenders provide 1.5" of flare versus stock, and I have very little clearance between the tires and the coil-overs.

I run 15x10 on all four corners with Hoosier 275/35/15 tires. I am using Spinwerkes series 82 wheels with 5.25" backspace. I use .25" spacers on the fron to clear my coil-overs. I also have the SubtleZ fenders on the car for added clearance.

My second 260Z (the one made in 04/74) has VIN RLS30-27435, so I think you can be assured that your car is an early 260Z and has the 240Z style rear strut towers.

If you have an early 260Z, then it will have the same strut towers as the 240Z. I am not sure on the cut-off number where the chassis began to resemble the 280Z (large bumpers and raised rear strut towers). I do know that both of the 260Zs that I have owned are the early style, and I have mixed and matched interior pieces that I used from a 240Z. The first 260Z that I owned was manufactured in 08/73 (RLS30-000481) and the current 260Z that I own was manufactured in 04/74. Both cars have more in common with the 1973 240Z than they do with the 1975 280Z. Neither has the big bumpers and neither has the raised strut towers.

I got the best suspension deal of my life from a guy who drove his car without getting it aligned first. He had just spent two years building a beautiful 1969 Cougar Eliminator. He painted it and replaced every single suspension component with new parts (upper and lower control arms, springs, steering box, center link, idler arm, power steering, ball joints, tie rods, and disk brakes). He did a quick tape measure alignment on it and took it for a drive. Within a day, he wrapped it around a telephone pole when he lost control in a turn (not even pushing the car). Obviously, he hadn't done as good an alignment job as he thought with the tape measure. Fortunately, I was in the market for new suspension for my 1970 Mustang Mach 1. I bought all of his new components for $200.00 (this was in 1987). A good day for me, not so much for him.

Maybe it's just the photos, but it looks like the mounting faces of your wheel and hub were not mating flat and flush. The area on the wheel at the inner bore and the area of the hub adjacent to the bearing housing are both shiny as if you had a very narrow area of contact. If this is true, then when you were torquing the wheel you were also putting the ears of the hub in bending. It may just be the pictures though.

Wow! Have you inspected the other side for the beginning signs of cracks? It may be possible to find some evidence on the other hub as to where the cracks are starting.

I am very interested to see the pictures of the failed hub for several reasons: I am running 275/35/15 Hoosier A6 wheels on 10 inch wheels (like you). I have the 4-lug hubs (like you). I am running about 400 rwhp (like you). I don't want my wheel to pass me on track (unlike you). I hope you didn't mess the car up very much.

There are two companies in the US that make upgrade kits for the T5. The two companies (Astro Performance and G-Force) advertise 500+ hp capability for their products. I know of several people running the G-Force in the American Iron racing series with success. I personally have an upgraded T5 from G-Force, but I only use my car for autocross. I am making 400hp/ 400 ft-lbs of torque at the wheels. Additionally, G-Force has a variety of gear choices and the choice of dog-ring or synchomesh.

Ah, I see. I'm obviously not LS savvy. I am still in the dark ages with my Windsor based Ford. Carry on...

Jon, You are essentially building a race car. Why are you not using a front plate / mid-plate to mount the engine? I love mine. The front plate essentially ties the strut towers together and helps stiffen the chassis, and the lack of the motor mounts on the side of the block creates a bunch of space for headers.

Jon is sending me some steering arms so that I can make the measurements. However, I think it would be a good idea for at least two people to make independent measurements to help catch mistakes. I will put together a figure and post it tomorrow to show the exact dimensions that I need. I am trying to put together an accurate model of the complete suspension so that I can see the interaction of caster, camber, SAI, pin offset, etc. There are changes that I want to make, but it is silly to make changes until you know exactly what you have so that you can determine what you want to change, and why.

Clarkspeed said,"I run a little higher front RC (I hope you measured to the ball joint center!)." That brings up a good point. I have had to estimate the position of the ball joint center. I know that it is offset rearward and inboard from the center of the strut axis. The inboard offset has the effect of raising the roll center, and the rearward offset provides mechanical trail. I can do the math to establish the relationship between the strut axis and the steering axis if someone has GOOD measurement of the ball joint center position relative to the strut. Anyone? If nobody has these dimensions, I can make the measurements myself. I have a spare strut and a ball joint that I have cut apart (to extract the ball), but I do not have a spare steering arm to complete the assembly. If someone can lend me one, I will be happy to take the necessary measurements and create a cad model of the front strut and ball joint. I would also publish the results for everyone to use.

I really only use the car for autocross though I hope to start doing track events soon. I have the rear about as low as I can get it without rubbing the tire on the inside of my SubtleZ rear quarters. I am doing my best to tune out the oversteer without adding ballast, but I will if I have to. I plan to install the new rear springs before the next event, and I will also have some ballast that I can add if required. I am trying to decide where to add the weight. The easiest place will be on the floor behind the passenger seat. Or if I am a little creative, I could add it between the differential and fuel cell.

Hey Greg. It's good to hear from you, and I will gladly accept any input that you have on setting up a Z car. Here is where I am at: Total Weight: 2632 (Front Weight: 1278, Rear weight 1354), (Left Weight: 1359, Right Weight 1273) Roll Centers: Front 1.9 inch, Rear 4 inch Spring Rates: Front 500 lb/in, Rear 425 lb/in (I am changing the rear springs to 400 lb/in before the next event). Sway Bars: Front 20mm with shortened arms, Rear none Struts: Front, Koni 8610-RACE Rear, KONI 8610-1149 Alignment: CAMBER: FRONT -2.2, REAR -1.9 TOE: FRONT 1/8" toe out, REAR 1/8" TOE IN CASTER: FRONT 6 Degrees TIRES: 275/35/15 Hoosier A6 mounted on 15 x 10 wheels at all four corners Power: 396 rwtq at 4000 rpm, 386 hp at 5950 rpm (greater than 350 ft-lbs of torque from 3000 rpms to 6000 rpm all measured in 4th gear. Gear: 3.36 CLSD, 1.94 2nd gear in tranny (7000 rpms is 73 mph) My current situation is that I cannot put the power down off the corners unless I have a passenger. The addition of a 120 lb passenger(my wife) makes the car SO much easier to drive. By that I mean that I can squeeze the throttle without the rear end wanting to take the lead. I am not under the impression that I should be able to hit the gas indiscriminately, but I would like to apply full throttle more quickly than I currently do. Toward that end, I am softening the rear springs to try and mimic some of the effects that I get from adding a passenger. Adding the passenger does many things: First, the added weight in the passenger seat balances the car left to right. Second, the added weight adds rear percentage. Without the passenger the car has 51.4 percent rear weight, and with the passenger, the car has 52.6 percent rear weight. Third, the added weight lower my rear natural frequency and changes the "magic number." By that I mean the percent of front roll resistance minus the percent of front weight percentage increases (5.4 to 7). At my next event I cannot take passengers, so I plan to play around with the lower rear spring rate which will lower the rear natural frequency and the rear roll resistance and hopefully improve off corner traction. I have been lowering the rear spring rates incrementally. I went from 450 lb/in to 425 lb/in, and saw some improvement. Next, I will try the 400 lb/in and see how it goes. As it is, I am nowhere near a push condition so I think I am going in the right direction. One place that I have not done any tuning is the shocks. Currently, I run box-stock Koni 8610s. I run them all on their softest rebound setting. They seem to have too much rebound and not enough bump. I am planning to get them revalved soon, but first I want to know where to start on the valving. Thanks for listening to my rant. Please respond with any useful input. Greg, someday I would like to check out your EP car.

With Passenger by a long shot. This car has way more than enough power and braking to accelerate the extra mass. My next mod is going to be the addition of a tall rear spoiler to help plant the rear of the car at speed.

I am planning to go run the Regional SCCA event at South Georgia Motorsports Park on March 15th and 16th. Unfortunately at regional events, the SCCA does not allow passengers. So I will be adding ballast to the passenger side floor. I ran this past weekend at Sebring, running the car both with and without riders. The car is so much easier to drive with a passenger. And yes, I think John Thomas could win a national championship in any given class even if he was blindfolded and driving a lawnmower. Clarkspeed, I may just have to take you up on that offer just so that I can socialize with a fellow HybridZ lunatic. Besides, I want to check out your car.