johnc

Its straight.

BTw... the answer to your question is: no.

"Once more into the race, dear members, once more, or fill the dumpster up with our shattered parts." (Paraphrased from Henry V in 1415)

Ding, ding, ding, ding! We have a winner! Congratulations Ed, you have asked the dumbest question of the week here on HybridZ. And for that, you get this: http://forums.hybridz.org/search.php?

If your car has a 50/50 weight balance then equal sized tires on each end help you achieve neutral handling in steady state cornering. Equal size tires also help reduce understeer under power as your car exits the corner. Some people argue that wider tires in the rear can help you put more power down on corner exit, but in the powerful 240Zs I've built and raced a wider rear tire would not have helped. Its kind of a viscious feedback loop: 1. A wider tire allowing more power to the rear tires also increases rear weight transfer. 2. This pulls weight off the front wheels and reduces their grip. 3. Reduced front tire grip under power exiting a corner increases understeer. 4. Understeer on corner exit requires a reduction in power to correct. There's a fine balance between available power and front and rear grip. You want enough rear tire to allow full power before corner exit and enough front tire to keep gripping as they lose weight transfer. One way to know things are setup pretty well is when you just barely lift the inside front wheel on corner exit. Like this:

One way to think about the LCA/TC combination is as a lower A arm. Looking up at the bottom of the car (as in the pictures above), there is a triangle formed by the LCA (side "A"), TC (side "C"), and an imaginary line (side "B") drawn from the LCA mounting point to the TC mounting point. That's the A arm. Ideally, there should be a 90 degree angle at the A/B junction. This requires an articulated joint at the B/C junction unless the orientation of the B/C junction can be made to allow parallel movement between the A/B and B/C junctions. If I was going to mess with the TC rod mount, I would do what I could to make this whole setup operate exactly like a true A arm. A long rod run through the LCA inner mount and clamped/tack welded to be at 90 degrees to the LCA and parallel to its pivot axis would give me a great indication where the TC mount needs to be and in what orientation.

You PCV valve is working exactly as designed. In high vacum situations (idle, drop throttle) the valve opens to allow scavanging of the pressure buildup in the crankcase. In low vacum situations is essentially closes. Remember, the whole PCV setup is a closed loop with one part of the loop in the air cleaner drawing in filtered air and the other going to the intake manifold. Its not acting as a big vacum leak. Also, make sure your oil cap is the non-vented type or you will introduce a leak.

No width difference. Run the same front and back.

One tip to help the Autopower bar out if you're welding it in: weld two .095" thick by 2" wide tabs to the top that also are welded to the roof support at the hatch hinge mount.

BTW... I'm going to start this month on a customer's 240Z that will be a national level autocross car. Our first decision, before any other work, was selecting a tire to build the car around: 285/30-18 Kumho V710s. All other chassis/suspension decision are based on that specific tire. We wanted at least a 275 width tire but overall diameter had to be below 25" because we cannot relocate the suspension mounting points per the class rules. The 30 series sidewall worries me so the suspension wil have to be made as compliant as possible and a lot of money will have to be spent on shocks.

Tire compound is much more important then tire width. A set of 185/60-14 Kumho V710s will stick better then a set of 225/50-15 cheap all season tires.

http://www.stockcarproducts.com/rodend6.htm Monoballs are the bearings that are in a rod end/heim joint.

Another variable in this caster debate is tire size. When I ran 275/45-16 S04 Hoosiers on the front I got rid of a lot of caster (down to 4) which helped even the tire temps out. I also reduced camber from 3.5 to 3.0 in front. Back when I was running 225/50-15s I had a lot of caster (about 7) and camber to make the S03 Hoosiers work.

Another variable in this caster debate is tire size. When I ran 275/45-16 S04 Hoosiers on the front I got rid of a lot of caster (down to 4) which helped even the tire temps out. I also reduced camber from 3.5 to 3.0 in front. Back when I was running 225/50-15s I had a lot of caster (about 7) and camber to make the S03 Hoosiers work.

The Autopower race bar for a 240Z is part # 60170L and does not look like the pictures posted earlier in this thread. I sell it for $339.00 which might be a bit more then what MSA charges because they can buy in lots of 10 and get a bigger discount then I. The harness bar is an extra cost option and I charge $61.57. Shipping on these roll bars is fairly cheap because they can go via UPS. I sent one back to Florida for $75. It takes about 3 weeks for Autopower to make and ship if they don't have any in stock.

http://www.katonet.com/Techinfo/Newsletter/2005/apr-jun-05.htm

Can't tell that by looking at their TC rod. Again, as discussed many times on this site, shortening the TC rod pivot length increases bind in the front suspension and affects the camber gain in bump designed into the 240Z's front suspension. It hurts rather then helps handling.

Can't tell that by looking at their TC rod. Again, as discussed many times on this site, shortening the TC rod pivot length increases bind in the front suspension and affects the camber gain in bump designed into the 240Z's front suspension. It hurts rather then helps handling.

I plan on building the ultimate (Uber) roll cage for a standard tub 240Z. Something that is completely ridiculous and makes most people go "Wow!" and smart people go "Why?"

Stainless steel fasteners are a crapshoot. The advantage of stainless steel fasteners is the ability to resist corrosion and heat. Common stainless steel alloys used in fasteners are 304, 302HQ, 315, and a few others. These alloys have good corrosion resistance, but are not heat treatable. Tensile strength is typically around 85 ksi and can be made up to 140ksi (just below Grade 8 ). Other, more exotic stainless steels can have tensile strengths of up to 170 ksi. (beyond Grade 8 ) but they are double and triple the price of a medium carbon steel bolt. I wouldn't trust a stainless steel fastener in any critical application unless I bought it from ARP or an industrial supply house that verified its strength rating. Nothing stainless from ACE, True Value, Home Depot, Lowes, etc. would go into any important suspension or engine part on my or my customer's cars.

http://www.textronfasteningsystems.com/eng_tools_f/grades.html Grade 8 and Metric 10.9 are both rated to 150ksi tensile strength and both are medium carbon steel, quenched, and tempered.

No, you're basically right, but I've become more mercenary in my thinking. Do I take a few days off work and build a roll bar in my car or do I spend $325 and 2 hours? Again, this is a street car that might see a few minutes at an autocross when I'm instructing. For the track car I'm building for myself I'll be spending a couple weeks building the "Uber" 240Z roll cage.

http://www.circleracing.com/ Call them.

That's funny! I am just going through this debate in my head right now. For my street 1971 240Z I might install one just because I'm really busy at the shop and probably won't have time to build and weld in a roll bar. If I had the time, there would be no debate. The Autopower bolt-in roll bars and cages meet the letter of the rules and improve the safety of a 240Z that's raced on a track. They are better then not having anything in the car and are by far the cheapest way to get something in your car to go racing. I've installed four Autopower roll cages and roll bars. One, installed in a Spec944, took a big hit and then hit a concrete K-rail. The driver banged his left elbow and it bruised pretty good but that was the only injury. The Autopower bolt-in cage held up pretty well and did its job. Now, extrapolating this one result from a 1987 Porsche 944 to a 1970 Datsun 240Z is stupid. But the Autopower cages do work. Also, Hiten Patel is famous for a huge wreck he had at LVMS where he put his stroker 240Z end-over-end and then into a dirt embankment at an open track event. All he had in the car was a Cobra racing seat, Sparco harness, and an Autopower roll bar. He walked away from the wreck. All the above being said, a well designed welded in roll cage will protect the driver far better then a bolt-in Autopower cage and can significantly stiffen the chassis (allowing at least a 150 lb. in. increase in spring rates).

Shopping for nuts and bolts at a local hardware store can be risky. I have often seen cad plated bolts in the grade 8 bin with grade 5 markings on the head. I have also seen bolts marked with the metric grade 10.9 and the grade 8 hash marks (which is it and why did the Chinese dual mark the bolt?). An industrial hardware store is probably a better choice. McFadden-Dale here in SoCal and you can always use McMaster-Carr (http://www.mcmaster.com). You can also still get most of the OEM nuts and bolts directly from Nissan or MSA.