johnc

321 .049 3"OD tubing is about $35 per foot retail. 304 .049 3"OD tubing is about $20 per foot retail. Mild steel .049 3" OD tubing is about $8 per foot retail. 321 .049 3"OD manderl U bend on a 4"CLR are about $135 each retail. 304 .049 3"OD mandrel U bend on a 4"CLR are about $100 each retail. Mild steel .049 3" OD mandrel U bend on a 4" CLR are about $35 each retail.

Me. I've welded up a .049 wall stainless 321 exhaust for a customer's BMW. Titanium would be a Titanic waste of money for an incremental weight savings over stainless. Also, thin wall mild steel (.049) works well if painted.

Generally, with equal size tires all around, Z racers run a wider front track then rear. If you are running unequal size tires the the end of the car with the narrow tires almost requires as wide a track as possible to retain some semblence of neutral handling. A good example was Guy Ankney's effort to create a champonship level autox BS 350Z. To get a more neutral balance in low speed corners he ended up running 275 width tires up front and 245 width tires on the rear with 1" rear wheel spacers. Within the limits of stock class rules he used tire and track width to tune out the 350Zs inherent understeer.

http://www.gearedbyunitrax.com/main.html They've rebuilt countless R160s, R180s, R190s, and R200s. Lots of them from me. They have an old guy in back named Carl that knows the Hitachi diffs well and he's trained a couple other guys there too.

That's true about EVERY vehicle manufacturer in the world. Statistically, over a large sample, some vehicles tend to be more reliable and have a higher quality feel. But individual vehicles even within a highly reliable and high quality OEM line can be Pieces of S***. Your odds of getting a POS Toyota are less then getting a POS Chevy, but there are still plenty of POS from every car manufacturer to go around. A blanket statement like "All [place vehicle manufacturer name here] Suck!" just shows ignorance.

Antoher way to say it is the wheel rate needs to be .5 to .7 times corner weight. Figure the motion ratio on a strut suspension at .98 and for the semi-trailing arm rear its probably something around .60, but that's just guess on my part. My Internet Engineering guess is: front spring rate about 350 to start and the rears at about 550 to start.

Karts are a hoot! Recently did a shifter kart day at WSIR's kart track. 105 degrees F and the 40 lap main just about killed me. When I came by start finish and was shown the crossed flags (signifying halfway) I just about pulled off right there. But I kept going and finished mid-pack in the "Master's" (old fart) class. I couldn't get out of the kart for 5 minutes after the main - I was whipped. Regarding handling, don't mess with your anti-roll bar. It will just fail. Front camber is critical to reducing understeer on the 240Z. I also helps turn-in. Tire sizes are also import (equal size on all 4 corners) along with driving style.

But wait... I ran poly TC rod bushings for over 10 years without a failure. I know a number of other 240Z racers and autocrossers who have similar experiences. The link above regarding the failure was on a 280ZX which has the tension rods going forward (so that they are true "tension" rods). Although it won't account for all failures, a good many of them are caused by over torquing the TC rod nut.

Fixed.

TC rod bushings are always a compromise. On a smooth race track under braking you want a stiff TC rod bushing. Once you're not under braking you want a compliant TC rod bushing to allow free suspension movement. On a bumpy race track under braking you want a compliant TC rod bushing to allow the tire to "give" for/aft a bit when hitting a bump at the limit of lockup. Without that give the tire can skip over the bump and lock up. Depending on driver prefernece and skill, its sometime better to accept a little squirming under braking then to have to deal with intermittent front wheel lockup. As I said, its all a compromise.

Then that was a defective casting. 24 psi is not much pressure for an aluminum casting to handle. You put more air pressure in your tires.

That's not bumpsteer. What you felt was a common issue with Zs when large wheels and tires are installed and/or the car is lowered. The alignment needs to be corrected to reduce this tendency. Bumpsteer is a physical steering change when a wheel goes up in its travel as a result of a bump or roll.

I don't know.

I've got 1GB of hi-res videos of the Rusty Old Datsun being chased by the Flying Miata around Buttonwillow. Unfortunately there's no sound. I might be able to upload them somehwhere, but 1GB is a lot to upload.

She's banned. Two posts and both were the same thing in two different forums.

Actually, changing 3rd gear in the Datsun 4 and 5 speeds is a cheater trick. Breedlove and Craig could do it as part of their $800+ rebuilds.

What will be the car's ride height when you're all done? FYI... ride height is typically measured at the front and rear of the rocker panels.

It depends on the sophistication of your dampers, how friction free your suspension is, and the condition of the track you're racing on. Here on the west coast of the US the race tracks are bumpy. In Europe and to a lesser degree the east coast of the US the tracks are smooth. In my case, I spent close to $14,000 on my suspension and wheels and I went with 275/45-16 tires. If I was running on smoother tracks I might have gone with 275/40-17s instead. Remember, the suspension on a 240Z is not a very sophisticated design. Just because an E46 BMW M3 can run 18" wheels with 30 series sidewalls doesn't mean it will work on our cars.

I would really, really like to hear your opinions on those dampers if you take your car on the track. How they feel on the street is not as important to me. Thanks.

About the widest tread width that has been made to work well on a 240Z (road racing and autocorss) is a 12" medium or soft compund racing slick. I know some folks who have tried 12" wide DOT-R rubber and it was difficult to get the tires hot enough to work well. I know that sounds funny, but tires are designed to grip the best in a fairly narrow temperature range. A 10" wide tire that's "in the zone" will grip better then a 12" wide tire that's too cool. Bigger is better only up to a point. Also, the 240Z strut suspension needs tire sidewall to help with compliance. The suspension has a noticeable amount of stickyness and friction (stiction) and tire sidewall helps grip by absorbing small road impertections that don't overcome stiction. If the tire complinace is not there, those small road imperfections cause the tire to lose a little bit of grip. Enough of those imperfections and the tire skates. Right now I know of no one racing a 240Z that has been able to make 18" wheels and tires work well at an autocross or on a road race track. You would need some pretty sophisticated dampers and a friction free suspension.

That's the idea. The engine is hanging from the eyes on chain while the car is up on a lift so I can squat under it and check the digital protractor and then make small adjustments to get the numbers right. Side to side adjustments are done tapping the sliders. Fore aft adjustments are done by lifting the each corner and walking it.

Sorry, this thread has crossed our political ban boundry...

BTW... you should really have them professionally inspected for cracks. Unless you know the history, used racing wheels are a scary purchase.

Its a cheater trick for showroom stock racers, although its questionable about how much it really helps an already stiff chassis. I would not use it on a car you plan to work on and keep for a while for the reasons mentioned above. It turns the area foamed into a single piece that must be removed as a unit and replaced if damaged.

The diff side stubs are basically interchangeable although the through-bolt type won't have a physical attachment to the diff. I've swapped back and forth at the race track when I've forgotten the proper spares. BTW... with the longer wheel travel involved, I wouldnt run the through-bolt stubs in a circlip R180 on a street car.