johnc

I too have trouble paying the kind of money Quaife asks for their products. I did purchase 2 Quaife diffs for the R180s I ran and that was back in 1998 as part of the first group buy. I really, really wanted one for my 350Z but I ended up buying a Nismo R-tune CLSD. Its not as good as the Quaife but it was $600 cheaper. BTW... my 350Z runs a R200 diff. Maybe I should measure the 350Z stub axles and compare them with some R200 stub axles I have lying around...

Anyone remember metal shop in high school? 'Nuff said...

Here's how an ideally setup mechanical grip 240Z should handle: Low speed corners (under 50 mph) - the car should oversteer in steady state corners and on lift throttle. It should have a higher rear slip angle ratio under power. Car should put power down very well in 2nd or 3rd gear. Medium speed corners (50 to 100 mph) - the car should be neutral to slight oversteering in steady state corners and on lift throttle. Car should have even to slightly forward biased slip angles. Car should put power down well and should transition from slight oversteer to slight understeer under power. High speed corners - (100 to 150 mph) - the car should be slightly understeering in steady state corners and neutral on lift throtle. Car should have a forward biased slip angle. Car should put power down and should be slighty understeering under power.

Put new washers in the OBX and sell it on eBay. Take the money and buy a PowerBrute or Nissan Motorsports CLSD. Last Saturday I saw an OBX equipped WRX break and lock up the rear wheels. We had to put a floor jack under the diff and roll it off course.

There's no limit. You can setup the chassis to do whatever you want it to do given enough time, talent, and money. A properly setup and driven 240Z can run down a Z06 Corvette, Viper, EVO, STi, or GT2/3 Porsche. Because of the vehicle's light weight in racing trim (under 2,200 lbs) it can brake, corner, and accelerate with the above cars using less horsepower, smaller brakes, and skinnier tires. You may end up spending close to the price of a Z06 Corvette to do it, but a 240Z can run with the big dogs. I don't have a 240Z at the moment (I'm building and racing a 350Z right now) but my Rusty Old Datsun did everything I listed above in a number of open track events during 2003 and 2004. http://www.betamotorsports.com/products/rod4sale.html

Congratulations!

What are you building the car for: Drift? Autocross? Road Racing? Street? Rally? My guess is drifting because of the emphasis in your posts and your member name. A RWD vehicle's sliding behavior (not oversteer, we're talking about sliding) is mostly controlled by yaw intertia, alignment, tire compound, engine torque, differential type, and driver. Alignment and tire compounds are the biggest contributors to how the slide is initiated. A zero toe rear setup, hard compound tires, and a low yaw intertia create a car that slides easily and is difficult to control.

Personally I think your big market is the restoration folks and you would limit your sales by going with stainless and delrin for the line mounts. Duplicate the cad plated steel and rubber mounts and your market grows. Properly bent fuel and brake lines in stainless and cad plated mild steel would be a big bonus for the Z community. There are a lot of differences between and within model years.

I was talking aobut the engine he built for Barney Oldfield's Golden Submarine. Barney ran the car starting in 1917 but Harry (and others) were back east trying to get the Bughatti U16 aero engine to work (it never did). The engine used in the GS was designed by Harry, redesigned by Leo, and built in 1915/1916. One of the first engines Harry Miller modfied was a Peugeot, which probably gave him some of the ideas he used in his later engines.

Crank.

From my experience the auto manufacturers are the ones that emphasize offset and the wheel manufacturers tend to focus on backspace. So when you read the wheel specs in a FSM or owners manual it talks about offset while the custom wheel spec sheets ask for backspace information. And yes, the thickness of the wheel mounting flange and the wheel center does have an effect on offset, which the backspace number makes clear.

Don't forget, in 1915 Miller built a 3 liter, supercharged, four valve head, chain driven dual overhead cam, stainless steel valved, block cradled, all aluminum four cylinder racing engine that made 200 hp on 72 octane fuel. There really isn't anything new in racing. EDIT: I was wrong on the engine specs I posted above. Here's the correct info: Engine Specification: 4 Cylinder all aluminum alloy, 289 cid, 3-5/8 bore x 7" stroke, 136 H.P. @ 2950 R.P.M., Single overhead cam, stainless desmodromic valves, dual intake and exhaust ports 4 valves for each cylinder, dual sparkplugs and magnetos.

Offset doesn't matter, offset doesn't matter, offset doesn't matter. What you need is 5" of backspace. Whatever offset that comes out to be, fine. If the wheel manufacturer needs an offset number to make the wheel, then either the manufacturer or you guys as part of the group by can do the math. Offset is a by product of wheel rim width, wheel center thickness, mounting pad depth, and backspace. Since we as wheel buyers can really only specify wheel rim wdith and backspace, we get an offset number and have to work with it. Wheel position can be adjusted using spacers. In the 4 sets of racing rims I've ordered for my own personal 240Zs I specify a 5.5" backspace and adjust clearance and fitment using wheel spacers. You guys should also be concerned about caliper clearance and center hole ID.

OK, I was asked to comment... You are not going to get stock OEM type fitment from a wheel that's 3" larger OD and 4.5" wider then what the 240Z was designed for. You will have rubbing on the frame rails and TC rod in front at full lock. You will most likely have to trim the front edge of the parking light valance to clear at least the passenger side front wheel when turning left. Steering will be heavier. Tire OD should be kept at 25" or less on the 240Z unless you plan on running bumpsteer spacers and/or relocate the front LCA inner mounting point. Even then, keeping tire OD below 25" is a good thing for these cars. Some sample tire sizes: 245/40-17 That's it in 17"... For that size tire a 8.5" rim is fine and here's a picture of a 245/40-17 on a 8.5" rim: A 5" backspace is typical for a coil over equipped 240Z. Spacers are sometimes used on the front for additional clearance and to get the front track wider then the rear for better handling.

ITS refers to a SCCA road racing category and class - Improved Touring S. The Improved Touring category severly limits engine modifications. Basically no internal changes beyond basic balancing and parts bin blueprinting. You have to run stock cards or FI but you can add headers and ignition modifications. The top L6 engine builders were getting close to 200hp out of an L24 engine built to those rules and the top builder got an SAE certified 208hp.

Monocoque and Kodiak wheels require 180 inch pounds.

L24 engines have been running to 9,000 rpms for decades in road racing applicaitons. These are not street engines that go for 100K miles but prepared race engines that operate for 15 hours before a refresh, which would be 1,500 miles if the car was run at 100 miles per hour for that time. Same is true for the 10,000 rpm Honda engine in the video above. Very, few people (maybe 10 in the US) are willing to put in the time, effort, and money to actually build a 9,000 rpm racing L6 engine. Same is true for an IT legal 208 hp L24. Its mostly a bench racing thing. Race away boys and watch out for splinters.

Plastic wheel rivets.

I supposedly have a customer coming in a few weeks to have me build a hitch with a small receiver so that he can carry bikes and a small utility trailer. I'll post some pictures when I get it done.

I've never thought intentionally droop limiting the suspension was a good idea and a lot of that thinking came from having to run on the bumpy tracks we have here in California. My thinking tended to follow Mark Ortiz's thinking but he has found a positive benefit from droop limiting along with others on this board (Cary).

Yes but.... Most people "think" they have an oversteer problem due to horsepower when they really don't. The real problem is understeer and the driver's right foot. Here's what happens: 1. At the threshold just below where the rear tires break traction due to engine torque, the car will generally be pushing pretty bad due to weigh transfer to the rear. 2. To compensate the driver has put in a lot of steering to get the car to turn. 3. The driver then thinks - "More power will reduce the understeer by breaking the rear tires lose." 4. Drive adds power. 5. Rear tires break traction. 6. Weight transfers forward increasing front grip, reducing rear grip, and the understeer goes away. 7. Because of the extra steering the driver has put in to compensate, the front of the car darts in the direction of the steering due to the new found front grip. 8. Rear tires are now sliding in the opposite direction as the fronts. 9. Driver's hands are not fast enough to catch the spin. 10. Driver gets scared and lifts off the throttle. 11. More weight transfers forward, increasing front grip and reducing rear grip while the chassis is rotating. This increases the the rate of rotation. 12. Car goes past 90 degrees and driver is now countersteering the wrong way. 13. Spin... This happened in your car at the autocross practice and last Saturday when I was an instructor at WSIR riding in a student's Mustang GT in turn 3. A staggered width tire setup can be used to balance available power with lateral grip. But, its generally only used with cars that have a rear weight bias. My old 240Z with 320 horsepower and a 48/52 weight bias ran a balanced tire setup and was very neutral. You can't compare what works in a Porsche 911 with what works on a 240Z chassis.

Again, what do you mean by longer repetitions? You posted the term twice. What do you mean by repatitions as the product of your calculation above?

The issue isn't weight, its grip. A narrower tire generally has less lateral grip then a wider tire, assuming the same tread compound. The 350Z is a perfect example. 225s up front and 245s in the rear give the car a steady state understeer. Switching to equal sizes front and rear significantly reduces steady state understeer.

A staggered tire setup is basically an understeering setup. That's fine for a street car. Keep your tire overall diameter at 25" or less.

Good luck Ernie and thanks again for the 810. BTW... I think you told me this was the first car you ever painted..