JMortensen

For a street car the stock setup is OK, and it is torque sensitive so I doubt you'd spin tires too often, but when I had mine like that it would occasionally spin one tire when I was going over a severely cambered turn. If you want to shim it up a bit we can get some shim stock from http://www.mcmaster.com. I think I used part #9011K85. We can go off of my previous shimming measurements and just throw in 4 shims at .004 thickness each and that should get roughly 45 lbs breakaway. You can run it just the way it is and I'm sure it would be just fine, but since we're in there anyway and it only costs about $15 or $20 to do it, if it were my car I'd do it. You're going to LOVE the difference it makes.

You might consider running the G Machine TC kit in the front and the rubber bushing in the rear. Having a less squishy pivot in front really does improve the feel under braking. The kit for the early Z fits the ZX, just mount it on the front of the TC bucket so that it looks kinda backwards from the way it gets installed on the early Z.

I thought that the first part of this sounded pretty similar to what I said in post #14, so I didn't feel a real need to respond. The rest is all conjecture. But if that's what you're looking for, here is some for you... I'm not sure about the effectiveness of the TC area modifications when done alone, and I think their usefulness would be greatly affected by the shape of the airdam and the front fenders. Again looking to the NASCAR model which I believe is overlooked too much in general, if the front of the fenders protrude past the wheel openings by a fair amount this should create a vacuum in the wheel wells which would assist in drawing air out from under the hood and make the TC mods and fender vent mods more effective. If someone was using the MSA IMSA flares which are basically aerodynamically backwards in my opinion (because they expose the front of the tire and have a large protruding mud flap type shape in back) then I think the TC mods would be much less effective, if they were able to do anything at all. I'm also not sure about the drip rails and windshield gasket. My hunch is that it would be better to have the windshield mounted flush with no gasket protruding into the airflow, and have it fastened with clips like a real race car. I have no idea where one gets the clips from though. I've done some quick searches on the net and haven't been able to find anything. On my car I've already cut off the drip rails in the process of fixing rust, so I think my goal is going to be to get the windshield net and quarter window flush with the outside of the car. I will also use the small mesh type window nets as opposed to the 1" thick nylon strap type, as my gut tells me that the small mesh type strung tightly will be better in terms of aero. I think a flush surface is better on the side of the car than having a bunch of different layers like the stock Z does, with the drip rails sticking out into the airflow and the quarter windows recessed back from the body line. By contrast I bj seems to think that the drip rails have a beneficial effect, tending to force more air out and around the window openings, but I'm not sure that I agree with that. I think it would take more testing to know who is correct on that point, but I'm basing my opinion on the majority of new car designs where the drip rails are integrated into the roof instead of hanging out on the side of the car. But when you're racing with the windows open I can't say for sure who would be right.

Replacing the pinion bearings is quite a bit more complicated than just replacing the carrier bearings. My experience has been that the outer pinion bearing just under the pinion seal is the one that goes bad. It is a ball bearing and relies on oil splashed up from the ring gear into the tube cast into the top of the housing to feed it. I think what commonly happens is that if the diff is run low on oil that bearing starves and then goes bad. I've taken a couple of these apart now and every single one has had a bad outer pinion bearing. In fact I had a guy Dave swing by the house yesterday (Zsondabrain from classiczcars.com) and we were checking out his 300ZXT LSD for damage. The LSD was perfect, but when you spun the pinion it felt like there was sand in the pinion bearings. I didn't take the pinion shaft out, but that is EXACTLY what the other R200 diffs that I have taken apart felt like, although Dave's was a bit worse than the others. I replaced this bearing on my own diff for the same reason, and then later I believe I found that this bearing was NLA. I'm not sure on that, so you should get the part number and check with Nissan, but that is my recollection. If that bearing is indeed NLA then I'm not sure what if anything can be done to fix the problem. As far as potential fixes to keep that pinion bearing happy, I have a couple of ideas which range from overfilling the diff just slightly to following bjhines lead and installing a cooler with the fill line plumbed into that tube that feeds the pinion bearing to ensure a constant supply of oil. Getting back to the question though, I would pull the carrier out and spin the pinion. If the pinion bearings feel crappy, then I would pull the pinion gear out and inspect the bearings, especially the outer bearing, and try to buy that pinion bearing and see if it is still available. If the pinion spins nicely, leave it alone, because it is kind of a PITA to get the pinion shaft out and back in, when compared to the carrier.

Pure conjecture to follow: I think the bump on the 280ZX acts like a "trip strip". If you have a relatively smooth surface and you put a speed bump like obstruction in the airflow the air hits the bump and separates, creating a vacuum, and this causes the air to try and fill that vacuum and head in the direction of the bump. This seems counterintuitive because you would expect that the fact that there is a low pressure boundary layer over the hatch would also try to suck air to the hatch. The fact is that this vacuum does want to be filled (with exhaust gasses mostly), but the trip strip works to create a stronger vacuum when the airflow is still attached, so it does it's bit before the air starts to separate naturally due to the shape of the object, and that means that it can redirect the air to curl back down onto the hatch before the separation begins. I would suspect that the VGs would be the stronger method of keeping the flow attached, while the bump in the roof is the less conspicuous way of doing the same. That's my theory anyway.

That's what I was thinking. Especially for a later 280, that's a pretty low weight!

This has already been gone over in some detail in this other thread: http://forums.hybridz.org/showthread.php?t=115294 But the short answer is that you are wrong, and this is why: The vortex generators are there on an airplane to energize the boudary layer so that the airflow over the FLAPS has some effect. It's the effectiveness of the FLAPS that increases the effectiveness of the control surfaces when the wing approaches stall. In the case of the car, when the flow separates there is a vacuum in the area where the flow has separated. This is less pressure on the hatch than what you have with non separated "low pressure" vortices traveling over it. So even without a spoiler, non-separated flow will give you more downforce than separated flow will. But the big benefit is when there is a spoiler or a wing involved the airflow to that "control surface" is energized, which makes it more effective in producing downforce.

Yeah, that'd be the reason. Those look like polyurethane bushings. Whoda thunk it? http://forums.hybridz.org/showthread.php?t=87758

Just teasing you and John there, Richard. Although there really is a difference between a race quality wing and the Wings West special.

No, that's comparing the old garage which was something like 17' x 20' to the new one which is I think 30' x 26' or thereabouts. It was a pretty big step up...

Damn guys! You need more room! Check this out, I've got some before and after pics. Before I had to suck in my gut and turn sideways to get around the front of the car with the garage door down. After I feel like I need more crap to put in this garage! BEFORE: AFTER:

.520/292 would be just about perfect for my engine. That's a good choice in my opinion.

I've got stock cast flat top pistons on L28 rods and L28 crank. When I built my engine I was REALLY poor, so did a lot of the work on the combustion chambers and notched the block and deburred it and all that myself, but the bottom end is basically as stock as it gets, although it was balanced.

Looks like he even still has them on the website: http://www.arizonazcar.com/piston.html

Dave used to sell pistons with the pin height for a 240 rod. Oh well. Don't want to be a jerk, but it sounds like you put your money in the wrong places. I'd save up for the custom forged pistons if I were in your position.

Well tight for cash and knife edge crank are kinda incongruous statements. Do you already have the crank knife edged, or is that part of your plan? If that's part of the plan, save the money there and buy the right pistons. Or you could buy pistons from Arizona Z Car. They have pistons that are .040 over and fit an L28 crank and L24 rods.

I can't speak to that, but I do recall there was some mention like "Don't say it's for a Nissan, just tell them the specs..."

No, that is for 6. They aren't 240SX pistons, they're custom whatever you want pistons. http://forums.hybridz.org/showthread.php?p=669978

I'd like to see John stocking a higher quality unit off of a real race car...

Are you going forged pistons? You could get the Ross pistons from Summit. Custom pin heights, whatever you need, and they're $460 something for pistons, rings, and retainers. Then you could set your deck height at 0. The problem with shaving and shimming is the piston is still way down in the hole (unless you're talking about shaving the block). With the piston down in the hole like that the quench is lost, which is a problem when you're trying to run higher compression on pump gas.