JMortensen

I've seen this problem firsthand. It may not be a 4000 rpm drop, but it can be big enough to have a pretty drastic effect. I used to autox with a friend who had a 510 and we were pretty evenly matched there, but we started going to big track events and it was a different story. At one of our first events at Streets of Willow we gridded up with him in front and when we turned onto the straight to go up the hill he needed to shift to 3rd and I absolutely left him in the dust. It was the 2-3 gap that was killing his L18 with cam and 44s. After that event I gave him an old close ratio roadster trans so that he could keep up. It turned out that I still had enough power to ditch him at big tracks, but at least he wasn't falling off an rpm cliff when going for 3rd. I believe Clifton had figured this out too. I know he was running the later ZX 5 speed as well in his turbo car, which is now cobramatt's insane V8 track car. There are other posts about the gear ratio spacing, I know I've commented on it quite a bit. I hate to see people go get a T5 out of a turbo 280ZX and put it in a NA car, because it has even worse spacing as I recall. The downside to the late ZX 5 speed is that 5th gear is supposed to be weak, so you might stay in 4th if you're really pushing it.

Just remove the cover, undo main caps, pry out the side stubs, and pry the LSD out. On the R200s they fall right out. Most carriers have to be pried out.

Sounds like it might be worth it to try 67.5s. FWIW, when my car was hot I never touched the gas, and only gave one pump before starting cold. Timing has a big effect on hot starting. Running without vacuum advance I ran about 18 degrees BTDC and it fired up pretty easily.

More aggressive than the helicals and can be shimmed tighter if necessary. On a helical you get what you get, unless you have different pitch helical gears that you can swap out. The aftermarket CLSDs offer the most traction. OS Giken, KAAZ, etc, but the price is high.

jnj run a welded open diff IIRC.

If you look back far enough, you'll find people saying they're limited to 300 hp before they strip the tabs off of the clutches. That's with the spacer in there and one clutch driving each axle. If you put in the extra clutches I think the capacity goes up quite a bit. Don't have a particular number, but I'd guess that you would be fine with 3 clutches per side.

I don't know if the halfshafts ride at a true 90 degrees from the diff. It's pretty close, but I've never put a square on one like you have done. As to the mustache bar, yes, it twists. In fact I've seen a few instances of people who have broken the front mount and strap and had the nose of an R180 diff lift all the way up until the U joint was hitting the bottom of the trans tunnel. The R200 mustache bar is quite a bit thicker, but I think there is a considerable amount of flexing going on there too.

Yes, but opinions vary.

All forms of all makes and models? Count me out...

You might talk to "Uncle Joe" Benson. He has a LS1 Z32. I believe he said it was something like 5 seconds faster than the 6 cyl when he first put it together, and that was a year or two ago. Yes, that is the Uncle Joe from classic rock radio. I don't believe he moved the firewall back that far, but I do seem to recall the firewall did have to be altered. Another anecdote is Dennis and Peggy Hale's aluminum V8 (215???) 510. They did move it way back for lower PMOI, did just what John described, put it together, found it undriveable and gave up on it. I think that a car like that could be sorted but it takes a lot of time and effort. They have quite a few racecars from what I understand, so they just put it back in the garage and took out a different one.

Sort of. The fact that they won't allow the electromagnetic valves (which basically allow you to get any cam profile and valve timing you want including jake braking on decel) means to me that there are still limitations. I wonder what would happen if someone showed up with a turbine powered car for example. I like the idea of NO limitations. Don't need pistons or rotors or any of that. Clean slate, you've got X amount of energy in whatever form, electricity, gas, diesel, methane, hydrogen, whatever you want, and you can make the car as fast as you can within that limitation.

Agreed. It's a known issue that the bar is close to or rubbing with 300ZXT shafts. Running shorter end links is a possibility, and I'd put the bolts in from the top so that there isn't a threaded end at the top.

The custom shafts that I'm selling are for the 300ZXT shafts. The problem with the NA shafts is that you have to cut the boots off and then clamp them back on, and they're tripod design which isn't quite as strong. If you're buying my shafts, you still need a left and a right because the differential side of the CVs still have to plug in correctly and they have different lengths.

It seems like the press likes the car, but a lot of people on another forum can't get over the shape and resemblance to the Ace and Gary car. I kept an open mind about it, although I did agree that the self-aggrandizing Nissan promo videos were a bit much. The main complaints are that the claims re: drag are unrealistically low and the car was a rolling chicane. I wasn't here to watch the race, but it sounds like it was doing pretty well. The real issue, and this one I have to agree with, is that you can't really compare it to an LMP2 car. The specs are totally different, so you're comparing apples to oranges. This was aero innovation, but again, with no competition it's tough to see whether what they were doing was good or bad. If the spec was make a car with that weight and limit the gas tank to 40L, then I think you could make some assessments on performance and you might see scaled down conventional looking cars competing directly, then you could make much more accurate assessments as to which was more efficient. As it was, not so much. I'd love to see a series where they limit the amount of energy that gets put into the car, set a min weight, and then let them figure it out from there. At least that way they could innovate more and I think it would be a lot more likely that the result might end up with huge gains for production vehicles.

Yes. The issue is that on the Z31 they ran one clutch per side to drive the axle and then put a big spacer in there to take up the room where the other two clutches should be. If you put too much power to it you'll strip the clutch. By replacing the spacer with the two clutches you will make the diff more aggressive and increase the breakaway torque, but it's really necessary to hold down a lot of power. If you get the NISMO diff or one out of a Skyline they don't have the spacer, so no clutches needed. The Skyline diffs are more aggressive than the Z31 with the clutch upgrade, so you're still not going too crazy with the Z31 upgrade.

Yes, the pumps do move a lot of fuel. I moved the linkage to where you get the most movement, then moved it back to the middle hole. I tried pump nozzles as high as 60 and ended up running 40s.

This matches what I found. Bigger pilot and normal size pump jet I think I ended up with 40s. I tried HUGE pump jets trying to get rid of the 2500 rpm stumble and found that the bigger I went and the more movement I tried to get out of the linkage the worse it got. Bigger pilots helped a lot though, and they work way up into the rpm range. They affect more than just idle and low speed.

The R200 pretty commonly wastes the outer pinion bearing that is right under the pinion seal. You have to pull the carrier and the pinion to get it out, but it's not that big a deal if you're not changing shims or trying to set the pinion depth. I would bet that replacing that bearing fixes your problem. The problem is that the bearing is tough to get. I thought it was NLA at one point, but the older part number had been superceded by the 300ZX part number. Check with the dealer and see what you can do. One guy actually had a ceramic bearing manufactured at one point. It was supposed to hold up better. Also there was some speculation that the problem might be static electricity jumping from race to race and if that is correct then a ground strap from the diff mount to the chassis might help (normally insulated by the mounts). I don't know if that one is true, but a ground strap is a couple $$$ at the auto parts store so I was going to do it on my car. Seems to me that I've seen this problem a lot more in the 300ZX, so my theory is that the 300ZX has the diff mounted at just enough of an angle to starve that bearing for oil.

That sound when you rotate the hub by hand is not normal. The only thing that should be rubbing is the brake pads on the rotor, and that sounds way too rough to be brake pads. You could pull the CV's and rotate the diff and the hubs independently and see if it is coming from one or both hubs.

Seems to me the difference is the suspension being at full droop when you're testing. You might pull the springs and compress the suspension a bit and then climb under there and see if you can see what is dragging.

There are two different things going on here: adding clutches to a 300ZXT diff, and shimming. Adding clutches will allow the CLSD to hold down more power and also make it more aggressive. Shimming makes the breakaway torque tighter. Adding the clutches is a very good idea. Shimming is probably not necessary for most people and will make the diff more likely to chatter.

The mounts are welded into the frame, so I don't think that is an option unless they were cut off and new mounts welded on. Could switch to a rear mounted bar.

Well, you definitely fixed the idle screws along the way, so now you should be able to really dial it in. It will be interesting to see where you end up with the pilots after all of that...

I don't think anyone has posted pictures of damage on those control arms, but I've had reservations about the design of the arms and the mustache bar and have said so repeatedly. I'd like to see what happened to yours when you get them off the car, just to see if my ideas hold up. If you're interested, I think I've designed a pretty good set of control arms. I have no intention of manufacturing them, but I think the design is solid, reduces bind in the suspension, and would be easy enough to copy. This thread has the whole discussion about how the arms bind and how to fix from start to finish and there are pictures of several different solutions. http://forums.hybrid...rol-arm-design/ Here are the pics of my end result. I may still change the design so that I have studs welded into the arms instead of bolts going through the monoballs and into the arm on the inners, but I think most would probably just run the poly bushings on the inside (could cut up a set of 280Z arms to start with) and then that isn't an issue: http://forums.hybrid...post__p__848687

Just in case you hadn't seen any of my previous posts about sliders for leaf springs, you might want to check them out assuming they're legal. Reduces stiction, locates the axle a lot better, rear end doesn't stinkbug when you hit the brakes, really really nice improvement when I autoxed my pickup way back when. I had mine on weight jacks too. Sorry if you've seen post from me this 20 times... http://www.speedwaymotors.com/Speedway-Heavy-Duty-Leaf-Spring-Sliders,5817.html