JMortensen

OK I know you have it wrong about how the LSD functions. Here's how it works. I've actually put quite a bit of effort into understanding these suckers and I'm convinced you're wrong... The ring gear is trying to spin the carrier and move the whole car forward, you're right. BUT!!!! The weight of the car resists moving forward, so everything that can move before that side gear starts to move will. So what happens is the car is resisting movement and as it is "taking up the slack" in the drivetrain, imagine all the U-joints are slightly moving and the ball bearings in the CV joints are rocking to one side to remove all the slack. At this same time the wheels are not moving, but the carrier does rotate forward. You can think of this as the case moving or as the side gears moving. Same difference. The side gears movement in relation to the LSD (they're basically rotating backwards relative to the motion of the LSD) drives the spiral gears outwards against the side of the case. They hit the side of the case and that is what finally forces the side gears to finally move along with the carrier. This is why you were turning the driveshaft and getting 30 degrees rotation before the wheels turned. The side gears turned backwards 30 degrees relative to the outside of the case during that movement of the driveshaft. All of the slack in the drivetrain has been taken up at this point and now the wheels start to move. Now in your case you have these springs on the side. The springs are trying to prevent the spiral gears from wedging against the edge of the case as hard as they might without the springs. I would imagine this is done either to prevent noise or to make the LSD work more smoothly. That's how it works. I may or may not be back tonight, getting tired and actually trying to finish some work, but I'm sure this will continue on into tomorrow. Looking forward to it! I love this stuff

Side gears are always the ones that the CV's or axles plug into, they're the big ones. That's the technically correct name. The helical gears are the little scroll ones. If you read that thread I linked to, me and Drax and blueovalz get into it about the different styles and there are some links (which are probably mostly dead now) that might help explain some of it. Bottom line is that the side gears drive the helical gears, the helical gears ride up the side gears and hit the inside of the case, where they rub against it and create friction which is why the gears are kept from turning at different speeds. If your diff has belleville springs in there between the gears and the case, then the gears will be compressing the springs and probably spinning them pretty hard against each other and the inside of the diff itself, which would explain why you're having the problem you're having. I'm pretty sure I'm right on this one, but we may have been disagreeing due to using different terminology...

I thought the Quaife was a 1 way LSD and didn't do anything on decel, that's why the FWD guys love them so much. I know the Quaife has adjustable preload, because John Coffey talked about having his adjusted previously in this thread: http://forums.hybridz.org/showthread.php?t=93879 I think the Torsen acts sort of like you describe, but my impression is that the Quaife is strictly a 1 way deal. Basically when you accelerate the helical gears "walk" up the side gears and in this case I guess they compress the springs, and it's the friction on the springs and the case that keeps the inside wheel from slipping. Seems to me like your solid spacer idea is a good one, although with it set up that way you won't be able to preload the gears so it might be more likely to spin one tire. You might want to do a little research online and see if you can find an exploded view of a Quaife and see how they adjust preload. The Tru-trac that I referenced in that above thread had a wedge on a bolt, and you tightened the bolt to preload the gears, but I have no idea how Quaife does it. I know the Tru-trac didn't have Belleville springs in it, but it was also notoriously noisy and made kind of a crunching noise especially when doing a slalom like maneuver.

If I could remember where I was reading about those things I could probably help you out. Unfortunately it's not coming too me. Basically the heavier the springs the heavier the oil should be. I'd use motorcycle fork oil since it does pretty much the exact same thing, and I seem to remember race cars using 40 wt, but I've got old motorcycle and moutain bike memories meandering around that same quadrant of my brain so don't quote me. The nice thing about it is if you want to change it again you can. Just get one of those suction pumps from Harbor Freight and you can keep changing it until you find what you like for the springs you're running.

Maybe J has more experience. My only experience is recently installing a fuel cell. Never used a surge tank myself, although I know people that have and they seem to work great. One guy was an ex-boss and he raced a Firebird in ITSS and never had fuel problems after installing the surge tank. I was just coming at this from the recently installed a cell perspective.

Maxtor if you want to run synthetic you can use just about any synthetic you want, just stick with 80W-90 and you should be fine. If you just want to pay more and get "the best", I use SWEPCO 201. Its not synthetic, but it is popular with the Porsche crowd which is where I heard about it. It runs about $40/gal online at various retailers. I don't feel that it is strictly necessary to use it but it works great, keeps the LSD quiet without additive too. Randy--all of the friction modifiers or posi additives whether they be GM or Chrysler or Ford are the same thing, so good move on the Ford additive. It's the cheapest too. In all honesty though, I am not too sure what to think about synthetic gear oil either. I did see the weirdest transmission failure with a friend's Nissan truck using synthetic. He worked at an auto parts store and was fanatical about changing lubes, etc, and he was running Valvoline gear oil if I remember. Anyway he calls me up and he was about 100 miles away stuck. I can't remember what the symptom was when it went bad, but it was on a long freeway stretch so I think it might have locked up the rear wheels or lost power or something (this is about 12 years ago now so forgive the fuzzy memory). If you're familiar the main shaft has a couple needle bearings on it that the gears ride on, and one of them was literally WELDED solid to the mainshaft. Never seen anything like it... just cruising at 70 and the heat in the trans is welding parts together... weird. That together with a couple more friend of a friend stories keeps me sticking with the SWEPCO...

Those are the originals. You can use those with pretty aggressive springs by changing the weight of the oil in the tube. I read recently where some race team was using the stockers on their famous Z, but I can't recall which one it was. If you want to switch to inserts you just drain the oil out of the tube, throw the piston part away and slide an insert right in.

Do people run dual exhaust on the RB's? I wouldn't think so... I would run the a stock tank and a surge tank because the cells are freakin heavy and a good one (Fuel Safe or ATL) is very expensive, and they require a LOT more installation especially if you don't want to fill it out of the hatch.

These distributors are extremely simple. That's the good news. The bad news is that the vacuum advance mechanisms are pretty much always broken. Even if it is disconnected it can still cause problems, because the ball bearings in the advance mechanism hold everything in line, and in my case when the bearings came out the stator tilted inside the housing, and the trigger wheel hit the stator. Not good. Here is a website that tells you how to go through the whole thing, including wiring: http://www.jrdemers.com/280ZX/distributor/distributor.html I used that page to rebuild mine and when I got to the vacuum advance I just took out all the unnecessary parts and JB welded the sucker solid so that it couldn't move at all. The mechanical is on the shaft, so I still have that working, but the vacuum is the breaker plate stuff that breaks all the time. The modules do go bad. Not frequently, but it does happen. If you want you don't have to replace the Nissan module, which is expensive. You can use a GM HEI module, or if you're good with wiring any number of other modules (a friend of mine uses Chrysler modules).

Relocating the pivot point works and there is nothing wrong with that approach. i just don't usually think of that one. Why up 1/4" to correct roll center by the way? Moving up will adjust bumpsteer more than it adjusts roll center. What I would do is move it up 7/16" and out whatever you want. 7/16" is what I found was the correct amount when I messed with my crossmember on this thread: http://forums.hybridz.org/showthread.php?t=106974 That amount may vary a bit from car to car, but that measurement should be in the ballpark, since I took it directly off my car and I had used a gauge to 0 the bumpsteer.

I think you can make 200 whp without porting. Cam selection has at least as much to do with it as the porting does in my opinion and most people go way too conservative with the cam selection. If you're not using the stock FI, you can get away with a pretty big cam. I'd suggest something in the .500/300 range and that should flow enough to get your 200 whp. BRAAP's favorite .520 lift cam would be a good one too. If you're not doing any porting, I'd also start with a L28 head because it will have the larger intake valve (and marginally larger exhaust) than your E31, and it seems to me that the P heads just look to be cast better. I agree with greenmonster80, a shaved P90 or P79 would be my first choice. And if you're going to do triples, get 44's or 45's and don't waste your time with 40's.

Wheel spacers...

I would be willing to bet that you're right and that the poly camber plates killed your struts. Technically you should only adjust your AZC control arms from the rod ends in the full in position to the rod ends extended out 5/16". That's probably going to change the camber something like .4 degrees or thereabouts. Any farther than that and you're actually putting the rod ends in a potentially weak position, because they are supposed to have 1.5x the thread diameter (15/16" in this case) engaged in the threads. Since the AZC arms don't have enough threads to meet that requirement, I think that moving the rod end out puts even more stress on the end of the arm than would otherwise be there. You might want to read these: http://forums.hybridz.org/showthread.php?t=123263 http://forums.hybridz.org/showthread.php?t=120668 I don't really know what the stock strut tops are supposed to have in them, it has been years since I was using one, I'm sure someone else will jump in and answer that question about the stock strut top.

I saw the same thing, but my impression of the problem was that the Z's used were all too high off the ground. Reading the Hot Rod article the first thing they did was make the airdam go right down to the floor, but the Z airdams look to be 5-6 inches off the floor. The 70's Camaro used in the Hot Rod article has a laid back front end like you describe too, but they were able to get the drag down to .201. If you have the magazine handy, and you look on page 114 at the bottom left corner, they were able to get a stock front end with very sharp hood and headlight areas areas down to .337 by using a huge airdam and grill plug, and then by copying the tail design from the first Camaro got the total drag down to .292. My gut tells me that a deeper, better airdam could get our Z's down to the low 3's or high 2's.

The payday thing is correct, but do not end your auctions in the evening. I ended some auctions at something like 6 PM on a Friday which should fill both the above qualifications and I basically gave most everything away. The problem I figure is that people were out on Friday night or on their way home and weren't there to bid. Since then I've tried to end auctions between noon and 2 PM and I've had better response.

I suggested that to Garrett when this happened to him, I don't think anyone has actually tried it yet. One obstacle may be the strength of the weld on the carrier, as I think it is cast iron and not steel.

I don't think so. Tire wear is going to depend on ride height and driving style. A stock Z driven like a commuter car doesn't wear the tires funny. A lowered Z will often times wear the insides of the tires, especially in the back where lowering the car makes it gain more negative camber. The front usually doesn't go anywhere near as negative as the rear, so what would likely lead to more wear on the inside rear tires than the fronts, but if you take turns hard that would probably mean that the fronts wear the outside of the tire and the rears wear more evenly. It's really not as simple as "Yes you need this" or "No, you don't". Have you had an alignment lately? Might be interesting to see where your alignment is at.

That's your problem right there. Those urethane "camber plates" are a lot thinner than the stock insulators. They're also hard on the strut shafts. Just like the broken TC rods with poly bushings, putting poly at the top of the strut requires that the poly flex in order for the suspension to move. Just like the TC rods, the strut will eventually weaken from this.

I'll second this. Also if you're looking for really high hp numbers skip the 40mm carbs and go straight to the 44's or 45's. That will generally bump the purchase price of the carbs up a bit too. Stock FI manifold is not a good option for max power, so you end up with a triple manifold and ITB's. There are the one offs like John Coffey's manifold or Ron Tyler's. If Ron starts mass producing his that would a GREAT option...

I knew a guy who used a copper HG on his BSA motorcycle. He was having trouble with it because I think the head wasn't flat (been a few years, but I'm pretty sure that was the problem) so it kept leaking at the headgasket. He would clean it and then re-anneal it, which was basically getting it really hot with a MAPP gas torch, and reinstall it. Once he finally got the surfaces machined flat he didn't have any more problems. I think I'd rather go with the HKS style if you wanted a metal headgasket, but the copper does work.

There are basically 3 common methods for adjusting camber in a Z. 1. Adjustable bushings. These don't really give you that much adjustment, but you might be able to even out both sides if you're lucky. 2. Adjustable control arms. This one is a bit misleading. In truth most adjustable arms shouldn't really be adjusted that far (5/8" rod end should be used for only 5/16" of adjustment), so maybe longer control arms is a better way to put this. 3. Camber plates or slotted strut towers. Slotting the strut towers doesn't give you much because the larger OD of the stock spring prevents you from adjusting very far at all. Like the camber bushings you might be able to even out the sides. Camber plates in conjunction with coilovers gives the spring a smaller diameter and that allows you more adjustment. This is really what you want if you're trying to dial in the handling of your car, but might not be the best choice for a street driver because it removes the strut insulator from the system which means a lot more NVH. If I were working towards a street car and had no interest in racing I'd probably do the bushings first. If that didn't give enough adjustment then I'd seriously look at slotting the top of the strut tower. It's free for one, and you could keep the insulators. If that weren't enough then I'd consider the other two options. Keep in mind that you want a longer control arm for more negative camber and a shorter control arm for more positive camber, and buy your arms accordingly.

Huge hp numbers maybe won't give a significant advantage at autox, but have you seen this thread? http://forums.hybridz.org/showthread.php?t=121278 HP numbers aren't quoted, but it appears to be in technical terms "friggin insane amounts of hp", and it looks like it can be made to work on the big track fairly well to me... I think I kinda came off like I had my panties in a bunch, and that's not really the case. I just think that there are a lot of people who believe the myth that you can't build a fast car without huge piles of cash. While its true that taking a car to a good speed shop and throwing a mountain of cash at them is one good way to do it, the other clearly involves years of researching on the internet and foregoing racing, and instead spending every day off or long weekend in the garage trying to figure out how to make it faster, welder in one hand, cutoff wheel in the other. Then again, maybe I should wait and see how fast my car is when its done before espousing my own methodology...

You're asking the wrong guy I guess. I'm ditching my L ASAP for an LSx instead. I'm tired of trying to squeeze blood from a stone and I'm not a big fan of turbo lag.

Looks like fiberglass to me...

L28 vs LS1??? No comparison. You'll make buttloads of power with the stock LS1 and the L28 (or L31) will be pushing it's max to make the same hp number. Once you start looking at the torque and hp curves, it becomes immediately apparent that the LS is going to have WAY more power in most of the rpm range, and the torque curve on those suckers is flat as a pancake. The LS is also capable of a LOT more power with a couple simple tweaks like a cam swap and some valve springs to complement it. There's just no comparison if you're looking for max power output. If that's the decision you are trying to make, L28 vs LSx, you really should do a LOT of searching and reading before you decide. They're SO different it's hard to understand why you would compare those two engines, had we not known that this was going into a Z that is...