JMortensen

I gotta go with the Mosler Twinstar. You can take down most Ferraris in a 6000 lb Caddy, at least in a straight line...

Try http://www.behrents.com. They had the best prices on everything except the calipers as I recall.

It's gotta be 87-89 turbo and not the SE model, which has a viscous LSD that won't work with your CVs. The SE models were pearl white with white wheels, so they should be easy to spot.

Those pics are GREAT Drax. I think it makes the whole thing easier to talk about. Thanks. You've made my point beautifully. The case does wear, and the LSD does require adjustment because of it. The aggressiveness of the LSD is based on how hard the gears rub on the inside of the case. Nodular iron will wear out too, as you pointed out. As to the lifetime warranty, that wasn't offered on any of the gear driven types I used to sell (the only one I can recall off the top of my head was the 2 year warranty on Tru Traks). Maybe Quaife has come up with a different material, or maybe they just factor the occasional replacement cost into the original sale price. Maybe it's like warrantying a Tokico or KYB strut. Sure the warranty is there, but how many people are smart enough to figure out that they even have a blown strut? Even if it's worn it's still going to be better than an open diff for a LONG time. Or the car changes hands and the warranty is no longer valid, can't find the original receipt, etc.

I'd keep the stock engine and swap it in every two years if mine needed smog... it's a bitch, but what other option is there? Not gonna keep it stock...

I absolutely love the current hard top version.

So where is the fuse??? Seriously, if I'm reading your description and looking at the picture right it sounds like the bearings have more to do with the side gears than the helical gears. The helical gears are what create the friction and limit the slip. That is weird though, it's the first time I've seen side gears with a bearing under the thrust washer, and I'm still not sure what the function of the bushing in the center is. Maybe the side gears move A LOT, and the bearing prevents them from binding and wearing into the case and the bushing prevents them from grinding on each other in the center???

That makes two of us, and I ain't gonna at that price!!!

I don't care if it's exchange rates, or labor prices or what, if I have to pay 3 times the value of any part, I'm not likely to buy it. There are plenty of quality LSD manufacturers here that could make an equal or better unit cheaper, there is just not enough demand. I'd love to have a Dana or an Eaton or a Trac-Tech positraction. Seems that those crazy bastards running those businesses would rather make 50,000 8.5 GM LSD's than 500 Nissan ones. That's where you and I disagree. I think that auto parts have a value that is not dictated by its country of manufacture, but rather by how good they are. So if there is no value gained I won't pay $50 for an Icelandic roll pin or $100 for a Siberian radiator cap, or $90 for a Ecuadorian ignition coil, or $1500 for a British LSD.

Truth be told if they were $450 and the clutch type was $500, I'd spring for the clutch type. I wasn't aware that we were getting such a "bargain". I also want cheaper gas, BTW. Maybe that's crazy too, since you pay 3 times as much for it. Doesn't make me willing to pay more. Makes me want to buy something else. I'm not after a $25K OS Giken head either... Exactly. RCNSC--relax dude. We're just arguing. No one should be getting their feelings hurt here, or getting uptight at all.

Drax, I don't know what Torsen diffs you were looking at, but you've got me confused as to how the ones that you opened up worked. You've got side gears with helical sections on the inboard side. The helical sections drive 3 long rotini pasta looking gears which sit in the middle. As you put power to the diff, the side gears want to move laterally before they actually drive the axles. When they move they drive the long gears against the inside of the case. Once they are up against the case and they cannot move anymore, then differentiation can take place. When it does take place the inside wheel must overcome the friction created by the gears rubbing against the case. The preload would be set by adjusting the side gear spacing so that the long gears are already engaged against the case. Without the preload the units spin VERY easily, at least the ones I've played with. Not sure how the TBR is adjusted other than jamming the gears against the case harder. As I said before, I know that the Gold Trak had different helical gears you could install with different pitched teeth. I assumed that this meant that they would try to walk off of the side gears quicker and hit the case harder. I've never seen the needle bearings you're referring to, so I don't know what to say about that. Seems counterproductive to the way the thing works to put a bearing on there. EDIT--Maybe the bearing is there to keep the noise to a minimum? I know the Tru-Traks are noisy, especially when changing from right hand turns to left hand turns and vice versa, like in a slalom. They make all sorts of creaking and popping noises as the helical gears get driven into the case and then overcome that friction and start turning.

That's impressive. Preload is the same thing you're adjusting in a clutch type by changing the thickness of the clutch pack, and you adjust it because of wear. But I ALWAYS hear the Quaiffe proponents talking about how it never wears, and never needs adjusting!!! Friction comes from work in the case of the ring and pinion or transmission gears, this is true. But when you are spreading the gears against the case to create the resistance instead of using the weight of the vehicle as in the ring and pinion or trans I have a harder time seeing how it is the meshing of the gears that creates the heat in the Quaiffe. There is no friction surface to increase the friction at the gear tips, so any increased friction comes from the tip of the gear digging into the case, which seems like it would be the primary heat generator. That's true, I've had my clutch style slip going into my old severely slanted driveway. But the one engineer I know who really turned me off on the Quaiffe kept breaking axles on his Midget, and didn't break them anymore when he went back to a clutch type. When I first became aware of them, I asked on the IZCC list, and several people who had switched to it had already broken stub axles. What that is worth, I don't know. Which sounds the same to me as having a worn out clutch type. Too little preload and it "goes open" and the inside tire spins. I don't see the difference. OK, so you can tune around it. I'm sure you could do the same with a worn out clutch type. If the inside tire never got light it due to less rear roll stiffness, it would be less likely to "go open" too. Also very impressive, and if it did fail they'd replace it, even if you were racing. I can't argue with that. Not sure I'm on board with this one yet. That part sounds good, except I like my car setup west coast style. About $1000 too much IMO. John's car is the fastest Z I've ever heard of, and he uses the Quaiffe. That says something for their performance. All I'm saying is that the gear units DO wear, they DO require adjustment, they do "go open" and they do cost too much. IMHO. The other question for me is that if the gear driven units are so wonderful, why are they widely considered the cheap crappy option for domestic racers? Maybe there is a design difference that makes the Quaiffe superior to the Torsen or the Tru-Trak. I can't see anything obvious in the exploded views.

How about "cubic bucks beats cubic inches"

RCNSC--have you seen the California Z kit? What you've done kinda reminds me of that kit. Looks good! I like that hood idea. Always wanted to vent my hood like that, even before I saw Terry's car. The only issue I would have is why have the back of the fender vented in front of the door and also have a big vent in the side. Seems like the side vent is unneccessary. Regardless, you need to start playing around with fiberglass!

I'd always heard they used the gear type. Plus, it's hard to equate anything we're buying for a couple hundred bucks to something in an F1 car. My experience has been that with one wheel off the ground you can spin the lifted side tire with one finger. In fact, this is the circle track cheater diff because it acts really open until you put power to it, so you can get through tech and they'll think it is open. I sold quite a few to dirt trackers for just that reason. I suppose you could adjust the TBR by shimming, but then you're going to wear the case that much faster. Ford had a different (possibly better) way of adjusting the bias on their Gold-Trak (I think?) with a differently cut set of helical gears. They were cut at a different pitch for different ratios. The Tru-Traks that I've seen have a block with a bolt and it's been a while, but I think they pull the side gears together or push them farther apart to adjust.

Auburns don't wear out clutches, they wear out the case itself. Kinda like the gear driven LSDs. They are not rebuildable, so as they wear they get less effective and eventually you just take them out and throw them away. They also chatter really bad, especially the Pro series. Viscous is reactive, not active. I've never heard a serious racer say they wanted to install a viscous LSD. I've heard people talk about changing the fluid to make it more aggressive. Maybe I just wasn't informed... I'll stick with my torque sensitive clutch style LSD, myself. Never heard that complaint about them not holding 300 ft lbs before. Good thing I don't make that much torque... Jon

The Quaiffe is a gear driven unit. People think that there is some magical gear in there that doesn't want to turn, and that's what limits the slip. This is just not the case. I'm more familiar with the Torsen, I've had a few apart, so I'm going to use that as my example. The way it works is the spider gears spread 3 long helical gears against the inside of the case. These gears need to turn in order for the wheel speed to differentiate, so they are forced to turn while rubbing on the side of the case. So the friction of the "toe" of the helical gears against the case is what limits the slip. You can "adjust" the preload by using a bolt to spread the gears against the case. Problems with this diff are: 1. They DO wear out. 2. They DO need to be readjusted from time to time. 3. They generate LOTS of heat since there is no friction surface, just metal on metal. 4. When a tire comes off the ground the gear type will transfer ALL of the power to that wheel instantaneously, in a Z this is bad because when that wheel comes down you've now broken a stub axle. Clutch style doesn't do that. 5. They slip! John Coffey has said on a few occasions that he's had problems with them slipping in high speed corners. He's also said that Quaiffe couldn't fix them. He did have another place to send them to that could get them to not slip anymore (EMI?) I've heard this same complaint from other racers now too. 6. Although I have to admit I haven't heard it in regards to the Quaiffe, I would estimate that I used to get 15-20 calls PER WEEK from Camaro owners with gear driven units that had just done their best grenade impression when I was selling diff parts. When I worked for a diff parts supplier we sold hundreds of Eaton clutch style posis (the good one not the Gov-Lock POS that comes in GMs) to people who had destroyed their gear type LSDs, and we had 20 Zexel Torsens on the shelf priced at $135 and we couldn't get rid of them. That's right... $135!!! Why is the Quaiffe $1200 when a Torsen is $135? I don't know. I've looked at a diagram of the Quaiffe and they appear to be very similar. Even a Tru-Trac is only $350. Domestic clutch types are in the high $300 range just for price comparison. To me the only advantage to the Quaiffe is smoothness and its low breakaway pressure. With such a low breakaway it doesn't tend to affect the turn in as much as a clutch style LSD. And you can use it as a cheater diff if you're in a class of racing that doesn't allow LSD. The advantages of a clutch style are price, consistency, durability, adjustability, and rebuildability. I know I stand in the minority on this one, but I have enough experience to feel that my opinion is warranted. Jon

I think you can get the Nissan unit from Precision Gear for $500 new, rebadged as "Power Brute" or something like that. Should be available in R180 or R200. If you want to change gear ratios, this would be the time to do it. A stock 240 with 4 speed would have a 3.36 and an auto would have 3.54, neither of which is very aggressive.

I'd dispute that.

Sounds like pinging to me. My best description of the noise is that it sounds like a marble trapped and rolling around in the front bumper. Kind of metallic tapping noise. Not a turbo guy but I would expect to see some fuel mods in your list and I don't. If you're upping the boost you need to increase the fuel too! Jon

Owen, if you're trying to figure out where the air is going like wind tunnel style, you might want to do the yarn thing. Just tape 2" sections of yarn all over the car, then have another car drive along side, in front, behind, and video the yarn. I don't think you'd really get much off of the smoke flare...

510six. That's the guy!!!

Well the trick in 510 circles is to use roadster comp front springs. They're REALLY stiff. You could also get some super stiff shocks (possibly the cheapo kind that have a schrader valve in them for towing). The ZX rear and the 510 rear ends are the same (almost) so you may want to see what the 510 guys are doing. There is a guy here with a 500+ hp 510 with a turbo L6 in it, he'd be a good guy to ask. I think it's sss510 or 510sss. I always get his handle screwed up. Jon

That perfectly sums up my feelings about drag racing!!!