JMortensen

FWIW - I've got my 5 point lap belts and my stock seatbelts both mounted on the same seat belt bolts in the floor. I've got the shoulders going to the roll bar, so they don't interfere. When I race I pull the 5 points out and pull the street belts out real long and latch them behind the seat. I tried just using the 4 point without the sub belt for a little while on the street, and you are exactly right Tim. Big PITA. The "head trauma" bars I've seen have been within 6 inches of the driver's head. I don't care what kind of harness you've got at that point. You are going to hit your head. My question was more is there enough benefit to the structure of the cage to justify this bar at all? Or were the cages I saw built by... less intelligent folk. Jon

One thing that always made me wonder: Why do people put the diagonal from the hoop to the passenger floorboard in? I always referred to it as the "head trauma" bar. Is there all that much to be gained over a 6 point cage? I've seen them in otherwise well built cars with no padding being driven on the street! At one auto-x I snap spun and did a 360. When the car stopped I smacked my head on the roof right next to the door hard enough to ring my bell with a helmet on. I gotta wonder what would happen in a similar situation on the street with no helmet going the other way. I think the "head trauma" bar might live up to its name. Jon

The only decent way to balance a tire is with a dynamic balancer IMO. When you balance dynamically, you have weights on the inside and outside of the rim (when they are needed). Sometimes on rims with no lip on the outside they will use stick on weights as opposed to hammer on weights. I prefer the hammer on style, but I don't think that there is really too much of a difference in practical terms, as long as the double sided tape is strong enough to hold on the stick on kind. If you don't have weights on the inside and outside, take them back to the tire store and have them do it again. Weights on one side of the rim only is a static balance. I had a guy who OWNED a tire shop argue with me that since his machine was a "Dynamic Balancer 4000" or whatever that the tires were dynamically balanced even though he only put weights on the inside of the rim. Of course I was there because of a vibration. A little shouting later and he rebalanced the wheels, and surprise, no more vibration. BTW-I had a set of 1/4 wheel spacers (not the bolt on kind like you have) where the center hole was about .010 too small, so even though it looked like the spacers sat flat against the hub, they didn't. They were just barely off the hub, sitting on the cone shaped pilot. I dealt with the vibration for a long time, until finally one of the spacers cracked and I replaced it. When I put the new smaller diameter one on, it lined up really close to the edge of the hub and I was able to see that it was not flush, and then was able to figure out what the heck was going on. Jon

I just "got it". You want to completely seal the entire engine compartment. So at some point the pressure through the radiator would be greater than the pressure from the cowl, so the air would vent. I'm with you now. What about at speed, say above 30 mph where the air would be significantly slowed through the radiator. Might cause some cooling problems. Something to think about. I've seen some cool things fabricated: MG midget with Corolla GTS drivetrain, 280Z rear suspension converted to double wishbone, Mini with turbo Subaru AWD, etc. I for one will be curious to see what you come up with. Also, I understand you not wanting the Vette (I'm not a big fan either), I just threw that out there because it seems like you'll be building a Vette style chassis and suspension. Jon

There is a lot of pressure at the cowl, because of the slope of the windshield. Its like putting a hole right at the base of a spoiler. I don't think you'll be able to exhaust air through the cowl at all. Have you looked at Terry Oxendale's car? He's BlueOvalZ in here. It might give you some ideas. His car is unbelievable! I think he's got pics in the album area. Good luck with your project. Jon

You want your car to hit 1 to 1.15 G's at what, 100 mph? Why not concentrate on the suspension? A well thought out Z suspension will get you 1 to 1.15 G's on a skidpad at around 40mph with sticky DOT race tires or slicks. I've no clue as to what the airbag suspension would do to your benefit. Seems like you'll just have to drag along a compressor and a bunch of wiring to make it work. If you want 18" wheels, a 350, upper and lower control arms, more aerodynamic body, and Vette rear suspension, why not buy a used Vette and some wheels? You'll probably have more money in a Z to get it that way then if you just bought the Vette to start. If you put wings on, you better match them front to back, or you'll end up with a car that pushes or oversteers really badly. You also better attach that gigantic wing in the back to something solid, otherwise you'll ruin the sheetmetal its attached to and have to buy a new hatch, especially if its not just for looks and actually produces downforce. A cowl hood is for putting air INTO the engine compartment. That's why they are "cowl induction" hoods. Body kits for Z's are usually just for looks, sometimes they are for racing so that you can get bigger tires under the fenders, but not specifically for downforce (at least none that I've seen). I don't think the G nose is a good idea for downforce. Look at it from the side. The bottom of the radiator opening starts a little below stock hoodline, and slopes down to the core support. This would act like a huge wedge driving air under the car, from what I can see. Jon

Two quick stories: One, a friend in a '71 was at an auto-x, right in the middle of his run the car felt "weird". At the end of the run he figured out that the drivers side A pillar had detached itself from the cowl. Completely detached. Two, took my ex-boss for a ride around Streets of Willow in my car a (he's been racing Porsches for 25 years, there's even a picture of his hand in How to Make Your Car Handle). He said, you might want to listen for popping noises. I betcha this thing is going to start tearing out the spot welds. I've never found a spot weld that's broken, but I still think about that every time I put slicks on my car. Jon

Check your mixture. Some people think Z's with SU's tend to diesel when they are rich. I always found that mine dieseled when it was lean. Lean mixture gets things hot in the combustion chamber, like the edge of the valves, those carbon deposits, etc. I'd turn the mixture screws out 1/4 to 1/2 turn and see what that does. Jon

I used to drive my 240 everyday and take it to the track and autox as well. It hasn't been a daily driver for about 9 months, but I haven't ripped the interior out yet, so it is still 2350 lbs with a full interior. When I race I run Yokohama A005 slicks, they are way too hard for a Z IMO, but you can't complain when you get them for free... I started with 250 lb springs front and back, 1.5 degrees neg camber front and rear, 0 toe front, and 3/16 toe in rear. I needed the car to turn in, and you do that with softer springs in the front, in my experience. In order to make that happen I reduced the front spring rate to 200, increased neg camber to 3 degrees, toed out 1/8", and increased caster to 6 degrees. I also increased neg camber in back to 2.5 along the way. The car still pushes a little, I think its the LSD more than anything else at this point. All of these changes took place over 5 years, one at a time. I'm running a 15/16 (24mm) bar up front and a 7/8 (22mm) in the rear. The car still has a lot of body roll, and it was recently noted that I am lifting rear tires while slaloming. I am looking to go to a stiffer front bar, or possibly cut my ends off the existing bars front and rear and weld some plates so I can go to rod ends and have some adjustability. I know a lot of guys run differently for the big track then the auto-x, and I've heard of people with Z's running stiffer springs in the front than the rear, and also running a small front bar and no rear bar. I think the guys that are doing that are running really stiff springs, like 500 lb. To make use of that kind of rate you have to have a full cage, and you would no longer be comfortable on the street. I always use my pyrometer and some white shoe polish to check that my alignment settings are correct. Shoe polish over the edge of the tread onto the sidewall to see how far the tire is rolling over. BTW, when I go to the big track I cut out some neg camber, to about 2 degrees and give it 1/16 toe in in front to get it to settle down a little. People who drive my car seem to think its tail happy, I think it still plows, FWIW. But I don't chop the throttle mid turn Jon

Cutting coils is fine, but you don't want to use a torch to cut them (spring will lose its temper). Use a cutoff wheel, and I'd go 1/2 coil at a time, as you can't put it back if you go too far. Cutting coils will also increase the spring rate slightly. Jon Mortensen

Has anyone looked at the 510 as it relates to the ZX suspension? Same semi-trailing arm setup, right? I wonder if the same mods apply, slotting the crossmember and such. For spring height and weight jacking you can install a Stock car style weight jack on the 510, should be able to on a ZX (???). Not exactly a bolt on, but if you're serious about it they are pretty cool. Big threaded shaft with a 1/2" square drive that sits above the top spring perch. You can raise and lower ride height and set corner weights. 510's have the steering box, so I imagine a lot of those issues have been worked out as well. I know a friend of mine converted his 510 steering to 5/8" rod ends. I was jealous of how easy it was to do. He just took the steering knuckles and the drag link to the drill press and drilled them all out to fit a 5/8 bolt (there are instructions on this in the How to Hotrod book if I remember properly) and bolted the rod ends on. Then he got your standard Pinto bump steer spacer kit from Coleman, and was able to change bumpsteer very easily at the tie rod ends. Jon Mortensen

Oops, just realized you've got a 280, at least by your name. Probably just had sagged out springs like the others said.

That's from Arizona's website. You got stock length springs because a 240 doesn't need to be lowered Jon Mortensen

I think what J is talking about is a carrier break, and I'm not aware of any Japanese car that has one, although I've been learning that I wasn't aware of a few other things about Nissan diffs. Basically the "step" where the ring gear sits is machined closer to the pinion shaft to accomodate lower gearing without a really thick ring gear. When you go to a lower gear ratio, the ring gear gets thicker, so a 4.10 will have a thicker ring gear than a 3.36. This is because the pinion has less teeth, so less diameter, and for the two to mesh, the ring gear has to be wider. I dealt with this A LOT in American diffs, and never saw one where they changed the shafts. It just doesn't make sense to change the shafts, even when there is a carrier break. Even in REALLY extreme cases, like 6.00 gears, you usually find another way around issues, like notched crosspins and grinding ring gear teeth. Also, at least in American stuff, the carrier shims are pretty much the same between the 4.10 and the 3.36, because the distance is made up in the ring gear and not the shims. The only time I saw people with the carrier shimmed to one extreme or the other was when they had the wrong carrier (with the wrong break) for the ring and pinion they were installing. I'd bet someone just started manufacturing these without actually taking one out of a car, and is plain 'ol doing it wrong. I'd suggest that BOZ complain LOUDLY to the manufacturer to prevent further screw ups. Jon Mortensen

Stop buying and start installing. Or buy some time at a shop and have someone do it for you. You've got enough there that you will get the results you are looking for. It seems from your posts that you are always digging your hand in your wallet. Put it in your toolbox and get the thing going! Your car doesn't need to have all of those parts installed to run. Install the suspension and brakes and take the rest of the stuff with you. Do the non-essentials last. I'm pretty sure I know where I'd put the stereo and headlight covers on my "things to do list". You should be able to get that suspension done in a matter of a few days if you have the tools. Its all nuts and bolts, except the coilover stuff.

Kinda looks like a bastardized Porsche 935 to me. See for yourselves... http://autozine.kyul.net/911/911_a13.htm The tail is actually quite a bit bigger on the Porsche!!! Jon Mortensen

I know this is kind of a new thread emerging here, but do you happen to know if the 12.2" rotors fit under aluminum wheels or only steel. I'm pretty sure Cup cars run steel, and it would seem that you've got a lot thinner material with the steel wheels. Not that steel bothers me, I just want to know so that I can buy the right stuff. Been looking at the Diamond Racing spun steel. They can be pretty light, but a little on the fragile side from what I've heard. Jon Mortensen

Your welcome. You don't NEED to take the dizzy out to get those parts off, but its definitely easier, except maybe for the reluctor. But you said you wanted to rebuild the dizzy, and you need to take it off to check the bushings. Its only 2 10mm bolts anyway. The reason your car would run lean due to the vacuum advance being broken is that you have a vacuum leak, so the engine is drawing fresh air after the fuel injection has determined how much fuel you need. You could just cap the vacuum line on the manifold that goes to the advance dashpot and see if that fixes your lean running issues. Don't have any idea how much the dashpot costs, I decided to go with mechanical advance only and disabled the vacuum completely. Check Courtesy Nissan's website, you'll probably find it there. Jon Mortensen

That's what I have in my car Watch the compression if you're not serious about running race gas. Unless you have owned that E31 since it was new you're probably not sure if the head has been milled. Mine was a virgin, but I ended up milling just enough to make it flat, like .004 or so, and I seem to be able to get by on 96 octane or so. I figured the octane out by cutting 112 octane leaded with 92 until it started to ping, then bumping it up a little from there for a little safety margin, ended up at 96. Also your E31 has smaller intake valves, so you would probably want to have the seats changed to fit the bigger 280 valves. If you run dished pistons compression is way too low, like low 8's. My machinist also told me not to run a 2mm head gasket, because in order for quench area to work the head and the piston need to be within .060 or so. I also polished the combustion chambers A LOT! There were lots of sharp spots in there, those are going to increase the tendency to ping, so you may want to do the same before you slap the head on the block. With polishing and unshrouding the valves I added about 4cc to 6cc to the chamber volume, made them all even within .5cc and improved the flow. The N42 would be a lot easier, just slap it on, and it would run on 87 octane. I love my motor, but I miss driving my Z. It really only comes out on special occassions or to go to the races. Used to be my daily driver. Jon Mortensen moderators - is it bad form to give this info after you've told the guy to search???

It sounds like you are dealing with a non turbo '82 280 ZX dizzy. If so, check this out: http://www.physics.ohio-state.edu/~jrdemers/280ZX/distributor/distributor.html This site is GREAT!!! He gives you the step by step instructions on the teardown/rebuild, and sells new bushings. Really helped me out. JD is a really nice guy too. I just bought a stator and reluctor from Nissan for ~$40. Be aware that the stator did NOT come with the magnet. I don't know where to get the magnet from... Oh, and don't ever trust anyone who tells you, "Yep, that's a good distributor right there. Just plug and play." It sure didn't work for me. Jon Mortensen

Best tip I ever heard for welding (not that I've heard too many): Assuming you are right handed, hold the gun in your right hand, then wrap your other hand around, just like you were shooting a pistol. Stick your pinky out on your left hand, and touch the material. With your pinky touching the material, you have another reference as to how far you are from it. Your pinky will steady you as well. Jon

Spotfitz, The LSD shouldn't make it harder to turn the driveshaft at all. It only does its thing when you go around a turn. When you twist the driveshaft with the car on jack stands, the only gears turning in the diff would be ring and pinion. Check to see if you have a brake hanging up. BTW - it should be difficult to spin the wheels in opposite directions with a clutch style LSD. Jon Mortensen

As far as I know, the Phantom, Power Brute, and others are all Nissan LSD's imported from Japan. In fact, I believe ALL Nissan LSD's are Nissan units, except for the Quaiffe. This info comes from the ordering dept of Randy's Ring and Pinion, who are the largest LSD and locker distributor in the country. I would love to find out that I am wrong here... but I believe that I speak the truth. Unfortunately, Randy's did almost nothing with Nissan. They only carried Auburn Gear, and didn't have any in stock when I left. Those were also supposed to be Nissan units. FWIW, the Nissan unit is pretty darn good. Very similar to Dana's PowerLok with ramping cross pins, which is a lot more durable and agressive than Auburn's cone set up, or Dana Trackloc, or Ford Traction-Lock, or even Eaton. Jon Mortensen

I've got no idea why you had the suction problem, but I don't think it was actually a suction problem. Having pulled many of these struts out of the tubes, I can tell you that the suction involved is not that severe. Possibly the strut corroded and was stuck to the side of the tube, bent strut housing, I don't know. As Mat said, the oil in the strut tube is there to transfer heat from the strut to the strut housing. If you have no oil your struts are going to get very hot and not be able to dissipate that heat. You should put some oil in there. I always use ATF, but I don't think it really matters what type of oil. I usually put enough in so that the oil level sits about 3" from the top of the tube. From personal experience I can tell you that I swapped a blown Tokico Illumina about a year ago and the paint on the strut itself (or is that powdercoating) was bubbled up quite a bit from the heat. There was a section of the chrome shaft which was heat checked and blue in color, like case hardening. They get HOT! :flamedevil: With the heat thing in mind, I've got to wonder if you would be able to seal the bottom of the strut housing with silicone and have it hold. I think you may have to weld the hole back up or thread it for a plug. Jon Mortensen

I'd like to see a braking system with aluminum hats and 4 piston calipers that would fit inside 15's. Road racing 15" rims and slicks are very common, 16's and 17's are not yet as common, so they are much more expensive. I may be wrong here, but it seems like the only common brake upgrade with 15's is Toy calipers and 280ZX rears or Ross's rear setup. If I am wrong please let me know. I don't like the Toy calipers because of their huge weight penalty (although I do have them on my car right now), and the rear doesn't seem to have enough braking power. At least my 280ZX setup doesn't and someone else was just complaining about another type too. Jon Mortensen