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Based on what I've read on this board the illumina setup you currently run is about the limit for spring stiffness without beginning to strengthen the chassis. Also 250 lb is about the limit for how stiff a spring you can run with the illuminas (although some have run stiffer without issues). I run 275F, 330 R with Megan shocks looks like I might have just a little less roll. The rates are probably too stiff for the chassis, but oh well I guess. As far as front/rear spring rates, I'm not an expert, but from what I understand, what youre ultimately doing when you "tune" the spring rate is changing the natural frequency of the suspension. Unsprung weight, corner weights, motion ratio, etc all influence this same natural frequency, but are typically not design parameters - spring rate is. It is a general rule of thumb to have the rear natural frequency be a little higher than the front. This is because the front hits bumps first and the rear needs to react faster. Once you choose a natural frequency you can live with there are equations you can use to back-calculate the spring rate necessary to achieve it. They are available in various books or online resources. My calculations have always yielded that the Z requires a stiffer rear spring than the front so I cant explain why some people run stiffer springs in front, but I'm sure they are legitimate. I'll let them speak for themselves. Finally, as mentioned before, I think youre going to run into trouble competing with the crazy stuff they have going on in Modified class. Especially if you want to keep some resemblance of "streetability" for your car. Unless youre set on running in EM, or have a previously unspecified mod on your car that forces you into that class, XP would fit your car perfectly. Also, unless I missed a recent update, I hear next year SM class is going to be allowing "any engine" to be used in cars that otherwise fit into that class. Either of these classes would fit your car well and give you plenty of competition to run against.

Here is what you do 1. Buy any LS powered vehicle. 2. Daily drive it while you restore the Z chassis. 3. Swap LS motor into Z and part out or scrap what you dont use to offset the swap cost. 4. Find a Geo Metro, or some other generic tiny car, to bum around to work in (I'm on step 4... but I skipped step 1 and 2 ) Seriously though, I think youre picking between two great cars. I've seen great examples of both at the local autox with very happy owners. I think individual price and vehicle maintenance/history will be what ultimately decide which exact car you will buy.

How much HP are you planning on? I run 3/8 lines for my LS1 swap (350 hp) with a surge tank and dont experience any fuel related issues. 3/8" line ought to support at least 500 hp, maybe more. It may not look as fancy but regular fuel hoses and fittings work just as well as AN fittings. Your car wont go faster if it has AN fittings on it.

Sorry for any delay, was in China on a business trip. Paid today.

Reputation is all relative and depends greatly on the audience doing the recommendations. The only shocks manufacturers that I know of that come recommended by race teams and shock engineers are Koni, Ohlins, Bilstein, and Penske. If I had to build a race coilover set I would not look at anything else for shocks. I run the Megan coilovers. I bought them because they were reasonably priced, were a complete kit, were adjustable, and were easy (for me) to install. They work well enough so far. Maybe Stance shocks are better, maybe they're the same. Either way, I dont feel I am a good enough driver to be able to take advantage of the performance difference between Megan and a more "quality" shock. The car is still a lot faster than me and I have a lot to learn before I'm ready to move on. Maybe someday, when I feel I'm ready, I can build my car with $400 shocks, just the right spring rate, etc, but that's not today. As far as I know AZC has not released information on their shocks or who makes them, so youre not (knowingly) buying yourself quality there either. Again, if you feel youre truly serious about coilovers, talk to John Coffey and he will set you up with known "quality" shocks.

One thing thats always interested me is why John only opted to use the large bracket and factory engine mount on the driver side of the motor when designing the mounts. There is far less "stuff" on the passenger side of the car so I dont immediately see why a similar mount would not fit. Just curious if you have any insight

With all due respect, I dont think s12 parts are that much more "modern" than s30 parts. The cars are still over 20 years old and utilize the same suspension design (mcpherson strut) as the Z cars, I dont feel you will find much of an improvement there. If youre indeed looking for "perfect" suspension, double control arm is what most people want up front. Only cars I know of that use those are the 3rd gen rx7 or the miatas. Perhaps looking at those is what you really want to be doing. If youre really interested in going with s14 hubs, s13 suspension, s12 subframe I have to ask.. why not just buy a 240sx parts car and go about swapping the whole suspension over to the Z car? The amount of work will be roughly the same since youre still going to have to modify pretty much everything to make it work. At least this way you will have a whole working car to start off of, you never know what other parts you may need. There is no "ideal" spring rate/shocks/alignment/etc, you chose that based on what kind of driving youre doing and how you would like the car to behave. If you search around you will find some good starting points for stock suspension Z cars. For your car it is unlikely those will work for you, I would expect several iterations of suspension tuning to get things where you want them. As the others have mentioned though, this is all theoretical, bench racing kind of talk. Fair enough, you might finish the car and it might handle great, but the actual improvement over a well setup s30 using the stock suspension might not really be as much as you would expect (or not at all). Going with "modern" s12/13/14 parts wont really save you money either. Z car parts are still plentiful and cheap. Z cars also have plenty of options for performance parts to suit almost any price range or application.

For most materials strength and ductility are not independent qualities. When you quench a metal it becomes "stronger" but looses its ductility. What you end up getting when you quench steel in water is a very brittle material. Though I am not an expert on welding I also imagine that during the welding process you create lots of internal stresses in the metal. If you quench the metal afterwards you are effectively freezing the internal stresses in the parts, which makes the structure weaker. I imagine that businesses that do a lot of industrial welding where weld strength was critically important would like to, if possible, anneal the metal after welding and cool at a very precisely controlled rate to achieve an ideal metal structure for their application.

For the longest time I've been using a set of Bomz "racing" seats in my Z. These look like the generic sparco/bride/whatever knock-off racing seats that a million different sellers sell on ebay. I bought them to replace my utterly destroyed stock seats and for $75 came at a great price. The seats are comfortable for daily driving and hold you well in corners. Once I started autocrossing though I noticed some ergonomic issues with the way the seats are positioned. Here is an old picture of my car with the seats: As you can maybe see, I have the seats as far back as they will currently fit and if I sit in the seat comfortably the top of my head rubs the headliner with my helmet. This is with me right up against the seat back (to make enough room to comfortably move my legs). If I sort of slide down more into the "well" in the middle of the seat I get a little more headroom, but now it feels like my legs more cramped than I'd like. Additionally the higher up seating position places the steering wheel low and close to my thighs. Recently I had the chance to drive a bone stock Z car and was amazed how much more better the seating position felt. I had plenty of leg room and head room. However, in the corners, both me and my passenger complained of sliding off the seat. My most obvious option is to modify my seat mounts and redrill the rails to allow the seat to mount lower and move farther back as per my liking. However, given how the seats fit now (see pic above), I am skeptical how much of an improvement I can make. This got me thinking are there any seats out there that mimic the stock seating position but have some bolsters to allow you to not fly off the seats in hard cornering? Many of the modern OEM and aftermarket seats look like much wider and sit higher than stock Z seats. Several of the seat install threads I've read all note this. Perhaps some sporty 80s cars have something that would fit? Anyone have any experience on what I might work?

David, Id like to jump on board if youre still taking more people. Id be in for 1 without any options.

Generally I'd agree with pretty much everything RebekhasZ said. Unless youre very serious about suspension you can get a very nice ride and good handling without spending a huge amount of money on suspension. Some good lowering springs and shocks, a good alignment, and some decent tires will make the Z drive so much better. For brakes, again, some good pads and shoes will be a great improvement. With an LS motor youd probably want some kind of LSD too. With this kind of setup youll get a nice ride, handling and brakes to complement your power. This will also be a great baseline to gauge how the car drives and what you want to do to improve it. One thing I would argue for though is replacing all of the bushings with urethane. A good way to save yourself the headache though is taking the suspension to a good machine shop. They pressed out my spindle pin and all the old bearings for a great price, and I didnt have to think twice about it. The new ones slip right in, then just reassemble, easy. The bushings made my car feel like new. It eliminated I dont know many squeaks and rattles and gave the car smoother more controlled ride. Definitely worth it.

Congrats on your first autox. Welcome to the addiction! I remember my first autocross event the damn electronic distributor wires went into the clutch fan under heavy braking. The car just suddenly died, red flag, and had to get help pushing it of course. Was super lucky the fan just pulled the wires out of the connector and didnt slice right through them. Plugged em back in after routing the wires a little more intelligently and made it back to grid just in time to run again! I still get people asking me "good to see you running again, so what happened a couple years ago when your car died on course?" Your car is looking and sounding good, just fix that fuel issue and youll be FAST! ...Damnit, now I have another person in California to be jealous of... I need to move down to where its dryer! Us Oregonians only get like 3 months of decent racing weather, so sad...

I have the same Zraceproducts mounting brackets. I run 1983 280zx calipers AND rotors. Some of these reman calipers do not come with the "mounting bracket." When you order make sure you order the ones that have it otherwise you wont be able to mount the caliper. As far as that huge steel piece, the ZXs came with 2 different styles of caliper, the ones with it and ones without it. I cant quite remember which years came with which. As far as I know the Zraceproducts mounting brackets are designed to use the brackets withOUT the large steel part.

I'm using a different LSD unit in my car but I had a very similar symptom. I had a shop install my LSD and it turned out to that the pinion nut was not torqued tight enough. This allowed the flange bolted to the driveshaft to spin at a different rate from the differential on decell and ended up grinding the splines on the flange off quite a bit before I made it back home. Pinion gear splines were still fine, but had to replace the flange. Not a hard fix, but definitely not fun.

http://www.tein.com/products/edfc.html Am I missing something or is EDFC just a controller that lets you bolt the included 4 stepper motors to the adjuster knobs on the shocks? If this is the case the only real hurdle you have to cross is actually figuring out a way to mount the stepper motor. Hood clearance and other issues might hinder the installation but the process isnt that complicated. Personally I dont know if people really adjust their shock settings that much that theyd need a system in place to be able to do it on the fly. Maybe in a rally car with varying surface conditions or if youre really trying to tune the suspension on a road car and simply cant come in to change shock settings...

It sounds pretty good. For what its worth, I used a magnaflow muffler and a glass pack in my LS1 exhaust. With this setup there is no harshness in the sound, just a solid V8 rumble. Its not loud at all, just very distinct and noticeable, even at high rpm. With the L6 I ran a 6-1 header with just a flowmaster muffler. It was VERY loud and resonated quite a bit. Made me wonder about putting in a glasspack to hopefully take of some of that out. I wonder if installing a decent flow-through muffler behind the glass pack would quiet things down enough for you.

I've been driving on a set of TTT LCAs for a while now. So far they have been working great. While I do believe that the lack of bushings at the hub end will transmit extra noise the arms still use a urethane bushing to attach to the chassis. This should work to dampen the vibrations at least a little bit. For what its worth when I put the LCAs on the car last summer, I did not notice huge increase in NVH over the stock LCAs with urethane bushings. All that said it sounds like stock LCAs will work fine for you. I got the TTT LCAs to be able to easily adjust rear camber and toe. If this is not something that is overly important to you there really is no necessity in buying them. There are also offset bushings you can buy to make the same adjustments if you're working on a smaller budget. I've also been using a grade 8 bolt as a replacement for the spindle pin for at least 2 years prior to installing the TTT LCAs. In either setup I had no problems with it breaking. If I remember right, the spindle pins neck down sharply in the area of the threads, which would create a point of very high stress concentration. Assuming the same quality of metal my initial thought was that a grade 8 bolt would actually be stronger than a stock spindle pin for this reason. You can achieve a lower ride height by cutting your lowering springs, coilovers are not required. Problem is, depending on how much you have to cut, after youre done you will not have much suspension travel. Not a good thing if you want proper handling.

There is no advantage in NOT doing the spindle pins. While they may not require service should you ever need to take apart the rear suspension (which you probably will since project cars are never done ) you will once again be looking at having to pull them out. Youre really not saving yourself any time and since the car is apart now you might as well do it and save yourself the hassle in the future. If you ordered all new urethane bushings with your big lot of suspension parts these will feel a lot better than the stock bushings. Getting those in there may be a good idea and, of course, you will need to pull the spindle pin to do that. Instead of using the stock spindle pins I replaced them with a long 5/8" grade 8 bolt. It seems to fit perfect and has stood up to a lot of abuse. Its also extremely easy to remove in the future.

For a Chump car $8000 is not unreasonable, my chumpcar team has at least 1500 into just the engine rebuild on our RX-7. In Chumpcar you are not allowed to run slicks. Street tires only, with a wear rating over 200 (if I remember right). Most people run Falken RT-615s or Dunlop Star Specs. For wheels, getting fancy wont buy you anything, any 14s, 15s, or 16s will do ok. As far as upgrades, keep in mind Chumpcar has rules for how much upgrades will add to your car's "worth." Springs, shocks, LSD, other improvements will greatly increase the value of the car dramatically, so most of those are prohibitive if you want to stay within the rules. Just for reference, our chumpcar RX-7 runs ebay springs with stock shocks and slotted top mounts to add more camber, no other suspension work. Engine is a rebuilt stock motor with a couple mods to improve cooling and oiling of the engine at high rpms. Driveline, exhaust, intake, etc are all basically stock. Our car, with the right driver (not me), was capable of hanging with some of the fastest cars on the track. A Z car is a fairly similar car and should not require much more work to get to perform well enough to keep up. I would say do as little as possible. Endurance races are many hours long and the more you mess with the car the more risk going wrong at the track. I feel its better to do less initially, get the car running and thoroughly test it to find its weak points. Once youve found them you can start thinking about what you can do to improve them. Consistency and reliability are much more important. Issues to improve braking and cooling will pay off, not necessarily increasing power or improving handling. Do what needs to be done to keep your car on track. Driving 5 seconds a lap slower than the leader is still faster than sitting in the pits. Organize your team so you dont waste time - 5 minute vs 10 minute driver changes can add up to a lot over 24 hours. Other stuff such as driver communication, driver comfort, crew support, are also things that may be worth thinking about. Endurance racing at this level is as much about these kind of logistical issues as it is about actually being fastest on the track.

I run a radiator designed for the V6 chevy G10 van (rock auto part number CU954). http://www.rockauto.com/catalog/moreinfo.php?pk=272157 I found it after my JTR radiator plastic end tanks started leaking. JTR builds their radiators custom but I wanted an off-the-shelf, no custom fabrication solution in case I ever needed to replace the radiator quickly. After much searching I found that this van radiator core is the exact same length and width as the JTR radiator so it fits their mounts pretty well. The core thickness is a little thinner (1.25 vs 1.375 I think) but so far I've done several autocross events in pretty hot weather and have not seen the temp go up at all. A word of caution, if anyone ends up ordering one be careful. There are a LOT of different van radiators available so its easy to order the wrong one by accident. Make SURE you check the size, width, thickness AND end tank design of the core you are ordering to make sure you get the right one. Otherwise it wont fit at all.

Looking good! It amazes me how similar our cars are, though I REALLY wish my car had paint like yours. Maybe someday...

I think the reason you're having trouble finding pictures is because the wheels are fairly new. I'm sure some will surface eventually... I'm in the same boat as you. I'd like to run wider wheels but for the same reasons as you am feeling a bit stuck. Problem with 15s is the even in 225/50-15 the street tire selection is fairly limited. If you want to run real wide tires 245/50-16 is a good size with plenty of options, this is the route I will probably end up going... if I can ever find 16x9 or x10 for a reasonably cheap price....

Thanks very much for the offer, however unfortunately I will have to decline. I'm currently running 15x7 panasports on my car. I love the look but the width really isnt there. I feel like if I give up my panasports I want to do it for wheels that are much wider than mine (ie 9 or 10 in. wide).

I'm looking for a new set of wheels for my Z car but my car isnt really good looking enough to warrant a shiny new set so I'm hoping someone can help me out with something used. I am looking for wide wheels - 9-10 in. wide would be fine, 16s preferable, 17s ok too. 4x114.3 bolt pattern, and low or negative offsets. Some used Rota RB-Rs from the group buy would be awesome. Some old, used Watanabes or Panasports would be even more so. If you have something else that fits the above PLEASE let me know, I'd like to consider any possibility. I do realize I may be asking for the impossible but I figured I'd take a chance, post this up, and see what happens. Thanks!

I'm confused if youre running no proportioning valve or the stock one. If youre running the stock one, it would be worth removing it and running full pressure to the rear, or putting in an adjustable valve and adjusting it so it gives more pressure than the stock valve. Aside from that I think that the Willwood 6 piston calipers are much more powerful than the 240sx rear calipers. Even with full line pressure to the rear it will not be enough to get rid of the huge brake bias. It will take additional work to get the balance more ideal with this setup. Putting a proportioning valve in the front could work but really kind of defeats the purpose of going to Wilwood 6 piston calipers in the first place in my opinion