ThreeDeadZs

Off track? Heck, you are right on! And, I think you are absolutely correct. Tokiko 5 ways are another option not mentioned, but your idea sounds well thought out. I was actually thinking of using a modified TEMS system, but your solution sounds the best so far. I hope to do this work during the summer, so if you are serious about your 76Z/Supra MkIII project, let's keep in touch and work stuff out together. If you like, I'll email you my phone number. If you are close enough, we might even visit in person. Matthew

That Tein system sounds just like Toyota's TEMS system (Toyota Electronically Modulated Suspension) which I could get salvage off a Supra MkIII. A computer senses any harsh movements and sets the system to "sport." There's also controls on the center console. Okay, we've covered tires, tire pressure, and adjustable shocks, but what else can be done to make a wet and dry use sportscar? Again, am I choosing the right donor, or is there something better than a Supra MkIII for this purpose? (Supra MkIII's are affordable when dead, Supra MkIV's probably are not)

From the Supra forum, I received the following advice from Jeff Mohler, which seems extremely accurate and complete. Please comment on this approach: ----------- "Well..wet driving is more of a suspension setup issue as well, a good suspension for dry use will cause issues in wet use. Tire selection..is huge, next is compliance. front swaybar..make it softer, if you can losesn the endlinks (mk3s you cant). [He's referring to 86.5-92 Supras] Set struts to as soft as you can, rear end..same thing, remove swaybar possibly as well. Tire pressure..5-10psi (depending) lower than dry performance cold PSI. Driver..dont do quick snappy things." ------------ I'm starting to think I cannot have it both ways, forcing me to choose wet or dry. Therefore, I'm considering adjustable struts (like Tokiko 5 ways, or a Toyota TEMS system), two sets of tires, and two sets of anti-sway bars. But is there a shortcut to allow me to have extreme performance in both wet and dry conditions without rebuilding my car every spring and fall? It's just a hunch, but I'd bet BMW's are made for all conditions... I can't afford a BMW donor, but perhaps I can copy whatever approach they use. Does anyone know?

Ron, are you saying that for wet weather driving, I'd be better off not reinforcing the Z body except as required to mount the subframes? I'd like to hear more about why the Celebrity was able to perform so well, and your interpretation of what to do to build a Z strictly for wet weather driving safety. Tires are obvious, but I've never read anything about how to make a wet weather car. Cary, are you saying that adding your roll bar made your car worse for wet weather driving? Let's ignore autocrossing and my idea of using Supra equipment for the moment. How should I build this car for slippery mountain roads? Perhaps I'll build two Z cars, one as my main transportation in the mountains, and one to play on dry mountain roads and autocross. Thanks for all your help guys, Matthew PS. I'm not exaggerating about the roads around here. Currently, I'm snowed in and expect to be for at least a week because I do not have a 4WD. All nearby highways are closed!

Bummer! How do I get a good comprimise between autocross and wet weather driving?

Let's stick to the subject at hand... What Nissan/Toyota/Mazda, etc would make the best donor for subframes for a 240Z autocrosser? Additionally, which do well in the rain?

Thanks, I'll look into front tension rod designs... I just got out my photos of my old 87 Supra's suspension and discovered something new. As far as I can tell, there are NO tension rods. The entire front end suspension is built as one system, and as far as I can tell from the photographs, only connect to the body in three ways: Subframe->frame rails Rollbar-> frame rails Struts -> Shock towers The function of the tension rods must be handled within the front subframe itself. Can anyone with first hand experience with Supras 86.5-98 (3rd and 4th generations) confirm or refute this? Another thought on center of gravity: The subframes will be much heavier than stock as will the backbone frame I'll need to build. All of this weight is on about the plane of the floorpan. Little or no reinforcement will exist above 24" off the ground, since I'm abandoning the idea of a rollbar/rollcage and the Z body and glass is much lighter than a Supra. Anecdotally, wouldn't this give a slightly lower cG than a Z, and much lower cG than a Supra? Is there such a thing as too LOW a center of gravity?

Re: Corvettes Actually, it's the other way around. The Corvettes, Lotuses, Open Categories, and in my case E Street Prepared all raced shortly after sunrise, just after we layed down the track in dry weather and it started to sprinkle lightly. We knew the rain was coming but the track was still fairly dry. It only began to pour midday and the classes that still had to race were only allowed to drive one lap so the event would be over before the rain got heavier. That's why you see non-competitive cars getting 40+ seconds later in the day (in one lap) and the best cars getting 80+ seconds earlier in the day (in two laps). One factor I never accounted for until now: The E Street Prepared Supra I drove had brand new (I forgot the brand) sticky racing tires that are normally slicked but he kept the treads for the moment. The suspension was completely worked by a professional race car builder, specifically as a dedicated autocrosser, and the owner paid $10k on just one session. I expect any moisture on the track would not have bothered this particular Supra MkII, but would have made the Corvettes squirrely. Please note I'm not even comparing my own driving to anyone. This was my first attempt in a car I didn't know and my times were just acceptable. I also didn't want to push it and damage someone else's car. I have no doubt Don McKenna could wipe the floor with me in any type of race, even if he drove a stock Citation and loaned me his Corvette! HOWEVER... He had to take two sets of runs, and knocked two cones down each on four of his six runs. He only beat the owner of the car I was driving once in raw times, even though he was the only competitor allowed two sets of runs that day. There may have been a factor we are not considering, like an equipment problem or that he was pushing himself extremely hard therefore hitting more cones. I've no beef with Corvettes, so I'll try to let this subject about Corvettes end peacefully. In short, I'm sure Don McKenna is a far better driver than I'll ever be, and any car I build will still not match his... but that day his squirreliness was scary! On careful review of the results, I find that he's the only Corvette that hit any cones. Ask him, maybe he'll remember why. I would guess that any well built race car with a budget of the price of a stock Corvette C5 would get at least comparable results, if not superior though without the luxury. To have a great stock car, all you need is money. To have a great homebuilt racecar, you have to have dedication, knowledge, imagination, tenacity, and do a lot of research, and spend months to years building it. Not to mention the trial and error. It's kind of like apples and oranges. Granted, stock Corvettes are great racecars, especially in the right hands. I find much greater satisfaction reading about custom work like yours, Ron Tyler! I thumbed through some of your posts, and really love the detail of your custom work. Off the shelf stuff (like a whole C5 Corvette) doesn't really interest me, if you know what I mean. PS. This is strange to end up taking this position, because I always wanted a Corvette, and would still love to have one. PPS. Let's stick to the subject at hand... What Nissan/Toyota/Mazda, etc would make the best donor for subframes for a 240Z autocrosser? Additionally, which do well in the rain?

Re: Brapp I misspoke. Yes modifying the suspension to fit would not work well. Thus modifying the body is the only way to go.

Re: Corvettes It's true that I do not know anything about Corvettes. However, I looked back at the records and in raw times only one out of the five corvettes in all categories beat me, and I was in a borrowed racecar that I was driving for the first time (I owned two of the same car and was in the same club, so he entrusted me with his baby!). The owner of the car I was driving (we each did three runs) almost matched the best raw time of the best Corvette, with my 200lbs in the passenger seat. One guy was allowed two sets of three runs, and he hit an average of two cones per run; I would be afraid to volunteer on the track with that guy driving. Many other types of cars were matching us and the Corvettes. Perhaps these were five Corvette owners who didn't know what they were doing? The car doesn't make the driver! This was an SCCA SOLO2 autocross in 1998. http://www.sfrscca.com/solo2/Results/1998/Slush/round6.html (note that some cars finished in 40 some seconds, but that is after it started raining and they were only allowed one lap instead of two. We and the Corvettes raced before the rain) I was driving a completely BUILT 1984 Supra MkII in E Street Prepared. However, I'm certain that on a larger, faster track there's no way I could have matched the Corvettes in that car, but someone could in a Supra MkIV Turbo. Re: cG Oh crap, I forgot! But if I use subframes from a heavier car (lightening it's body as far as the suspension is concerned) wouldn't my cG be lower than the donor car? Therefore, quoting Chassis Engineering by Herb Adams, "It is easy to see why a lower center of gravity will result in less roll angle." Any thoughts? Re: Struts vs. A Arms I'm sure every type of suspension can be well done, I'm not really comparing the types necessarily. However, I expect a design penned in the 80's or 90's will be an improvement over one penned in the late 60's, no matter which type of suspension is selected. Re: tube frame vs. roll cage vs. backbone frame ABSOLUTELY! Thank you! I'll use a backbone frame.

Hey Richard (260DET) I just noticed that your recommendations do not include how you are doing your current project car. How well is your S13 suspension working out? Effectively, you've done exactly what I'm talking about - using the complete front and rear subframes and equipment from a donor car. Now that I see you have done exactly this project, I'll put very serious consideration into the GTR and Z32 subframes as you recommend. Which engine will you use in your project? Or is the car on the road yet? If I chose to copy your project, would you be forthcoming with the details? I really like your photo gallery. There's a small shadow at the center of one of your pictures that is extremely enticing!

Re: Brapp I would say the Supra MkIII is like your description of the Corvette C5 in point 4, except the vette likely outmanouvers the best stock Supra. I believe point 5 in incorrect. I wouldn't change the donor's geometry at all, no matter which donor I choose. If necessary, the wheelbase may be shortened by a couple inches. This will cause one problem I read about called bucking, but a change of only a couple inches should not cause it. I'll make the body match the suspension, not the other way around. The suspension will expect a lot more weight, so the shock and spring rates will have to be reduced. Re: RonTyler You are absolutely correct, and this did not escape my attention. I have two books on race car chassis engineering that I periodically reread. From these books, I know what problems to watch for. The new subframes will probably have to be mounted to a rollcage that will act as a tube frame. I only decided this after starting this thread - thanks to the group's input. Re: Heavy85 Your are right, thanks for the wake up call. My goal is a car that I can enjoy driving around wet roads in the mountains without fear of going off the road. Many people die here in one car accidents. I even went off the road once due to debris in the road that blew out both front tires instantly. Had I been going the other way on that road I wouldn't be around to tell you about it. Autocross is just a game to me that I would like to participate in. I have no intention of beating others, just challenging and improving my own driving. Driving where I live is much like autocrossing already, but double the speed and add blind corners, deer in the road, old ladies going 20mph, idiots who cannot stay in their own lane, occassional semis which are too big to stay on their side on a curve... Manouverability could save my life. I want a fun, fast, manouverable, comfortable car for driving under 60mph. Heck, it could even have a top speed of 80mph for my purposes. Writing this makes me think more of a quick rev 4 banger like an SR20, but the 2JZ-GE VVTi (1998 to 2003? in luxury cars after the Supra was discontinued) should give me instant response across the entire power band, and tuners don't want this engine (those that can fit a straight six want the turbo version) so I can actually buy a low mileage engine relatively cheaply. Then, if I get power hungry and get deeper pockets, I can build a 2JZ-GTE with as much as 1000hp with stock internals. Such power would be absurd for my car, but I'm just pointing out the benefits of the engine design. Re: Pop N Wood's question: Based on the San Francisco Region SCCA website, I found Supra MkII's (~82-86) and MkIV's (93-98) winning in their classes, but no MkIII's even listed. MkIII's are luxurios GT cars that are extremely heavy (3500lb curb weight) and made for high speed racing like a Corvette. How many Corvettes do well in Autocross? The ones I raced appeared to have a hard time staying on the track and never seemed to be able to use all their power. They don't have enough room to throw the weight around. What benefits are there to the Supra suspension? That was answered by Richard (260DET) "Using the Supra stuff will give you a nice wide track, five stud wheels, power steering, modern geometry, big brakes......" and I responded, "plus the subframe mounted Double A Arms you mentioned earlier and power rack and pinion steering mounted on the frontside of the front crossmember which supposedly eliminates bumpsteer." Also, and I'm just guessing here, I know the suspension was not revised much between MkIII and MkIV, so I should have several equipment options available to me. When I was active with SOGI (a Supra club) there were many members with modified engines that could wipe up the floor with supercars. But the MkIII is just too *#@^ heavy! To get similar results from a Z suspension, buy the complete brakes and suspension sets from Arizona Z car for $3800 (I just checked) but that still doesn't account for the rear end and CV shafts. Up front, you would need to do heavy modifications (if even possible) to match the front mounted steering rack and other design improvements. Then you will still have a 1969 design using McPherson type struts. The Supra MkIII (and many other new suspensions) are double A Arm and was designed in 1985 or 1986. The Supra is a high end car and built of expensive components. The original Z car was built to be economical, and was built of cheaper components. That said, I'm still not convinced I've chosen the right donor. I still have to give serious consideration to S13's, S14's, GTR's, Mazdas, and other Toyotas. Another part of my idea is simply to use EVERYTHING from one car, whichever donor is best for my application, not just a Supra. I actually bought my first Z in order to swap in a 2JZ in the first place. Since I like the engine so much, it seems only natural to use absolutely everything else. Also, it would be a matched set and would require nothing aftermarket except coil over springs. Plus, I'm a Toyota guy. I know their products extremely well. Building this car with Toyota equipment would take advantage of my previous experience. Nissan is quite similar, of course.

Absolutely, and that's one of the benefits. As long as the subframe connection points are within the unibody, it should work like it did for Maichor's 200SX rear suspension swap. If the connection points are in inconvenient locations, I'll add a rollbar/rollcage as a partial frame and connect it to the the floorpan at the subframe connection points, or directly to the subframe. Fender flares can hide the tires. BTW: BlueOvalZ, I just went through some of your photo album. Your car is AWESOME! How many years and dare I ask, how much money have you put into your car? I'll bet you are an engineer.

"Why not just drive a Supra?" That's like asking why build a hybrid at all! Here are my reasons... feel free to correct or comment on anything: 1. Avoidance of California SMOG laws. The cutoff is currently 1975. Now I could use a 75 Celica GT for nostalgic reasons, but the Z is a better body for a straight six. 2. Roughly 25% reduction of weight over Supra MkIII, whose curb weight is 3500lbs. 3. Supra MkIII's are notorious for being expensive to repair, especially under the hood, and especially if you don't do your own work. 4. Supra MkIV's are completely out of my financial reach. This project would be cheaper to build than buying the lowest priced MkIV, but should outrun and outmanouver the base model... especially below 60mph which is about as fast as one can drive in the mountain twisties. (Roads here are BARELY two lanes wide) Plus I would like to autocross and I don't mind being in the "open" category, as I once did in a heavily modified Supra. 5. My project had little to do with Z cars at first: I was planning a project since age 18... 21 years ago. 6. The price of this project should be less than installing a Chevy 350, big brakes, 5 lugs, support for 10" tires, bump steer mod, and so forth, but probably outperform that approach. (I'd love some feedback on this thought) 7. The original Z body is a beautiful classic car that is too old to look 'old' if you know what I mean. It's the only classic body I can buy (and I have collected three complete, worn out Z's already) 8. A Supra MkIII in stock form would need reconditioning by now, a reconditioned/upgraded one is expensive to buy, and a distressed Supra MkIII can be bought for practically nothing as a donor car (in California at least). Parts/Modifications for this model will continue to be available for a very long time. But, due to reduced weight, suspension and brake upgrades from stock Supra components should be unnecessary. 9. A reason I'm sure many on the forum can relate to: it would be unique... yet even better if it inspires copies. I'll document my project in case anyone wants to copy it. I like the idea of checking on a lighter system, like from a late model RX7. But unless there are significant adantages, I'll pursue the Supra. Matthew ThreeDeadZs 73 240Z partially restored, still has wiring and intake problems 74.5 260Z #12 doesn't run due to intake problems 73 240Z parts car, barely runs due to intake problems 88 Toyota Camry - always runs 88 GMC Van Previous Toyotas: 90 Supra Turbo Targa, 87 Supra NA Targa, 75 Celica GT, 85 Celica GTS, stock 77 Corona, 80 p/u, 86 p/u, 90 p/u Too many other previous cars to list, since I generally kept at least two at a time.

Yes Richard, using a Supra's subframes would have those benefits, plus the subframe mounted Double A Arms you mentioned earlier and power rack and pinion steering mounted on the frontside of the front crossmember which supposedly eliminates bumpsteer. Now that you mention newer Mazdas, I'll check compatibility of those and other potential donors before settling on the Supra. What other subframes (than 240SX derived ones) have been successfully installed in a Z? When originally planning this project in 1998, I took my camera in to a tire shop and when they had my 87 Supra secured overhead on a lift, they let me snap over a dozen pictures of the stock suspension. I have these pictures in front of me and confirmed my previous statements. If there's enough interest, I'll scan and post relevent pictures. [bTW: Laying the camera on the ground allows distant shots from eight feet away, exactly vertical for comparison.] Matthew ThreeDeadZs 73 240Z partially restored, still has wiring and intake problems 74.5 260Z #12 doesn't run due to intake problems 73 240Z parts car, barely runs due to intake problems 88 Toyota Camry - always runs 88 GMC Van Previous Toyotas: 90 Supra Turbo Targa, 87 Supra NA Targa, 75 Celica GT, 85 Celica GTS, stock 77 Corona, 80 p/u, 86 p/u, 90 p/u Too many other previous cars to list, since I generally kept at least two at a time.

Yes, I agree that doing complete subsystems would be easier than piecemeal work, which is exactly my point. I'd transfer the whole floor section that contains connection points to the rear subframe, like Maichor posted doing with a 240SX rear subframe. Then I'd mount the whole front subframe, hopefully with no more than modifications/additions to the frame rails and modified strut towers. With this, there would be no Z running gear left at all. The Toyota Supra MkIII (86.5-92) stock suspension is very stiff (I had two of this model) and I have read it only differs from the Supra MkIV (93-98) supercar in revised rear subfame mounting points. Another nice point about the MkIII model is that due to how expensive it is to repair and the failure rate on stock 7M engines, a donor with good suspension should be able to be found cheaply here in California. I'd use the 2JZ series engines which replaced the 7M series in 1993.

I've been reading this forum for a long time, but this is my first post. How reasonable would it be to install the complete front and rear subframes from a late model sports car into a 240Z? This would accomplish swapping the complete suspension, steering, and brakes; and the engine and transmission if desired. Maichor's 200SX rear suspension swap shows me the rear could be done, and it seems like the front would only require modifying the frame rails and shock towers to match the donor car's geometry. I read somewhere on this forum that some Japanese tuners may be swapping whole floorpans, but cannot confirm it. Because of personal preference, I'm inclined to use the subframes from a Toyota Supra MkIII and an engine from a Supra MkIV. What models would make the best donors in the opinions of forum members? Is this a worthwhile approach? ThreeDeadZs 73 240Z partially restored, still has wiring and intake problems 74.5 260Z #12 doesn't run due to intake problems 73 240Z parts car, barely runs due to intake problems 88 Toyota Camry - always runs 88 GMC Van too many previous cars to list