Dan Baldwin

175/14 Aspect ratio (not included in tire size back then) is between 75 and 80 for the original stock tires. My stock Toyo spare is exactly the same diameter as the 215/60HR15s I used to have. Diameter very close to 25" Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

Whoops, I didn't look at your picture closely enough. My mount is a welded up stock one, so slotting the holes was no prob. Now I see it's not an option for you. Hmmmm...... I guess there's little bending stress from operational loads in the flimsy direction of the moustache bar, but I'd still feel kinda funny about preloading it to mount it up. That looks to be your only option if you want to use that mount. Or you could have a stock mount welded up. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

I just slotted the holes in the front mount after two tries, one with the holes forward, and one with them aft. The holes in the mount wanted to be even with the stud instead of offset. This resulted in a pretty good fit. I did, however, also use a curved '72+ R180 moustache bar, so my fit may be different from yours. Anyway, I think it's a good idea to try to mount things up unstressed, so I resorted to filing. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

Contact patch area is approximately the weight on the tire divided by the pressure. So a 275/40ZR17 will not give you a significantly increased contact patch area than a 175/80-14. A wider tire will, however, give you a better contact patch SHAPE for cornering. I still don't see why so many people think that a TALLER wheel and tire is better for performance. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

First of all, yes, you're nuts if you spend $5k on that hardware. There are MUCH cheaper ways to make a Z handle and brake. You say you're frustrated with the car. Why? What's wrong with it? How is it behaving that is not to your liking? Zs handle pretty well in good stock condition with some decent tires. There are lots of reasonably priced upgrades you can do. Stock brakes w/ race compound pads and Nissan shoes and fresh fluid also perform very well for me on some pretty brake-intensive tracks. See commentary under this thread: stock power(?) brakes?..with a 350?? I've been steadily improving my Z over the past 6 years or so, and have made it into a fairly quick road course time trialing machine (pics here: http://www.zccne.addr.com/members.htm and results here: http://www.comscc.org/~comscc/results/index.htm). I have NEVER come to a point where I felt it was necessary to drop 5 grand on the suspension and brakes. You can make it work just like you want it to for far less. What kind of raceway is it that you'll be "casually" racing at? If you have $5k burning a hole in your pocket, you'd be much better off investing it, donating it to charity, or spending it on loose women and Remy Martin cognac. Or better yet, why not spend it on something that will actually make you FASTER?! Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

I mentioned that I was using CarboTech Kelated Metallic pads. This is incorrect, I'm using CarboTech PANTHER pads. Just ordered a new set and Larry at CarboTech set me straight. The Kelated Metallic compound is used at the front for street/autoX ONLY. Kelated Metallic may be used for the rear shoes for track usage, however. BLKMGK, I now see that we've been in agreement all along about leverage. i.e., taller tires have greater leverage against the brakes, so the brake pedal has reduced leverage against the tire contact patch. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

I slotted and enlarged the holes in my '72+ moustache bar for my R200 install. Still hangin' in there after 5 years, 25,000 miles, and about 25 track days. Also had to slot the holes in the front diff mount, which was also welded up (made solid) to eliminate need for the strap. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

No U.S. Z had a limited slip until 300ZX Turbos starting in April of '87. These were 3.70 clutch-type LSDs. Any April '87 - '89 Turbo has this except the all pearl white SS models, which had a viscous LSD. The clutch types are a very easy retrofit, requiring either slotting of fastener holes in the forward diff mount and moustache bar or use of 280Z R200 mount and bar. 280Z R200 input and output flanges are also required. The viscous unit, I'm told, can be made to work if new snap-ring grooves are machined in the 280Z output flanges. Aftermarket Quaiffe LSDs (similar to Torsen) are available, I believe for R180 and R200 diffs, for ~$1200 for the LSD unit only. Dan Baldwin '71 240Z 3.1 (3.70 LSD from 300ZX Turbo) COMSCC #7 SPB

Regarding leverage, taller tires give you REDUCED leverage, for acceleration and braking, as the extra height is INcreasing the torque required for a given level of acceleration or braking. I can definitely tell the difference between 225/50-14s and 225/50-15s, the 14s offering better acceleration and more braking gs per pound of pedal effort. I totally agree with BLKMGK regarding tinkering w/ drums, what a pain. I discovered this past season, however, that by going back to Nissan shoes (had been using $$ racing compound), I didn't have to adjust them NEARLY as much. Once a day at the track, compared to once per session. Tolerable at the moment, but I'll probably go to disks one o' these days... As far as FUGLY goes, to me super-tall wheels/tires on a small car like a Z give a sorta wagon-wheel appearance, especially if the wheels are FWD offset. Seems to me the whole trend in the large-diameter direction is to scale the wheels up to match the current crop of HUGE cars. I think that was one of the problems with the first Z concept, it was a decent-sized (i.e., reasonably and appropriately small) car on too-tall 18" wheels. Looked like it was on tippy toes. So they "fixed" it by replacing it with a positively IMMENSE car on 20" wheels! yuk. Shorter wheels => less unsprung and rotational mass, better gearing, lower c.g. height Dan "less is more" Baldwin '71 240Z 3.1 COMSCC #7 SPB

Some DOT race tires are more street-worthy than others. Toyo Proxes RA1s and Yokohama A032Rs in particular. I've also heard of folks running Kumhos on the street. Hoosiers, however, are definitely track-only. Too fragile for the street (a piece of broken glass = puncture), and probably don't grip as well as good high-performance street tires until warmed up. I have a set I use when I go to the track, but don't use them on the street. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

oops, that should read One tire found in 205/60-*14* size, not 15. Yok AVS Intermediate, BTW. Dan

205 might be all you wanna run on 6" wheels. Unfortunately for a lot of us, the current trend towards too-tall wheels and tires (in my opinion, needed only to compensate for the visual bulk of the current crop of too-big cars. Supposed performance benefit from taller wheels is questionable at best) means very little is available in the way of high performance tires for <16" wheels. Tire Rack lists exactly one (1) tire from a search done in the Ultra High Performance and Max Performance categories for a 205/60-15 tire (zero tires shown for 215/60-14). Five (5) 225/50-15s are listed in these categories, and ten (10) 225/45-16s. No signs of this ridiculous trend abating (sigh). Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

Any braking system in which the tires are not the limiting factor is inadequate. On my track-driven Z, ~2500 lb. with me in it, ~190hp, the tires (sticky Hoosier R3S03s at that) ARE the limiting factor. (Note: track tire size of 225/50-14 means I get VERY good leverage against the pavement. Brakes are PLENTY responsive with 225/50-15 street tires, too. Taller tires DO require increased effort at the pedal for the same deceleration rate, though energy dissipation remains the same.) At tracks like NHIS, Lime Rock, Watkins Glen, Mosport (check here: http://www.comscc.org/~comscc/results/index.htm for lap times), brake pedal remains FIRM for 20+ minute lapping sessions. For longer than that, a couple of clicks on the parking brake *may* be required to adjust the rear shoes on the fly. Again, I'm running STOCK calipers, rotors, wheel cylinders, drums, and shoes. I'm currently using CarboTech Kelated Metallic pads, but have also used Porterfield R4s and Metal Masters with no problems. I use Ford heavy duty brake fluid (cheap, with a 550F dry boiling point), which I replace before each track event. I do have braided stainless flex-lines. If you absolutely MUST do an upgrade, consider the solid-rotor '79-'83 Toyota 4X4 truck 4-piston calipers. This can be done pretty cheaply and easily. Only parts required are the calipers. Only mods required are rebending of the hard lines and trimming or removal of the backing plates. Front/rear brake bias is minimally affected. As for me, my Z money lately has been going into aerodynamics (spook, spoiler, headlight covers), suspension (offset rear control arm bushings to zero the toe). The next wad o' cash will be going to the cylinder head (porting, decking for compression increase). Bottom line: Why spend money on mods that won't make you faster? Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

I thought all 240s had a booster. My '71 does. Regarding braking capabilities, I've said it before and I'll say it again, the stock setup in good condition with fresh brake fluid and with decent lining materials (Metal Master, Porterfield, CarboTech, Hawk, etc. up front and stock Nissan (NOT Pep Boys, AutoZone, etc) shoes in back) will work far better than most realize. That's what I've been running for years, and I can brake with modern cars with much more impressive brakes easily at the track, even after 20 minutes or so of hard usage. Of course if you have over 200hp AND do extended lapping sessions at the track, you might need more. For a street or strip car, you do not. Braking performance is limited by tire grip, and no amount of $$ spent on bigger better brakes will change this. If you can keep the stock system balanced, and don't have problems with overheating the fluid or lining materials, it ain't too bad. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

Hey 383, yeah, that was my Z at World of Wheels! Zfan, if you're doing only street/strip stuff, the stock system is fine. If, however, you plan to take the car to a road race course for extended lapping, you'll likely need more. The Toyota calipers BLKMGC mentions are actually 4-piston calipers. Have about the same piston area as stock Z calipers, so shouldn't screw up front/rear balance. Various rear disc options are out there, but be mindful of balance ramifications. Getting the balance front/rear wrong can INcrease stopping distances if there's too much front bias; or worse, lead to serious instability if the rears lock first. Again, note that the stock system CAN be made to work well, and if you're not REPEATEDLY braking hard from high speeds (i.e., lapping at a road course) to the degree that you're overwhelming the stock system's capacity for rejecting the heat, then you don't NEED to spend much on brake hardware. You also want to try to keep from adding unsprung and rotational mass if at all possible. Dan "braking with big-braked M3s at the track" Baldwin '71 240Z 3.1 (stock rotors, calipers, drums) COMSCC #7 SPB

If yours is a track car and you need the camber from them, you might inspect them for wear and if they're OK use them. Not recommended for a street car, and not needed. For my street/track car, I lengthened my control arms for more camber and used the polyurethane bushings. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

Some questions: What do you use the car for? Street only or some track duty? How much power ya got? My '71 has (WAG here) about 190 hp. I mainly do track events with it (15 - 30 min. sessions) and I've found that braking is pretty damn good with the stock braking system, even at brake-intensive NHIS. Cheapest upgrade you could do? Fresh brake fluid (Ford heavy duty is cheap and has a 550F boiling point), good pads (I've used Metal Master, Porterfield R4, and CarboTech, all are good for track usage), and NISSAN shoes. I used racing compound shoes last year and was forever adjusting the damn things at the track (was getting a long pedal, presumably from shoe wear). Switched back to Nissan shoes last event at Lime Rock and didn't have to touch them all day. Unless you are making over 200hp AND do some track driving, I'd say the stock system is just fine, assuming that the calipers and wheel cylinders are in good condition. Remember, your maximum braking performance is limited by tire traction, and no amount of bigger, badder braking hardware is going to increase tire grip. Oh yeah, stainless steel brake lines might be a good idea, esp. if your lines are the stock originals! I *finally* replaced mine last year, and the pedal did firm up a bit, though it was alright before. Try to get the most out of the system you have before you go spending $$$ on stuff you may not need. (note that this frees up $$$ for go-fast hardware elsewhere!) Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

Good point about autoX vs. road race. No first gear corners at any of the tracks I've been to. 70 still seems like a lot, though. Mine's probably at ~18 - 20 lb.-ft and does do a little, I can feel the clutch pack grab and release during corner exit. I'll see how it does with a softer rear bar setting. How tricky is it to shim a clutch pack? I'm picturing myself on the garage floor surrounded by shims of various thicknesses scratching my head. Dan

In my opinion, the correct amount of breakaway torque for an LSD is the LEAST amount that will prevent inside wheelspin. On my car, the 23 lb-ft the '87 300ZX turbo diff had when I installed it 4+ years ago was enough when running on good street tires. Now, running Hoosiers, it's not, but I'll be installing rear camber bushings to eliminate excessive rear toe and re-evaluate (less rear toe should allow me to soften the rear anti-roll bar, which could give me back the inside rear traction I need). The spec numbers I remember for a stock 300 turbo diff were 18-30 lb-ft. The breakaway for a NISMO unit is listed at 45 lb-ft in the catalog. I suppose with gobs of hp more breakaway might be needed, but I can't imagine you'd need more for a naturally aspirated L28 in a well set-up car. Higher breakaway torque => more understeer + greater frictional losses. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

Don't worry about them, they're stiff enough in the directions that matter. They would be flimsy in reacting fore/aft loads, but those loads are taken at the forward control arm pivots. In lateral and vertical stiffness, those flimsy hangers are very stiff. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

An N42 head is the early 280Z head. Has similar combustion chamber volume to the '71-'72 E88 heads. On an L28, this head will give 8.3:1 compression with dished (280Z) pistons and 9.8:1 (now that's more like it!) with flat-top 280ZX pistons. Probably the best stock head for an NA L28, as it's the only L-series head that offers decent compression, has the bigger valves, and doesn't have the hated round exhaust ports with their evil liners. The P90 head was used on ZX turbos. Generally considered to be a good head with good combustion chamber design, but it has a ton of cc volume. 8.5:1 is all you'll get with flat-top pistons, 7.4:1 with dished. It's the head to have for a turbo, though. Dan Baldwin '71 240Z 3.1 (N42 head) COMSCC #7 SPB

I'd say these dyno results don't look *too* terribly bad. A broad power band and flat torque curve that does drop off way too early. Interesting that someone mentioned he'd be better off with less carburetion since his power peak is at such a low rpm. Actually, he needs MORE carburetion to MAKE more high-rpm power. He needs 45mm webers with 36mm chokes in order to make power above 6000 rpm. Assuming that the handy-dandy equations in "How to Modify Your Nissan/Datsun OHC Engine" are correct: throttle bore = sqrt(disp/cyl * max rpm/1000)*.82 main venturi = sqrt(disp/cyl * max rpm/1000)*.65 136 rwhp isn't too bad for a mild 2.8 liter L-series engine, maybe 170 at the flywheel? Definitely more to be had, though. Also, regarding big numbers that are regularly bandied about for NA L28s, any dyno numbers that are from the engine builder are to be taken with a HUGE grain of salt. Not meant as any kind of dis to engine builders, but it is definitely in their interests to "correct" their numbers a bit more than an independent dyno will. Dan Baldwin '71 240Z 3.1 10.1:1 CR, 2" SUs, 290/.503" cam *maybe* 155 or so rwhp (will dyno one o' these days) COMSCC #7 SPB

280Z R200 output flanges fit right in the '87 300ZX LSD I got for my '71, no problem. This should be a VERY simple swap for you. Note that the 90+ diff is a different beastie, though. Won't fit without some major work. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB

If you want to put a viscous diff in an early Z, some work is required. Specifically I've heard that you need to machine new snap-ring grooves in one or both output flanges. $300 shipped sounds good to me. If viscous is what you want, I wouldn't pass up the opportunity as they are somewhat rare. I'm assuming you're talking about the '88 SS viscous, right? 90+ diffs won't fit an early Z without a fair amount of fabwork, I'm told. Dan Baldwin '71 240Z 3.1 (w/ clutch-type LSD), a World of Wheels in Boston right now! COMSCC #7 SPB

I think SCCA requires the top of the roll bar to be 2" above the top of your helmet. I have a Momo Rookie seat in my '71, mounted to twin ratchet slides also from Momo, which only required redrilled holes in the stock seat supports to fit in the car. My helmeted head is ~3-4" from the headliner. Dan Baldwin '71 240Z 3.1 COMSCC #7 SPB