Hello, everyone; I'm new here and new to the 240sx.

I was wondering what mods can be done to the suspension for traction. I'm thinkin' of purchasing a 240sx and swapping in an sr20det in the near future, but I'm disappointed at the times some of you are claiming (high 14s at best on stock 7psi) because my current car (as well as newer versions of itself) can hit high 12s with only 230rwhp in a car that weighs almost 1000 more pounds than a 240sx! The trick is in the extensive aftermarket traction aids like boxed LCAs and relocation brackets and other components that enhance the suspension geometry...

Basically I want to know what can be done to the 240sx to achieve similar times with less weight and horsepower, which is the main reason I'm converting. Further, what suspension setup does the 240sx have (my Trans Am has a 3-link panhard bar setup, and traditional muscle cars had 4-links...).

Thanks in advance, everyone!

LSD is the most common.

Well... LSD isn't exactly a SUSPENSION upgrade, but it will assist in traction for sure! The 1/4 mile times you refer to are a little suspect.. but if true, it might be due to the monsterous torque numbers you show in your signature. In your case (the Trans-Am) you guys have a solid rear-axle right... so you have options like traction bars and what-not to eliminate wheel hop and plant the rear wheels better. With an IRS set-up you really can only make the suspension stiffer to help traction. That is a big reason why these imports aren't exactly made for drag racing. The 240sx is an amazing car for auto-X and hillclimb racing. They are alright for drag racing... but not really designed for it. Your pile of Detroit steel (no offense intended) is made for shooting down a track in a straight line.....

No offense taken. An LSD would help as I understand they are rare in Nissans for some reason (I had one std on my car, but it's busted), but getting back to suspension mods, how is the rearend held to the car? I haven't looked under my mom's 84 Mercedes 300D (independent rear) to see how it's done and what can be done, but it has to have some kind of leverage producing mechanism, right? ...Or are airbags the only way to press the rear wheels to the ground?

Also, you're right, the T/A does have a solid rear (that tears up my driveway like crazy), but it's got coil springs, so your auto parts store "slapper" bars won't work (they're for old leaf sprung muscle cars), but I do have "links" connecting my axels to the car's unibody that can be tweaked for more traction... so there's no equivalent mechanism to tweak on these cars?

By the way, I see you guys' point about the 240sx being a handling car, not a straight line dragster, but with the sr20det engine swap and some mods, I was just concerned the lightweight car would become like my T/A if you just stomped on it (it doesn't move; just smokes the tire for three seconds).

Thanks for the thoughtful responses!

Later,Chris

Ah.. I forgot about the coil-spring rear-end.. but there are still ladder bars.. or aftermarket linkage to improve traction and geometry on your car. For example older Ford Rangers and Explorers used a front coil-spring suspension refered to as TTB or Twin Traction Beam. It is coil sprung, but axle placement is handled by the traction bars. I know what you mean about leaf-spring traction bars.. they connect from axle to front of leaf spring.. reducing the torsion effect of heavy acceleration on the spring.

The reason these setups will not work with IRS is because we have linear vertical wheel travel (directly up and down) With coil-springs you have wheel travel in a radius from the forward linkage points (wheel travels in a semi-circle up and down). On the 240sx the suspension is mounted to a sub-frame that in turn mounts to the unibody chassis.

In a nut shell.... LSD with beefy springs to eliminate wheel hop as much as possible... maybe some kind of rear end lift to help weight shift to the rear during launch. But it will never act quite like your T/A... just not meant to be! As far as outright acceleration, the KA24DE has very respectable torque numbers for a 4-banger, but again it's not like a V8.

You can purchase JIC Traction Rods for the rear that replace the rubber bushing with a solid metal one (pillow ball). You will need a LSD to gain good off the line traction.

So how much do LSDs run for an independent rear car? I know posi diffs even for my car aren't cheap, but I can get a Powertrax from summit for like $400 or Auburn Gear sells a real posi diff for only $300. I heard something like $700 for a Nissan LSD; aren't there any cheaper alternatives?

Thanks for the info, I remember about the linear travel thing, now that you mention it, maine; I guess when I get the 240 with the sr20, I'll just have to be gentle on the launch... I wonder what's gonna happen when my mom drives it (she's got a lead foot; I'm always scared to death when she drives the TA, lol).

Later,Chris

Mom will have to be educated in the art of turbo driving. Serious turbo damage can be had when you spool a cold turbo. Best to drive till the car is fully warmed before you spool the turbo to its max.

The cheapest way to get an LSD is to buy one with it already, or find one in a junkyard. There are about a dozen threads started on how to determine if your car has VLSD. Search and find out, then buy one already equiped, or look for a junkyard car that had it.... couple hundred bucks tops.. easy install as well!

[quote=" Chris69427 because my current car (as well as newer versions of itself) can hit high 12s with only 230rwhp in a car that weighs almost 1000 more pounds than a 240sx! [/quote]

I find this highly unlikely. A 3800 pound car(1000 lbs more than my 2800 pound 240sx) would need a lot more than 230 RWHP to hit 12's in a 1/4 mile. If you are actually hitting 12's then either your HP number is severely underestimated or your car's weight is severly overestimated. What kind of trap speeds are you getting?

I agree that those 1/4 miles numbers look a LITTLE curious, but the car is a torque monster, and IS designed for straight line performance. Maybe not enough to garner those kinds of results, but not entirely impossible.

Yeah, I exaggerated the weight a little; my TA only weighs about 3500lbs, maybe 3650 with driver... but my point was that the 60 ft times were so low (some of these guys do wheels up launches--one front wheel, anyway-- with this little power!) and so once the car got moving, it was enough power to get this low a time...

I know the guy who did it with a 94 six speed Z28; and he said he put in on of those Currie built Ford 9" rears that are bullet proof and he was launching it at like 5,000rpm (impossible on a stock GM 10bolt-- you'd break an axel for sure), so it was pretty extreme, but the only engine mods were headers and a K&N filter! He had it dynoed and it was something like 234 point something...

Anyway, I was just making a point; my numbers were a little off, sorry.

Back to the subject, did S13s come with a VLSD? I was not aware that econo cars (as American 240sx's are) would've had such a nice performance part... If not, what cars should I check for that did have it? Z32 300ZX TTs are scarce in the junkyards around here, lol!

Later, and thanks again!Chris

P.S.NismoFreak, I was thinking of installing an MSD ignition box with a rev limiter that I could set at a low 4,000rpm and since it's a cockpit mount design, I could then flip it off after the car's warmed up, preventing damage to the turbo. Would this work, and if 4,000rpm considered safe to rev a cold T25 turbo on an sr20det?