curious about shell/chassis longevity...and a way to verify condition

[sw20>>s14]

so i was wondering if there was some kind of definitive sign that your chassis is over...obviously if the frame is unrepairable, severe collision, etc...but when do you call it quits and move on to the next car?

i got my s14 in pretty bad condition, but after roughly a year of reversing the previous owner's neglect; my car is fine...motor and tranny is strong (for the time being)...but i have accepted the fact that if they malfunction in the near future, i will replace them...but if the chassis is bad, its over...

i dont know, kind of a useless thread, but i guess im seeking comfort from fellow peers to continue to pour countless money into it...i plan on making the car track worthy and a lot of punishment lies ahead of its life...so i wanna make sure that my car is a worthy canidate for the part...

are there ways to test if your chassis is still straight and true? would body shops be able to use a frame rack and tell you if your chassis is within "specs" (if such specs even exist)...

if any of you knew me at all, you'd know that im very insecure and always have doubts...im just trying to decide whether i should continue to pour money into it or if i should find another s14 thats had a better childhood...

and to put things into perspective:

-ive bapped the back once and got the rear pulled (minor one; not as bad as it sounds)
-no major accidents that i know of
-one fender bender on the pass front from previous owner
-has the infamous pass door sag (most s14s do)
-no doors, trunklid, moonroof, etc. are misaligned (signs of minimal chassis deflection or previous repairs)

[ranisron]

sw20>>s14, no means to thread jack, I would also question and add upon... to what/where/how types of rust (or rusty) conditions do people consider the chassis' integrity has been compromised? For example, if you see rust around the frame rail, do you consider this to be "end of your 240sx"? or for example, you see rust around your front area, do you consider your chassis integrity compromised?? etc.

Ron

[HyperTek]

does it drive straight? how many miles? If it doesnt drive straight after a wheel aligntment and u know there isnt any bent suspension arms, that oculd be a sign, otherwise Id keep it.. If you wanna go hardcore, you can stitch/spot weld the chassis, or fill in certin areas with foam, taht should feel like a "revive" since it will make everything solid again.

[m0rex]

Another thread jack not really. Anyways i got some rust under my door well a lot of rust like 12 inches by 8 inches. Looks like shit and im going to weld it but i also had a head on collision with a curb and having my car low took apart most of the front suspension like at 32 mph i hit that shit. Fix it but i want to know some signs that can say "stop wasting your time and money."

[!Zar!]

When every you crash your car abet it be hard or, "soft" It jarrs your chassis a little. Most call it tweak. And what can happen is your car handles better to the left or to the right; say if you place your car on jack stands and only three of four are supporting your car. You can try to mitigate it by having your car corner balanced and aligned. But eventualy you might start felling the effects.
Most of the time if you have to think about this seriously then it might be best just to purchace a shell and swap everything over.

[The Riot Hero]

as far as the guys with rust issues, it absolutely could be the end of your 240, from my experience of working on and owning tons of 240s. normally by the time rust becomes visible to a normal person walking by it, like rockers rusted, wheels wells rusted, it usually means the the car is about the crack in half practically, strut towers can go through your hood, frame rails over the rear axle can start falling apart and the ass end will feel weird and crackle when youre turning on a bumpy road. etc. when you look in your wheel well and you see your engine, its pretty much time for a new chassis. as far as logevity of the chassis, thats tough. it could be a car with lower miles, no accidents but the owner had some gay ebay cilovers on it that bottomed out constantly (experience) and seams will get weak. other then that, theyre unibody and very stiff, they dont really get "worn out". if you plan to seam weld the car, very good idea to put it on a frame rack and make sure everything is straight no matter what.

[projectRDM]

The FSM has a page where they list chassis measurements from various points to determine frame alignment. If you wanted to get technical you could do this on some of the easier to measure places and get an idea. As far visually checking rigidity you can look at seams or pinch welds for stress lines or fractures in the paint. Sometimes the body glue will pull away or lift in an area that's abnormally worked over too.
On older hatchback Mustangs you could always see paint defects in the quarter panels just below the hatch opening, usually caused by the chassis torquing when the car was driven hard, the paint was actually stretching across the surface of the panel to the point it would fade or crack. Signs of abuse like that aren't as apparent on an Schassis but it's still something to look for.