Question on OEM springs

[adampecush]

There is no disagreement that targas "flex" more with the roof off. The disagreement is that you can permanently deform the car chassis by driving it "hard"(this is not flex, it is permanent deformation). You will not "bend" the chassis over time from driving it hard. This would be called creep, and it absolutely does not apply in this case (requires HIGH temperatures and prolonged stress). A one-time overload (such as an accident) of the body steel past its yield point would be required to bend the chassis. The steel body of the car will also not soften over time. If you were to deform the metal, it would actually strengthen as a result of cold work. The only way the car structure would lose strength is if the spot welds which hold the panels together begin to fail. If this was to happen, the body of the car would become progressively weaker (and more dangerous) before failing catastrophically.

For what its worth, my targa sits perfectly on the roof when unscrewed.

 

[bsupra]

There is no disagreement that targas "flex" more with the roof off. The disagreement is that you can permanently deform the car chassis by driving it "hard"(this is not flex, it is permanent deformation). You will not "bend" the chassis over time from driving it hard. This would be called creep, and it absolutely does not apply in this case (requires HIGH temperatures and prolonged stress). A one-time overload (such as an accident) of the body steel past its yield point would be required to bend the chassis. The steel body of the car will also not soften over time. If you were to deform the metal, it would actually strengthen as a result of cold work. The only way the car structure would lose strength is if the spot welds which hold the panels together begin to fail. If this was to happen, the body of the car would become progressively weaker (and more dangerous) before failing catastrophically.

For what its worth, my targa sits perfectly on the roof when unscrewed.

If ur targa sits perfect, ur car is perfect.

Just keep continue driving ur car hard without strut bars and brace for support. Just do not blame me one time when u go for alignment one day then they end up not being able to do it. But if your car got strut bars or any kind of support, u should be ok.

And metals do get weaker over a period of time. When the body of your car flexes, the part of the body/chassis which suffers from stress the most changes properties and actually increases to a sudden change in temeperature. Thats why it get weaker by suffering from abuse for over a period of time.

Go search on properties of metals first then let me know what u find.

 

[Poodles]

Actually, the targa is slightly bowed to allow it to properly seal (hence why it has to be installed in a specific order).

Also, many muscle cars are LESS stiff because of their ladder frame chassis. Also, many muscle cars are unibodies as well (Camaro, mustang...) and they are TERRIBLE in convertable form (Mustangs came with subframe connectors stock, and they're still weak). Get under one of those cars and then get under a supra and if you can't see the difference you're blind...

 

[GC89]

How prone are ours to getting "tired" and not holding the car at the proper height? I've looked around and couldn't find any real information on it though I suppose I could always just take some measurements and see what's what with mine.

Thoughts?

I had a 90 targa before and I had that height problem. The body shop told me that MKIII supras are prone on twisting the body specially driving when the targa is off and aggressive turns. We did not any cracks on subframe just the body alone is twisted. I could have made it straight again but it would cost more than the value of the car. I had a friend that wanted the car even on its condtion so I sold it to him. I bought an 89 turbo hard top and eventually found a nice 91 turbo with sunroof and been happy with it ever since.

I think our MKIII's needs more frame support if its going to be driven aggressively.

How did we get from spring longevity and resilience to chassis flex?

and of course a targa will flex more than a hard top with the top removed. You are removing 4 critical tie points on the chassis. With the top on they are virtually the same other than weight. If you tweak the cars frame your did something very wrong.

Now back on topic:
The easiest way would be to measure your cars ride height and compare to factory specs. This could be affected by lots of things though so its hard to draw a definative conclusion.

 

[bsupra]

Actually, the targa is slightly bowed to allow it to properly seal (hence why it has to be installed in a specific order).

Also, many muscle cars are LESS stiff because of their ladder frame chassis. Also, many muscle cars are unibodies as well (Camaro, mustang...) and they are TERRIBLE in convertable form (Mustangs came with subframe connectors stock, and they're still weak). Get under one of those cars and then get under a supra and if you can't see the difference you're blind...

You know what, do I have to say SOME everytime I say something. Ok not all muscle cars have that frame and body that we mentioned before, SOME. AND I DID SAY SPORTS CARs IN CONVERTIBLE FORM ARE TERRIBLE(LOOK AT PAGE 2) thats why I said hard top supras is more stiff than targas. I KNOW THE DIFFERENCE THAT YOU ARE TALKING ABOUT SPECIALLY CAMAROS FROM 93 and UP.

SOME body of cars do get weak over a period of time specially on how much abuse it takes. SOME cars not durable like others. OUR CARS IS NOT MADE WOLVERINE CLAWS OK.

ALL IM TRYING TO EXPLAIN IS THE BODY FLEXING BETWEEN A TARGA AND A HARDTOP. CONVERTIBLE AND TARGA CARS FLEX MORE THAN HARD TOP CARS OK PERIOD THE END. I ONLY USED OTHER CARS CHASSIS FOR COMPARISON AND I KNOW SOME OF THE DIFFERENCES.

AND IM GOING TO SAY IT AGAIN. I AM NOT PERTAINING TO YOUR TARGA SUPRA. AGAIN SOME.

AND WHEN I SAID LET YOUR TARGA SIT ON TOP OF YOUR CAR. I KNOW IT WILL HAVE A SLIGHT BOW ON TOP BECAUSE OF THE RUBBER. WHAT IM SAYING IS WHEN U LET IT SIT ON TOP(WITHOUT THE SCREW), LEFT FRONT CORNER WILL BE HIGHER THAN THE RIGHT FRONT CORNER THEN VICE VERSA ON THE REARS.

 

[Poodles]

Yep, bad bushings can affect ride height, alignment can as well...

My car doesnt sit as high as a lot of other supras I've been around, but that's not exactly a bad thing...

And YES the targa is SUPPOSED TO SIT THAT WAY. That's why it's CRITICAL to tighten the bolts in the correct order.

Also, even 60's model Camaros are WET NOODLES in convertable form and that's why they sell braces for those cars. Targa Supras are heavily braced (the DOORS are used as stress members) and don't suffer the same issues as other cars.

Also, wikipedia is a terrible referance since it's leaving out damn near every sports/supercar out there (Corvette, Koenigsegg, Zonda, ect ect ect) that all have removable roofs and don't get bent out of shape from driving hard.

I've driven the piss out of my car on crappy back roads at breakneck speeds with the top off. Does it shake and shimmy a bit? Yep. Did i have a single issue putting the top back on? NO.

If your car is warped something happened. Jumped a curb, driven into a ditch, ect that would NOT be reported on a carfax if it was minor enough and a single car wreck.

Really, you're beating a dead horse and unless you were the original owner of the car YOU CAN'T KNOW.

 

[bsupra]

how did we get from spring longevity and resilience to chassis flex?

And of course a targa will flex more than a hard top with the top removed. You are removing 4 critical tie points on the chassis. With the top on they are virtually the same other than weight. If you tweak the cars frame your did something very wrong.

Now back on topic:
The easiest way would be to measure your cars ride height and compare to factory specs. This could be affected by lots of things though so its hard to draw a definative conclusion.

ok, first of all, i only asnwered the guys question about ride height. Ive been though all this with my 1990 targa.

Second, ok with targa off, the car will flex like u said. But i am not talking about just the chassis. The body of the car is the one that actually tweaked. My 89 and 91 are even in height all around except for my targa. And your right, when you tweak ur cars body, you are doing something wrong. But it does not always mean just accident, it can also happen with long period of abuse specially track driving with hard cornering without having proper support on the cars body.

And last, about the ride height. When toyota measured ground clearance off my 1990 targa. All the underbody components(including both subframes) are even. But when they took the measurements from all the body points, thats when they found out that the body was tweaked. They also said its normal for some convertible cars and it was an easy fixed, all they have to do is pull my car and it will be straight again but it will cost me more than the value of the car.

 

[bsupra]

Yep, bad bushings can affect ride height, alignment can as well...

My car doesnt sit as high as a lot of other supras I've been around, but that's not exactly a bad thing...

And YES the targa is SUPPOSED TO SIT THAT WAY. That's why it's CRITICAL to tighten the bolts in the correct order.

Also, even 60's model Camaros are WET NOODLES in convertable form and that's why they sell braces for those cars. Targa Supras are heavily braced (the DOORS are used as stress members) and don't suffer the same issues as other cars.

Also, wikipedia is a terrible referance since it's leaving out damn near every sports/supercar out there (Corvette, Koenigsegg, Zonda, ect ect ect) that all have removable roofs and don't get bent out of shape from driving hard.

I've driven the piss out of my car on crappy back roads at breakneck speeds with the top off. Does it shake and shimmy a bit? Yep. Did i have a single issue putting the top back on? NO.

If your car is warped something happened. Jumped a curb, driven into a ditch, ect that would NOT be reported on a carfax if it was minor enough and a single car wreck.

Really, you're beating a dead horse and unless you were the original owner of the car YOU CAN'T KNOW.

Ok here we go again. I SAID FOR A LONG PERIOD OF TIME OF ABUSE. AND DO I HAVE TO SINGLE OUT EVERY MUSCLE CARS TO YOU, I SAID I JUST USED THE CHASSIS AS FOR EXAMPLE. I AM NOT TALKING ABOUT DIFFERENCES ON MUSCLE CAR OK

AND YOUR RIGHT. RIDE HEIGHT CAN BE AFFECTED BY ALIGNMENT. THATS HOW EVERYTHING STARTED ON MY 1990 TARGA. WHEN I FIRST HAD THE CAR I NOTICED PULL ON ONE SIDE AND THE CAR IS NOT EVEN IN HEIGHT. I REPLACED ALL SPRINGS, SHOCKS, WHEELS, TIRES AND HAD THE BUSHINGS REPLACED UNDER THE CAR, THEN TOOK IT FOR ALIGNMENT. THEY GOT IT AS CLOSE AS POSSIBLE TO FACTORY SPECS BUT THE CAR STILL PULLED TO THE RIGHT. AND THATS WHEN THEY DID THE MEASUREMENTS AND FOUND OUT WHAT IS CAUSING IT. I THEN TOOK THE CAR TO AN ALIGNMENT SPECIALIST AND THEY WERE STILL ABLE TO MAKE THE DRIVE STRAIGHT BY PULLING THE RIGHT FRONT WHEEL AXLE ASSEMBLY FORWARD(WAY CHEAPER THAN PULLING THE WHOLE CAR TO MAKE IT STRAIGHT).

AND WHY YOU GONNA INCLUDE SUPER CARS IN THE COMPARISON? THOSE ARE BUILT TO BE DRIVEN HARD. THEY HAVE ALL THE SUSPENSION AND BODY COMPONENTS FOR THE TRACK. DO YOU THINK THAT SOMEBODY WOULD BUY $100K CAR AND GET BENT LATER ON. THATS COMMON SENSE. DAMN! HOW HARD IS IT TO UNDERSTAND THAT MKIII SUPRAS ARE NOT THE SAME LEVEL AS SUPER CARS. OUR CARS ARE IN THE MIDDLE LIKE 300Z AND 3000GT'S. AND PLEASE DO NOT COMPARE IT TO NEWER CARS LIKE 350Z'S BECAUSE THEY ARE MADE WITH NEWER TECHNOLOGY AND BETTER SUSPENSION. JUST THINK ABOUT PROBLEMS OUR MKIII'S HAVE ON THE REAR SUBFRAME THAT CRACKS. ITS BECAUSE IT DOES NOT HAVE ENOUGH SUPPORT UNLIKE THE LATER YEARS.

 

[gaboonviper85]

Ok here we go again. I SAID FOR A LONG PERIOD OF TIME OF ABUSE. AND DO I HAVE TO SINGLE OUT EVERY MUSCLE CARS TO YOU, I SAID I JUST USED THE CHASSIS AS FOR EXAMPLE. I AM NOT TALKING ABOUT DIFFERENCES ON MUSCLE CAR OK

AND YOUR RIGHT. RIDE HEIGHT CAN BE AFFECTED BY ALIGNMENT. THATS HOW EVERYTHING STARTED ON MY 1990 TARGA. WHEN I FIRST HAD THE CAR I NOTICED PULL ON ONE SIDE AND THE CAR IS NOT EVEN IN HEIGHT. I REPLACED ALL SPRINGS, SHOCKS, WHEELS, TIRES AND HAD THE BUSHINGS REPLACED UNDER THE CAR, THEN TOOK IT FOR ALIGNMENT. THEY GOT IT AS CLOSE AS POSSIBLE TO FACTORY SPECS BUT THE CAR STILL PULLED TO THE RIGHT. AND THATS WHEN THEY DID THE MEASUREMENTS AND FOUND OUT WHAT IS CAUSING IT. I THEN TOOK THE CAR TO AN ALIGNMENT SPECIALIST AND THEY WERE STILL ABLE TO MAKE THE DRIVE STRAIGHT BY PULLING THE RIGHT FRONT WHEEL AXLE ASSEMBLY FORWARD(WAY CHEAPER THAN PULLING THE WHOLE CAR TO MAKE IT STRAIGHT).

AND WHY YOU GONNA INCLUDE SUPER CARS IN THE COMPARISON? THOSE ARE BUILT TO BE DRIVEN HARD. THEY HAVE ALL THE SUSPENSION AND BODY COMPONENTS FOR THE TRACK. DO YOU THINK THAT SOMEBODY WOULD BUY $100K CAR AND GET BENT LATER ON. THATS COMMON SENSE. DAMN! HOW HARD IS IT TO UNDERSTAND THAT MKIII SUPRAS ARE NOT THE SAME LEVEL AS SUPER CARS. OUR CARS ARE IN THE MIDDLE LIKE 300Z AND 3000GT'S. AND PLEASE DO NOT COMPARE IT TO NEWER CARS LIKE 350Z'S BECAUSE THEY ARE MADE WITH NEWER TECHNOLOGY AND BETTER SUSPENSION.

you make yourself look so very stupid when you post this crap....you have no clue about metallurgy....and or properties of metal....so please dont even pretend like you do!!!

you have no clue...so please stfu....and if you honestly think you know so much then why dont you tell me exactly what kind of steel our supra bodies are made from mr.metallurgist.

 

[Poodles]

LOL

Modern cars are usually WEAKER as they have crumple zones.

If they measured ride height and it was fine on the subframes but supposedly the body wasn't straight, then it was in a wreck or the subframe mounting points are screwed (yet again, FROM A WRECK). You have no idea how many times I've seen it. had a friend that had a Camaro that went into a ditch. Body looked fine though the panel gaps where a bit odd. BODY GOT TWEAKED.

Was it reported to insurance? No. Could you tell by just looking at the car? NO.

Unless you 100% know the history of your car, SHUT UP. You DON'T know, and you absolutely CAN'T know.

 

[bsupra]

you make yourself look so very stupid when you post this crap....you have no clue about metallurgy....and or properties of metal....so please dont even pretend like you do!!!

You have no clue...so please stfu....and if you honestly think you know so much then why dont you tell me exactly what kind of steel our supra bodies are made from mr.metallurgist.

what are u even talking about metallurgy? Did i even get to that point? All it is is about targa and hard top. And some suspension components. You are the one that making your self look dumb. I even said "try to research and tell me what he finds"(page 2). If u r the engineer you tell us. But do not call me dumb. Everything i said was all from experiences and research when i had my 1990 supra.

If u want. I will do my research for u and find out what metals makes the mkiii supra from the chassis/body to wiper blade arms.

 

[bsupra]

lol

modern cars are usually weaker as they have crumple zones.

If they measured ride height and it was fine on the subframes but supposedly the body wasn't straight, then it was in a wreck or the subframe mounting points are screwed (yet again, from a wreck). You have no idea how many times i've seen it. Had a friend that had a camaro that went into a ditch. Body looked fine though the panel gaps where a bit odd. Body got tweaked.

Was it reported to insurance? No. Could you tell by just looking at the car? No.

Unless you 100% know the history of your car, shut up. You don't know, and you absolutely can't know.

ABOUT BODY WORK, OFF COURSE U CAN NOT SEE IT OUTSIDE. BUT U WILL SEE IT UNDER/BEHIND THE SKIN IF THERE IS ANY SPOT WELDS BANDO OR ANY KIND OF REPAIRS.

YOU KNOW WHAT. WHEN I BUY A USED CAR. I DO NOT DEPEND ON INSURANCE NOR CARFAX BECAUSE IM NOT THAT STUPID TO JUST DEPEND ON IT. I OPEN UP AT LEAST THE COMMON PANELS THAT GETS HIT LIKE THE TRUNK(WHERE THE TAIL LIGHTS AT SPECIALLY), DOOR PANELS, THE FRONT BUMPER AND ETC.


ok you know what i never told you to shut up. Now you shut up.... When i compared about modern cars. The body/skin of the car may be weak, just because for weight issues on older cars but suspension for track and support for chassis for handling like the 350z now you tell me modern cars are weak suspension wise. You r again now being dumb for generelizing all cars. its some cars

 

[Supracentral]

If you idiots can't have a civil conversation on this topic, I'm going to lock it.

And stop trying to shout other people down with a larger font it's bad behavior..

Tone it the fuck down people. I'm starting to get tired of babysitting this pending flamewar...

 

[bsupra]

If you idiots can't have a civil conversation on this topic, I'm going to lock it.

And stop trying to shout other people down with a larger font it's bad behavior..

Tone it the fuck down people. I'm starting to get tired of babysitting this pending flamewar...

ok im sorry for the bad behavior. I just cant stand when some people could not take opinion from others expereince. All i did was shared my experience on my car to guy that posted the thread but some followed it by negativity from what I said. I never pointed out that its their car. I said some.

ok i apologize

 

[Poodles]

You missed my point, driving in the ditch didn't cause any body damage, it just tweaked the chassis (was pulled straight on a chassis machine).

The new owner will never know, and if he had sold it with the frame tweaked they wouldn't have known either unless they went and measured (which he took it in to make sure it was ok, the guy is anal about his cars).

Car was in no accident. Previous owner just probably drove the car with the targa off most of the time then driving it aggrssively. Most targa owners in here knows this problem. Thats why most tragas leak and some have the screws keeps on getting lose on the one side (these is a common problem that most targa owners know about). I supra owners put braces on the roof everytime they remove the targa.

If the supra had u unibody chassis it probably not have the problem but instead they made two seperate subframes without enough support to hold the car. I would suggest installing reiforcement especially when driving it on the track.

This is how it started. Twisted chassis is rare, I've heard of only one instance of one getting bent that wasn't in some kind of accident and it was a big power car with the top off and he drag launched it...

No hard feelings, but it's not common on our cars.

 

[bsupra]

You missed my point, driving in the ditch didn't cause any body damage, it just tweaked the chassis (was pulled straight on a chassis machine).

The new owner will never know, and if he had sold it with the frame tweaked they wouldn't have known either unless they went and measured (which he took it in to make sure it was ok, the guy is anal about his cars).

Ok for this to get over with, im going to stop now. I shared my experience on the first replied i made to the guy started the thread(page 2). If u some of u could not take it, so be it. ok for my self, it may be rare but its possible. All it was probably based on the crack subframes i have seen and the two targas i looked before I found my 89 and 91 supra. I think all of these was from my bad experience with my 1990 targa which was my first supra.

 

[adampecush]

And metals do get weaker over a period of time. When the body of your car flexes, the part of the body/chassis which suffers from stress the most changes properties and actually increases to a sudden change in temeperature.

whoa...what? care to back this up with anything?

Go search on properties of metals first then let me know what u find.

Not something you want to get in to with me.

 

[bsupra]

whoa...what? care to back this up with anything?



Not something you want to get in to with me.

Ok i already told the admininstrator that im going to stop but your running your mouth so here is your reference.

http://www.boulder.nist.gov/div853/Publication%20files/NIST_RSI_thermal_fatigue_keller.pdf

http://www.avweb.com/news/maint/184271-1.html

http://www.metallurgist.com/html/MetalFatigue.htm

Read! its called metal fatigue. If u want to look it up. search it in google metal fatigue and metal stress.

And No, you do not have to be a matallurgical engineer to figure this out. Grap a paper clip and bend it back and forth then when it breakes, ask your physics teacher why. then let me know.

let me know if you want more reference

 

[adampecush]

Read! its called metal fatigue. If u want to look it up. search it in google metal fatigue and metal stress.

I suggest you do some in-depth reading and understand what fatigue actually is. It is not the degradation of the mechanical properties of a material. It is the initiation and propagation of cracking due to the application of cyclic stress. In the case of steel, this stress has to be greater than a threshold stress (aka the fatigue limit), otherwise, cracking will not occur. Guess what, vehicle bodies are designed with this fact in mind.

If your vehicle body has been weakened by fatigue to the point that it is noticable, catastrophic failure is iminent. I have yet to see fatigue cracking destroy the body of a supra, but hey, never say never. The rear subframe is a different story.

Grap a paper clip and bend it back and forth then when it breakes, ask your physics teacher why. then let me know.

Better yet, ask a metallurgist (ahem). When you bend your paper clip, you strain harden it, reducing its ductility. Continued bending reduces its ductililty to the point where it can no longer bend and remain intact, so it breaks. Some call this low cycle fatigue, but it is not.

And No, you do not have to be a matallurgical engineer to figure this out.

Apparently you do.

let me know if you want more reference

no thanks.

 

[Supracentral]

Ok i already told the admininstrator that im going to stop but your running your mouth so here is your reference.

You are really pushing your luck. Someone disagreeing with you is not a reason for you to behave like this. Using the phrase "running your mouth" implies that the person has nothing of value to add and is just talking to hear themselves speak. One more personal insult and you're getting an involuntary vacation...

I suggest you do some in-depth reading and understand what fatigue actually is

Since Adam is a metallurgist, you might want to follow his advice and stop running your mouth. (Understand what I mean about that phrase now?)