355 Berlinetta vs GTS vs Spider is there much difference

According to Ferrari, that's all.

It's possible a Spider may weigh 100lb more (that's pretty close to what Ferrari claim anyway), but a GTS? I doubt it.
It's impossible to see how or why it would weigh more than 20-25 lb more than a B.

 

To say a GTS panel offers no rigidity is just incorrect.

When the car is sitting on its wheels, it will be reaction the normal forces of the weight on the chassis at the wheels, causing the car to want to bend like a u-shape (sag in the drivers seat). With no roof panel, the car will be able to flex. With the roof panel attached, a level of added strength will be introduced to the center of the car just as if it was a GTB. Now, If you get the car air born, or standing proud of its suspension (or on a lift), the roof panel will separate and offer no rigidity since it's only pinned on one side and not hard fastened (therefore, it's no help in tension).

Also, in twist as looking from front or rear, the roof panel is pinned in the back and latched in the front and therefore will provide a benefit in torsional stiffness.
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Ok, this is rich. You pat yourself on the back as being the most knowledgeable and experienced owners here and then you school me to use "IMO"... Nice.

For one, try not hiding behind a screen name such as "Nikki Sixx".

 

It's difficult to find a thread to answer one's exact question, but from my F-Chat searching I was able to find out:

1. Berlinettas and GTSs came out at the same time
2. There is no frame reinforcement difference between B and GTS, therefore
3. GTS is less rigid than Berlinetta due to no structurally attached roof
4. Spider has added reinforcements, meaning it is possibly more rigid than a GTS

Even then, these differences are all theoretical. One would have to drive or ride in all 3 models, back to back, on the same road at the same speeds, to even hope to differentiate structural rigidity.

 

OK Bob...Dave is technically correct in an absolute engineering sort of way but his engineering is poor at best. He does not seem to understand that 2 latches less than 4" wide over a 36" roof panel offers very poor retention form or resistance form and lack rigidity. Furthermore, he does not understand that rubber coated pins, roughly 1/2" in diameter, on the other end of the panel make for even less retention of the roof panel and completely lack any useable rigidity. Is there some friction there? Well yes. Can that resist a measurable rotational torque? Well yes. Is this miniscule amount meaningful? No.

I guess if an engineer really wanted to razzle dazzle us with engineering he would whip out the Finite element analysis or go to a GTB and a GTS and measure it like the old school racecar builders.

 

Dave,Dave,Dave... What I'm saying is put your dick measuring tape away. You are embarrassing yourself and rubbing a lot of people the wrong way with your bulldozing ways.
This is called a community for a reason and your a newbie in these parts so act with some assemblance of humility and respect. You push people around and I for one don't like it so stop it. Get it?
Maybe you actually are only 4' tall and if that's the case, I guess the result of that complex is what the 355 community will have to continue to suffer through.

I have clocked over 60,000 miles over 8 years of ownership over all 3 variants and have had the cars torn down to the shells and back several times. I have engineered many solutions for the car as other members here have. Many of these guys know this car at a molecular level. Learn and share buddy.

 

I'm not an engineer, but there is no way the Spider could be more rigid than the GTS.
No. Way.

If the GTS has no extra reinforcement at all, where does the extra 22 lb of weight over the B come from?

 

I understand what you're trying to say, but that is one of the most obnoxious posts I've ever read on here. IMO.

You're last paragraph is a prime example of exactly what you are trying to criticise Dave for:
Blatant dick measuring.

He has every right to post whatever he wants, and you have every right to disagree or consider his posts in any light you like (as I have yours above).

THAT is a community.

 

Infact, this is correct. The GTS with the roof panel removed you can feel it "give" in hard cornering and in particular if the car is either accelerating or decelerating with a torsional load you can feel it even more, it is more pronounced that the spider. The B also can be felt twisting at the track if you are paying close attention.
When you watch some cars on the track such as Rob Lays or Gator Greg's car, even those seem to look as though they twist a bit. There is a post on here somewhere recently of a 355 on a road course with a different engine in it which has absolutely no flex in it at all. I think SOCAL posted it. The most awesome 355 ever!!!

 

Nikki, once again you school me while patting yourself on the back.

I will agree that sometimes my post may come off as you say but the written word is hard to interperit and you quite frankley may not be reading it right. In addition, some of the folks here just never admit that might be wrong. Case in point, this thread has two dentists (while very intelligent guys) telling engineers they are wrong. Just like FBB above failing to see how the GTS panel pins and rubber, will add strength in compression to body flex. That's an absolute fact and not my opinion. If I took the roof panel out and stuck in a piece of 2x4 it would do similar. As I already stated twice, in tension it won't help because one side is only pinned and this can be seen when lifting the car and the panel separates.

Congrats on your 60,000 miles but that does not really change my view of someones credentials I don't know who does not post his name, profession or location.

Many folks on this forum have become my friends and I've helped people anyway I can, what have you done?

Time for the ignore list even though I like Motley Crue

 

Hi Steve ( and fellow Aussie) , well I'm a half breed.

Agreed about last paragraph. I was rolling my eyes at myself as I was typing it but look at post 48. That's a nice piece of encouragement right there.


My sword remains sheathed.

 

That MAY be true (I have no idea), but the argument is about the GTS with the roof panel IN.
In which case there is no way in the world a Spider would be more rigid.
You can argue all day about whether it's as rigid as a B (my guess is it is not, but barely enough to notice unless you're on a track driving like a pro).

It's all good. Personally I enjoy Dave's contributions. (For one he's one of the few defenders on here of the F1 box, and we need as many as we can get. )

My point is, if we all agreed on everything all the time this would be an incredibly boring place.

There are several posters who constantly have me shaking my head - and I bet there are several posters who constantly shake their head at everything I contribute - but that's what makes this place interesting.

Otherwise, why would I (or anyone else) bother?

 

Dave, I design and manufacture Advanced ground guidance systems for airports. Both on the equipment side and on the software and control systems side.

What we do for a living is irrelevant. This is about trading information and sharing experiences about the cars we love. I love participating here. Let's keep it inclusive and try not to step on people's toes.
Don't put the Crüe on ignore buddy, you'll miss some good old fashion shouting at the devil, which we all need to do from time to time.

 

What we do for a living is valid in technical discussions. And, I'm not stepping on the shoes of others anymore than they are on mine.

But, weather offical ignore list or not, it is time to ignore a few so to keep these pointless debates down. That's really what I need to learn for I don't need to prove it to myself. And if some chose to ignore me, I'm cool with that too since you can't befriend or please all.

I'll continue to try and bring positive posts to this board thru technical data as I learn especially as my new project gets underway.

 

Good luck on the resto. It's a beauty of a car, congrats.

 

There is nothing in that drawing that isnt a given and understood from the beginning,

Dave you are a mechanical engineer. You do not design automobiles. I am a dentist and I do not design automobiles. Your elevation of your credentials over others knowledge and experience in various phases of design principals is pompous.

The pins, joints and rubber will allow the body of the car to twist torsionally as they are not rigid, resilient connectors. The body has inherent limits just because of structural integrity as to how far it will twist but I would bet that any forces under load can push whatever resiliency those attachments have to their limits with resultant twisting.

As far as compressive load downward on the body, I bet if you could carry that load to the extreme and actually bend the car that way you would see that top pop off like cork. Again it will deform to the limits of the connections and then resist.

As Tim said, when doing structural analysis on these things, all flexible components are removed first. I would think that is because their impact on results is negligible and not material to understanding the load distribution.

 

Anyone on this website who claims that they can tell the difference in stiffness between a 355GTS with the roof on and a 355B, when driven at legal, sane speeds on public roads is full of ****. IMO.

Or, is a racing driver in disguise (who is still not driving at legal speeds).

There is no way in the world that any normal driver, driving at legal, fast but fun speeds could really suggest there is a meaningful difference.

I'd even go so far as to say there is no way that any normal driver driving in the above conditions could detect a significant flaw in stiffness or performance with the Spider version, either.

But of course there'll be the self appointed heros in their manual Bs who dream that they can.

 

This ^. I would bet that 90%+ of the owners and posters have never had their car on a track (and about half of them it seems drive them about 500 miles a year. My favorite are the posters that say "I've never owned one but drove one once and (fill in the blank)".

 

Bob,

Over the last 25 years, I have lived a very technical life. I have work for GM in the largest engine assembly plant in the world. I have designed custom automated assembly and test machines (primarily for the automotive industry), many with extremely high forces and structures to support them. I've done product design. I've built somewhere between 30-50 comp eliminator dragster chassis and associated components (from raw tubing and stock), I TIG weld, I can use fabrication equipment, I am a self-taught machinist (manual and CNC), I have designed using many different CAD systems and now design using Solidworks 3D modeling. I have 1 US patent, 1 currently under office examination and others ready for submittal soon. I'm a guy in the trenches, I'm a guy that does - not a guy that directs others (although I do have employees in my 17+ year business). On top of these credentials, I left one on the most important out - I can't spell to save my life…

I state my credentials to support my position and give background to where my statements and opinions come from, I don't do so to be pompous in any way. In fact, admittedly, John K is far more in touch with theoretical engineering than I am (it's been a while since I crunched calculations like he does) I love to learn and continue to do so everyday.....

Have you ever driven a GTS, Bob? Have you ever removed a GTS top and reinstalled it? Have you ever felt the top in your hands? Well, I have done all for my car is a GTS.

When I put my car on the lift, the roof panel separated which illustrates a flex in the body causing the dimension from the front windshield to the rear pillars to increase. Obviously, when placed back on the ground the gap was returned to normal. Therefore, the car does flex in that degree of freedom. Remove the top, and I'm certain the distance (while driving hard) can reduce to less than the length of the roof panel and therefore with the panel on, it would be in compression and providing rigidity. The same goes for torsion about the axis of the car. Dismiss the pins and latches all you like, but they are still connectors and do provide strength. How much rigidity does this add? I have no idea and the only way to know would be through testing and analysis. I've stated from the start, it adds rigidity - I never stated how much and I did say less than a GTB.

In summary, do what you would like with this post or others. I'm done with the constant debate with you over the chip on your shoulder. Ironically, I received a PM the other day inquiring why you disagree with every statement I make (from a member who feels I'm helpful to him). He said to me, DrBob would disagree if you said there are 12 eggs in a dozen.

Throughout our brief friendship, Bob, you never took the time to listen, you just talk. If we were on the phone for 60 minutes, you were talking for 58. You are a good, and extremely intelligent man but you don't know the most about every topic. Learn to listen once and a while to folks that do have experience and knowledge in other areas - especially when they do so for a living.

Peace and be well - I'm out of this one

 

I would agree, most drivers would probably not be able to tell. Drivers who do a lot of racing might though.

 

I think it's easy to tell the difference top in or out. I have tracked the car once top in or out but again, most noticeable in slower off camber approaches.

I build cars and calibrate efi for a living. That doesn't give me any type of chassis stiffness certification but I've driven many cars fully caged, convertibles that flop around like a soggy noodle and everything inbetween. Yes the roof connections have give but the panel in place at the very top of the car is in the best position at the extreme opposite of the floor to offer some resistence in torsional loading.

 

With all due respect, how do you call Dave a newbie here when you have only been a member since last march with under 200 posts?
I really don't think that the roof on a GTS will add any rigidity to the car but tomorrow I will ask a guy who will know since he has been in on the design of a few of these cars. Maybe he will help clear up some misconceptions on either side here.

 

This thread is the usual load of bollocks about nothing of any great importance. So, just another day on the 348/355 section

 

Mind your own words Dave. You are not the end all of all things 355 and your technical background does not translate 1:1 on every topic. This issue does not require an advanced degree in auto design to understand.

I have not latched or unlatched a 355 targa, but I have owned two other Targa cars in my life so I am very familiar with how they work.

I won't even stoop to the level of discussing interpersonal relationships in public. You are immature Dave. I have a PM box as well.

 

I have also owned a 95 vet with targa and it was different - fasteners on the connections - they are all not the same.

And Bob, did I not recently email you suggesting we simply stop this BS and just ignore each other? You are stooping to a different level by attacking every post I make. Let's just move on please.