355 Berlinetta vs GTS vs Spider is there much difference

I certainly doubt that rubber joints do anythjng in terms of structurally connecting parts. They are just convenience seams.

 

Wrong. It helps in side to side movement (it's pined) and inward bend. Outward bend is another story

 

Not wrong. The connections aren't rigid and the seams are rubber. It will twist around the assembly.

 

Ok Bob, not like I have an engineering degree...

I'll be sure to tell you how to pull teeth

Looking at the side of the car, with top on, the center cannot flex as it can with roof on, in compression, not tention. And it will add rigidity to twist since it's pinned and the front is latched.

 

Hey Dave. I design restorative solutions on abutments that include lateral, vertical and torsional forces every single day. I build structures on titanium supports that account for rigidity and forces that are in function 24/7

You aren't the only one that has knowledge on these matters

Unless they use a morse taper in the interface it is a sloppy fit to allow it to seat and will move on those pins and fasteners.

Under load I suspect that there is significant movement of the connected pieces as they are lined with rubber and latched with non rigid connectors.

Simple engineering Dave.

 

I could tell a difference in body flex with my previous GTS if the top was in or out.

That's not to say it was at all bad. Probably the best open car I've driven in terms of rigidity. I've driven some that shake and resonate over every bump.

With the top out on the GTS I noticed it mostly in slower off camber maneuvers like pulling into a driveway, not noticeable in most driving situations at speed IMO.

 

Funny, I employ several engineers in many different disciplines. It's fun showing them a thing or two they don't know from time to time ;-)!!

Anyway, what I KNOW, based on ownership, and Dave will now find out since he is a brand spanking new owner of a B, is that the B is stiffer than the GTS. Even with the top on.

 

Post your engineering degree Bob. I'll sketch this out tomorrow from a PC

 

Thank you, from one with owenership experience

 

Ha! Your a real pain in the ass Dave.

I mean that in the nicest way possible ;-)

 

Fixed it for you as they do.

 

Can you fix a 4' tall blow hard? LOL!!!

 

Dont forget the weakness of the rear subframe, once the front and rear start flopping around it's like a fat girl doing the hula.

Any model at it's best is unacceptable for performance by todays standards, goodness it's just street cars if they did not flex they would self destruct even more then they do now

 

Hey Dave my engineering degree is right after my name. I am an engineer if structures, spans , supports that are in function with forces from all directions in a harsh environment with thermal changes and. Bacterial destruction.

I am az designer of systems to replace and restore lost and missing structures involving the use of materials from natural to titanium and everything in between.

I treat abraction destruction daily due to flexing of abutments similar to buttress breakdown

I design and use resilient and non resilient abutments in deciding whether a span should be supported by either with titanium interfaces.

Your top is held in my pins and clips that are far from rigid and your seams are lined with rubber. If you think those interfaces are offering squat in terms of rigidity I'm glad you are not designing anything I'm relying on

They are sloppy fit joints designed for ease of removal , not rigidity

 

Ha, I just think there are too many guys around here who must think they have 4' dicks because they sure like to swing them at each other all day.
My teen age drama queen daughters can get along better.

 

I don't understand since that quote was only thanks to someone who ones a GTS posting actual experience

 

There is definitely movement. If you drive with your fingers where the panel meets the car you can feel movement between the two. I'm not saying it could possibly be as stiff as a berlinetta, just that it does to some degree offer resistance to twist. (and compression as Dave mentioned)

 

It will offer resistance to deformation at the limits of its resiliency. In other words, as far as the rubber will compress

The pins are sloppy. The latches are flexible. Saying they offer rigidity is like saying my latches on my spider to make the car more rigid when the top is up.

It's just simple material flexure. It is not a rigid attachment and will flex.

 

Even if the attaching points are not 100% free of flex it still offers resistance to body twisting. If the pins/weatherstrip/latches are being loaded (and flexing) they must be to some degree resisting that movement even if it is not completely stopping it.

I'm sure a Spyder is slightly stronger with the top up and latched.

I would also say they are stronger with the doors closed.

Open both doors on a GTS, remove the roof panel and jack up one front corner. Would the doors close well and would the top line up perfectly? If not it would seem those parts are helping keep the chassis in alignment when they are in place.

 

Just for the info pile

When we would check chassis rigidity all flexible components were removed and a fixed ballast was used to simulate actual weight distribution. Then the destructive test began.

This was back in the 90s I know those new fandangled cameras and lasers changed the game

 

Agree. Any resistance is resistance but in this application the forces generated I bet push that resiliency to its limit.

Just a question. Do GTS have a greater or lessor degree of buttress issues than GTB?

 

From what I've read GTB's have far more buttress issues, I'm sure because the rigid roof can put more load through them.

 

Many of us are accomplished people on here Dave. Some more than others.
You help the community with a lot of quality posts and well researched information that I myself have referenced and, I'm one of the most knowledgeable and experienced 355 owners on FChat. There are many others on here that have forgotten more than I will ever know about the 355 and many other topics.
We all learn here and share. Use your considerable skills to do what you do without pushing people around sooner or later you'll get schooled.
Try "IMO" once in a while. It will take your edge off and continue the upgrade of this section.

Thanks.

 

As I would have thought. There is no stress breaker as in the GTS seams to allow the flexure occur.

Like a bridge that isn't allowed to bend. The GTS bends.

 

Bob is 100% correct. In fact all 355's are flexi-flyers. There is nothing rigid in the 355 gts roof or its connection to the car. In fact you can move the attached roof with your hand! A lot of the reason for going to the aluminum chassis of the 360 is rigidity. Even cheapo GM went this route on the non-base corvettes.

A funny thing, my 348TS progressed from streetcar to occasional track car to dedicated track car to 348Challenge car with bolted challenge cage to full welded car dedicated racecar. The change in stiffness from bolted cage challenge car to welded cage dedicated racecar changed the chassis feel so much I had to start all over with the suspension and learn to drive the car all over again! The bottom line these cars flex and badly. The 355 flexed so bad that the factory had to add shock tower stiffening plates to the raced 355C (all GTB's) or the heavy springs would tear the front of the chassis apart. Even casual trackday guys with 355C later added the stiffener plates if the cars did not already have them in there. It is even rumored (I have not seen it with my own eyes) that the last run of 99's were delivered with these plates. But as streetcars under 85mph 90% of the time they are just fine the way they are.