Methods to mounting body to frame...

[drumseven]

RT as usual awsome,great documentation, thanx for the advice very helpful , keep it up I'll be paying attention! Thanx

[usmc_butler]

great video RT 

[RT]

drumseven, you are correct.
Anything bonded to the back of a panel will make it thicker there.  The condensation problem may not be as big as the distortion that shows when the panels are in the heat of the sun and expand more over open spaces than at thicker, bonded locations.  If you bond the body, make the bonding at edges and corners to reduce the effect.
I didn't bond my body, I bolt it on.  My body may be different than others because I have it separated into many panels, just like the original.
Watch my video:

Replica Lambo body panel bolt locations

RT

[drumseven]

I like the idea of urethane at mounting points especially the gravity points ,plus one of my concerns is without something between the body and steel( bondo Mar glasses or urethane), more possibility that on a cool evening condensation could tend to outline any steel directly against the body does this make sense, or am I completely overthinking this?can anyone elaborate!

[plans4sale]

 Windshield urethane is perfect for bonding fiberglass to metal. Urethane (though not for windshield application) is commonly used in boats and OEM metal and composite car parts for reason. It's super strong yet flexible enough to soften the stress taken during driving. Lots of builders use resin instead that makes the connection too stiff, so no wonder cracks appear eventually.

[rodrieguz]

My car has been on the road since 07, the body was glued down with windshield urethane along the upper body supports and bolted along the lower parts , rockers f/r, bumper, door latch area etc.  I have not had any issues with this method whatsoever.  The car rides just like a regular car.  No squeals or rattles.

[tonypaul]

While I think creating cushioned mounting points is a good idea, I still dont see it working well. Knowing what all I had to do to attach my Diablo Roadster to a stretched Fiero frame I couldnt see it working. There are just so many cavities and crevices that require long support mounting it would seem that cushioned (flexable) would cause stress points. But there are way smarter people than me when it comes to these replicas that Im sure make it work. On a custom built chassis I could see it working better but I still have trouble seeing the full picture.

I kinda wish this disscussion was going on while I was building mine, I might have tried it. I had to go back and redo my my Roadster roof by making the mounting holes bigger in the body and making the rear attachment kinda a floating attachment. When I drive over big speed bumps or a steep driveway my removable roof squeeks and rattles from the movement of the body. Had I keep the mounting holes small where the pins go in they would have cracked the fiberglass around them. But in a positive matter, should something happen (accident/electricial failure) to where my doors wouldnt open I can pull a couple pins and flip the front latches and the removable roof will pop right off.

[plans4sale]

I thought I'd read somewhere that someone said to make your body mounts "flexible" so the fiberglass has some room to move around a little as it heats up and cools down.  I was planning on using rubber cushions between the brackets and body to give it some extra flexibility while still keeping everything in place for alignment.  I do think that a body that is mounted too stiff to the chassis could be trouble waiting to happen and this is made even worse on a one piece body.

I'm definitely not an expert in this area so I'm curious to hear what others have actually done vs. plan to do and what the experiences have been.

Thanks,

Chris

 I was writting this advice for years at Madmechanics and Kitcentral, many people argued and doubted the advantage of soft mounting points, and I can't understand why so many builders still don't do that and permanently attach their body kits with body-to-epoxy-to-metal hard mountings instead of using screws and rubber bushings/cushions as a vibration isolator to soften the stress the body panels take during driving or fast temperature changes (especially in cold weather when the engine compartment gets hotter after a while).

[01Lambiero]

The windshield sealer on your mounting points should allow for expansion and contraction in the sun.  I don't remember seeing any posts mentioning this problem on other forums.  There were two cars at Carlisle last year.  One was a deep purple and the other was an almost black/purple.  These people would be my guess to send a pm and ask them about body shift as neither car is what I would call a neutral color.  Both are on KC, "Jimbo" and "EX".  Sometimes the "what if" questions lead to a snipe hunt for a non existant problem that we really don't need to worry about.  We already have enough to go around.  As to replacement body panels (a real good idea but you had better buy them now instead of looking for them 8 years down the road),  maybe we all could use a course in "Defensive Driving" so that we don't scratch our babies! 

Jim

[SchulzeA]

I thought I'd read somewhere that someone said to make your body mounts "flexible" so the fiberglass has some room to move around a little as it heats up and cools down.  I was planning on using rubber cushions between the brackets and body to give it some extra flexibility while still keeping everything in place for alignment. 

I plan on using these style bushings designed for motorcycle bodies. You use shoulder bolts with a shoulder slightly longer than the bushing thickness so the bolt can be tightened down yet the bushing still floats to some extent. It also allows the ability to remove body panels if needed.

[rotarycraig]

Am33r. I believe cki can make any panel you would need. I got a quote for the inner door assy from them.

[am33r]

Chris I think its the case with everyone too.

A Thin, Replaceble, Easily-Detached, Front Lip would be an Ideal Solution for front-end Scratches. No one made this yet?

Speaking of the parts, did any of the kit makers mind if one were to ask them to lay only a certain part of the Fiberglass kit; like making a Bumper with Fenders attached, Etc.  Shouldn't cost more than $1k or whatever the cost may be. Should make sense to them I think too.

[jdinner]

I have done the following on all my cars the same way.... Make a steel frame-work to match the body curves in several places.
Weld that to the frame. Upon final assembly inject windshield urethane between the metal and the fiberglass.
Make sure to leave about a 3/16" to 1/4" gap for the urethane. I seems to work for me..
After the body is fitted and 'glued' in place I added extra supports that are bolted to the frame and urethaned to the body.

[No Bull]

Chris raises a good point. I wonder also ( For a Roadster at least) if one were to mount the whole front end separately, then the rear end separately. Then the two rockers alone in between. Think if the rear end is crashed and you should replace it also of course flexing of the uni-body.

This was one of the number one reasons for me wanting to split my one piece body up and go with separate front and rear bumpers. 

Since the car sits so low, it's just a matter of time that my front bumper is going to take some damage and I want to be able to unbolt it, locate another OEM splashed front bumper and bolt it on.  This is one way of guaranteeing that everything is going to fit correctly five years from now (as long as OEM splashed bumpers are around) and things like the grilles will fit exactly.  It could become a problem at some point to locate a separate G28 front bumper and then replacing it on a one piece body would take some major work.

I'm now thinking of extending this to the fenders and even the windshield pillars so the car is easier to service and all of these panels will flex and act independent of one another.  The windshield pillar panel will be the one panel that will be glued down to the windshield frame for stability and strength.

Just another way to build it.   

Chris

[am33r]

Chris raises a good point. I wonder also ( For a Roadster at least) if one were to mount the whole front end separately, then the rear end separately. Then the two rockers alone in between. Think if the rear end is crashed and you should replace it also of course flexing of the uni-body.