Got some fiberglass quarter panels for the porsche to make it wider.. the quarters fit really well but where it meets with the pillar it will need to be moulded. the quarts go to the door jamb in the trunk area and under the quarter window trim that those spots arent an issue.. im trying to get ideas on how to bond this and not have it show up in a hot day.. ive seen pics of cars with the same quarter panels but never in person. anyone have any suggestions? hers a pic of the quarter.

I'm very familiar with these panels as had a customer do these for years.
Is there a sure way not to have a problem, well no but after about two years of trial and error we did stop having problems.

First those panels need to set out in sun for a week.

Fit and refit and refit again.
There are areas on the panel that you will need to use sheet metal screws to hold in place as some areas cannot be clamped.

One of the things we learned is these panels must be clamped or screw tight, when bonding, no losey goosy!
So test clamp and drill you holes before bonding and you may only be able to do one at a time because lack of clamps and vise grips.

Use only the Duramix 4188 on these and reason is it does not have the spheres for gapping purposes and this we have found is very important.

I'm skipping the prep as I'm sure you know or if not instructions come in cartage.

Clamp panel as tight as you can and make sure you have plenty of sheet metal screws where needed and plenty of clamps.

At jambs with a rag wipe off any excess bonding material that oozed out.
Let set for full cure in clamped stage, I think its 16 hours or about for full cure.
Next with a 3 inch roloc grinder prep all your spots to be tapered into the body and taper the glass as gradual as you can on the edges. Make sure all excess Duramix is gone.
Areas than need tapering spray two coats of epoxy and let set over night, this is one of the most important steps as the metal and glass will expand at different rates and the epoxy will make or break the job.
Apply a fine strand fiberglass like duraglas, kitty hair. and finish with filler.

As you get into the bonding, feel free to call me and we can get you threw this.

Thanks.. thats what i wanted to hear. this is my personal car and i want i to last and look good for a long time.. ive glued fiberglass to metal before but never moulded it.. ill try this out when i get to that stage in a few weeks. thanks again

RE: 4188, I should have said 4189 I think. Large panel adhesive you want with 45-60 minute working time.

Also, I should point out this guy was building these full time for a race team that raced around the world, so there was some abuse that may not apply to you. It was a weird deal as each car had to have a show finish and all it would take was one eraser size bubble to show up and the owner came unglued. No pun intended, for sure.

4188 is the large panel adhesive..

Another thing that i noticed with these are they are made completly from cloth and not matt then cloth. should i cover this with 2 layers of mat? Im epoxy priming both side but in nj its freezing cold and really hot at times and i dont want weave showing through.

We never had a problem with anything showing through.
We epoxied and used 2K primer and painted.
I would not fool with it.

But do let set in sun before applying epoxy.

I'm not sure if this applies here, but some of the fiberglass parts I've been asked to bond have had a somewhat small "contact patch" where the glass meets the metal. In these cases it is necessary to build a flange to mount the part. I like to have a minimum of a 1/2" wide contact bead all the way around the part, and maybe more in the case of a quarter skin like that. I might post a mini-tutorial on the subject if there is any interest.

Well it seems like when they made these they basically just shaped a bulge on the stock quarter panel and made the parts from there.. i can get a good 3inch bond line all around.. but i think 1inch would be all that was needed.