Modifying Body Panels on C5
Thread Starter
Le Mans Master
Joined: May 2006
Posts: 6,774
Likes: 363
From: Midland TX
Modifying Body Panels on C5
I used to do LOTS of custom Fiberglass work on C3s - so I really had that system down pat. However, I have never tried to modify any body panels on a C5 since these are not "just" Fiberglass anymore.
Has anyone seen any videos, books, instructions on what materials, procedures need to be used to successfully modify these newer material panels in a way that will last?
Has anyone seen any videos, books, instructions on what materials, procedures need to be used to successfully modify these newer material panels in a way that will last?
Drifting
Joined: Mar 2013
Posts: 1,496
Likes: 353
From: Little Rock Arkansas
The roof (if equipped with body colored top or FRC), hood, doors, rear quarters, lower rockers, and - if standard fastback coupe - halo between the targa and rear hatch are Sheet Molded Compound (or SMC). SMC is a type of molded fiberglass and thus has similar qualities to it, but it does have it's own special repair and modification techniques usually involving an SMC bonding material. GM has used SMC on cars for some years up to the introduction of the C5, including the GM F-bodies and the Pontiac Fiero P-body, to name a few.
Simply searching online for SMC modifying or modifications should yield you an array of various methods to working with SMC.
The front fascia, rear fascia, and the front fenders are Reinforced Reaction Injection Molded (RRIM) urethane. These panels would follow similar techniques to modify urethane. However as with many custom urethane pieces, it may be more beneficiary to create something that could be used as a buck to pull a mold from and create a single piece out of the same material, rather than attempting to modify a urethane component that is designed to flex with a more hardened material, and thus could potential damage if you drive the car frequently.
Simply searching online for SMC modifying or modifications should yield you an array of various methods to working with SMC.
The front fascia, rear fascia, and the front fenders are Reinforced Reaction Injection Molded (RRIM) urethane. These panels would follow similar techniques to modify urethane. However as with many custom urethane pieces, it may be more beneficiary to create something that could be used as a buck to pull a mold from and create a single piece out of the same material, rather than attempting to modify a urethane component that is designed to flex with a more hardened material, and thus could potential damage if you drive the car frequently.
Thread Starter
Le Mans Master
Joined: May 2006
Posts: 6,774
Likes: 363
From: Midland TX
The roof (if equipped with body colored top or FRC), hood, doors, rear quarters, lower rockers, and - if standard fastback coupe - halo between the targa and rear hatch are Sheet Molded Compound (or SMC). SMC is a type of molded fiberglass and thus has similar qualities to it, but it does have it's own special repair and modification techniques usually involving an SMC bonding material. GM has used SMC on cars for some years up to the introduction of the C5, including the GM F-bodies and the Pontiac Fiero P-body, to name a few.
Simply searching online for SMC modifying or modifications should yield you an array of various methods to working with SMC.
The front fascia, rear fascia, and the front fenders are Reinforced Reaction Injection Molded (RRIM) urethane. These panels would follow similar techniques to modify urethane. However as with many custom urethane pieces, it may be more beneficiary to create something that could be used as a buck to pull a mold from and create a single piece out of the same material, rather than attempting to modify a urethane component that is designed to flex with a more hardened material, and thus could potential damage if you drive the car frequently.
Simply searching online for SMC modifying or modifications should yield you an array of various methods to working with SMC.
The front fascia, rear fascia, and the front fenders are Reinforced Reaction Injection Molded (RRIM) urethane. These panels would follow similar techniques to modify urethane. However as with many custom urethane pieces, it may be more beneficiary to create something that could be used as a buck to pull a mold from and create a single piece out of the same material, rather than attempting to modify a urethane component that is designed to flex with a more hardened material, and thus could potential damage if you drive the car frequently.
I mainly was concerned currently with modifying the hood.
Team Owner
Joined: Mar 2001
Posts: 21,325
Likes: 3,841
From: small town in S.E Pa. PA
St. Jude Donor '03-'04
Repair and modify just like a fiberglass panel.... don't overthink it..
I installed my rear brake scoops using fiber glass resin and fiberglass mat... it was my first attempt at doing body work , I used simple fiberglass resin found at pep Boys.. I did those scoops 13 years ago and they have remained completely intact without any hint of a problem. here is shot of my scoops then , and now.. 13 years later.. they have never been touch since I first installed them.
13 years later.
I installed my rear brake scoops using fiber glass resin and fiberglass mat... it was my first attempt at doing body work , I used simple fiberglass resin found at pep Boys.. I did those scoops 13 years ago and they have remained completely intact without any hint of a problem. here is shot of my scoops then , and now.. 13 years later.. they have never been touch since I first installed them.
13 years later.
Intermediate
Joined: Oct 2014
Posts: 45
Likes: 2
From: az./ut. border
I own a F.R.P. shop & agree w/ e.t. with one exception, the hood as flexible as it is should be done w/ epoxy resin. something like a rocker is very well supported & will hold up fine w/ polyester resin.
Team Owner
Joined: Mar 2001
Posts: 21,325
Likes: 3,841
From: small town in S.E Pa. PA
St. Jude Donor '03-'04
Not sure exactly what you are doing, but the hood does have a reinforcement substructure... but again I am no expert.. just offering my one time attempt, and the good results over time... But if a Pro says use epoxy resin, then that's what I would use... although I may have used epoxy resin too.. I just used a two part mix of resin that was specific for fiberglass repair that I found on the shelf. It was only an experiment, when I did it.. But it turned out very well.
Thread Starter
Le Mans Master
Joined: May 2006
Posts: 6,774
Likes: 363
From: Midland TX
This was my first custom fiberglass attempt on my C3 back in 1972. Car was a foot longer, 8" wider and 3" lower by the time I was done. 11 years later when I sold it, no stress cracks anywhere and had the car over 160mph at one point.
