Dumb question (probably) about paint and bodywork

[pyronuc]

So obviously, the external surfaces of the fiberglass roadster body needs to be sanded and filled to get rid of seams, and then prep and paint. but what about the underside? Most of the underside would be hidden from view by the aluminum paneling and such, but sureley some of it must be visible after the car is completed.

So my question is, is the underside of the fiberglass typically just left as-is with raw fibers showing? Or do most people put some sort of skim coat on, prep, and pain the underside, too? i'm probably anal retentive enough to want to paint the underside just so there would not be any visible unworked and unpainted fiberglass visible anywhere. But I don't know if this is typical, or just going way too far overboard.

I know virtually nothing about fiberglass bodywork and paint, and I plan to let someone who knows what they are doing take some of my money to do it for me. I just want to get some idea of what I should be trying to get done in regards to paint and bodywork.

[QSL]

rubberized undercoating or bedliner coating

[NukeMMC]

As QSL said, most folks will undercoat in some fashion. This is very important in the wheel wells where those gummy tires will toss a stone and put a dent in your paint from the underside. Some have smoothed things out and painted with aluminum color to make it look like an aluminum body.

[Hans944]

My Roadster has the underside of the hood painted the same color as the exterior car body including the gold stripe. My car also has the chrome Factory Five hood hinge which is a nice touch finishing off on the under side of the car. You might consider these options for your car...

[Hans944]

26395

Pyronuc:

Here's a picture of the inside of my hood described above..........

[edwardb]

As others have said, you want to paint the underside of the hood and trunk lid same as the body. For the underside, most guys use truck bed liner. Typically a couple coats over the entire inside, and an additional couple in the wheel wells. For appearance also to prevent any damage to the glass from rocks, etc. Also cuts down on the "pinging" of stuff hitting the wheel wells while you're driving. I think most also coat the tire side of the splash guards as well. I did. Picture of my Mk3 body at the painter getting the bed liner treatment before color and clear on the good side:

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%20Mark%203%20Roadster%20Build/Misc%20Pics/photo_3_reduced.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%20Mark%203%20Roadster%20Build/Misc%20Pics/photo_3_reduced.jpg.html)

And by the way, the lines in the body aren't seams. They're parting lines. The body is molded in one piece without any seams. There are multiple pieces to the mold so it can be disassembled and the molded body removed. Those lines are where the mold pieces separate.

[Dan Babb]

At a minimum, put a coating in the wheel wells (for protection) and also the whole front half of the car. When the car is finished, you can see parts of the body when you have the hood up. if you don't black out the whole front half (at least the lower portions of the front half), it can look a bit cheesy and unfinished.

[pyronuc]

Thanks guys, that's a lot of good information. I had definitely planned on doing the underside of the hood/trunk just like the top side, so I was more concerned with the body itself. Truck bedliner spray sounds like a good idea. I was planning to so some type of undercoating type spray for the wheel well aluminum pieces, but I hadn't thought of doing bedliner spray on the underside of the fiberglass, too.

Do you guys just use the home bedliner spray kits? Or do you take the body somewhere to have a professional Rhino Lining sprayed in? Also, does the bedliner coating make it harder to attach the vent louvers? The FFR build manual has you just sort of stick them in with silicone. I don't know if the bedliner spray would make it better or worse to stick the louvers in. I guess it would be possible to attach the louvers with silicone and then spray the bedliner spray on top of the louvers (with the slats covered with tape). What's the best solution here?

[skullandbones]

If you have any concerns about weight you might want to concentrate the rubberized stuff or bed liner in the critical areas. Most of the underbody will not be exposed to rocks. You can put an adequate finish on the rest of the body with a simple undercoat paint to smooth it and give it a dressed feel. I rubbed my hand over the areas to evaluate the condition and applied undercoat paint accordingly (sanding some of the ruffer places when needed). This can vary quite a bit from body to body. The MKIVs are probably smoother than the MKIIIs. If you're not careful you will find some extra unexplained pounds when it comes to the final scaling of your project. IMO, WEK.

[montyals]

It's really about personal preference. You can coat the underside or leave it raw. I doubt you'll be hearing any pebbles "pinging" or any other noises over the engine, sidepipes, and wind noises. In over 8 years of owning these cars I can't say I've ever heard any road derbis noise while driving. No affect on the paint either. I have however coated the aluminum under-carriage areas with rubberized materials for general noise reduction.

[Ray]

I rolled Herculiner on the underside of our car. Two coats on the body, four coats in the wheel wells. I just taped off an inch or so around all the edges to ensure that stuff would "stick." I also know of at least one car that got a "star" crack in the nose paint from a rock bouncing off the radiator and up under the nose. That convinced me to undercoat the car.

Ray

[Jeff Kleiner]

DIY Herculiner or Duplicolor Bed Armor bedliner. I've used both, they look and perform the same but my preference is for the Bed Armor because it cleans up (prior to curing of course) with soap & water rather than Xylene which is required with Herculiner. Believe me, you'll wind up wearing plenty of it so easier clean up is important!

Jeff

[SnowCobra]

DIY Herculiner or Duplicolor Bed Armor bedliner. I've used both, they look and perform the same but my preference is for the Bed Armor because it cleans up (prior to curing of course) with soap & water rather than Xylene which is required with Herculiner. Believe me, you'll wind up wearing plenty of it so easier clean up is important!

Jeff

What sort of prep is required prior to applying any undercoating? Does a mold release cleaner need to used or any mechanical scuffing?

Thank you,

Ryan

[Jeff Kleiner]

There isn't mold wax on the underside but I still give them a wipedown with MX190 cleaner/degreaser or similar. It doesn't hurt to run over it with 60 grit on a DA to knock loose any stray bits but you're not trying to make it smooth.

Jeff

[Fred Yarema]

I brushed on a coat of silver catalyzed car paint on the inside after the outside was painted. The surface of the rough fiberglass doesn't show the brush strokes and didn't have to worry about overspray. Nowhere near the weight of rubberized or urethane coatings and is holding up well. The small amount of the inside fiberglass visable under the hood looks like the backside of an aluminum body. With the red gelcoat on the MKIV's, silver looks a lot better than pink!

[Stengun]

Howdy,

I plan on using bedliner on the underside of my Spyder to give it a more "finished" look. One medium coat should do the job just fine with two coats on the nose.

Paul