Help with Bodywork

[Colin Dalzell]

I am now at the "plan for bodywork stage". I have never done any bodywork before /ubbthreads/images/graemlins/confused.gif but would like to do most of the prep for painting myself this time.
Could any of you master craftsmen, please recommend a good book or better yet be able to describe the best products and steps to prepare the body - seams, edges, gaps and other build ups needed to smooth out/align the contour/body lines.

Any and all help/suggestions greatly appreciated.

 

[Howard Jones]

Can you tell us what you need to do to the bodywork? What I am saying is do you need to do mainly surface prep or do you have fit line issues. Will you need to add lenght to the doors for example. Are the doors flat surfaces in the correct plane in relation to the spider in and around the side air scoops? These sort of things will require the most work.

I was final sanding the spider last night and as I was doing it I wished I had at least sanded off the clear coat before I mounted it on the car. Where are you in your build?

I have a GTD and am just finishing my body prep.

 

[Bill Bayard]

Colin,

Give Peter Delaney a buzz. Between his 40 and his Vette, he

has practically sanded his fingerprints off! His bodywork

experience(lessons learned) should help you out a lot.

Between the two cars, he has tackled all sorts of problems,

from minor(filler/primer/sanding) to major(sanded some

edges too far, and had to build them back up, etc.)

His 40 looks great, so he must have learned something along

the way.


Bill

 

[Mark Worthington]

Blaine, I would suggest you look around for a local expert who can help you...at least help you get started. Preferably someone who has fiberglass experience. I am by no means an expert, not even a decent beginner, but I have learned a lot being around guys like Hershal Byrd and Bill Hough. You can only get so much from a book; you can get so much more from someone who is experienced.

Good luck.

 

[Colin Dalzell]

Hey Howard, the body is completely assembled and the doors are fit nice and snug. There is some build up required to get the spider to meet the doors (ie. the door is a smidge higher than the spider but it is fit perfectly to the chassis and it will be easier to build up a little rather than touch the doors). I also need to build up a little around the doors to get a consistent gap. Most of the rest will be sanding down the seams, smoothing with bondo and filling the odd crack, bubble hole in preparation for the primer.
Thanks

 

[Brian]

Ahhhhhh, smoothing with bondo, filling cracks and pinholes. Hence Mark's advice to find someone who has been around the horn a few times, if you use the wrong products, the stuff may craze, creep, pop-out, crack or engage in some other behavior that will have you pulling your hair out 18 months after the paint job.
The books are good, but get some experience on your side. I have shot a half dozen cars with a variety of products, but consider the experience to be of little value with a fiberglass body.
Brian

 

[Mark Worthington]

Colin, please accept my apologies for calling you Blaine. This wouldn't have happened if you lived in Bellingham or Seattle!!!

 

[Neal]

Colin,

Find someone locally that is familiar with glass work. Most fillers used on these cars are epoxy based. Check with the Corvette club. I'm sure there is someone in the area that would be more than willing to help.

 

[Steve Kulper]

Hi Colin,
Before you go altering any door edges or lines, make sure you fit everything on the car that can change the way these lines fit later.

IE: doors seals and cathes, rear clip locks, front clip locks etc.
When you are happy with the adjusments of all these working parts with everthing working, do a final check by putting the car back on the ground with its wheels on. You should do thes with the motor and gearbox in aswell. This will give you a true indication of how the car settles on its wheels with all or most of its weight. If you are happy with the fit and gaps, now is the time to figuire out which lines need to be modified.

Steve

 

[Howard Jones]

Colin, I would NOT use bondo at all. Now before you choke, there is a way. Here's what I have learned. To add height say along the front of the door on top of the spider just behind the windshield. I had to raise the door fit line in this area by about 3/16 nearest the door down to nothing along the windshield. First I sanded the area until I had all the clear coating off the fiberglass. Leave at about 150 grit finish. Do not sand through the color coat at anytime unless you can't get there any other way.

Then I layed on three layers of glass mat each progressively smaller in size with the common edge at the door opening and the bottom layer not quite reaching the edge of the windshield. This will give you a steped effect. Now sand the buildup to as close to the correct contour as possible. Next finish fill the rest with VET PANNEL ADHESIVE and use this in place of bondo elsewhere.

This is good stuff. It is made to fix corvettes and is much harder than common bondo. It will not srink but it does use up sandpaper. Don't put on anymore than you need to.

As to along the edge of the doors to make them longer, so to speak. This will be hard to do without removeing them from the car. So take them off, go ahead you will anyway, many times. Mark the original location and you should be fine. On my car I found I could leave one of the hinges in place. By loosing the other one only it made it pretty easy to realine the door when I put it back on.

Now stand it up so that the edge to be lenghtned is horzontal and facing up. Sand the edge flat. Now you have a 1/4 inch wide surface, clean and with a 150 grit finish.
Cut a strip of glas mat 1/2 inch wide and long enough to add 1 layer to the full lenght of the area of the door to be added to. Glass the strip on and let harden. Now you have a nice wide surface to add additional thickness to. I have been able to add three or four additional thickesses of mat onto the first one. If you try to skip waiting for the first strip to harden the additional strips will usually slid out of place. When all the strips have hardened you can sand off the excess and end up with a hard edge. Should you need to add door thickness in this area lay on glass mat so that it covers over the edge strips you just trimmed. This will sort of interlock the two and make the edge very strong. Finish with a little vet pannel adhes.

But first. Make sure you have gotten everything to fit as good as it will with everything in place. Make sure you have all the hardware, seals, door locks, lights everything mounted and inplace BEFORE you start cutting up or fiberglassing anything.

I would sand off the clear jellcoat, LEAVE THE COLOR, on all the pannels before I started any of this and befor fitting them If I had to do it again. It would have been a lot easier to work on them off the car.

You will need a airboard, orbital sander, rubber hand block, and I even used a hand board a lot. Buy the sandpaper for the boards by the roll. Its cheaper that way.

I used a lot of 150 grit paper and finished with 240. Anything more agressive, like 80 grit, just created more work for me later. I am going to let the painter finish sand the whole car before he paints it. Someone here told me not to use water when sanding fiberglass, I didn't and I was ok. It has something to do with moisture getting into the fiberglass and screwing up the paint later.

This part sucks and it took me 6 months but you will save yourself thousands of dollars. The dust can't be helped, wear a mask and blow out the garage from time to time with a leaf blower. Cover the gocart part of the car with a tarp when you have the clips off. This will save you some cleaning later.

Build some long saw horses and wrap them with old towels to place the clips on while you work on them. They will be helpful for the sills also.

Fiberglass work isn't hard and you can always grind off what you don't like. Tap plastic has all the materials and a lot of good pamplets on this stuff. Use as much fiberglass as you can with a minimum amout of vet pannel adhesive and you should be OK.

 

[Colin Dalzell]

Howard, thanks so much for the words of encouragement. I am in an area where there isn't a quality fiberglass repair shop for over 100 miles so thought I would do most of the main prep work myself. I will give it a go and let you all know how it turns out. I also plan to let the painter do the final sanding but I'm sure it would cost big bucks to get him to worry as much as I will about the panel fit.

 

[Peter Delaney]

Colin, I am not sure whether you got my email, so I'll post my reply here (it pretty much echoes Howard's advice) :

------------------------
Hi Colin,

Thanks for the complementary remarks - totally undeserved ! Almost everything that I have learned about bodywork has come from an expert - I have a '71 Vette which is undergoing a total body-off rebuild & all the major external work is being done by a mate (Scott) who has been in the business of rebuilding / L/R converting mid-year Vettes for 20 years. Over that time, he has made all the mistakes & has figured out the best way to work with f/glass. Scott's job on the Vette is everything that can be seen & my job is the rest (fun places like underbody, interior, etc). As we have progressed in parallel, he has been teaching me all the tricks, so any apparent knowledge of the subject on my behalf has come from Scott !

For what its worth, here are some tips & stories on bodywork :

Power Tools :

The only power tool that I used was a simple Dremel, fitted with 60grit sanding drums - my first Dremel lasted about 2 years, so now I am on No2 - worth their weight in gold ! They are perfect for trimming back the overhanging rough edges of glass that you have added to door edges, etc. (Some of these were up to 1/4" thick - no fun by hand).

Another thing which would have been useful is an air-powered die grinder & a couple of fluted bits - one rounded & one straight. My air compressor didn't have the throughput to run one of these, so I had to make do with the Dremel. In hindsight, I should have spent a couple of hundred extra $ & bought a bigger compressor - that would have not only let me run the die grinder, but also a belt sander (handy for glass work & also on steel, etc).

Filling Faults, Etc :

Scott has learned that you never use filler (Bondo / bog) for anything larger than half a match-head in size. Larger volumes will ultimately shrink & settle at a different rate than the surrounding glass, & you end up with slight "sink-holes" which only become visible months after painting. The other reason he avoids filler is that it has a different hardness from that of f/glass, & this can make the flat-stick-sanding job tricky - the paper tends to bite a bit more out of the softer filler & you can end up with slight flat spots on convex curves.

Basically, Scott does any mods / fills which are larger than a pin-hole with glass & resin. The trick is to machine out the area, feathering the edges, then lay glass/resin in until it is proud of the surface. This approach takes a fair bit more effort with the sanding, but leaves a uniform surface.

Most of the faults on my bodywork involved little areas where there were voids between the blue gel-coat & the underlying f/glass, and spots where air had been trapped between the mold & the gel-coat. Make sure you suss out these with a small screw driver - its surprising how big a void was under some fairly small imperfections. I just dug out the gel-coat until I got back to the point where it was well bonded to the f/glass, ground the areas back with the Dremel, then glassed them up. There were very few of these in the bigger / flatter panel sections, but quite a lot in the more complex shapes & tight curves (inner door skins & intake ducts on the rear clip).

Scott's motto - "If in doubt, grind it out" !

General Glass Work :

I used chopped strand mat & wax-free polyester resin for all the bodywork. Some resins have wax in them & this percolates to the surface where it stays tacky for weeks. I am told this is designed to seal the surface if it is going to be left bare - but it is a bastard to sand (clogs the paper in seconds).

Scott's tips on good glass work are :

- Grind / sand the area, blow off dust
- Wipe down with acetone
- Build up another couple of layers beyond what you think is enough
- Consolidate resin/mat (with one of those grooved rollers), then consolidate again

Panel Gaps :

Panel gap work will depend on how good or bad things are now. I found that the gap between the vertical front edge of the door & the front clip was the driver - it needed to be nearly 1/4" to allow clearance as the doors are opened. This meant that "Lexus Gaps" of around 1/16" would have looked out of place elsewhere, so I just made them all about the same as those front door edges. I also found that the bigger gaps allowed for having to shut the doors somewhat "firmly" to overcome the resistance of the door rubbers - at one stage I had 1/8" gaps around the door tops, but found that the "give" in the rubber allowed the doors to hit the roof before relaxing back to the correct position. Gaps of around 1/4" solved this problem.

If you need to build out door edges, etc, I found that the best way was to square off the edge with the Dremel, run one layer of glass over the edge (with about 1/4" overhang on each side), let it set & provide a wide base for the next layers, then run up to 6 layers at a time over this. I first tried 4 layers in one hit & ended up with them all falling on the floor ! If you need to build up an edge, and also the adjacent flat panel surface, I found it best to do the edge first, machine off the overhang, & then lay glass on the panel surface so that it crosses the new edge build-up - this way you get some "cross bonding" that adds a lot of strength to the bonds.

Body Filing :

For rough body filing like shaping large areas of raw glass add-ons on panel faces, I started with 32grit on a flat stick or piece of exhaust pipe (for concave curves), then on to 80grit to get rid of the big scratch marks, then on to 120grit over the whole car. All of this needs to be done with long diagonal strokes around the curves - never to-&-fro in the one area. I found that because of the flexibility of f/glass, I had to have the rubber seals in place around the doors & rear clip, and latches tensioned down, to hold everything in its final place while doing the body filing across the panel gaps.

The big tip that I got from Scott was to use a long stick (10-12" x 3" wide) for the sanding. Apparently, it is impossible to avoid ripples if you use a shorter sanding block.

With all that done, it is probably best to run a fairly heavy coat of spray polyester filler over the whole car (see Paint System below). I made the mistake of running 4 light coats on & paid the price when we found hundreds of tiny pin-holes later on - I should have really wacked it on. The stuff is quite easy to sand back (nowhere near as bad as raw glass or gel-coat) & a 400grit dry finish is all you need before priming.

Another important tip I learned from Scott is to never use water in the sanding processes on raw glass, filler or primer - always use dry paper. The tiniest bit of water can stay in pin-holes for months, & will result in a humidity bubble in the final paint. The only downside to this is DUST - there will be bucket loads of it on you, the garage, the house, the neighbours, etc !! I figured that I put about $1,000 worth of filler over the car, & ended up with half of that floating around as dust !

My other big mistake was to wait for Scott to run a very light guide coat of GM Flat Black over the car - this is what showed up all the pin-holes, minor lumps & bumps, etc which are impossible to see when the car is in flat primer. If I had done that myself, I would have saved big bucks.

Paint System :

This is one of Scott's big hobby-horses - choose a complete system from one manufacturer & stay with it. We chose Spies Hecker (a DuPont company) as Scott had got his best results so far with this. The system was as follows :

- First coat was a thick spray polyester filler called Raderal
- Block back with 80grit, then 120grit, then 400grit
- Touch up any areas "sanded though" with thinned Raderal
- 4 x coats of Vario primer
- A light guide-coat of GM flat black
- Block back with 400grit
- Lightly grind out the pin-holes revealed by the sanding back of the guide-coat
- Fill with Vario filler (compatible with all other Spies Hecker products)
- Block back filled spots (400grit)
- Touch up areas over & around these with Vario Primer
- Final block back with 400grit
- Base Coat : Spies Hecker - 4 coats
- Clear Coat : 2-pack Spies Hecker - 4 coats
- Leave for a couple of months, then buff
Colin, I hope that this will be of some help.

Kind Regards,

Peter D.
---------------------------------

 

[Howard Jones]

Peter I've taked to so many body men over the last 6 months I had forgotten you were the orginal sorce for most of the stuff that worked for me. Thanks Again!

Colin Do it Peters way! I ended up removing most of the stuff I did before I was sold on almost ALL fiberglass and VERY little body filler. You'll be fine and you will learn a lot. Start with a complete sanding of the whole body then go back and start with the smallest stuff first. This will help you learn how to do this stuff in small areas and small amounts of resin mix.

Lastly durning the winter when its wet outside fiberglass takes a lot longer to harden up. If you can, finish before it starts raining.

 

[Colin Dalzell]

Peter, thanks for the answer to my email question. I appreciate the great detail in your response (gleaned from your hands-on experiences). It does sound like a rookie can at least try. I will keep everyone apprised of my progress.

 

[Dave Wharran]

Eastwood has some neat items that I found indespensibe for body work. One item is a 21" semi flexible hand sanding block.
Click HERE

It is flexible enough to follow the contours of the body yet long and stiff enough to sand out ripples.
They also sell "guide coat" black paint in spray cans. Mist it on and sand it off.
You think the body is pretty good until you start sanding the black back off. It is "unforgiving" in the pin holes, low spots, ripples, and other inperfections it shows up.

Bodywork and painting is a long, dusty, dirty process....
but the paint is one of the first things everyone sees...

 

At the risk of alienating myself from most of the previous posters on this subject I will give you my input. Use the filler but use it correctly. I have had much experience in the body business including a restoration shop doing 100 point show cars.I have done all my replicas with filler. After fitting all moving parts I would block sand the whole cars gel coat with 80 grit paper. Thats when you find major low or high areas. This is where you would prepare the surfaces with flexible disc grinder. The trick is to roughen the surface to give the filler adhesion.Shape it with a grater and finish with 80.When all filler work is complete you should let all cure for a couple of weeks.Then remove door seals, latched and prime with a urethane high build primer such as Dupont URO 3-4 coats.Let this cure for a couple of weeks also.All this cure time will eliminate any later shrink down. After the uro primer has cured block sand the primer with 180 grit dry.Then repeat the priming again using the formula for a sealer ( using a thinner mixture)3 coats. At this point another 2 weeks cure time is suggested.Final sanding should be done with 400 grit paper. I like to block sand the final sand followed by some hand sanding to finish up. I also agree that a system of products should stay the same so that all is compatible. I prefer the Dupont Chroma Base system using 3-4 coats of color followed by 3 wet coats of clear. Wet sand finish with ultra fine color sanding paper and buff followed with a polish.This is the way I have been doing them and have had very good results.Hope this helps and I hope I didn,t offend anyone.

 

[Peter Delaney]

Denis - no problem mate - it just goes to show that there is more than one way to skin a cat (apologies to any cat lovers) !

My guess is that it comes down to 2 things :

- Using the right (compatible) filler which has characteristics very similar to the underlying f/glass, or just using glass & matching resin.

- Patience : as you point out, waiting times between the various processes should be measured in weeks, not hours.

This latter one is where I have seen most blunders - guys taking a raw car to some local shop (without f/glass experience) & getting it back a week later. These sorts of shops are looking for a fast turn-around, & yes, it looks great at first - but then the problems begin to surface (literally).

Kind Regards,

Peter D.

 

[Howard Jones]

Denis, I think that the more people who add their experiance to this forum the better off we will all be. When someone has something to add that comes from having done al lot of cars like you have then thats even better.

One of the things about GT40 bodywork that I don't believe many who have done metal cars or cobras for example have had to deal with is the edge lenghtening of fiberglass doors and clips. This is an area that is very important to the overall body fit issue. The edges IMHO must be done with fiberglass and very little filler or they will surely crack or dent if made out of soft filler. You are right about light buildup on the flat pannels to get a nice smooth look but again some of these cars require as much as 3/8" build up the achive this. That is again IMHO way to much filler and should be built up first with fiberglass. Of course filler has a roll as a final finish product.

The thing that you have made clear is to allow the whole car to cure foe quite a while before going to paint. This is one of the reasons why if I had to do it all again I would fit the bodywork on to the chassis and finish all the fit lines and pannel alinement before I moved on to the fun stuff. This way the body would cure for a year or more while the remaining mech. systems were commpleted. Then after the car was running and more or less sorted I would pull it apart again for paint.

I little filler won't hurt anything as long as it isn't used for edge buildup or layed on to thick.

 

Agreed, The large buildup of edges should be done with fiberglass. A little filler to an edge is acceptable. Keep in mind that any fiberglass that does not have gel coat or filler over it will probably show print thru in time.

 

[Howard Jones]

Good point. After trying a lot of stuff I came to the final solution. For thicknesses in excess of 3/32 or so add glass mat sheets to build up. Sand down to proper contour. Glaze over with Vet pannel adhesive to seal area. The paint guy confirmed same just yesterday.