steel vs. fiberglass

What are the advantages of steel vs. fiberblass flares. I am considering upgrading body with flares and front wings and I am trying to figure which way to go?
what about steel in back and glass up front?

lastly; what's the difference w/ flares in rear vs. the whole rear quarter being replaced?

Well, the accepted wisdom is that fiberglass flares expand and contract at different rates than steel, leading to inevitable hairline cracks where the two substances meet.

Of course, Warren Hall (learn that name, if you're going to stay on this board) has more wisdom than what the rest of us accept.

I'll quote from an old post of his:

posted 11-13- 06:21 AM

Marcello,

Since I have to add a disclaimer about any bumps, or 'external' forces beyond your control, I'm sure you understand ...

However, it is possible to bond fiberglass to steel with a reasonably strong, stable expected service life! One prerequisite is that the fiberglass be on the thick side, around 1/8" or 3 mm thick, which is heavier than normal, but it guarantees a more stable structure so flexing would not normally occur, and thus minimize any tendency for the paint to crack. As far as the bonding process, it consists of three phases:

1. Epoxy adhesive instead of the 'normal' polyester cheap and weak stuff used by the fiberglass industry!

2. Steel pop-rivets applied in a zig-zag pattern, rather than the normal straight-line pattern prone to a stress pattern called the 'zipper effect' ... all holes to be predrilled prior to applying adhezsive, and 'Cleco's (a temporary fastener used to align panels and sections in the aircraft industry for riveting) used for alignment.

3.Metal-filled epoxy filler to be used prior to painting ... rather than typical 'Bondo-type filler'

The above process was used by me in 1969 to affix an air scoop to a VW Beetle ... paint shop would not guarantee against cracks, but the first 1/4" long crack did not appear until after 21 years, and only grew to 3/8" ... one crack after that period of time seems rather stable to me!!! The car was autocrossed with solid motor/trans mounts in place, so body was subject to above normal stresses and vibration for approximately five years after bodywork and painting!

There may be other methods that would work, but my suggestion is to get the heaviest, strongest flares you can find, and install them in the strongest possible manner with materials known to be strong and durable!

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Warren Hall
1973 911S Targa

Steel still seems safer (for flares), but clearly it's not the only possible path. Fiberglass made sense to me for my rear RS-style bumper. I figured it was better to have a $100 piece where a collision is going to take place than some $1500 authentic factory part.

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Jack Olsen
1973 911 T (3.6) sunroof coupe

WHAT ABOUT REPLACING THE WHOLE REAR QUARTER LIKE THE ONES GT RACING SELLS VS THE FLARES THAT THEY SELL

people have been bonding 'glass to steel on cars for a long time. It take tallent, good quality products, tallent, time, and lastly tallent. If you don't have some of those, than pay someone who does. As to GT racing quarters VS flares, I doubt it is a full seem to seem quarter panel. It will most likely still need to be bonded to the remainder of the stock panel some where. The benifits are an overall lighter weight panel and hopefully less chance of stress cracking due to better placement of seems vs just bonded on flares.

just my 2 cents

I've never used glass fenders, front or rear, because of durability. You will bolt lots of things to the front fenders. I believe that on a car like a 911, that has no frame, the fenders may serve a structural function to some degree. Steel rear flairs are just plain more durable. You will never have to worry about a crack in your expensive paintjob with steel flairs.

AJUSA.com has a great deal on galvanized body parts, check it out.
jack

Just look at all the new exotics and you'll soon realize that you can glue just about anything together. The problem becomes were the two meet visually. I have had fiberglass parts that were strong and held without fail. The problem was where the fiberglass ended. because the fiberglass was think, it required a lot of plastic to blend it into the body. Note: Bondo is not as good as either fiberglass or steel. Within two years there was a hairline crack in the bondo all the way around the part.

The only way to do this "right" is to butt weld steel flares to the quarter panels (it makes no difference if you replace the flare or the quarter panel, they both should have butt joints. QPs require a longer weld seam with greater chances for warping and other screw ups). When people put on fiberglass flares, they frequently just remove enough of the old fender lip to clear the tires and leave the rest hanging. What you car looks like from inside the wheel wells may mean nothing to you but many of us peek.

I just received a quote from a high quality shop and asked about flares just for fun. They indicated about $2,000 on top of all the other work for butt welds like the factory used. Add another $3k for slant nose fenders.

Rich