Urethane Vs. Fiberglass
Drifting
Joined: Feb 2006
Posts: 1,877
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From: Ok! So you don't believe in conspiracies, but will you acknowledge the possibility of there being coordinated activities in secret places? Texas
Borrowed from internet site:
* Fiberglass VS. Urethane
We're often asked about the difference between these two materials and which one is actually better. There are many factors to be considered in the answer to this question.
Overview of the Two Materials
Urethane is flexible but very difficult to customize or repair in any way.
Fiberglass is rigid but can be readily repaired or customized by a competent shop.
Points to be Considered
Purchase Cost
Fitment
Ability to Customize or Modify
Cost and Ability to repair
PURCHASE COST
If you are purchasing a quality part or kit, the urethane products are probably going to be slightly more expensive.
FITMENT
Generally speaking, a urethane product will fit a car slightly better right out of the box due to the control in the manufacturing process.
However, a urethane product CANNOT be fitted as exactly as a fiberglass part. Fiberglass products usually require trimming or filling during installation.
ABILITY TO CUSTOMIZE OR MODIFY
A good custom shop can modify or customize ALL fiberglass products. Fiberglass is a material that can be shaped, changed or fitted to any application. These mods can be reinforced to produce significant strength and durability. Urethane cannot be reworked or modified with any degree of durability.
COST AND ABILITY TO REPAIR
Urethane parts are flexible and will absorb very small 'hits' without creating serious damage (cracks or holes). However, once urethane is cracked in any manner, it is usually sent to the scrap pile out back.
Although our shop has perfected methods of repairing urethane parts, at best, the repair is temporary and cannot be guaranteed.
Fiberglass parts are totally repairable. Most damaged parts, within reason, of course, can be repaired by any shop experienced with fiberglass. Proper repairs on fiberglass parts are durable and should be permanent.
Let's look at a repair cost scenario on a full bumper replacement kit.
Suppose there are a couple of good sized cracks in the front bumper. Normally, with a urethane kit, the bumper will need to be replaced.
Usually, the part cost is approximately $425.00 + $125.00 (average) in shipping. The labor to remove/replace and paint will be a constant cost in either replacing or repairing. There will probably be a time delay of up to 4 weeks until the replacement bumper arrives. The same cracks in a fiberglass bumper can probably be repaired immediately for a labor cost of $150.00. In most cases, unless the damage is very severe, this means a savings of $400.00 to repair a fiberglass front bumper rather than replacing a urethane bumper.
Last edited by Mister Peebody; Mar 9, 2009 at 04:17 PM. Reason: additional info
Le Mans Master
Joined: Nov 2005
Posts: 6,993
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There are ways to repair Urethane today. You can get replacement front/rear fascias all day for $200 at swap meets or the Internet. Last one I bought (front) was $200 WITH all the lights and ducts in it. It was even the correct color.
Instructor
Joined: Mar 2008
Posts: 120
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From: Scottsdale AZ
Depending on the quality of the fiberglass... Fiberglass can be harder than sheet metal, I've seen a case of a fiberglass bumper on a car that hit a coyote and the only damage to the bumper was pretty much the paint job and some spiderweb cracks, but it was easily fixed, where urethane bends and stretches and its a PITA to fix.
Burning Brakes
Joined: Oct 2007
Posts: 813
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From: N E area of state Kansas
Glass can also be molded in two not show seams. I have that done on my C3. There is also a truflex material which has some resin mixed in the fiberglass to make it more flexible. It will not be as flexible as urethane though. I vote for fiberglass.
I also think over time urethane warps a bit. Wavy bumpers on the C3. And, it can be seen with how C5s get that dimple in the urethane on the side where it connects to the glass. You won't have that with fiberglass.
I also think over time urethane warps a bit. Wavy bumpers on the C3. And, it can be seen with how C5s get that dimple in the urethane on the side where it connects to the glass. You won't have that with fiberglass.
Race Director
Joined: Feb 2008
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From: Maker of Sharp Objects, AL - Roll Tide
St. Jude Donor '10-'11-'12-'13-'14-'15-'16-'17
St. Jude Knife Maker
Having experience in working with the two of them, I would much rather work with glass any day. Urethane/plastic parts have their advantages, but as stated before- they are a nightmare to fix. Glass is rigid and it doesn't move much. when you perform bodywork on it, the fillers and top coats have a stable foundation.
Plastic on the other hand is against anything being applied to it whether it be fillers, paint, repair materials..As with any body/paint process, your prep needs to be spot on. If it isn't, plastic is the most unforgiving. You can take that to the bank
Also, most modern day paints have enough flexibility to be applied to plastic. The manufacturers know that there are more and more cars rolling off the line with plastic parts. In addition the painter also has the option of adding a flex agent if he/she deems necessary.
Plastic on the other hand is against anything being applied to it whether it be fillers, paint, repair materials..As with any body/paint process, your prep needs to be spot on. If it isn't, plastic is the most unforgiving. You can take that to the bank
Also, most modern day paints have enough flexibility to be applied to plastic. The manufacturers know that there are more and more cars rolling off the line with plastic parts. In addition the painter also has the option of adding a flex agent if he/she deems necessary.
