Fiberglass parts for a daily driver?

[JHanson]

Hello all,

As with (I suspect) most 911 SC owners, I'd like to enhance the performance of the car as much as possible without altering its basic reliability and durability - or the 25 mpg I've been enjoying on the highway.

One obvious route is through weight reduction. So I'm considering such things as a Getty Design fiberglass engine lid, trunk lid, and perhaps their 'Yellow Bird' front and rear bumpers.

What I'd like to know is, how do fiberglass components - especially such often-manipulated things as engine and trunk lids - hold up under everyday use? I live five miles down a dirt road, which would exacerbate any weaknesses. Would carbon fiber be better (or worse) in that regard? (I lack the funds for one of those lovely aluminum engine lids.)

Thanks for any real-world experience.

[chris 964]

TVR, Lotus, Renault, Aston Martin all use glass fibre panels. I have front and rear IROC bumpers on mine, all you have to look out for is klunking into thing, kerbs etc... steel/alloy will bend GF just snaps.

[Flieger]

It all depends on the quality of the composite panel. Carbon fiber is stiffer but it all depends on the resin whether it can flex. The gel coat will crack no matter what with the flexing and impact from small stones. Carbon fiber is more likely to be done to a higher standard but you can get fiberglass cheaper from those same CF manufacturers and expect similar quality.

Generally, though, you get what you pay for.

I think hood, lid, and maybe bumpers should hold up fine.

Say no to fenders, doors, or roofs.

[JHanson]

Thanks to both of you. Definitely not risking composite doors, fenders, or roof panel. I think I'll start with the hood and engine lid and see how it goes, then decide on bumpers. And I'll save my originals.

[IROC]

I've had GT Racing fiberglass front/rear bumpers and a fiberglass tail on my street driven car since 1997 and they still look great.

[faverymi]

Corvettes are fiberglass, they look pretty good as far as durability.

I had an old sand buggy, looked ugly, never cracked.

[JHanson]

Mike, thanks for the real-world experience. That's encouraging.

[Roby466]

I have a carbon fibre hood. It's ok but I used to have a hood protective cover for my other car (from our host) so I could put stuff in the trunk and don't worry about it denting the hood when I hit a bump, it won't attach to a CF or FG hood. Also, the light does not have the appropriate holes to be installed (I will drill a new hole to fit my light in, so that's not a big problem)
The main issue is that the hood shocks are WAY too powerful for a CF or FG hood. I tried my old and worn out shocks (that could not hold my SC’s metal hood up) on and they would bend the hood when I tried to close it. I am going for an "ultimate hood strut" from our host. Not as practical as hood shocks but it will do… CF hood is a bittersweet, not sure if I would not prefer the original metal hood but the car came with it.
It is a definite weight reduction though. So excellent for a race car.

[Nathans_Dad]

As an aside to this thread, what decrease (if any) in crash safety is there with a fiberglass bumper vs a steel one? If you leave the bumper shocks in place on a backdate does that make any difference in the protection afforded?

[spuggy]

Originally Posted by Nathans_Dad

As an aside to this thread, what decrease (if any) in crash safety is there with a fiberglass bumper vs a steel one?

If you're going to hit something hard enough that we're talking survivability, I really doubt it'll make any difference at all, as the impact bumpers were purely for cheap repair after low-speed collisions.

I don't think there's any significant difference in a 50MPH crash between an impact bumper car, an impact bumper car with fibreglass bumper caps and an early fixed-bumper car. The car will get bent.

I daily drive with fiberglass caps. I wanted to re-fit impact bumpers - at least at the rear. After looking at the ride height and the bumper height on the majority of folks that would be hitting me - there's simply no point.

If you leave the bumper shocks in place on a backdate does that make any difference in the protection afforded?

Nope, they'll just push straight through the F/G. And a Nerf bar under the caps is for your benefit, not crash protection. There may be some window where you'll trash the caps but the Nerf can put the force into the chassis via the bumper shock mounts and save the panels that would otherwise get crunched - but it's probably pretty small.

[RWebb]

put Euro crush tubes in to save wt. but still retain 'crushability' - you have to replace after each accident is the downside

my FG parts are doing fine after a few years on them

to save wt. you want to remove the heater blower and other heavy stuff in the rear; firewall sound deadener, etc.

[JHanson]

Thanks, fellows.

I agree about the fiberglass bumpers probably not being much of a downside in anything but a low-speed collision. My biggest worry is this: Supposing someone rear-ends me after I install fiberglass bumpers in place of the federally mandated impact bumpers, and the collision results in a very expensive repair - and then the offender's insurance company discovers that I deliberately compromised the standard crash protection. I'll bet a lawyer could make a case that the insurance company's liability is void, or at the very least limited.

It's something to consider, although I don't run my life worrying about every such possible scenario. Otherwise I'd drive a Volvo.

[RarlyL8]

Supposing someone rear-ends me after I install fiberglass bumpers in place of the federally mandated impact bumpers, and the collision results in a very expensive repair - and then the offender's insurance company discovers that I deliberately compromised the standard crash protection.

That is a good point and drive's home that you must be willing to take the risk.
My car has F/G front and rear bumpers with zero protection underneath. Been driving 10 years that way.
I treat this car like it is a motorcycle. There is no safety in the front or rear.

[Flieger]

My car is all fiberglass and I just drove about 25 miles to the mechanic with no door bars since I removed them for easier access to the wiring I want tidied-up.

[davidbir]

Originally Posted by Flieger

My car is all fiberglass and I just drove about 25 miles to the mechanic with no door bars since I removed them for easier access to the wiring I want tidied-up.

Flieger: If that bothers you don't even go NEAR a Lotus Elan

[Flieger]

I thought about it once at an intersection, but it does not worry me. I will have the cage back together again soon, for when I do my spirited driving.

[JHanson]

Since I also ride a 1970 Triumph Trophy, even a Lotus Elan would feel like a tank.

[Flieger]

Originally Posted by JHanson

Since I also ride a 1970 Triumph Trophy, even a Lotus Elan would feel like a tank.

Maybe that's it. I ride a bicycle on canyon roads with the fast motos and cars on weekends flying by. I can get some of the bikes on the downhill (especially those Hardley Ablesons, when they are not blocking- which they are always doing). After that, the 911 feels really secure.

[jasonlee]

I have front and era ruff style bumpers on my SC, from TRE. Quality pieces and have held up very well. No protection behind them. Just very aware of whats in front and behind me. Like it was said above, drive like a motorcycle, with not protection front or rear