iroc bumpers

[flipper]

Does anybody have pics of a narrow body car with iroc bumpers? And where is a good place to find those bumpers?

[TRE Cup]

here is what we offer
we also make one for 74-77 "narrow" stock rear fenders

[hkspwrsche]

As long as we're on the subject.. what holds these up? I've been concerned about crash protection...
thanks

[Schuey]

I purchased mine in a group buy (see ultimate RUF thread) from BWMotorsports...they're still in the packaging, etc. I was going to do my 911SC, but I decided I was going to buy a C4 and kept it stock in case a potential buyer wanted an original example...PM or e-mail me if your interested...they are very high quality...

Kevin

[Formerly Steve Wilkinson]

Also take a look at Getty Design's, on their website. I bought mine from them--IROC front "bumper," RS rear--and the fit was perfect on both ends of the car, which I understand is rare. (Many companies make what they refer to as "race-quality" f/g bumpers, which is their way of saying, "Hey, these aren't intended for concours cars, soi you might have to do a little fitting.")

As for what holds them up...nothing that would give you any more crash protection than sticking your sneakered feet out the front or rear of the car. They are not, and never were, intended to be bumpers. They are aerodynamic parts designed for racecars. They are secured to the car pretty much by one's own ingenuity, using small nuts and bolts and even sheetmetal screws. The stock-bumper rams and brackets are intended to be removed from the car and have nothing to do with holding on f/g parts.

STephan

[NoLift911]

Originally posted by Formerly Steve Wilkinson
Also take a look at Getty Design's, on their website. I bought mine from them--IROC front "bumper," RS rear--and the fit was perfect on both ends of the car, which I understand is rare. (Many companies make what they refer to as "race-quality" f/g bumpers, which is their way of saying, "Hey, these aren't intended for concours cars, soi you might have to do a little fitting.")

As for what holds them up...nothing that would give you any more crash protection than sticking your sneakered feet out the front or rear of the car. They are not, and never were, intended to be bumpers. They are aerodynamic parts designed for racecars. They are secured to the car pretty much by one's own ingenuity, using small nuts and bolts and even sheetmetal screws. The stock-bumper rams and brackets are intended to be removed from the car and have nothing to do with holding on f/g parts.

STephan

Agree with Stephan on the crash protection. Funny thing is looking at these photos they look exactly like the bumpers on my car after the stock bumpers were modded - all rubber removed front and rear (no... not the accordians). Once everything is welded shut, filled and bodywork is done they are smooth and look great. FG fits like ass - looks it after a short period of time and is not a substantial weight savings over stock once all of the rubber bits are removed, euro crush tubes and a club sport front valence with no fogs, headlamp washer nonsense removed.

From the front and rear they look like IROC FG bumpers - from the sides it looks like a stock Carrera with accordians. I went back and forth on this for awhile - and after being in a rear ender that totalled my SUV - my health and life is more valuable than the FG bumpers. Just not worth it.

If you want crash protection FG is not the way to go on the street - on the track sure.

-Jeff

[Elombard]

Do a search for screen name "iroc" his look beautiful. Also the thread on Orange cars has his.

[mmastro]

Originally posted by Formerly Steve Wilkinson

They are secured to the car pretty much by one's own ingenuity, using small nuts and bolts and even sheetmetal screws. The stock-bumper rams and brackets are intended to be removed from the car and have nothing to do with holding on f/g parts.

STephan

I have an RSR front bumper (reported to be a GT Racing unit) and it had steel plates w/ bolts integrated for intallation on the stock crush tubes. Now, I did have to modify a second plate as well as my crush tube to install but it wasn't that bad.

I didn't know that not all of them were fitted w/ this setup.

[dd74]

Originally posted by nolift911
FG ... is not a substantial weight savings over stock once all of the rubber bits are removed, euro crush tubes...and a club sport front valence with no fogs...

-Jeff

Jeff - is there anyway to verify the weight difference between what your modifications accomplished and the f/g bumpers.

What's a club sport front valence? Have any photos?

[NoLift911]

Originally posted by dd74
Jeff - is there anyway to verify the weight difference between what your modifications accomplished and the f/g bumpers.

What's a club sport front valence? Have any photos?

Verification...photos...of course not

My car is having the glass installed today so pics forth coming. The CS front valence is just a valence with no fogs - I do have a photo of that before it was installed.

I do know that the box of crap I picked up from the parts that were taken off was substantial - all that rubber crap adds up and you save about 12lbs for the euro shock mounts alone see this:

Euro crush tube weight vs US

CS pics: (I had the front plate holes filled in on mine)

[Formerly Steve Wilkinson]

My rubberless stock aluminum front bumper "blade" alone tangibly weighs a lot more than the entire Getty Design IROC air dam, just judging by holding the bumper in one hand and the Getty piece in the other--dunno what the numbers are. And the single-piecd Getty air dam replaces not only that bumper "blade" but the rubber bellows, the entire valence, the rubber spoiler lip, the two heavy bumper rams and attendant brackets, the rubber trim strip, the bumper "smile" and two of the four front lighting units.

Stephan

[911teo]

I bought FG bumpers from TRE and I am very pleased with the results.

To mount the front bumper we retained the 2 stock struts. Crash protection is not one of FG bumpers forte... but they are not just held in place by little nuts as someone wants to imply.

For the rear bumper the struts were omitted (so this is LESS safe).

When you are talking about safety in a crash there are different variables.

One of the most important aspects is the energy that is absorbed by the vehicle. With FG bumpers we are replacing an alluminium structure with a FG one. I am not in a position to calculate the different properties of FG and Al in absorbing kinetic energy. All I know is that what is not done by the bumper has to be done by the vehicle's other crumple zones.

It is important to reduce the kinetic energy that is transferred to the body. The body will stop in a crash. And the energy must be dissipated before the body comes to a rest.

KE=0.5mv^2

So you want something that breakes, deforms, sacrifice itself in an impact. You want to keep v (velocity) as low as you can (KE is a function of the square of v).

In a crash the v sustained by the body increases at an increasing rate (up to a point). Seatbelts, airbags etc help reduce the KE (by reducing the V) that has not been absorbed by the car's crumple zonesa.

Hitting a wall in a tank could actually be more dangerous than in a 911 with fg bumpers.

But since KE-0.5mv^2 the distance is also important in defining the kinetic energy (not as much as Velocity though).

So in the example of the wall the tank and the fb 911 have no escape, they both have to stop against the wall...

But now imagine the tank hitting the 911... As the tank is less flexible it will "walk over" the 911.
In this case the tank will have more room/distance to dissipate the KE.

What am I getting at with all my ramblings? I am just saying that it is difficult to generalize. The bumpers that were put on these cars in 1974 were the result of a change in the law, not a safety decision made by PAG.
Yes it looks like Al should absorb a little more energy than fb... but that's about it. The rubber was there for the pedestrians and the struts are still there in most street applications (at least on the front).

Please flame me if I am wrong. I'd love to understand this better.

[Formerly Steve Wilkinson]

If you're saying you achieved any level of safety by affixing your f/g bumper to the stock rams, that's ludicrous. You might just as well bolt a piece of quarter-inch plywood to the rams, for all the good they'll do it.

I "implied"--said outright, actually--that the real fiberglass bumpers are held in place by "nuts and bolts" because that's what those of us do who are using the bumpers for the situation for which they are designed, which is as aerodynamic fairings for track use.

Yes, I drive my car on the street too, but I do so knowing full well that I have no energy absorbtion in the bumpers and that the only way to achieve such energy absorbtion would be to replace the rams and attach a stout, U-shaped structural extrusion of aluminum to them.

To say that attaching a piece of fiberglass to the rams will help you even though I could kick through that structure with sneakers on makes no sense. Your formulas are cute, but here's another formula: EAoF [energy absorption of fiberglass] = IFoaTB [impact force of a tennis ball].

Stephan

[ipapilot]

That's funny Stephan.

[Moses]

My fiberglass bumpers have held up well to the forces of high speed collisions with large insects.

[911teo]

Stephan
I guess we are saying the same thing. There is no need to get so worked up.
The only difference is in the capacity of alluminium to absorb kinetic energy vs fiberglass.

Maybe I am not using "real" fg bumpers and I will complain about that with TRE ...

[Formerly Steve Wilkinson]

Uh, didn't you say, "Please flame me if I am wrong"?

We're not saying the same thing at all. You're saying you are depending on a piece of thin, lightweight fiberglass to "absorb energy." I'm saying it won't absorb any more energy that the well-placed kick of a foot, and it certainly won't hold together long enough to communicate a single erg or dyne or whatever of that energy to the bumper rams.

The capacity of an extruded, carefully structurally shaped, half-inch-thick piece of aluminum to absorb kinetic energy versus that of a purely aerodynamically shaped piece of fiberglass less than half that thickness is probably equivalent to something like the strength of a toothpick versus that of a 16-penny nail.

I spend two 12-hour shifts every week as an EMS volunteer in our small town's ambulance corps. You wouldn't believe what I see when we get called to an MVA (motor-vehicle accident), particularly on the New York Thruway.

I want you to stop thinking, for your own sake, that you're doing yourself the slightest good by assuming fiberglass will absorb any more energy than a large pillow tied to your bumper.

Yeah, I'm worked up, but at least in part for your sake.

Stephan

[911teo]

I am saying the difference between stock and fiberglass is the different capacity ot the materials to absorb kinetic energy.
And that is only a small piece of the puzzle.
Is alluminum better than fiberglass? Yes. How much? I dont know and it looks like neither do you.

And please refrain from those patronizing comments... they are out of contest.

[Formerly Steve Wilkinson]

I quit, you win. Even though my remarks are out of "contest" and you can't spell aluminum.

Chow,
Stephan

[911teo]

uh sorry... U cant spell CIAO though... ahaha