Rear Bumper Concept Explored w/Sketch

[kach22i]

I've grown to admire the many variations and innovations applied to the Porsche 911. Don't get me wrong I love a stock car, have one myself.......but things change.

To be sure not all changes are as successful as others, but somebody's gotta lead the way and take a chance once in a while, right?

Below are some bumpers I like, the one thing I see is that the middle recess limits how much the rear bumper can be tucked-in without looking like the reflector is prone to shopping carts and the like.

Porsche Photos by kach22i | Photobucket


The 964 featured below and the Gt-Racing fiberglass bumper have the top lip which would allow for a more even and consistent pushing in of the bumper (for less moment force and aesthetics)



Below are some quick sketches/studies, looking seriously at the "Alt-2 scheme. I think some ventilation and license plate lighting could be worked in too.



My list of "things to do" on my car is pretty long, just day dreaming at the moment.

This is what the car looks like now.



Below is what altering the bumpers could look like, other threads show actual photos and not faked photos.



I currently have a black replacement hood on a silver car, looks cool so I'm keeping it that way.

My opinion regarding painting the bumpers black to match the accordion bellows and rubber bumper trim is simple, black mid-year cars look awesome - I think it's partly because they are monolithic and avoid the hodgepodge look of contrasting accents.

Question is; has this rear upper bumper lip modification been done before on an stock/original aluminum bumper. And if so where and when................... a link and or picture would be appreciated.

[Chuck.H]

I have about a 1" tuck on my '89 -- I like the look a lot. I took off my stock bumper, removed all the rubber pieces, and made a fiberglass mold from it. From this mold I made a carbon fiber bumper and when I mounted it I tucked it in one inch. It was easy to tuck, I just drilled the bellows bolt holes farther up the bumper, along with new lightweight mounting (removed the 5mph bumper shocks). Sorry I don't have a better pic, but maybe you can zoom in on this one to see. It's painted with plasti-dip.



Chuck.H
'89 TurboLookTarga, 375k miles

[kach22i]

Originally Posted by Chuck.H

I have about a 1" tuck on my '89 -- I like the look a lot.

Yea, it looks good from here, and this is my first black bumper image without resorting to a computer program or colored markers.

One thing this image brings up is the license plate placement.

With the original bumperettes and rubber trim it's hardly noticeable that the plate doesn't quite fit the framed space and protrudes at the top and bottom.

Once all cleaned up (minus trim) plus with the rear bumper pushed back an inch the license plate begins to interfere visually.

I'm pretty sure that on a lowered car allowing the bottom edge of the plate to drop down another 1/2 inch or more could result in some scraping on drives and inclines, although I have no reports to quote in which to support this fear.

On the off-center license plate installations I can recall, the plates were mounted pretty low, I'm not aware of any issues though..............just making some observations and perhaps some conjecture.

Chuck, I don't see any lighting bolts or bumps for lighting the plate. I have found some nice aluminum frames with built-in lighting and even built-in rear brake lights. I'll post them should I find them again.

EDIT: Not the one I had in mind, but not bad at all.
Cheap, Easy, Lightweight Duck tail license plate lights!

Originally Posted by tdatk

I used these liteNboltz that are led and metal. YMMV
http://www.truckaddons.com/Catalog/subpages/DEI_lightnbolts.htm

I could not find my bookmark, so I just Googled it and found something very similar - same price too.


Billet Specialties 55220 - Billet Specialties License Plate Frames
http://www.jegs.com/i/Billet-Specialties/135/55220/10002/-1

Billet Specialties#135-55220
Billet License Plate Frame
Plain recessed with light

[kach22i]

An example of a nice bare bumper, very clean looking. This car can be found in the forum, my complements to the owner.



A relatively minor modification to start with.



Now to lighten it up with open grille work, perhaps strengthening the top and bottom flanges will lessen the effects of such an open web.

Porsche Custom Photos by kach22i | Photobucket



The beautiful blue car below has been posted in the forum before, and with the bumperetts removed clearly shows the naked form of the rear bumper.

Porsche Custom Photos by kach22i | Photobucket


A few holes to lighten and to help ease the rear bumper from acting like a parachute is a direct but perhaps not very sophisticated approach.

Porsche Custom Photos by kach22i | Photobucket


The red car below puzzles me, it doesn't appear to feature the indented middle part. Is it just the angle which gives this impression, or perhaps it's an aftermarket fiberglass rear bumper? Why would anyone put rubber trim on a fiberglass bumper? It's got to be stock aluminum.

Porsche Custom Photos by kach22i | Photobucket


EDIT
I found a real one with holes.

Post your Ducktail Pics!!

Originally Posted by juicersr

[NoLift911]

Thanks for the compliment - I stumbled on this thread and saw my car in it (nolift)...my bumper has been milled on the inside for lightness so it is a few lbs. lighter than the standard blade even after you remove the bumperettes and rub strips, and I installed the euro crush tubes which are good for about an 8lb savings.

I like your sketches - one thing I thought about doing with mine is adding the RUF slots (aka yellowbird) on the corners and then add mesh screen behind. Never thought about anything for the front.

[DG624]

I have thought about a revision but it is hard to improve on the factory bumper...the bumper guards look bad but the basic shape of the car is good. A fellow Pelican poster had a revised rear bumper guard that was smaller but fit the factory bolt holes (SI banker is his user name).

The rear bumper holes may be more relevant since they reduce drag. How much would the holes improve rear stability and reduce drag?

[kach22i]

One thing I've pondered is the affect the cooling air draw (intake suck) has on air flow over the vehicle, plus I ponder the affect of exiting air at the bottom which may disturb the flow under the car.

Does the bumper and rear valance truly get an opportunity to act as a parachute under these conditions?

I think that at lower speeds the flow under the car would be over powered, and perhaps even bounce upward.

However at higher speed the flow under the car would be swept up the discharge air in a horizontal manner (right?).

It is at higher speeds where rear bumper holes may make a difference.

Also at lower speeds perhaps the holes would act as intake draw supplies for the cooling fan.

Again I must state that I have not found wind tunnel testing stills or video which support these theories.

I have seen several track cars (race cars) which remove (and or slot/perforate) the rear valance and bumper.

Removing weight off the aft are cause enough for these ventures/experiments to merit our attention.

[Unobtanium-inc]

Forgive me for saying this, but based on almost all of the photos posted here, this thread should be renamed the "Ugliest Bumper Mods Thread." Seriously, almost all of the ideas here, both conceptual and executed, look pretty bad to me. The RUF rear bumper is an attractive mod with good design, and will be lighter than any of the modified factory bumpers. For less money, a factory european bumper looks great, too. - Matt

[kach22i]

Originally Posted by Unobtanium-inc

"Ugliest Bumper Mods Thread.".......The RUF rear bumper is an attractive mod....

The goal is not so much to make the bumper beautiful, but to allow one to tuck in or push back the bumper (about 2-inches) without the license plate kissing the reflector, or a shopping cart denting your engine lid.

The RUF rear bumper which I think is in one of my composite sheets is indeed a nice design, but I'm pretty sure it is made of fiberglass and offers no real protection on a street car.

The indented middle part of the bumper on the mid-year and SC's was ditched on the 964's and 993's, so the proposed modification is not out of character for a Porsche, it is just the next step.

I think the indented middle part of the rear bumper was intended to protect the license plate, with the European plates being very long. However with the addition of bumperrets (Euro and US) it seems the indent is rather redundant.

Perhaps the addition of bumperrets was an afterthought?

Maybe there was a strength increase through the curves, or less mass hung out the tail by tucking the middle part in, and that was the driver on this design element.

The Germans are not known for doing expressive things for the sake of flair, there is a hard core practical reason behind the rear bumper design, and to know the reasoning behind it will answer why it is such a curiously bent noddle shape.

[Chuck.H]

Originally Posted by Unobtanium-inc

Forgive me for saying this, but based on almost all of the photos posted here, this thread should be renamed the "Ugliest Bumper Mods Thread." Seriously, almost all of the ideas here, both conceptual and executed, look pretty bad to me. The RUF rear bumper is an attractive mod with good design, and will be lighter than any of the modified factory bumpers. For less money, a factory european bumper looks great, too. - Matt

Perhaps, but the stock bumper location plus the huge rubber bumperettes look ridiculous to me. Mine's basically stock looking with all the rubber stuff removed, and tucked in a bit. As to the lights, I have the license plate bolts with the LED lights built in.

Chuck.H
'89 TurboLookTarga, 375k miles

[kach22i]

This is a very nice bumper, somehow I've forgotten about...........perhaps the one of a kind front is the reason.

turning my SC into a one of a kind

Originally Posted by rfuerst911sc

Originally Posted by rfuerst911sc

turning my SC into a one of a kind

Originally Posted by rfuerst911sc

[john walker's workshop]

one i made, in steel.

[Ronnie's.930]

The side shots of the cars with tucked-in bumpers make the thing look like it is puckering up to take a s@it (or perhaps tightening up in order to hold one in)!!!

[kach22i]

This one is very clean looking, with the plate lights looking like tiny bumperettes.

EB Porsche 911 SC RS Front Bumper in paint - Ferdinand Magazine: Daily Porsche Blog


Of course if you have something special to show off and don't mind letting it all hang out, anything goes.

http://www.superstreetonline.com/features/sstp_1302_1976_porsche_911_carrera/


EDIT:
One of the best custom or non-stock bumper threads I've been able to find, hidden in another part of the forum. See link below.

Rear bumper upgrade?


Another nice rear bumper.
http://www.classicporscheblog.com/lime-green-1974-2-7-and-1976-orange-3-0-carrera-porsche-911




Just about the coolest thing I've ever seen in the forum.

Mid Engined 911 3.3 Twin Turbo
Mid Engined 911 3.3 Twin Turbo

[rbogh901]

Originally Posted by john walker's workshop

one i made, in steel.

This is similar to what I have, maintaining the stock 911 bumper profile although mine is a bit tucked under...

[kach22i]

Originally Posted by rbogh901

This is similar to what I have, maintaining the stock 911 bumper profile although mine is a bit tucked under...

Are these two rear bumpers adaptations of early year bumpers (with middle extentions) grafted to mid-year cars?

Steel, not aluminum?

All custom then?

A link to the original thread would be appreciated rbogh901, thank you for posting.

Below are some topical images I've acquired lately (mostly off the Pelican forum, some from Rennlist), but because they are stored on my computer weeks ago I don't have links for them.

Might be a 964 in this first saved shot, not sure.


Just some random stuff of interest.










EDIT..............answered my own question about the blue car.

73 speedster

Originally Posted by john walker's workshop

.................. the rear bumper was made by fitting the center section of a front bumper to the original outer wraparounds, SC rear fender extensions were fitted to mate up with the SC flare (some reshaping needed so the bumper shape blended in properly), the lower bumper panel is 18ga sheet metal, extended down to hide the monty muffler. behind it is a stainless heat shield, wrapped in heat blanket (as well as the whole muffler and turbo), so the paint will stay on the bumper. the wrap around bumper allows the use of a rear reflector.

[kach22i]

More on that blue car by John Walker's Shop.

Ultimate Retro Speedster Thread




Original thread, images no longer show up.
73 speedster

[jakekooser]

That black car is mine [WAS RICH] and the fiberglass bumper was on the car when I bought it in November. I am not sure what it is exactly, as the car is an '86 Carrera dressed up like a 964 with a 3.8 RS wing.... well, you get the picture.

[DG624]

George, I am interested in losing weight (on the car) and reducing drag...appearance is also important. I think it is much easier to bore some holes in the bottom of the stock bumper (underneath) to release air at speed and reduce heat buildup and then eliminate the rubber bumper piece and fill the holes and incorporate a longer rubber strip and use some modified light for the rear plate.

I have not seen done but it would reduce weight and improve air flow while looking much cleaner. The bumper protection would decline but there would still be protection. Can you make a photoshop version?

[evan9eleven]

Originally Posted by john walker's workshop

one i made, in steel.

Nice work John. Do you do this kind of custom work in-house? I'm considering steel bumpers over FG and a nice custom solution would be great.