How to save 15 lbs for $60

[captainjman]

All kidding aside, seems like you did an excellent job. I know nothing about insurance and mods.. but obviously you are pretty good at fabricating parts for your car. Good job!!

 

[Cozmo]

slebidia you had me until you said "tap". I've never even thought about doing that before. :biggrin: I guess I've never worked with metal. I'll leave this to the more adventurous people.

Thanks for chiming in with more info Ross. That's something I would never expect a vendor here to do. Most of the time they try to protect their interests or keep things to themselves but you said "hey if you want to try this, here's what we've learned" which is awesome.

 

[e.pie]

hey nice exhaust :tongue:

 

[Black 94 #400]

slebidia you had me until you said "tap". I've never even thought about doing that before. :biggrin: I guess I've never worked with metal. I'll leave this to the more adventurous people.

Thanks for chiming in with more info Ross. That's something I would never expect a vendor here to do. Most of the time they try to protect their interests or keep things to themselves but you said "hey if you want to try this, here's what we've learned" which is awesome.

What He Said + 1 About Are Vendor Here :wink:

 

[MvM]

Excellent write-up and good idea too :smile:

Have been thinking about doing this mod for a looong time.

I actually crashed my previous NSX backward at the track.
My car had the steel rear bumper beam and I crashed so hard that the whole beam was pushed inwards into the trunk, turning the trunk bottom into a piece of wrinkled aluminum and at the same time bending the rear chassis beams (but luckily not beyond the monocoque).

I got the car fixed (at a high price) but I COULD REUSE THE OLD BUMPER BEAM !!

The beam itself was only slightly bent in one corner which could easily be fixed some (heavy) hammering. Two of the mounting holes where a bit enlarged but that was about the extend of the damage to the beam itself.

 

[RYU]

I'm doing some exhaust and diffuser work so I decided to do this mod while I had everything apart. It's pretty amazing how much weight is saved and, as Billy said, it's past the rear axle so it matters even more.

It was an easy project mechanically speaking but all the precise measuring almost drove me nuts. Afterall, if you don't get the mounting holes aligned properly you will have a misaligned bumper cover or simply a bumper that won't properly mount to the car. Either would annoy me to no end.

I made a slight modification in that the license plate bracket on mine sits a bit higher by 1/2" because I haven't decided on a diffuser design yet and didn't want the license plate to sit so far down (I hate that about the USDM plates). I also do not have access to a tig so I bolted this bracket to the beam by tapping M6 holes. As an aside, I tested how much torque would be required to strip out those threads... I went up to 45 ft/lbs and the thread still held. Pretty neat. I did also use loctite on the bolts just in case.

I suggest this mod to anyone who's into DIY projects but buy the STMPO piece if you haven't got the patience.

The pic below is before I drilled the access holes for the styrofoam.

 

[StmpoRaceProducts]

I'm doing some exhaust and diffuser work so I decided to do this mod while I had everything apart. It's pretty amazing how much weight is saved and, as Billy said, it's past the rear axle so it matters even more.

It was an easy project mechanically speaking but all the precise measuring almost drove me nuts. Afterall, if you don't get the mounting holes aligned properly you will have a misaligned bumper cover or simply a bumper that won't properly mount to the car. Either would annoy me to no end.

I made a slight modification in that the license plate bracket on mine sits a bit higher by 1/2" because I haven't decided on a diffuser design yet and didn't want the license plate to sit so far down (I hate that about the USDM plates). I also do not have access to a tig so I bolted this bracket to the beam by tapping M6 holes. As an aside, I tested how much torque would be required to strip out those threads... I went up to 45 ft/lbs and the thread still held. Pretty neat. I did also use loctite on the bolts just in case.

I suggest this mod to anyone who's into DIY projects but buy the STMPO piece if you haven't got the patience.

The pic below is before I drilled the access holes for the styrofoam.

nice job... and yes... the measuring is a pita… the 3x3 beam is not a perfect match to the stock beam… imagine making a jig…lol

FYI - If you tapped the beam for the bumper mounts like the plate holder... sandwich a washer on each side and increase the torque of the bolt.

45 lbs will hold any license plate... but if anything hits you... you'll be lucky it weighs 45 lbs

 

[sparky]

..however the money you save by doing this will cost you much much more if you ever get rear ended. Since the insurance will probably find out you tampered with a safety device and they could claim that there could have been less damage than really occurred. STMPO sells a similar device and I certainly hope that all the guys running those on the street aren't planning on committing insurance fraud if they ever get in an accident.

I would put a disclaimer saying "off road use only" or some such thing at the beggining of your post.

what a load of over-dramatised *&*&% ...

 

[slebidia]

I'm glad to see other people are taking on this project.

 

[whitebois]

I am doing this this winter. I think if you fill the bar with crazy stuff insulation which expands it will add signicant strength to the bar. If its enough to make a difference in a wreck i am unsure.
Also when its apart i plan to rig up a hidden hitch like they have for porsches.

 

[StmpoRaceProducts]

I am doing this this winter. I think if you fill the bar with crazy stuff insulation which expands it will add signicant strength to the bar. If its enough to make a difference in a wreck i am unsure.
Also when its apart i plan to rig up a hidden hitch like they have for porsches.

I would not recommend towing anything from this part based on how the bumper beam is attached to the chassis..

You will ruin your car..

If a tow hitch is important... take you car to a fabricator that understands the nsx frame design and strength build something other than a bumper beam with multiple mounting locations along the frame with tons of triangulation.

 

[nsxotic911]

I am not phyiscist.. but I am not convinced on this whiole safety thing for the bumper beams when you get in an accident over 60 MPH or anythign over 5 mph for that matter. Bumper beams are there for 5 mph accidents to limit damage to the frame rail and mitigate insurance repair costs. They slow down the energy marginally while the frame absorbing overhwelmingly the majority of the energy in any sort of higher speed collision. It doesn't take much force to bang up the beam with a hamer and reduce it's "effectiveness." Placing a thin sheet of metal (relatively) around a bowling ball isn't going to do much to limit the energy when you drop it. At 60 MPH, I don't see them having more than a 5 mph difference, if that.
BESIDES, INSURANCES OFTEN WON'T EVEN PAY TO REPLACE THE BUMPER BEAM IN AN ACCIDENT when it's banged up but not torn apart and still stays on. If what some are saying that it provides significant safety measures, if that's not a "safety violation" I don't know what is.

As to insurance not covering the costs - insurance's responsibility is to bring the car back to it's "origional condition" (bleah) - and unless you're the origional owner of the car, I assume you're not looking underneath the bumper to inventory every little part that's there. Besides.. do you really want your car back after it's been in an accident..? Maybe for parts..

Most importantly, I have found ZERO literature that provides any sort of testable or scientific claim that it reduces injury to occupants. Here's a quote from Volvo's site (see below for reference)

"The components of the rear part of the car are highly integrated, making repairs very expensive. Therefore, both customers and insurance companies require that the damage of a low speed crash should be limited to a few components which are easy to replace. In order to minimize the damage to the car body, the rear bumper beam must be designed to absorb all the energy from a crash. Due to the complexity and cost of repairs, the optimization of the bumper system becomes a very important and challenging topic."

Here are some hopscotch references to back up my scientific claim. Notice at best vague references reference to improved safety of occupants.

http://wardsautoworld.com/ar/auto_bumper_battlegroundautomakers_insurers/
http://www.shapecorp.com/diversity/bumper-beams/
http://www.rcar.org/Papers/Procedures/BumperTestProcedure.pdf
http://www.landmarkford.com/press-r...ty-repair-costs-of-aftermarket-copy-parts.htm
http://www.dynamore.de/de/fortbildu.../advanced-simulation-techniques-for-low-speed
http://www.enginsoft.com/applications/automotive/volvocar.html

 

[whitebois]

I will have to try to understand this trailer issue. I am talking a very light trailer to haul wheels to the track. The porsche folks have been doing this for years. I have been on the of their sites showing diy for bumper hitches and the beam looks similar to the one on the nsx. On the other hand, i do not want to damage anything or see anyone get hurt...
Thanks

 

[StmpoRaceProducts]

I will have to try to understand this trailer issue. I am talking a very light trailer to haul wheels to the track. The porsche folks have been doing this for years. I have been on the of their sites showing diy for bumper hitches and the beam looks similar to the one on the nsx. On the other hand, i do not want to damage anything or see anyone get hurt...
Thanks

Porsches aren’t made of aluminum.. The motor is in the rear (typically) and so is all the structural integrity of the car.

I understand what your trying to do and I’m trying to help.. not say it’s a bad idea. It’s unattractive in every way…

But to explain…

The only mount this bumper has to the chassis is with the 2 brackets shown in this pic (#3 and #4)

Those brackets bolt up to #26 on this pic.. the brackets have studs on them… attacked via 14mm nuts… all nuts sandwiched between aluminum sheet metal

You want to make something that connects to this piece #1 in the pic

using this mounting location (steel rear tie downs)

personally.. I would leave the brackets bolted on there and weld directly to them.. they are made of steel... yes the word steel has been used yet again when referring to the nsx.

I would also make something that also attaches to the rear bumper beam.. and I would keep the steel bumper beam too... just remove the entire assembly at the track..

But reality for me would be… unless your rocking hoosier r6’s or r4’s… just drive your car to the track with r-compounds mounted to the car… they don’t wear that fast if you don’t get them hot and it’s just unattractive in every way

Thats just me.

 

[whitebois]

Hey no insult taken at all, really. I dont want something f'ugly for sure, that is why i checked out the porsche hidden style behind the bumper. But you know, when i was looking at a cayman diy it looked like the bumper was an AL beam with two attachment points. On the NSX those points attach to flimsy aluminum sheet vs porsche they may connect to strutural steel.. That explains why no one has an nsx track trailer! Either that, or the porsche trailers are unsafe!
Thanks

 

[BATMANs]

A few more safety items I've removed.

LOL :biggrin:

 

[whitebois]

just finished 02+ lower rear valence and replace steel bumper beam. Mine (91) weighed 38 lb when I had it out of the car with all the brackets and bolts taken off of it. The Stimpo beam weighs 8 1/2 lb so that would be roughly a 30 lb savings. This was not a hard job. Just have to go slowly and do things right. I bought a used drill press off Craigs list which was a great help in drilling straight holes and in boring a large diameter hole in the square aluminum to help with accessing nuts inside the bar.

 

[sparky]

Go to Metalsupermarkets. Pick up one section of 3 inch square tubing .120 wall thickness 56 inches long.

well I did that and 56 inches is OK, but now I've done it I'd recommend 62". This would ensure the bar spans the whole styrofoam length. See image attached for visual explanation

 

[whitebois]

2nd that- i was wondering why is looked a bit short.

 

[RYU]

well I did that and 56 inches is OK, but now I've done it I'd recommend 62". This would ensure the bar spans the whole styrofoam length. See image attached for visual explanation

2nd that- i was wondering why is looked a bit short.

Longer than 56 is ok if you trim the square bar to accommodate the curvature of the foam. Alternatively, you can shave down the foam. I looked into making it longer too but I didn't want to do either of the above.

 

[redbird92]

Hey
Ross
Did you ever get your Straight and get these made ????

Still waiting

 

[StmpoRaceProducts]

Hey
Ross
Did you ever get your Straight and get these made ????

Still waiting

I have the jig finished and completed the move. If you would like a bumper.. just pm me or email ..lol.. or call and dont pay till its ready to ship

It could go out this week.

Regards

 

[whitebois]

Funny the new NSXDRIVER has a diy on a track day trailer and its done just the way Ross advised not to do it! After having my bumper off i will not attach a trailer after seeing how the car is put together back there.

 

[Meeyatch1]

Anyone who removed your steel OEM rear bumper beam....I need one, and was curious if any of you would be willing to sell me your OEM steel beam?