Impact Absorbers...

[Lwanmtr]

Im curious if anyone has ever made their own impact absorbers to mount on the metal bean, as opposed to paying the $600 each end for them?

Mine are pretty past it, so going to need new ones and the thought popped in my head..hehe.

[81dmc]

You really do not need to replace impact absorbers, and if the outer coating looks like crap, you can always recoat them.

[Lwanmtr]

the front crumbled....the rear is split right in the middle..a bit more than just the coating worn off

[81dmc]

the front crumbled....the rear is split right in the middle..a bit more than just the coating worn off

Damn. For the front , I'm afraid you'll have to buy either a new or used one, however, for the rear, I would just use some epoxy then recoat it.

[Lwanmtr]

What kind of epoxy? Im really new to all this restoration stuff

[81dmc]

To be honest, I really don't know what would be best...

That being said, I usually just use JB Weld for all my low-cost redneck repairs...

[Patrick C]

the front crumbled....the rear is split right in the middle..a bit more than just the coating worn off

How about some photos?

To re-coat them, use Plastidip.

http://www.homedepot.com/p/Plasti-Dip-11-oz-Black-Rubber-Coating-Spray-11203-6/100131010

[Lwanmtr]

Here's a pic. You can see the split right down the center. The left corner is kinda bent, but ok.

40181

[81dmc]

Here's a pic. You can see the split right down the center. The left corner is kinda bent, but ok.

40181

That one seems in better shape then mine. Just remove, repair, repaint, then reinstall.

[Nicholas R]

That doesn't look like a cause for replacement to me. I agree; just re-coat.

[Lwanmtr]

Ok. cool. Is there a decent filler or whatever to use to fill in the split and the other more prominent cracks just put in a lil more stability?

[Patrick C]

Ok. cool. Is there a decent filler or whatever to use to fill in the split and the other more prominent cracks just put in a lil more stability?

Probably something like this: http://www.autozone.com/sandpaper-and-body-repair-tools/body-repair-and-accessories/bondo-1-oz-epoxy-flexible-bumper-repair-compound/69590_0_0/

[Lwanmtr]

Ahh ok. I'll go check that out. Thanks

[Josh]

I used spray foam to fix some missing chunks of my impact absorbers.

[Lwanmtr]

Gonna head to lowes in a bit, Ill look for that foam, I think I know what you're talking about there..thanks.

[john 05141]

After 8 years of ownership I discovered last winter I do not have that in the from end of my car. It is just not there.
I cannot pay 600€ for that. No idea if the rear one has that too.

It cannot be so hard to make that myself with insulation foam. It only functions as a shock obsorber nothing more/

Jan

[Lwanmtr]

If I knew what material to use and how to attach it to the plate, Id think about making my own for the front.

I filled some of the big gaps in the real with foam, should be all cured tomorrow so I can spray the sealer on it.

[Rich_NYS]

If I knew what material to use and how to attach it to the plate, Id think about making my own for the front.

I filled some of the big gaps in the real with foam, should be all cured tomorrow so I can spray the sealer on it.


If I was going to make an impact absorber, I'd get measurements from an intact unit and make a form out of waxed cardboard and use two-part foam. I used this type of method when I used to work as a taxidermist. It would be very easy and cost a helluva lot less than $600.

[Rich_NYS]

If I was going to make an impact absorber, I'd get measurements from an intact unit and make a form out of waxed cardboard and use two-part foam. I used this type of method when I used to work as a taxidermist. It would be very easy and cost a helluva lot less than $600.

Here's a pretty good example:


https://www.youtube.com/watch?v=Qr84vYlKLpE

[Lwanmtr]

I dont know how to make molds or anything like that...and mine would be useless as a template...lol

You still have the issue of the plate that holds the absorber...mine is fine (a little bent, but it would be usable), but I'd think most who need new absorbers, probably have damaged plates..or none at all.

But, yeah, Im sure they could be produced for alot less than $600

[Rich_NYS]

I dont know how to make molds or anything like that...and mine would be useless as a template...lol

You still have the issue of the plate that holds the absorber...mine is fine (a little bent, but it would be usable), but I'd think most who need new absorbers, probably have damaged plates..or none at all.

But, yeah, Im sure they could be produced for alot less than $600

It's just cardboard cut to shape and taped together, after it sets you can use a rasp to further shape it. You could make a template off someone else's....could probably even get someone here to trace theirs on paper and mail it to you.

Make the damn thing and post pics! -lol

[Lwanmtr]

Yeah, if someone who had their's exposed and wanted to make tracings and measurements, I'd experiment in making one.

edit...their impact absorber exposed (figured I need to clarify that...lol)

[81dmc]

Yeah, if someone who had their's exposed and wanted to make tracings and measurements, I'd experiment in making one.

edit...their impact absorber exposed (figured I need to clarify that...lol)

I can take measurements from my car which has the fascia off. Once a rough square one is made, you can just sand to fit.

[Lwanmtr]

Cool. Just need to find out what the best foam or whatever to use that will be as close or better than what the absorbers use. Looked around last night, but since I dont know what I'm looking for I couldnt find anything..hehe.

[DMCVegas]

Here's a pretty good example:


https://www.youtube.com/watch?v=Qr84vYlKLpE

Not trying to troll, but that kind of urethane foam just seems like a terrible idea. The reason being that it isn't reusable. If it gets bumped one time, it's gonna get crushed and need replacement. That's more of a sculpting foam, rather than an impact absorbing one. Because what if you're in a parking lot, and someone hits your car and takes off. The elastomeric fascias will just pop back into place, and you wouldn't know that anything happened. But the frame and crash protection is now gone, and if you do get into any other sort of collision, you're gonna have damage.

The stock Impact Absorbers just look like huge upholstery foam from seat cushions that were molded into shape. If you're missing them or need to rebuild them, why not consider buying some high-density seat foam, cut sculpt, and trim to fit it. Then paint and seal it?

[Lwanmtr]

That was my thought too....Maybe next time i go to home depot I'll see what they got. I havent been able to see a new one, so Im not sure what the squishy-hardness ratio otta be...hehe

[DMCVegas]

Since they're really only low-speed bumpers, perhaps another choice might actually be Impaxx foam. It's the same extruded polystyrene foam that GM uses for their bumpers. And again, you could just buy blocks of it, and split and file it until it fits.

http://www.rollbarpadding.com/products/cat-14

[Rich_NYS]

I'll take a closer look at my rear unit that I have off, I'm pretty sure it's very similar to polyurethane foam.

[DMCVegas]

Polyurethane, yes, but it's a flexible type. Again, like a seat cushion. Rob Grady has even spoke about this of how it acts like a sponge where for a couple days after a wash the car will still drip water from the bumpers.

The type of foam used in that video is not a flexible type and is resistant to water (which is why the OEM impact absorbers are coated). That's an expanding foam which remains ridged, and is used in heavier densities for sculpting.

http://www.shopmaninc.com/foam.html

The polystyrene *is* an alternative if someone was up to the challenge, though admittedly taking a perfect OEM foam impact absorber and creating a mold out of it to cast more impact absorbers would probably be simpler. Especially if you were to construct a jig that suspends a bracket inside of it, below the final surface level, and you just poured the flexible, impact grade polyurethane mixture in.

But I ain't gonna lie: After the cost of the chemicals, let alone molding the pieces, $600 from DMCH seems like a reasonable price.

[Lwanmtr]

According to that site 5 cubic feet (which should make more than 1 absorber) is only $264. Unless there's something else.

If a mold were made you wouldnt need to suspend a bracket, since you'd have the parts that form the holes in the absorber to hold a bracket up, you'd only have to make sure the bracket stays put and isnt forced out of the mold.

[DMCVegas]

The site I linked to is using the solid foam that you do NOT use for impact absorbers. Look at the descriptions of the applications for each type.

This is a great example video to demonstrate what I'm talking about here:


https://www.youtube.com/watch?v=-TEYm1hxDL0

Take a look at the final two tests that deal with foam in particular. One foam is WAY too rigid, and offers zero protection to the structural frame which it is protecting. Then we have the final foam which does it's job, but consider for a moment that it is completely sacrificial. After that impact it permanently deformed and did not go back to it's original shape. That is a problem.

What we need here is a much more firm version of the seat foam.

http://www.noroads.com/delorean/projects/3281/images/201312-seat.jpg

You'd need to spend the money on acquiring a perfect specimen of an Impact Absorber, and then would have to spend more money on a mold for it. Next you need your chemicals for both the different parts of the foam mixture, but also the resistant coating to prevent it from sticking to the mold itself. That isn't going to be cheap, and I've no idea how much cheaper than just buying a replacement part. If it is cheaper, take the difference in cost between the two, and decided if that savings is worth your time.

[PJ Grady Inc.]

The site I linked to is using the solid foam that you do NOT use for impact absorbers. Look at the descriptions of the applications for each type.

This is a great example video to demonstrate what I'm talking about here:


https://www.youtube.com/watch?v=-TEYm1hxDL0

Take a look at the final two tests that deal with foam in particular. One foam is WAY too rigid, and offers zero protection to the structural frame which it is protecting. Then we have the final foam which does it's job, but consider for a moment that it is completely sacrificial. After that impact it permanently deformed and did not go back to it's original shape. That is a problem.

What we need here is a much more firm version of the seat foam.

http://www.noroads.com/delorean/projects/3281/images/201312-seat.jpg

You'd need to spend the money on acquiring a perfect specimen of an Impact Absorber, and then would have to spend more money on a mold for it. Next you need your chemicals for both the different parts of the foam mixture, but also the resistant coating to prevent it from sticking to the mold itself. That isn't going to be cheap, and I've no idea how much cheaper than just buying a replacement part. If it is cheaper, take the difference in cost between the two, and decided if that savings is worth your time.
Excellent post and a good reason for people to think hard about what they're getting into when they want to make their own parts. Especially when it's a direct safety related part if it's not correctly engineered and executed you are taking your, and possibly a passenger's, life into your own hands. There is much to consider before attempting this. BTW I have very good stock of the rear impact absorber's and can work a "deal" if anyone is interested. No can do on the fronts though as I only have a couple on hand.
Rob

[Josh]

Here are some things to think about:

-The delorean is not a specimen of engineering excellence. I do not see the need to hold OE parts to such a high regard.
-When it comes to safety, the delorean is pretty bad. Take a look at the crash test on youtube. I dont see how changing the impact absorber material slightly is going to cause any difference in a crash over dusty, 35 year old foam.
-Most modern cars have a hard styrofoam material under the bumpers, with no give to them at all.

[Lwanmtr]

Yeah, thats why I havent undertaken making the thing. Id hate to use something thats not gonna work either too hard or too soft...specially when its something thats for safety. And would definately not go back on the car until it was tested.

[DMCVegas]

Here are some things to think about:

Well, let us talk about these for a moment here...



-The delorean is not a specimen of engineering excellence. I do not see the need to hold OE parts to such a high regard.

Well, the DeLorean isn't quite as bad of a car as you think. There actually are 3 Big Reasons here to maintain the OE parts:



-When it comes to safety, the delorean is pretty bad. Take a look at the crash test on youtube. I dont see how changing the impact absorber material slightly is going to cause any difference in a crash over dusty, 35 year old foam.

Here is our first reason: Passenger Safety. Like I said before, the car isn't as bad as you think. Those videos do look pretty bad, but the telemetry data that was collected from inside of the vehicles told a much different story about how the passengers would have survived with minimal injury. This was confirmed with a records keeper who interpreted the data for me. If you want the data binder, it's on file here:

http://www.ncac.gwu.edu/ncac/

Along those lines, the safety aspect also follows as to where the bumpers help absorb impacts from more common, low-speed collisions where they offer protection to the safety systems to ensure that they are not pre-compromised and end up placing you at risk. Which we'll talk about next...



-Most modern cars have a hard styrofoam material under the bumpers, with no give to them at all.

They do, yes. And there are varying degrees of extruded polystyrene foam bumpers for impact absorption as you saw in that previous testing video I posted, along with it's results. Which brings us to reason number two, Structural Integrity. With low-speed collisions, you positively NEED impact resistant foam in place to absorb the energy so that the crumple zones are protected. Then after the small impact, the foam returns to it's original shape and is ready to go through another low-speed collision like nothing happened. If those safety systems are bent and pre-compromised as I said earlier, you risk SERIOUS injury to the passengers inside as the front impact tubes, rear crossmember, engine cradle, chassis, and even the underbody may already have been bent or cracked. Then they just pass the energy through to the passenger compartment. That would result in passengers receiving far more trauma than the factory engineers ever intended for them to, which could lead to serious injury or death.

But as you say, polystyrene which is used on common cars doesn't bend, so what's the big deal? Well, Rob Grady brought up a damn scary point that I didn't even think of at first.



Excellent post and a good reason for people to think hard about what they're getting into when they want to make their own parts. Especially when it's a direct safety related part if it's not correctly engineered and executed you are taking your, and possibly a passenger's, life into your own hands. There is much to consider before attempting this.

Notice the part that I underlined. With an OE part, any resulting bodily injury in an accident, be it normal or excessive, would be the responsibility of those people who engineered the car. If you substitute the incorrect parts, or even outright omit them, you could be in in serious trouble and run the third big risk of Legal Accountability. Accidents happen, and no one intends for them to happen. That's why they're called "Accidents" and not "On-Purposes." However, if you have an accident where you have a seriously injured passenger, or perhaps you hit a pedestrian, you have now opened yourself up to a massive risk. A good lawyer could easily piece together a case against you where your substitution or omission of proper OE parts has now shifted the blame for "excessive" injuries from the manufacturer of the car, or even sheer happenstance, over to you. Something as simple as an OE impact absorber could mean the difference between just having an accident, and being bankrupted or even criminal neglect, or worse an involuntary manslaughter charge against you.

You might not hold such parts in "high regard", but they do benefit you in many ways you don't even realize. Either replace with NOS parts, or recreated ones that meet OEM standards.

[Josh]

I was waiting for a long winded reply Robert, thank you for that. :rolleyes1:

I suppose I should just junk my car then as I am a rolling liability.

And trust me I know this car way better than you do, from a design and engineering aspect.

[PJ Grady Inc.]

I was waiting for a long winded reply Robert, thank you for that. :rolleyes1:

I suppose I should just junk my car then as I am a rolling liability.

And trust me I know this car way better than you do, from a design and engineering aspect.

Sorry I have to side with "long winded" Robert on this one and I know a thing or two about these cars. Remember this car was designed by some pretty decent engineers and those designs were DOT certified through crash testing. Personally from what I've seen (and experienced when somebody center punched my previous D) these cars go through in a crash situation I can't think of an air-bagless car I would feel safer in during a collision. I've done many collision repairs on these cars and very few people get hurt in a Delorean accident unlike the "other" cars involved. Please don't be offended but that is my opinion.
Rob

[Rich_NYS]

Polyurethane, yes, but it's a flexible type. Again, like a seat cushion. Rob Grady has even spoke about this of how it acts like a sponge where for a couple days after a wash the car will still drip water from the bumpers.

The type of foam used in that video is not a flexible type and is resistant to water (which is why the OEM impact absorbers are coated). That's an expanding foam which remains ridged, and is used in heavier densities for sculpting.

http://www.shopmaninc.com/foam.html

The polystyrene *is* an alternative if someone was up to the challenge, though admittedly taking a perfect OEM foam impact absorber and creating a mold out of it to cast more impact absorbers would probably be simpler. Especially if you were to construct a jig that suspends a bracket inside of it, below the final surface level, and you just poured the flexible, impact grade polyurethane mixture in.

But I ain't gonna lie: After the cost of the chemicals, let alone molding the pieces, $600 from DMCH seems like a reasonable price.

I checked my rear absorber, it's very rigid, but I was able to make an impression in it with my finger that I think will spring back to shape. I'm interested to know what the originals were made of. I don't think it's very much like seat cushion foam. I also realized the front unit has recesses for lights so it wouldn't be as easy to duplicate as the rear. I'm sure I could easily reproduce a rear no problem.

[Rich_NYS]

Take a look at the final two tests that deal with foam in particular. One foam is WAY too rigid, and offers zero protection to the structural frame which it is protecting. Then we have the final foam which does it's job, but consider for a moment that it is completely sacrificial. After that impact it permanently deformed and did not go back to it's original shape. That is a problem.


Is a DeLorean impact absorber supposed to be multi-use? I'd rather sacrifice an impact absorber to save the frame, etc. versus the other way around.

What's Rob's .02 on an absorber post-impact?

[PJ Grady Inc.]

Is a DeLorean impact absorber supposed to be multi-use? I'd rather sacrifice an impact absorber to save the frame, etc. versus the other way around.

What's Rob's .02 on an absorber post-impact?

I believe they are reusable unless excessively torn or the reinforcement bar is bent.
Rob

[Rich_NYS]

I believe they are reusable unless excessively torn or the reinforcement bar is bent.
Rob

Interesting......thanks Rob.

[Nicholas R]

You guys can all compare different thoughts and opinions on foam differences, or one of you can just buy a durometer gauge and test the bumper for yourself. :wrenchin:

Get the durameter of the existing bumper, find a replacement foam with the same durameter. Brand new foam bumper; no change to the safety. If I had to guess, I'd say you're in the Shore E durameter range.

http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=Shore+E+durameter+tester&rh=i%3Aaps%2Ck%3AShore+E+durameter+tester

Also Josh if you're junking your car, there are several parts I'm interested in :wink: Though based on this discussion about the need for OE parts, I guess we're both living on the edge, haha.

[opethmike]

Don't listen to Josh. He doesn't know anything about engineering.

[Lwanmtr]

Yep, This is why I started this thread to see if it was possible, difficult or even recommended. From what I've read, I'll take my chances with the $600 one from dmc.
If I were experienced in engineering, fabricating, molding, etc I might be inclined to at least test out different materials, etc....

[Nicholas R]

Don't listen to Josh. He doesn't know anything about engineering.

I just want his white letter tires and galvanized frame. I don't think I trust any of that drive train. Engine swap people are crazy...:mallet:

[opethmike]

I just want his white letter tires and galvanized frame. I don't think I trust any of that drive train. Engine swap people are crazy...:mallet:

Especially Corvette motors - yuck!

[Bigchip]

Has anyone considered using laminated foam trim the big box stores?

[Bigchip]

Has anyone considered using laminated
Foam insulation from the big box stores

[mr_maxime]

During my tear down, I started peeling off the flaking black pieces from mine. I thought about recreating them with some type of furniture foam, but went down a youtube rabbit hole of making a mold for polyurethane foam instead. Smooth-on has a bunch of tutorials and different densities of flexible foam, then it'd just take a flexible coating. Obviously, making the initial molds would be the most time consuming part, but then it'd be rather easy to start refoaming any other bumper.

[AZ-D]

Filled the large gaps with expanding foam, then used heavy duty duct tape to wrap the whole thing. Turned out great IMO.

Sent from my SM-N950U using Tapatalk

[mr_maxime]

I didn't read the full thread before posting but are people seriously saying that the cracked, hardened and flaking OE absorbers safer than a Diy repair? I'm with nick on this, just use a durometer and find a foam that matches. You're not driving on 40 year old tires, why would you trust 40 year old crumbling bumpers?

[DrJeff]

I rebuilt my rear bumper with this stuff (https://www.rollbarpadding.com/product/id-69). The original rear foam was destroyed by moisture but the front was in good condition. I resurfaced both with rubber paint (which I can't find the link for).

Jeff

[mr_maxime]

What did you use to shape it?

I'm hoping flex seal will do the job recoating my old one for now.

[Lwanmtr]

I used a plsti-dip spray to coat mine...works fine..is flexible enough to crush on impact, but strong enough to hold it together.

[dmcerik]

I've got a handful of these impact absorbers stuffed away in the attic. Probably 3 or 4 parts cars worth of them. I have no idea the condition, but if someone is interested in them, and picking them up locally in West Michigan, I'll go take a look this week.

[DrJeff]

What did you use to shape it?

I'm hoping flex seal will do the job recoating my old one for now.

I cut the Impacxx Foam up with a hacksaw and then used a metal file to shape the corners. I used two pieces (because of the shapes it comes in) to make up the rear bumper - which I shaped to fit like the stock absorber around the aluminum bar. I affixed it with mounting tape.

Jeff