What happened to the "New Underbodies"

[silverhair01]

Haven't been on here in a long while. A topic that frequently comes up is interior noise level so this has probably been discussed ad nauseum. Seems like a new underbody design would improve the interior sound quality to a degree. What ever happened to the new underbodies made of updated materials? Can't seem to find an updated thread on it.

Also, other than simply improved materials on the underbody, what redesigns do you think would improve the noise level in the car? It seems like breaking up the monobody into compartments would yield something worthwhile since right now the trunk, wheel wells, and compartment surrounding the engine is basically one piece (or assembled to be one piece). Maybe making the cabin a single separate compartment would cut down on the noise. Lamborghini's monocoque uses foam surrounded by carbon fiber in certain areas to cut down on the noise level.

[louielouie2000]

If you look at this post, I'd file the new underbodies in the same category as the DeLorean Solstice:

http://dmctalk.org/showthread.php?11...l=1#post164362

My guess is that putting new underbodies in these cars which have not been crash tested and certified is a gamble DMC Texas either would not, or could not take. Meaning, they'd be opening themselves up to a possible litany of lawsuits... at worst, possible criminal charges if someone ended up badly hurt, or dying in a car with a replacement underbody.

Also- I'm guessing the cost/benefit analysis of producing redesigned underbodies quietly shelved this idea long ago, too. After all, it's not exactly like new underbodies are an in demand item. Generally speaking, if your DeLorean needs a new one, it was totaled in the first place. I'd have to imagine the amount of people willing to totally tear down and rebuild their cars for the sake of getting a new underbody is a very tiny audience indeed.

Regarding the idea of injecting sound deadening foam into the underbody, I've often thought of that myself. There is a risk with unintended consequences, though. If you filter out ambient engine and tire noise, would wind noise, squeaks & rattles suddenly become that much more pronounced? The area these cars could most improve in would be by adding sound deadening in the doors, and adding acoustic/laminated glass all around. However, neither of those are feasible options. Plus, if you look at the areas of the underbodies where you can inject sound deadening foam, they aren't exactly in areas which would filter out noise from the cabin. The areas of the underbody which have measurable negative space is in the rear pontoons and beneath the front fenders. Stuffing either of those with foam wouldn't do a whole lot, I wouldn't think.

[sdg3205]

The big appeal of the new underbodies to me was the weight savings. I believe they were 50% lighter, shaving off around 200 lbs IIRC. As awesome as that would have been, still not worth the costs.

[Mark D]

The big appeal of the new underbodies to me was the weight savings. I believe they were 50% lighter, shaving off around 200 lbs IIRC. As awesome as that would have been, still not worth the costs.

I've been doing some pretty extensive weight mods lately by going on a diet. So far I've reduced curb weight by around 35 lbs.

I also only fill the fuel tank up 1/2 way so I'm saving about 40 pounds there as well.

In all seriousness though I agree the market is pretty small for the redesigned underbodies. At the time I think DMCH was talking about using them on the electric DMC's. I think they've only built 2 or maybe 3 of those including the initial prototype. I wonder if those are the only cars built with the new underbodies, or if there have been any 'new builds' that used it. A full rebuild from the ground up is about the only other scenario I can think that would make sense for one of these.

[David T]

I've been doing some pretty extensive weight mods lately by going on a diet. So far I've reduced curb weight by around 35 lbs.

I also only fill the fuel tank up 1/2 way so I'm saving about 40 pounds there as well.

In all seriousness though I agree the market is pretty small for the redesigned underbodies. At the time I think DMCH was talking about using them on the electric DMC's. I think they've only built 2 or maybe 3 of those including the initial prototype. I wonder if those are the only cars built with the new underbodies, or if there have been any 'new builds' that used it. A full rebuild from the ground up is about the only other scenario I can think that would make sense for one of these.

There are enough underbodies and derelict donor cars around so the costs associated with making the bodies for the small market doesn't pay. If DMCH was making as many cars as they projected then they would have to make underbodies. Even a heavily damaged underbody can be repaired, it is only fiberglass. Copying an underbody and making them is a LOT simpler than redesigning and building them from scratch. If noise is the problem make sure the rear window is secured all around including the bottom. Use Dynamat or equivalent sparingly. Seal all holes. Turn the radio up louder.

[Delorean Industries]

This is a highly inaccurate appraisal of the under body situation. Being at the forefront of this market I can tell you in detail the shortage that exists and why even we are extremely invested in engineering a modern composite replacement. The factory GRP tubs degrade at an accelerated rate once used as the composite is constantly stressed. Add in wear and tear, poor storage and exposure to the elements and you have a tub much weaker than original. Early planning for the development of a superior composite consisted of testing six body tubs ranging from early to late production and one extreme high millage example. For argument sake I will not get into how some are more like others regardless of vin in terms of construction. We then provided a complete car "exposed" with only structural related items installed. IE Everything exterior minus doors being removed. The car is currently being put through a variety of stress tests determining the over all strength of the design. Calibrated sensors are installed all over the tub by drilling and installing rivnuts giving an at rest dimension at rest and stressed dimension under load. (the sensors are mounted to two stationary points and measure the expansion and contract under various conditions) Once this is completed the car will be returned to us. This test will then be repeated with our modern chassis installed allowing for us to compare the data and put a hard number in terms of a % increase in gained.

While we (or I) are known for going to the extreme with engineering components for this platform even I would suggest this as over kill if the current tubs were worthy. I'm at a point looking at the future of this car exponentially. The tubs are now considered to be consumables.

[TTait]

Josh,

Are you trying to match the performance of a NOS underbody, or go stronger? If you go stronger, that would affect how the underbody absorbs damage in a collision. You could run into issues by going too strong in some areas, couldn't you?

T

[Delorean Industries]

Exactly this is why the detailed examination of the factory components is crucial. We have drawn the entire body and designed "how we will make it". Thanks to modern design techniques we know the exact strength and function of the modern composites. If we were to copy exactly what was originally made with modern composites the body would be indestructible in comparison to the original specs. In comes the extensive research of the factory tubs. By determining the over all strength of the original in every way possible we can directly add and subtract where needed by contouring our design.

The question that is lingering now is this. How far do we take this? Our manufacture of choice has the ability to conduct extensive ratings on the tub. This is where it goes from expensive to out right in sane. Before proceeding to that and possibly working to meet the exact DOT ratings for the car originally (which you can do with enough money). I have decided to invest in man hours only moving forward. They will continue to work on figuring out exactly what it will take plus or minus to make a modern equivalent with modern composites. At the very least this venture will net me person tubs to use on my own builds.

When the R&D stage is complete I will then be presented with mold costs and production run options. To do this we were quoted on the design portion described above and in previous posts. This so far is staying within budget. We were also given a ball park for complete fully designed components instead of just copying the original there after so we could decide up front if the testing and design portion was worth while. Amortized across given cost of final product per piece (based off average size molds, material cost, autoclave time etc), design and test, molds etc easily crossed into this being a non profitable venture from the start in comparison to the current market need. I went ahead with it anyways.

Remember it's only money and what's the point in living if you don't constantly have a challenge. My parents keep telling me they wish I could apply my drive and ambition to something that actually matters. Maybe someday after I learn the hard way a few more times.

[David T]

The way to build new underbodies today would be a process used in the amateur aircraft home building and boat building. Make a negative of the body out of wood. Do a wet layup of composite cloth and resin and then vacuum bag it. You would have to make it in pieces and then glue them together. Unless you want high production rates you can't afford molds. You are closer to the problem than I am but I see underbodies as a problem in the distant future. For the near term there will be plenty of donor cars that come with a lot of parts and the most important thing of all that CANNOT be reproduced is the Title. When underbodies become scarce less derelict cars will be restored, their underbodies being valuable and reused. Today many underbodies are being cut up and thrown away because no one wants to ship or pick them up and they take up a alot of room. Like the S/S frames, there was some demand and some were made but what happened? Why is it you can't get them anymore?