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Sport Classic Aluminum Tank R&D Thread

89934 Views 404 Replies 76 Participants Last post by  gusman77
This thread separated from the discussion about a limited number of custom Sport Classic gas tanks, as started by brooksie.

The purpose of this thread is to keep track of ideas, and to solicit donations for the R&D and prototyping of a production aluminum alloy replacement gas tank for the various Sport Classic models.

The goal of this project is simple: To develop a solution and a product that will replace the problematic plastic tank on Sport Classic motorcycles with a high-quality aluminum alloy tank, suitable for polishing or painting. We are trying to keep the cost down, while providing a high-quality solution that uses stock parts for ease of use. That is why it is necessary to have everyone's help.

To achieve this goal, several steps need to be taken:

* Obtain high-quality "virgin" Sport Classic tanks that will be used to do the initial scanning in order to make the mechanical drawings. We have had offers from other members to use their warranty replacement tanks for this process. This is the desired route, as it utilizes existing "free" parts as opposed to purchasing new ones. Should we not have enough "virgin" tanks from forum members, we should purchase that model's tank from Ducati in order to scan.

The objective of using "virgin" tanks (tanks that have never held gas) is to create the master designs from parts that have no verifiable spread to them. Ideally, the fitment of any tank that will be used for modeling will be verified before scanning to ensure that we have the best starting point for that piece.

If the need arises to purchase tanks for the purposes of modeling, I have set up a Paypal donation pool for the forum members (see below), so that we can purchase the tanks from Ducati. Use the link below to contribute to the "Save the Tank" fund. Suggested donation is $40 (US), based on responses, and the cost of the tanks. If you can't swing $40, then any amount will help.

Each model tank should be about $1878, and we have guesstimated about 150 people interested. Once we reach the magical amount, I will purchase and verify the fitment, for the necessary remaining parts, and then send the tanks to the scanner as chosen by the group.

At the end of the modeling, if tanks were purchased, they will be sold here or on eBay, and the proceeds used to either repay the people that donated, or to roll back into product development.

* Product development. From the discussion in the previous thread, there are a few steps that come between the initial scanning and the resulting production. They include CAD time, and some testing to verify the model and molds are stable. The donation pool will also be used to fund this stage of the process, with either existing funds, fresh donations, or the money from the tank sale.

So far, consensus has been to keep the overall exterior shape the same as the original model, but undoubtedly there will be other design choices that should be put to a vote. I will post various polls for these, and keep track of them here.

* Production. Forum member Hardball has expressed interest in producing the tanks when the designs are complete. Any funds that have not already been allocated to obtaining tanks, or R&D will be used as necessary to help set up production.

* Refund policy:

If the whole deal should fall apart before the tanks are completed, or you are not interested in participating after you have donated, I will refund the donations where possible. If for some reason Paypal is unable to refund the donation, or I can't refund it to you directly, it will be forwarded to the AMA or Abate.

I want to personally also take the opportunity to say a few words. I, like you, really love my Sport Classic, and although Ducati is rumored to be working on a replacement tank for the failed plastic parts, I think this option of an alloy tank is too attractive to pass up. It really is with all of your help that this project will succeed, and I want to thank you all in advance for helping make it a reality.

I can think of nothing better, than to have a group come together and come up with a solution that will please all of us, and really enhance the beauty and reliability of our bikes.

Thank you.


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The first order of business is to figure out to total cost of the project.

We would need to find someone who can quote CAD time, and any other steps before the plans make it to Hardball's hands.

Hardball, can you specify exactly what you need from us in order to do a production run, and what you would deliver?

I have the ballpark figure from Hardball's last calculation that the tanks, when in production should be sold for around $1000 (US), and will be sold as a kit that will need to be welded and pressure tested (around $100 ballpark).

If we need to purchase all three SC tanks from Ducati, the price there is $6150 (with CA tax). Forum member elementfmfl has offered to use his warranty replacement tank from his Sport 1000 as the first model. elementfmfl, please let us know if that will be possible.

Unless I'm mistaken, the Sport and PS style tanks are the same, but for the fairing mount bosses. Is this accurate? If so, we would only need two tools made. One for the S1K and PS style and the other for the GT style. I believe the S1K can be adapted for the PS style by adding brackets, which could be provided along with the tank as a complete kit, similar to the Air-Tech race-only kit.

We can get the scanning and CAD work done here. Basically it comes down to taking the raw data files, making a conforming 3D image, massaging it for symmetry and then looking for problem areas the tooling can't produce efficiently and modifying them accordingly. After the tool geometry is finalized, we can add the filler, vent and fuel pump bosses, as well as any mounting bosses required, either as weldments or as features of the base pan.

As I've said previously, the tooling is the tough part and therefore the most expensive part. The cost of the tools determines much of the per unit cost, based on the quantity of parts we run. A $10,000 tool adds $20 per tank to a run of 500 units, but $200 per tank for 50 units. I suggest we bring this project to the stage of tooling cost quote for the S1K/PS tank and then see what the cost vs. level of interest ratio is. If we get a good response, we can then attack the GT tank. This will save both time and money during the pre-production phase.

The ballpark quote I gave you was based on a run of 500 units of one type (meaning off 1 tool), unwelded. Welded, pressure tested and completed units would obviously cost more. As an option, we could also produce them in brushed or polished finishes at extra cost. All these prices are quantity sensitive, so the more we make in the first run, the less expensive each unit is...so this is one case where "The More The Merrier" really applies.

Although I expect to get considerable feedback from interested members about the features and design of the tanks, please bear in mind that it may not be possible to incorporate ALL of your great ideas in a production unit. Please don't be insulted if your idea is not usable in production. This is particularly true in terms of the shape of the shell itself. Other features may be possible to add as options.

Just for hahas, I'm going to get my seat cowl and front fender run through the scanner too.:D I'm looking forward to your feedback.
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We're trying to determine that as we speak. If you look up the poll thread (above in this thread), that is where we are capturing the pricing data.

As for your offer, what services would you be able to give us? What production method would you use? What quantity could you supply, and how quick would the turn around be?

Hardball has already made an offer to hydroform and brake-form a two-piece tank from aluminum alloy. I don't have all of the details to that process...Hardball, would you like to chime in?

Rever Corsa should be encouraged to cost out the unit as well. I'll let him speak for himself, but my guess is that he would be buck-forming the tanks out of 1000 or 3000 series alloy, and probably in 3 or more pieces. Let him describe his preferred method.

My intention is to Hydroform the shells. This is a production process capable of producing thousands of parts from one set of tools. Essentially, it involves the cutting of a solid steel tool which looks just like the shell of the tank, less 1 metal thickness. That tool sits below a ring designed to conform to the base of the tool, which grips the sheet of aluminum for forming. The top of the sheet is compressed by a heavy rubber bladder backed by pressurized hydraulic fluid, just as the tool is forced through the ring. This shapes the metal in one stroke, and is repeatable to within 30 thousandths of an inch. We can use nearly any aluminum alloy to produce the shell, making a thinner, stronger part. This would be mated by TIG (possibly MIG) welding to a brake-formed (punched, stamped and air-bent) base pan, which would include any mounting bosses and fuel pump housing. This is the same method by which many production fuel tanks are made today.

See: http://en.wikipedia.org/wiki/Hydroforming
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I agree, my intent with respect to managing other's money, is to get them the best bang for the buck.

In that spirit, a little pricing competition/information is a good thing. And we can all decide which path makes more sense.

Bruce, your process sounds very modern and well thought-out. I look forward to seeing what ReverCorsa brings to the table.

Excellent. Seems we're all on the same page.
Something that I have wanted to bring up:

Will the aluminum tank have any drawbacks with respect to fuel staying in the tank for a while?

Another poster had a comment about ethanol and it's ability to act as a dielectric and possibly corrode aluminum.

Would it be a good idea to have the inside of these tanks coated as a precaution?
Given that the heads, pistons, cylinders, intake manifolds and FI/carbs on most modern vehicles running gasoline/ethanol blends are all made of aluminum, I'm not terribly concerned. Tanks can always be Kreemed or coated in a similar manner if desired.

See: http://www.nmma.org/lib/docs/nmma/gr/environmental/E20_Position_Paper.doc
I wish you were on the west coast so I could make it in to check out this shop. Always been interested in your kind of work.

Tanks being Kreemed I agree something like that can be done. Fiberglass tank vintage guys that have Kreemed their tanks are concerned about this new blend of heavy ethanol stuff. Coated tanks still sound like a way to go but what product would be the question.

I've used POR-15 for coating tanks to keep them from ever rusting and the stuff is hard as nails but I haven't had time to read up on how it handles certain chemicals.

Some of the vintage guys I've asked have said they still drain their coated tanks. Looks like this Ethanol just sucks ass!.

So long as the ethanol is less than 15 to 20% it really shouldn't be an issue. E85 (85% ethanol) is another story, but the tank would be the least of the problems. Tanks can be plated, anodized, passivated, iridited, coated...the list of treatments is long. All of these are an added cost, but worth considering. The tanks can be formed in steel, or even stainless steel (although I'd have to modify the tool).

Here's a few pics from the shop. Mostly sheetmetal stuff:

Just a few of the toys at my disposal.
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Really impressive stuff!
Thanks...gotta do something for a living.

Just did a little homework. ATL, the racing fuel cell company, is about an hour north of me. They make custom ETH/METH resistant fuel bladders if there's a real need. Some really trick filler necks, too.

Also, I can get the tools run plus size (meaning add a metal thickness) to add capacity, if desired.

I'm missing something in this discussion...are you saying that your company does hydroforming, or hydroforming of parts of this depth ?

Also, based on my somewhat limited experience in contracting for hydroform for small aerospace tankage ( around 2 liters volume) in aluminum, I would believe that your est. of $10K for the tooling is, shall we say, modest, eh ?

We do, and we have specialized vendors who do what we cannot. One of them hydroforms stainless steel sinks that are both larger and deeper than this tank will be.

I have great respect for those of you who work in the mil-spec and aerospace industries, however your production methods, QC and specifications are considerably higher than those which are acceptable in the consumer products market, and rightly so. 200 or so people cannot be killed in an instant by one improperly formed sink.

These standards and the sometimes limited production runs understandably increase the costs of the tooling as well as the end product (hence the famous "$600 NAVY toilet seat")*. I've stayed out of this market for these reasons, as well as the liability insurance costs, which are roughly 3 times what I already pay.

The tooling is specified in accordance with the expected quantity of the production run. For +/-500 pieces, we do not need extra-hardened, TiN coated or specialized materials for the tool. Nor do we need to meet a mil-spec with the end product. Different ballgame altogether. I'm pretty confident we can bring the tooling in for a reasonable number.

Even if I'm "modest" by half, and the tooling comes in at $20K, that still adds just $40 per tank to a run of 500 tanks. Not a deal breaker in my opinion. We'll know more after the scanning and CAD processes are finished and a proper tooling quote can be done.


*[edit] NAVY's $600 Toilet Seat
The P-3C Orion antisubmarine aircraft went into service in 1962. Twenty-five years later it was determined that the toilet shroud, the cover that fits over the toilet needed replacement. Since the airplane was out of production this would require new tooling to produce. These on-board toilets required a uniquely shaped, molded fiberglass shroud that had to satisfy specifications for the vibration resistance, weight, and durability. The molds had to be specially made as it had been decades since their original production. The price reflected the design work and the cost of the equipment to manufacture them. Lockheed Corp. charged $34,560 for 54 toilet covers or $640 each.[1]

President Reagan held a televised news conference in 1987, where he held up one of these shrouds and stated: "We didn't buy any $600 toilet seat. We bought a $600 molded plastic cover for the entire toilet system." A Pentagon spokesman, Glenn Flood stated, "The original price we were charged was $640, not just for a toilet seat, but for the large molded plastic assembly covering the entire seat, tank and full toilet assembly. The seat itself cost $9 and some cents.… The supplier charged too much, and we had the amount corrected."[2] The president of Lockheed at the time, Lawrence Kitchen, adjusted to the price to $100 each and returned $29,165. "This action is intended to put to rest an artificial issue," Kitchen stated.[1]
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Good news.

I rode up to my dealer today, and asked them about taking my #3 replacement tank to be scanned after it comes in, before the swap.

They were cool with it, and I will offer it as a backup if elementfmfl is unable to do so.

Things are starting to click.

If anyone has a GT tank in a similar situation, please let me know.
Muy bien!

Any further word from ReverCorsa?
That's a damn good observation. I had forgotten that the PS/S has the ignition lock forward of the triple clamp.

Bruce, I am thinking that we may need to plan to separate out the two sport tanks again. Right now, the PS/S mounting kit poll is almost dead even.
To answer both of you, I would say it depends. If I understand correctly, the difference is the cylindrical clearance around the frame mounted ignition switch on one versus the other. I'd have to check them out, but if the general shape of the tanks are the same, we can either cut away the clearance on one, or add a false edge on the other. Bear in mind that the tool just produces the basic shape. We can add or remove material as desired after forming.
Here's a pic of the tank top


(Thanks to chromekid01 for the 2nd image)
Perfect, thanks. 1 tool makes both tanks. :cool:

Now I wanna get my hands on a fairing, LOL!
Had my S1K all apart today. We're gonna need to have something like the pump housing (udder) on the tanks. Ours can be cleaner than the odd black lump on the stock unit, but it has to be below the main tank and toward the rear. It also has the rear tank mount off the back end of it.

The bottom of the tank poses the only tricky part of the whole exercise. The stock unit tapers out from the top down and then there is a parting line where the roto-mold tool opens, after which the tank tapers back in. Our tank may need to continue to taper out at that point instead (or at least go flat) in order to make the shape in one stroke. I'll need to get a good look at the PS/S style tanks to make sure we clear the fairing mounts.
I'm a member at one of the triumph sites, loads of folks have been pretty disheartened by the delay in getting tanks from TA Baker and the Tank Shop for their Thruxtons etc, seems they're very small outfits with a 6 to 8 month waiting list :eek:

sounds like never-never land to me :)
Once we've got these tanks dialed in and shipping, we can always scan a Thruxton tank...;)
Yep, agreed - that's really not what the Tank Shop does. In general I'd say the discontentment with waiting for their work is unreasonable. They're artisans, and incredibly skilled ones at that. They're not shy about the turnaround time; people wait because there aren't many shops that are able to do what they do.

But they're the wrong people for this kind of job for sure.
Exactly...they do beautiful work, one at a time. And I can beat and buck-form a tank or 2 myself. But that's not the quality or price point we're after here.
so i know i have been a strong advocate of the idea of keeping the tank stock (except for capacity), but i have been staring at the side of my bike, pondering if i were to get rid of the battery box (gel batteries etc under the seat) that would leave a large lump of plastic there (fuel pump). is there a better place for this to go that may make this tidier, more attractive but not compromise capacity?

We were discussing that previously. Gonna do my best to clean that detail up, but the pump needs to stay pretty much where it is. The 'udder' it lives in doesn't need to be so ugly though.
If we want to get rid of the udder altogether, we may need to go to one of these external units.


We'll still need a "mini-udder" at least, regardless of which way we go, and we'll need to baffle it to prevent fuel starvation in extended turns.
Another (non) status update:

TANKS TANKS TANKS...we are waiting for them.

Me: Dealer screwed up and forgot to order the replacement. Another 40 days (special order paint for SE)

Hardball: Says his tank will be in any day now.

Elementfmfl: Any status???

It's maddening the time Ducati takes to do a tank shipment from Italy. They probably had to start another batch, or something.

Another note, I did see a GT tank on eBay. When I asked the seller about any potential spreading, he said that he didn't know. I figured that it was best to wait for a member to get a replacement under warranty before scanning.

Hardball, any status updates on your side?

Just got the call that mine shipped...should be here by now, but haven't heard from the dealer yet. I'll keep you posted.
Hardball could probably give some good insight here...

We're not going for six sigma, (I doubt any source part from Ducati would be that good) but tooling for this tank is kind of expensive, >10k. What would you think if you took a used tank, went through the scanning and tooling to find it had spread a bit, all subsequent copies had this flaw, and the tooling is ruined as a result?

I'm not saying that this would happen, but with any project, the more care you put into the prep, the better the outcome. And I feel that Ducatisti should enjoy a high level of quality.

Could we take a tank and scan, and make modifications to the CAD file to fix any spreading? Possibly, but without tooling for a prototype and testing the work, we wouldn't know if we got it right, and also increasing the cost.

I also dislike Ducati's turn-around time for parts, but that's the reality of things.
Word is that my tank is in Jersey, so I should be able to get ahold of it right after the holiday. Hopefully I can abscond with it without causing any headaches for the dealer so we can get the scan done.

Six Sigma is not on the menu here. What we're after is a net part scan. We can manipulate that data file to make the unit symmetrical and blemish free and then export that data to the CNC machinery that forms the tool. The result will be more dimensionally accurate than the tank we begin with.

Have a great 4th of July holiday!
Santa came early this year...

Looky looky what arrived today...:D

Let's get to work!
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F'nA, 'bout time :D

Is your bike out of commission, or can you check fitment on it?

I'm getting all excited! :)
Right? But it's here!

Not really necessary to check fitment on my bike. All we're after at the moment is the surface scan. The baseplate can be tweaked after the fact.
Tank is on its way to the scanner tomorrow...
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