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PostPosted: Thu Oct 27, 2011 2:50 pm 
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Joined: Wed Feb 23, 2011 6:00 am
Posts: 91
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Location: South Kakilaki
I thought I would add a new thread here about my monocoque fuel tank issues. You may have read a bit about this problem last year when I went to Carlisle and the tank decided to finally give the last heave ho. Forgive me if you all know about monocoques but for those that do not, the monocoque is a unique type of Manx for a number of design details. My problem results from the ethanol that has been added and now is being increased voluminously in our gas supply. The fuel tank is molded as one with the body...so it is actually a sump where the back seat area is on manxes. It was then covered with a lid which is was laminated plywood and fiberglass. The theory was to have as much weight over the rear drive wheels as possible. When I first restored it, I used a military fuel tank sealant called AC236. It is impervious to jet fuel, diesel, gasoline...you name it. It is, I have found, not impervious to alcohol. Over time, the alcohol has softened and eaten through the sealant and has eaten the gelcoat and is now seeping through the glass matte. This is a problem.
Another monocoque owner solved this by having a mold made of his original fuel tank cover, cutting the old lid off, molding a new lid and inserting an aluminum tank (custom fit) into the sump. The "new" lid was then replaced. Sadly, the lid mold has disappeared. 


Unfortunately, my tank lid is deformed from the alcohol so making a mold of it is not an option. My only option at this time is to find another monocoque and have a mold made of the tank lid. I do not want to make a reproduction lid since it would not be original (as designed by Bruce). 


I began by removing the fuel cap flange and started to scrape the paint off of the lid. The color underneath is a polyester primer (made by Omni) which I applied when I repainted the manx 12 years ago. As I am scraping the paint away, the paint actually smells like gasoline...that tells you how much that glass has soaked in the gas. I am hoping to remove the polyester primer and sand/buff out the original gel coat on the lid to keep for reference. The person that did the other monocoque told me he had to chisel and destroy the old lid on the other car....I am hoping to maintain as much of the lid in one piece as possible. 


I am not sure how often I will post to this forum but wanted to get this out there for people to check it out.


Chris


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PostPosted: Thu Oct 27, 2011 2:52 pm 
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Joined: Wed Feb 23, 2011 6:00 am
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Location: South Kakilaki
I had tried to attach images but they did not attach for some reason.

I am trying again..
ImageImageImageImageImage



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PostPosted: Thu Oct 27, 2011 3:39 pm 
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Joined: Tue Mar 30, 2010 5:00 am
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Location: Ventura, CA
Just a thought... Sprint cars & most other types of race cars, use a fuel cell & there are several different styles.
There are a couple different fuel cell companies, that make a bladder that goes inside & fits the shape your fuel cell. The flexable material (it looks like rubber) they use, withstands alcohols in particular, so even if you had to run a 100%, it would survive. The biggest problem would be making a template of the inside of the Monocoque's fuel tank. The next problem is the bladders are quite expensive.
The last bladder I helped design was for a West Coast Super Modified & as I recall it was actually made back East somewhere & cost around $500.00, but that was around 15 years ago.
You might try Googling "fuel cell bladders" or contact a race shop that carries sprint car stuff.

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Michael Cates
ManxManiac
#958
Ventura, CA
Original Meyers Manx "Xena"
M1609C8S22


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PostPosted: Thu Oct 27, 2011 6:46 pm 
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Joined: Wed Feb 23, 2011 6:00 am
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Location: South Kakilaki
Yes, that is an option to consider however I have not been able to find anyone that could make a bladder that would fit into the hole and expand into the two sumps on either side of the transmission. The trouble has been with the number of seams required to make the bladder conform to the inside shape. The more seams, the tougher the bladder becomes to compress and fit.

At your prompting, I began another search to see if there are any major improvements or options out there.


I will let you all know how it transpires.


Chris





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PostPosted: Thu Oct 27, 2011 9:07 pm 
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Joined: Thu Mar 11, 2010 6:00 am
Posts: 320
Location: Vernon, CT
Chris - When I was racing FVee's many years ago, we made our own fuel cell / bladder for the car.  It was made of uncoated sailcloth (yes sailboat material), whith a plastic covering that soaked through the cloth because it was uncoated.  We made a triangular shape to sit on the floor and behind the seat.  Yours looks like it would be a rectangle.  The outside was flexable, and then to give it shape, we filled it with small pieces of helicopter fuel cell foam.  Just throwing some ideas out for you.  Tom

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Tom & Kathleen Iacoboni
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Vernon, CT
1968 Meyers Manx, 1971 Manxter S, 1972 KickOut SS (WIP)


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PostPosted: Fri Oct 28, 2011 6:33 pm 
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Joined: Thu Apr 08, 2010 5:00 am
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Location: SoCal
Reading matter on the subject of fiberglass tanks and ethanol.   http://newboatbuilders.com/docs/Ethanol.pdf

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Ed


Last edited by Ed-Chenal on Fri Oct 28, 2011 7:10 pm, edited 1 time in total.

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PostPosted: Fri Oct 28, 2011 8:18 pm 
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Joined: Thu Feb 25, 2010 6:00 am
Posts: 234
Thanks Ed that is interesting reading ... and the clearly explains what happened the side tanks on the Mangosta ... I ended up building a steel tank that replaced the rear seat. I don't like back seat passengers anyway, it's a safety issue for us.

Chris keep us informed on fix.
Mark & Carol


Last edited by 1856 on Fri Oct 28, 2011 8:21 pm, edited 1 time in total.

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PostPosted: Fri Oct 28, 2011 8:32 pm 
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Joined: Wed Mar 10, 2010 6:00 am
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Location: Pacific NorthWest
Doesn't Eastwood have something that you swirl around in the tank that would keep the gas (and alcohol) from touching the glass? I know on this old motorhome (GMC) that I have the fuel tanks get rust in them and this is the fix. I can ask to see what the product is that they use if interested.

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Gary Berry
Prosser, WA
1971 Turista
1969 ManxVair
Member #1112


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PostPosted: Thu Nov 10, 2011 6:10 pm 
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Joined: Wed Feb 23, 2011 6:00 am
Posts: 91
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Location: South Kakilaki
Yes...Eastwood makes a tank sealant. Consider flipping an entire car around to coat the tank...Yikes.I used a military sealant which was impervious to jet fuel, diesel, gasoline etc. but not alcohol....they did not disclose that at the time..I received a bulletin about it since I had purchased the material. By then it was too late.


The tank itself is rectangular...but not really. It has all sorts of shapes in it. Consider that it was almost literally wrapped around the transmission, starter, bowden tube, axles and shock mounts. 


I may have an option here. There is a very obscure fact about number 4 monocoque. The fuel tank was cut out in 1995 to fit an aluminum tank from the underside. The fiberglass tank portion is still around...ie...this is the buck for fitting/designing a bladder.


I spoke to a shop that makes bladders...they requested fully dimensioned drawings of the tank...fat chance there. If I can get my hands on the tank, I can send a copy of it to the manufacturer.


There is HOPE!


Thanks for the input.


Re the Mangosta....yep...integrated fiberglass tanks....Bummer that... I love the Mangosta design.


Chris




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PostPosted: Fri Nov 11, 2011 3:33 am 
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Joined: Thu Feb 25, 2010 6:00 am
Posts: 234
Chris thanks for the kind words ... We tried about every thing off the shelf and over the counter with no lasting successes. There is a new epoxy type product that I've
used recently, it was developed primary as a repair liner for underground wastewater piping. The process includes a silicone membrane that in inserted into the pipe. then the membrane is inflated to meet the couture, next the epoxy is pressure injected between  the pipe and the membrane.  The epoxy sets very fast and  membrane is deflated and removed. The product is advertised to work in very toxic environments including petroleum and alcohol and more, as we can imagine... It seem that this could be the fix ... If this process and product interests you let me know ...
Mark


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PostPosted: Tue Dec 13, 2011 3:45 am 
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Joined: Sat Mar 26, 2011 5:00 am
Posts: 103
This is a tank sealer product which probably has the best feedback from owners of motorcycles with fiberglass fuel tanks. Not really sure how you'd apply it but hope it helps

http://www.caswellplating.com/aids/epoxygas.htm


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