gas tank

Olli · Post by **Olli** » Fri Jun 16, 2006 3:27 pm

Will one of the "long range" aftermarket VW tanks fit inder the hood of the Manxter? Those that are on the road, what is the true capacity with the tank (stock) installed at that angle? Any issues with fuel pick-up? Gauge accuracy? Olli

Tom-Kathleen · Post by **Tom-Kathleen** » Fri Jun 16, 2006 10:04 pm

Olli - I would think the long range tank would fit. Definitely Maybe! You would have to know how much taller it is VS the stock tank above the "flange" where it sits on the body. We went against the grain and used an early tank ('67 down). The old filler neck hole was capped off and moved more towards the center (and rear) of the car. The shortened neck is @ 1 1/2" tall and there is @ 3" clearance to the hood. So that means the tank could be 4 1/2" taller and still fit. The slope of the hood may reduce that. I can send you pics if you need it. Tom

Olli · Post by **Olli** » Sat Jun 17, 2006 2:23 am

Yes Tom, pictures would be appreciated. Thank you. Olli

Complex One · Post by **Complex One** » Sat Jun 17, 2006 7:43 pm

Olli, I spent a good amount of time trying different Type-1 VDO Sender units thinking that this was my problem with inaccurate gauge readings where actually what the primary problem ended up being was with the float on the sender unit. Considering that a stock fuel tank in a Manxter mounts more on a downward angle towards the front of the vehicle than a stock Type-1 Beetle you have to also compensate for the float angle as well. I was able to do this by rotating the float rod and float clock wise to the point where, when mounted on the top of the tank, the float then sat level to the fuel in the tank and not level to the top of the tank as it was originally. Obviously, which I seemed to have initially forgotten myself, liquid seeks its own level regardless of how much you have raised or lowered your front end suspension so you must match the float to your fuels leveling in the tank and not the other way around. Once I did this to mine I also spent some additional time on the float arm angle as well. Starting with an empty tank and with the sender out of the tank I attached a ground wire to the senders mounting plate and the feed wire and then turned on the ignition so I could get an actual reading of the sender unit from all the way down to the top position. On my particular VDO sender there are (2) tabs at the bottom of the senders base that act as stops so that you can adjust the top and bottom travel of the float arm. Too far one way or the other and you can actually loose signal as the contact will simply leave the actual opposing senders arm contacts. Once these are both set you can also adjust (bend) the arms angle below the mounting base so that, when mounted in the tank, it gives you the best readings as the fuel level decreases. I used a large piece of cardboard and layed the circular base of the sender just off the edge of the cardboard so that the sender body and arm angle could be traced onto the cardboard. This became my initial starting point of reference. At this point I began my calibration of the sender by adding (1) US gallon of fuel to the tank so that when setting the lower level of the sender and the float I could set it to (E) on the gauge by adjusting the arm angle until it read accordingly. This way when I actually see (EMPTY) on my fuel gauge I know I still have approximately (1) gallon of fuel left in the tank and had better start looking for more fuel pretty quickly or grab one of the spare fuel cans from under the hood provided I had remembered to fill them.

Using the original cardboard trace (OEM Factory Arm Angle) and if my fuel gauge reading was then above (E) with the sender mounted to the tank I then increased the arms angle a little each time and re-tracing on the cardboard until I achieved my desired gauge reading. This way if I ever need to replace the sender unit again I have a really good starting point of reference for the replacement sender... provided I don't loose the cardboard template in the meantime.

The only immediate problem that I have from all of this is that when the tank is completely filled to the neck my gauge still will not read completely full. The needle stops just ever so short of the FULL line on my VDO gauge but so far I have also never run out of gas... since doing this calibration to both my fuel senders stop tabs, arm, and most importantly making sure that the float on the end of the senders arm is truely level to the fuel in the tank and not to the tank itself. This leveling of the float made the most difference in all in my oppinion. As for using an extended travel fuel tank that mounts in the OEM position on a Manxter I looked into this a little for mine (16 gallon capacity) http://www2.cip1.com/ProductDetails.asp ... C10%2D2510 but opted for a new standard capacity size tank instead as I was pretty sure that this increased height would not fit under the hood of my Manxter, especially at the front side. I don't believe there would be any clearance issue towards the rear (passenger compartment side) with an extended travel tank but I really don't think it will clear on the front side as my stock tank does not have very much room above it already once the hood is closed and latched down. Maybe yours is different? If you find out anything different using an extended travel OEM mounted style fuel tank I would be most interest myself as I could certainly use the extra fuel capacity in mine as well. Hope some of this information is helpful.

Olli · Post by **Olli** » Sun Jun 18, 2006 8:37 pm

Jim, Thanks. Great write-up. I think that it will not only help me, but others as well. I am looking at getting a fuel cell (tank) custom made to fit our Manxters. Advanatages would be; a level tank, capacity (Hoping for 10 gallons, maybe a bit more???) and the ability to use it all, a more practical filler location, provisions for vent and tip-over check, return line for us that are running EFI, and a larger fuel outlet fitting to help get the needed volume to the higher HP engines. The filler can be a flush aviation/auto racing style. It would be possible to run an in-tank pump too. Oh, and I think that it would look pretty cool too. It will not be a bladder lined tank for that would run somewhere in the $1500-$2500. range from either Fuel Safe or ATL. I spoke with both and ATL is actually only about 15 minutes from me. I am still curious though. How many gallons will the stock tank hold in that angle that the Manxter dictates? And can you actually get it all? I must fess up that I threw my donor tank out a year and a half ago as it was an el-cheapo aftermarket that was paper thin and had pin holes. And my donor came from the desert. Other wise I would be in a better position to judge for myself. The mock up is nearly done and I will make 3 of them and send them out for bid to shops that specialize in making cells(tanks) in aluminum. I will post a picture of the mock up when it is done. Olli

fubar · Post by **fubar** » Mon Jun 19, 2006 12:57 am

If you calculate your cubic inches on your cardboard mock up and multiply by .00433 or divide by 231 you should get your gallons approximately. You have to consider material thickness, volume of baffles, sender, pump, and possible warpage if you use stainless. You may also avoid the 6061 t-6 aluminum everyone has a hardon for, it cannot take the movement. (expansion, contraction,etc) 5052 .080" would be the minimum I would recomend. .100" is better yet. Also the 5052 can be formed with a tighter radias punch without fracturing. VDO makes a universal sender that will adjust to just about any tank size. The calibrating has been very well detailed in this thread. I wish I had read that a couple weeks ago when I changed mine... Also air testing the new tank (5 psi max) and spray it with 50-50 mixture of water and bubble stuff from the toy section. Once it has had fuel in it most welders with a brain won't touch it...

Tom-Kathleen · Post by **Tom-Kathleen** » Mon Jun 19, 2006 1:31 am

Olli - go here http://smg.photobucket.com/albums/v226/ ... C00150.jpg for a pic of Kathleen's gas tank. If you need more info, let me know. I would be interested in this new gas tank you are thinking of making. Keep us informed. We have to try that fuel sender setting stuff. The sender we are using now is not good. Thanks for the info! Tom

Lee · Post by **Lee** » Mon Jun 19, 2006 4:26 pm

I have been reading this thread with great interest. The gas tank gave me some challenges I had not previously thought of. "How many gallons will the stock tank hold in that angle that the Manxter dictates?" I don't have a Manxter (would love to have a Dual Sport one someday), but the tank in my Siggy Manx also sits at an angle. I can get a little over 8 gallons TOTAL in the tank before the gas starts pouring out of the filler. The filler is in the center of the tank. Letting a full tank sit out in the sun guarantees it will pressurize and fuel pours out of the vent line. For this reason, fueling up is the last thing we do before hitting the road. I go by the odometer to see how much farther I can go. The fuel gauge is a backup, sort of a reality check. It reads full when the tank is full, 3/4 when it's half full, 1/4 when you have about a gallon left, and empty when the tank's empty. When the odometer reads 100 miles, I find a gas station. The farthest I have gone on the 8 gallons is 160 miles. On desert trips, I dump the extra 5 gallons I carry into the tank once I have gone more than 100 miles. This gives me a total range of about 230 miles, assuming worst case of 18 MPG. I ran out of gas shortly after getting my Manx on the road. I assumed I had 10 gallons in the tank, but when the gauge suddenly dropped, I knew I was doomed. It happened north of the closed El Toro Marine Base in Orange County, CA. There are no services in that area, but there was a nice gentleman working on the trees who let me use his cell phone to call a friend. I recommend everyone carry some extra gas, then see how far your buggy will go on one tank. Running out of gas is no fun!

Olli · Post by **Olli** » Tue Jun 27, 2006 10:27 pm

I finished the mock-up and it is looking like 12-13 gallons. I don't expect this to be as cheap as a VW aftermarket tank. But I think that it will be more practical, safer, and look better too. It will be made from .100" 5052 and it will be foam filled along with an aviation style flush filler, have a sender, vent with a tip over check valve, return fitting, and a nice large fuel supply fitting with a sump. I have decided to NOT go with an in-tank pump. Cost will be $550-600. with the accessories. Olli

fubar · Post by **fubar** » Tue Jun 27, 2006 10:44 pm

Something else that might be cool to have incorporated would be a dual pick up like on a motorcycle. That would give you a couple gallons in reserve. You could even put an electric change over switch. Another advantage is that most of the time you would not be sucking fuel off the bottom of the tank.

Olli · Post by **Olli** » Sat Jul 08, 2006 2:36 am

The final mock-up is now on the way to the fabricator. They will make an auto-cad drawing from it, and then send it to me for my approval. I made a duplicate mock-up so that I will be able to verify the dimensions. 4-8 weeks . Olli

Olli · Post by **Olli** » Thu Jul 20, 2006 2:07 am

Cad drawing is done and approved. 13 Gallons. 4-6weeks. Olli