fuel tank mounting

maylar · Jun 1, 2020

I just installed a cNw head steady on my 74 MKII Roadster and it's hitting the bottom of my fuel tank. I can hear and feel the tank buzzing and it goes away if I lift up on the back of the tank. Rather annoying considering the $$$, but it is what it is.

I figure to add a piece of the foam that came with my Shorai battery under the tank and also put a flat rubber tank washer on the rear mounts to add some distance to the clamp. Sound like a plan?

batrider · Jun 1, 2020

Was able to raise the tank slightly that way and it was enough to keep it from hitting. Try to make it level or it will look terrible.

swooshdave · Jun 1, 2020

There should be a pad under the back of the tank, did you not have one?

Fast Eddie · Jun 1, 2020

As swoosh says, there should already be a dense foam pad there. Perhaps yours as disappeared? Or crushed down?

Shorai battery foam is no good for this application, it squashes down to nothing. I know cos I tried it !

jaydee75 · Jun 1, 2020

Definitely need to pad enough to prevent rattle, due to danger of wearing a hole in your tank.
Jaydee

swooshdave · Jun 1, 2020

A while ago a bought a tank pad from Old Britts. It was like a memory foam and immediately squished down and was useless. I’ve got it sandwiched now between two pieces of closed cell foam cut from HF floor mats. With the Proddy tank it needs to sit up high to clear the oil tank. It works for now but I’d like a better solution. On my Ducati it’s got a pad that looks like it’s made from horsehair. Not sure what it is exactly.

maylar · Jun 1, 2020

Fast Eddie said:
As swoosh says, there should already be a dense foam pad there. Perhaps yours as disappeared? Or crushed down?

Shorai battery foam is no good for this application, it squashes down to nothing. I know cos I tried it !

Yes there is a foam pad there, replaced when I last painted the tank about 12 years ago. Thanks for the tip regarding the battery foam, I had though it'd crush down too.

I think 1/4 inch will be enough, I can get rubber or foam from McMaster. Anybody know the composition of the factory stuff?

swooshdave · Jun 1, 2020

1/4 seems awful thin. The rubber band puts a lot of stress on the pad. I have no idea what the factory originally used but I'm very curious.

jaydee75 · Jun 1, 2020

When I recently cleared my tank, I addressed the wear points on the tank. One pic below shows the wear points, and the other pic shows the padding specifically on those points. This is in addition to other padding and padding on the frame.
Jaydee

Tornado · Jun 1, 2020

My repro tank needed dimpling where the DT. Headsteady was contacting. No more foam to raise the tank could be used without resorting to longer mount studs. So I rigged up a bit of 2x4 with a 1/2" hole near the middle, ran 1/2" carriage bolt and nut with washer onto the bolt. Placing threaded end in wood hole, positioned dome head against tank at HS witness mark, then wound down nut against wood to push dome into tank metal. Only needed 1/8" of deformation each side of tunnel to achieve enough clearance.

maylar · Jun 1, 2020

swooshdave said:
1/4 seems awful thin. The rubber band puts a lot of stress on the pad. I have no idea what the factory originally used but I'm very curious.

I just need to raise the tank a little bit. Whatever I add will go on top of what's there already. I'm intending to add one additional rubber washer at the 4 mounting points to compensate.

I'm thinking of this stuff:

rubber sheet

acadian · Jun 1, 2020

I struggled with the same problem, replacement pads just compress until the tank starts vibrating, more problematic with the madass gantry as there's not much clearance with the cable tower to begin with.

Ended up buying one of these RV support pads, made of recycled tires, 1.75" thick, won't compress like foam and still dampens the vibes

some time on the bandsaw and you can have your own custom fitted pad, I offset mine slightly to the left to give the cable tower a bit more clearance

DogT · Jun 1, 2020

I used a couple pair of zorries or flip-flops from the dollar store. That's some nice rubber, won't compress or wear out. You can match the tank color too. And it's cheap as the dickens. I think I got 2 pair for $1.50. I even cut out some circles to put under the front studs too.

fuel tank mounting

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