Jump to content

Gas tank connected to earth


Recommended Posts

Before refixing the tank in the car I was wondering including some rubber between tank and body at the screw holes just to avoid any possible vibration then I wonder if it is a really good idea as maybe tank needs to evacuate static electricity?

Edited by Jctr6EFI72
Link to post
Share on other sites

The tank should be earthed for the fuel gauge sender

I have run an earth wire that connects the rear lights, numberplate light, fuel tank and the under dash earth points to the bolt on the bulkhead that the the battery earth cable is connected to. This dedicated earth circuit has improved the brightness and  reliability of the lights for very little cost and effort.

George 

Link to post
Share on other sites

The tank forms a structural member when bolted in position  and helps provide rigidity to the body, so I don't think rubber mounts would be a good idea. There shouldn't be any vibration. Also as you say I would have thought the tank should be earthed to avoid static build up.

Mike.

Link to post
Share on other sites
22 hours ago, michaelfinnis said:

The tank forms a structural member when bolted in position  and helps provide rigidity to the body, so I don't think rubber mounts would be a good idea. There shouldn't be any vibration. Also as you say I would have thought the tank should be earthed to avoid static build up.

Mike.

The tank is subject to loads as a consequence of the body flexing without doubt but whether it is intended to be a structural member is debatable - the lower mounts are cut outs and the bolt holes quite generous for the size of bolt.

Earthing is probably a good idea but I'm not aware of sparks/static setting the fuel on fire in the TRs.

Link to post
Share on other sites

I chuckle at the thought of any part of the body being truly structural! I shudder that the fuel tank might be trying to be so. FWIW, if the designer's intent had been that the tank were structural, then it would have been fitted using interference fit connections of some kind, or high tensile bolts (for what is called a high strength friction grip connection) *with* a torque setting. As our '60s predecessors may have said, "chill, dude". Or, stress not (see what I did there?).

As for anti-static earthing, it can't do any harm. For a laugh, you could also add one of those dangly strips that were so popular in many parts in the '80s, which were meant to stop the car building up static charge and then jolting you when you touched the body as you got out. Or not.

<tin hat on, ducks>

Link to post
Share on other sites

I have just installed a new aluminium tank into my 1969 TR6. There was foam padding to each side and behind the tank. It was a very snug fit and even before I tightened the holding bolts there was very little opportunity to vibrate or move. I did not use rubber washers as they weren’t there when I dismantled old tank. I can see advantage of running a separate earthing cable but didn’t do that either (good idea I will look at). But my fuel sender unit earth is good, and fuel sender is working well.

I’m pretty sure the foam padding was original (52 yrs old) so highly likely not fire rated safe but my logic was if I have fire its more likely the source would not be the foam and least of my problems next to the fuel tank. I’m guessing foam was original. If any folks know more would be interested. Did original fuel tank have padding around it?

Link to post
Share on other sites
12 hours ago, Martin50 said:

I’m pretty sure the foam padding was original (52 yrs old) so highly likely not fire rated safe

Mine has lost its foam, assuming it was an original item. Sounds (ouch!) like a good idea to reduce drumming. In your case, might as well be safe as the original foam may be not only not flame retardant, but actually flammable and in a toxic way...

Link to post
Share on other sites

My use of the term ‘structural member’ was perhaps not the best choice of wording, the point I was trying to make was that loads due to flexing of the body shell pass through the tank. That’s my understanding from previous forums on the subject, though I may be mistaken.

Reference earthing, it is a standard requirement in industry that components in fuel storage or transfer systems are bonded together to avoid the possibility of sparking due to potential difference between them.

Mike.

Link to post
Share on other sites
10 hours ago, michaelfinnis said:

My use of the term ‘structural member’ was perhaps not the best choice of wording, the point I was trying to make was that loads due to flexing of the body shell pass through the tank. That’s my understanding from previous forums on the subject, though I may be mistaken.

Reference earthing, it is a standard requirement in industry that components in fuel storage or transfer systems are bonded together to avoid the possibility of sparking due to potential difference between them.

 

Fair enough - I was being a bit persnickety! I wonder if the necessary stiffening would still be provided if the tank were mounted via rubber bushes. And you get no argument from me on bonding of fuel systems. I've seen the result of static build-up in another place. Here's a pic :blink:

Link to post
Share on other sites

Actually the more you think about it the more about it the more intriguing  the subject of body stiffness becomes. I’ve read other articles and forum posts referring to the tank providing stiffening, and about a firewall between the tank and cabin helping with the same. But given that the TR’s are built on a separate chassis which is the major structural element ( except the 7 of course) I wonder what part the body is intended to play in stiffening the whole. It would be interesting to know the original design philosophy, though I’m going a bit off thread.

 

Link to post
Share on other sites

The body is merely a cloak to hide the driver sitting upon a box section chassis.

The body is almost entirely single skin and deforms as you would expect...easily and with the smallest resistance to intruding objects. That means cars/vans/trees etc, the best way to have an accident is in a frontal diagonal plane, that way the wings (which are either secured (ha) by spire screws into clip ons ) can absorb impact along it's lengthy although the wheel arch intruding into the vertical plane by almost 80% weakens it greatly and most members will have seen how the wings crumple here. The inner wings and wheel archs contribute to slowing the crumple effect but not until the chassis is reached either by the front wishbone attachements or actual chassis sidewall does markedly superior resistance be met. The ultimate protection of course being the engine block.

The body was designed purely superficially as a modelling ploy as it's philosophy and does not add anything to structural stiffness, indeed one of the most deadly TR accidents is a side impct into the cockpit area.  Which even with the fuel tank acting as a structural member due to it's box and welded construction which under normal roadgoing flexing of the chassis and shell (very apt description in this case) does give a degree of cross car stiffness. But only because of it's bridging affect over numerous single panel welds. A side impact places the tank under crumple and twisting loads and a seam spliting in the tank is a common result which is why the rear of cockpit firewall is fitted to try and give protection from fuel for the cars occupants. The arguments over whether it is effective or not, being as it is normally rivetted to the cockpit rear frame and floor should be addressed to the RAC and/or Motorsports association who won't let you compete in races without one fitted, I guess they've seen enough accidents to reason that "not making the perfect the enemy of the good" should be applied to a car which normally has a 3mm hardboard panel fitted with screws between fuel tank and car occupants !

As we've said before and presumeably you've read within past threads a well fitted rear roll over bar with diagonal bar preferably joined to the chassis where possible or at least structered panelling (wheel arches or at floor at wheel arch weld areas) goes a long way to saving your life when the car topples over which is mostly at low speeds ( I've seen 3 all at under 30mph and in competition) as against the 90mph sideways out of a corner which we all imagine. It also adds a HUGE amount to across car stiffness and preventing a car side impact intruding too far into the cockpit. Again no argument that an 8 point fully welded roll cage to the chassis is the perfect answer, but as before fit what you can do, it's better than nothing.

Mick Richards 

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.