Stumped On Rear Gas Tank

I am installing the 15 gallon tank for the 78-86 CJs from MTS in my 67 CJ5. I got all the hardware and skid plate from MTS. I had to make a few kids to the skid plate to make it fit (trim away front drivers corner to fit where the crossmember slopes down, remove the extra angle on the back lip of the skid plate to fit) and everything was going well until I tried to dry fit the tank/skid plate assembled to figure out where to drill some holes.

My problem: There is a strap that goes across the tank to hold it down that bolts into the back of the skid plate.


If I bolt the tank down before I install the tank/skid plate, the bolt blocks my ability to put the rear lip of the skid plate back as far as it looks like it is supposed to go and the front lip of the skid plate is way off from the crossmember where it attaches.


If I try to bolt the hold down strap through the frame and into the rear lip of the skid plate, it is a hairy beast to try to bolt down. That also would make it such that I would need to lift the cab if I needed to get to the tank in the future, but then it fits really nicely in the front crossmember.

Any ideas what to do? It seems like I either need to ditch the top strap (seems like a really bad idea), come up with a different way to hold down the strap that doesn’t interfere with mounting the skid plate, put more bend into the end straps to narrow the front-back distance of the skip plate, or fab a bracket to hang off the front crossmember that allows me to accept the skid plate offset in front.
Thanks in advance.

 

Is it the nut or the excess bolt protruding thru the nut that’s causing the problem?

If I’m understanding the problem correctly, I would either a) cut the bolt so it fits flush with the end of the nut or b) drill a hole in the frame for the nut and bolt to protrude thru and allow the entire assembly to sit where you need it to.

 

If there were no top strap, it looks like the top surface of the skid plate should contact the bottom surface of the rear crossmember. In other words, the skid plate should be bolted up from below. Because of that, either the bolt or the nut would block my ability to position it properly.

If I could weld a bolt through the strap, that would solve the problem, but I’m not sure that would be strong enough. It may rip through the strap.

 

On my cj5 the anchor bolt fits better to the rear. But mine came with a rear tank. Ron

 

This is how mine is too.
Makes removing and installing the tank a complete PITA.

 

So in the back center of your tank starting from the top, it goes bolt, strap, bottom of rear crossmember, back lip of skid plate, washer, nut?

 

Picture from below, looking up.
The long stud is the fuel tank strap where it comes through the rear of the frame.

 

Weld the bolt to the strap. Use as long a bolt as necessary for your ease. Doubled over 16 gauge strap will hold a 1000lbs roughly.

 

In his often cited thread, @Boyink welded nuts to the frame but didn’t mention what was going on with the top strap. I was thinking about welding nuts to the frame and putting the strap below the frame with the skid plate. So it would go from the top: welded on nut, bottom of rear crossmember, strap, lip of skid plate, lock washer, bolt. My only concern is whether that would squeeze the tank too much. I pushed out the side straps to compress the front to back distance of the skid plate and that helped with fit.

Any problems with that plan? This would make it so I could drop the tank and skid plate without taking off the tub.

 

That sounds good. A long bolt gives room for adjustment without compressing the tank. There are probably a half dozen ways to do this.
It may take more work to put in but easier to service. I have a different tank but used a a thin rubber mat between the tank a skid plate.

 

I’m going to dry fit it with the tank tomorrow before I weld in the nuts. I appreciate all the advice.

 

Dry run confirmed that tightening the strap down as would occur if I welded a nut into the frame and put the strap below the rear crossmember would squeeze the tank too much. @vtxtasy ’s recommendation of welding the bolt to the strap looks like the best plan so far. I will weld nuts into the frame for the other reap mounting bolts. This may allow me to drop/install the tank with the tub on if I can get someone with baby hands to reach between the recess on the tub below the tailgate to guide the bolt into the hole in the frame.
What is that recess for, anyways?

 

If the skid plate snugs up to the frame, do you even need that top strap? Some rubber blocks between the tank and the bed would hold everything in-place. That is essentially what I did on my 3B, with just enough space above the tank to keep the sender and wiring from getting crushed.

 

I'm planning to upgrade to the 15 gallon tank in our 58 CJ, and am a novice when it comes to Jeeps. This thread has been helpful and since it is current, I'd like to ask a dumb question- where do you put the filler? It seems too high to use the original but maybe I'm wrong. I'm planning some ammo boxes with lids in lieu of wheel houses so I can set relocate battery to passenger rear corner and I could also stick filler in one also.

 

I still have an NOS AMC filler bezel like that hanging in the shop. I originally used one on my 3B and bought a spare.

 

The recess was for the old hitch/drawbar attachment.

 

@Boyink , thanks for the response. You definitely have the naming rights for this mod! It looks like your strap bolt attachment is in front of the places where you would attach the skid plate to the frame. That would be ideal.

Here are a few things I have learned so far using the MTS parts.
1. Really good dudes at MTS. Very helpful. I was talking to them about the options for the vapor recovery tubes. @Boyink put a segment of tubing between the stubs. MTS guy said the stubs were 1/4 NPT and he probably had plugs in the back to throw in. My tank arrived with the plugs installed.
2. I went with the skid plate from MTS because I didn’t know exactly what the OEM version was like, but I did have to make some modifications. I removed an extra section of angle that was spot welded into the rear lip of the skid plate. It got in the way. I had to trim down the drivers from corned because it interfered with the chamfer of the front crossmember. If I had to do it again, I would fab my own. I have very crude fabrication tools and that would have been fine for this skid plate. If you fab your own, you can make sure that bolt holes (including the hole for the top strap) are exactly where you want them.
3. I wasn’t 100% sure where to trim the pintle support. I took it back to the gussets between the front crossmember and the frame and there was plenty of room. I wanted to leave the gussets if possible.
4. Edit: DON’T put your rear shackle nuts out or you won’t be able to remove the shackle bolts without dropping the tank!
5. Put a little extra bend into the side straps to cinch up the front-back distance before you start drilling. My impression was that the skid plate could have been a little more boxy and less like a U. You could even bend the skid plate a little more if you done fab one up.
6. I welded downward facing bolts through the rear crossmember instead of nuts because I thought it would be easier to line up the holes and bolts and easier to threat nuts onto bolts instead of bolts into nuts when I am lying underneath the jeep.
I’m waiting for the paint to harden and I will install the tank later this week. I will let you guys know whether what I just said was wrong!