- Thread starter
- #1,241
It's a fuel tank and I don't want to burn because of a bad mounting solution so I appreciate your input. Heading out for dinner.
Builds 86 Xtra Cab Build (4Wheelunderground 3 link front, 4 link rear and 3.4 swap) (2 Viewers)
- Thread starter aztoyman
- Start date
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I don't see the issue, the rubber you have under the plates should allow a little flex.
Even with out the bolts on the sides I don't see the tank rocking,and if it does gusset on the straps is not going to stop it.
The gussets would need to be welded to the base plate, and I really don't see room for that in the front.
If your concerned I think the plates on the sides would be the way to go.
JMHO
Getting really close, you must be excited !!
Even with out the bolts on the sides I don't see the tank rocking,and if it does gusset on the straps is not going to stop it.
The gussets would need to be welded to the base plate, and I really don't see room for that in the front.
If your concerned I think the plates on the sides would be the way to go.
JMHO
Getting really close, you must be excited !!
ntsqd
technerd
My concern is that if the mount frame isn't really rigid then it will twist in some situations and that has the potential to start fracturing the ends of the tank at or near the bolt holes. Without those end bolts the tank is freer to twist in the straps and much less likely to to start to tear. At least that's the way that my mental FEA analysis program is seeing it.
Totally understand your concern I just don't think gusseting the straps is the answer
I would think the four straps pulling down the flat surface of the tank to the flat surface of the mount would be sufficient to keep it from rocking
If it was a completely round tank that would be different.
Adding some gussets to the base plate to turn it into a cradle would be ideal
ntsqd
technerd
If that bottom plate can twist when the chassis twists then it is going to put that torsion into the tank. We want to avoid that as much as possible. Option A is to make the tank mount as rigid as possible, and then 3 point mount it to the chassis. Option B is to build the mount such that when it does twist it can't really apply that twist to the tank.
I understand the issue, the base mount seem to be resting on the frame at the side and clamped to the cross pipe so yesI think there will be flex in the mount.
I would also be concerned that when this flex/twisting is happening it may cause the straps rip or tear where the mounting holes are drilled.
I would rather see slots cut in the sides of the mounts and have the straps pass under the mounting plate eliminating the bolts mounting the straps to the plate this would go a long ways to keeping the tank from rocking on the plate.
Sorry for the hijack more then happy to delete my post, just trying to help!!
I would also be concerned that when this flex/twisting is happening it may cause the straps rip or tear where the mounting holes are drilled.
I would rather see slots cut in the sides of the mounts and have the straps pass under the mounting plate eliminating the bolts mounting the straps to the plate this would go a long ways to keeping the tank from rocking on the plate.
Sorry for the hijack more then happy to delete my post, just trying to help!!
- Thread starter
- #1,248
Back from dinner. No, you guys are not high jacking my post. I don't want my fuel tank cracking or breaking loose.
The bottom mount is pulled down on top of my frame rails right on top of the fish plated section. I used M12 grade 10.9 bolts. I didn't think there'd be any twisting taking place but I'm not trained in mechanical engineering. The reason I attached it to the cross tube is because to keep the top level, the back rail of the mount is only 1" tall. The front rail is 3" tall. Would it be less likely to flex if it was just clamped down on top of the frame rails? I thought that tube added support to the frame there.
My uneducated thought was that the additional attachment I wanted to add 90 degrees to the bottom mounts on the end of the tank would take care of it potentially rocking forward. I didn't think of the mount underneath twisting at all. It "feels" solid but a full tank of fuel in a violent movement, maybe not. I read MANY posts on off road forums of cracking aluminum fuel cells. Seemed to be unsolved until they went to bladder type cells.
This is the space I have to work with. If I have to make a different mount, I will.
The bottom mount is pulled down on top of my frame rails right on top of the fish plated section. I used M12 grade 10.9 bolts. I didn't think there'd be any twisting taking place but I'm not trained in mechanical engineering. The reason I attached it to the cross tube is because to keep the top level, the back rail of the mount is only 1" tall. The front rail is 3" tall. Would it be less likely to flex if it was just clamped down on top of the frame rails? I thought that tube added support to the frame there.
My uneducated thought was that the additional attachment I wanted to add 90 degrees to the bottom mounts on the end of the tank would take care of it potentially rocking forward. I didn't think of the mount underneath twisting at all. It "feels" solid but a full tank of fuel in a violent movement, maybe not. I read MANY posts on off road forums of cracking aluminum fuel cells. Seemed to be unsolved until they went to bladder type cells.
This is the space I have to work with. If I have to make a different mount, I will.
- Thread starter
- #1,249
Would adding X braces in this help?
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- Thread starter
- #1,250
@Broski, yep, I'm feeling like I'm getting close to being able to start it at least. Still a LOT of work. I'm not looking forward to body and paint. Part of me wants to leave it fugly but functional.
I've already been working with one good arm for a couple years, My right arm is damn near useless. I've needed a shoulder replacement but I can't go down until my wife is better. I see the ortho surgeon next month so I really want to get some stuff done.
I've already been working with one good arm for a couple years, My right arm is damn near useless. I've needed a shoulder replacement but I can't go down until my wife is better. I see the ortho surgeon next month so I really want to get some stuff done.
- Thread starter
- #1,251
When I got under the truck, this was glaring at me. The two rock anchors. I've talked to others running the same suspension and they said it hangs up enough to bug them.
I'm going to use plate and make it bolt to the rod end bolts. Basically a square slider instead of welding tube between them. I need to be able to remove them. My muffler is directly above that space on the driver side and my parking brake linkage is at the passenger side so they need protection.
Truck is sitting on the bumps. Floor to bottom of the frame below the cab is 21 1/2".
I'm going to use plate and make it bolt to the rod end bolts. Basically a square slider instead of welding tube between them. I need to be able to remove them. My muffler is directly above that space on the driver side and my parking brake linkage is at the passenger side so they need protection.
Truck is sitting on the bumps. Floor to bottom of the frame below the cab is 21 1/2".
One of my wheeling buddies has the same 4wheelunderground setup as yours and yes he get hung up on those. I think your plan is a good idea.
I think your mount is more then strong enough. The flex is going to come from the frame flexing as your rock Crawling not the weight of the tank.
If you can get the straps to pass under the mounting plate instead of bolting to the top. then add flat stock pieces say 2x2 or 2x3 weld at a 45 off the sides at each strap to create a cradle then the four straps would be sufficient to hold the tank in place yet allow enough movement for the flex.
@ntsqd may have better ideas.
I think your mount is more then strong enough. The flex is going to come from the frame flexing as your rock Crawling not the weight of the tank.
If you can get the straps to pass under the mounting plate instead of bolting to the top. then add flat stock pieces say 2x2 or 2x3 weld at a 45 off the sides at each strap to create a cradle then the four straps would be sufficient to hold the tank in place yet allow enough movement for the flex.
@ntsqd may have better ideas.
- Thread starter
- #1,253
I'll pull the tank and straps off the base plate and set the tank and assembled straps down into that space and see what my options are. Nobody is hurting my feelings so keep the suggestions coming. I made all that with scrap so I'm only out my time and I still had fun building it.
ntsqd
technerd
Perhaps the way to go is to put some saddles that the tank sits in on the mount, and then bring the top straps all of the way down to the mount - put the anchors for those bolts directly on the mount. One strap's worth:
remember that Toyota's of that generation hard mounted the tanks... I don't think this mount will see much, if any torsional stress.
ntsqd
technerd
They are hard mounted, but the mounts are deliberately not super torsionally rigid. Everything, including the tank itself, was designed with that mounting in mind. This tank is different and is oriented 90° from the OE tank location.
- Thread starter
- #1,257
ntsqd
technerd
I only showed one of either 2 or 4 straps as I expected that they'd all be the same. Mostly just to get across the design that I had for consideration. Looking at it now I think those little gussets under the existing lower straps would take a lot of the rocking out w/o needing to do a bunch of re-work. Maybe just weld the lower straps to the mount and extand the gussets down the front and rear sides of the mount?
Oddly those early Mustang fuel tank's mounting method have popped into my head a couple of times. Too bad this tank doesn't have a similar flange because then the mount could be made similar to the opening the Mustang unibody and 4 single bolt clamps could be used to hold it in place.
You asked about putting X's in the underside and I'd only do that if you're going to make the mount use two mounts at one frame rail and a single mount at the opposite frame rail.
Maybe make the skid tubes between the rock anchors bolt the angled flats of each mount instead of using the rod end bolts? Then you don't have to pull two rod end bolts and have part of the suspension flopping around loose just to remove the skid just to get at the muffler or the p-brake stuff.
Oddly those early Mustang fuel tank's mounting method have popped into my head a couple of times. Too bad this tank doesn't have a similar flange because then the mount could be made similar to the opening the Mustang unibody and 4 single bolt clamps could be used to hold it in place.
You asked about putting X's in the underside and I'd only do that if you're going to make the mount use two mounts at one frame rail and a single mount at the opposite frame rail.
Maybe make the skid tubes between the rock anchors bolt the angled flats of each mount instead of using the rod end bolts? Then you don't have to pull two rod end bolts and have part of the suspension flopping around loose just to remove the skid just to get at the muffler or the p-brake stuff.
This would work well, creating a saddle out of the straps and hard mounting them at the same time.
Extending the gussets down the front and rear sides is what will make the difference.
Obviously @ntsqd is better at explaining things better than I
- Thread starter
- #1,260
Thanks for all the ideas.
The only reason I didn't weld the lower 1/8" saddles was because of how they obstruct pulling the bed. I can unbolt the whole mount though if I do.
Welding something directly to the frame was my original intent but I didn't want to cut and grind on my frame if this tank choice didn't work out.
Would a welded in cross member in that location serve as a better platform without flex?
The only reason I didn't weld the lower 1/8" saddles was because of how they obstruct pulling the bed. I can unbolt the whole mount though if I do.
Welding something directly to the frame was my original intent but I didn't want to cut and grind on my frame if this tank choice didn't work out.
Would a welded in cross member in that location serve as a better platform without flex?
