Help securing tank mount

Marc11

Premier Member
#1
Looking for some help from someone smarter than me.

My aux tank is mounted to a plate which takes place of my passenger seat. To add additional security over the three pin connection points designed for the seat and not a 50 pound fuel tank, I added four 1" x 2" aluminum flat bar tabs bolted down to the frame of the bike at each corner that run across from left to right of the plate.

As the plate is on a downward slope from the rear of the bike to the front, the two front tabs will not sit flush with the plate, the rear are fine and flat, but the fronts will not sit flush, only the very front edge of the tab will contact the plate because of the slope of the plate.

Any idea what I need to do to get the tab to at flush? I'm assuming I need to bevel the hole for th bolt on the tab but not certain that is the best or even a correct approach.
 

EricV

Premier Member
IBR Finisher
#2
You will need more than just the seat latch to pass tech in most rallies, so good on you for working on that.

Pictures will help. ;) I think I understand what you're working with. You're trying to keep the plate flat, but the frame is angling down to the front.

How about a hole in the plate that allows the bolt to run strait down, then a beveled aluminum spacer to fit the gap?
 

Marc11

Premier Member
#3
Yes I know I need more than the seat latch which is why I added the four tabs bolted to the subframe. Although it passed tech in 2019, I don't want to press my luck.

I can post up pics I need to resize them first.

But you understand the issue, right now I run a bolt through the bar and into the subframe. The tab is just being pressed against the plate, it's not bolted to the plate right now until I get everything set right.
 

keithu

Premier Member
#4
I don't know if this helps, but some T-slot tubing (80/20, etc.) might be useful because you can create joints with infinitely variable angles. Here you can see that a vertical T-slot posts bolt to L brackets that are mounted to the subframe, which is at an angle. You don't need to use these exact materials, but by attaching something through the Y-axis (left to right) of the bike rather than the X-axis (front to back) you might be able to get a strong connection. I imagine it will be difficult to find a beveled washer of exactly the correct angle for an X-axis mount.
 

Attachments

Marc11

Premier Member
#5
Thank you. The front to back mounting works fine, it's the left to right where the issue comes up.

Your idea of the t-slot tubing is good, I'm going to research that. Thanks.
 

Marc11

Premier Member
#6
So this is what I came up with....

The mounting plate initially locks into the two rear tabs and one front pin seat locking locations on the bike. We know this is too weak.

I ran two 2"*1"*12" aluminum bars from the rear to the front of the mounting plate.

I then bolted the rear of each bar to the rear subframe of the bike.

I drilled and added two bolts, one midway and one at the front of the bar on each side.

The idea with the side bolts is to ensure the bar is tight against the plate and also, should a seat mounting point fail, the plate cannot move or rack on the bars as the front and middle bolts prevent that.

It's rock solid, plate does not move at all.

Questions in my mind is if this is enough or do I need to further secure the front of the plate to the frame? Not sure, I cannot think of a scenario where the plate could come loose outside of both rear bolts breaking and all three seat locking points failing.

Open for thoughts and suggestions.

Pics here:

https://photos.app.goo.gl/cUBgQnDFprZzCnyf8
 

EricV

Premier Member
IBR Finisher
#8
Looks very secure now. I assume the cell will be bolted to the black plate, so no movement should be possible in any direction at this point.