Drilling holes in frame

[solidstateirons]

Hello, once again with another question. Thank you all in advance, you have been lots of help since i started this project.

Here is my question, I am trying to mount a sportster gas tank that has the mount tabs like this tank below but the front is the same as the back (will mount on the sides)



So I was thinking on drilling holes going thru the frame and weld bungs on each side to mount the tank. Will that weaken the frame? or welding the bungs will be like there was never holes. I would like to know if you guys have any inputs on how to mount this tank without weakening the frame.

Thanks again!

 

[figure8]

Going off the pic the front mount looks like it should clear the frame and mount to a neck gusset or whatever you so choose to weld there to secure it. As far as the rear mount, I think you'll be fine if you use some kinda bung welded in place of the hole you drill. I doubt it'll weaken to the point you'll notice it or have problems later on.
If you have doubts then just weld a mounting tab in the rear of the tank and have secured to a single bung such as this.

 

[solidstateirons]

Going off the pic the front mount looks like it should clear the frame and mount to a neck gusset or whatever you so choose to weld there to secure it. As far as the rear mount, I think you'll be fine if you use some kinda bung welded in place of the hole you drill. I doubt it'll weaken to the point you'll notice it or have problems later on.
If you have doubts then just weld a mounting tab in the rear of the tank and have secured to a single bung such as this.

I was actually considering that idea for the rear part of the tank but my "fear" is welding and have the tank leaking. Also I only have a MIG welder and I think with a TIG would look much cleaner if i end up doing the rear tab like that.

 

[figure8]

I hear ya man, if you have concerns about doing a tab in that fashion on the tank just do the two through the frame, I'll think you'll be fine. Just keep an eye on it from time to time.

 

[solidstateirons]

I hear ya man, if you have concerns about doing a tab in that fashion on the tank just do the two through the frame, I'll think you'll be fine. Just keep an eye on it from time to time.

Should i drill holes and go thru the frame? or drill holes and weld bungs?

 

[angus67]

I drilled through the frame and sleeved it with a small peice of tubing, and used the right size shoulder bolt. Same tank.

 

[barncat]

(2) 6mm dia holes drilled through the frame, while not ideal, will have no significant safety impact.

what that will do however is create an annoying metal to metal buzz between tank and frame, even if you attempt to isolate with rubber and foam strips etc... a bike i bought a while back was already setup with a peanut tank. never again... i will only mount tanks with full rubber bushing isolation.

and yes, if you attempt to weld a tab to the tank there's a very good chance it will leak unless you're experienced at TIG. it takes way less than a pinhole to leak, plus a used tank must be rinsed internally with water before welding...