Advice for tank mount tab that repeatedly fails please... - The Jockey Journal Board

Go Back   The Jockey Journal Board > General Discussion > The Board

Reply
 
Thread Tools Search this Thread Display Modes
Old 04-21-2019, 11:37 AM   #1
Dan Boy
Senior Member
 
Dan Boy's Avatar
 
Join Date: Sep 2009
Location: Norfolk, UK
Posts: 2,444
Default Advice for tank mount tab that repeatedly fails please...

I was out riding yesterday and it became apparent that I had a fuel leak from the tank. Nothing major and I got home fine but this is the second time this has happened, I fixed it the first time but I am looking for a long term solution to this particular problem.

I should say that at this point, I am no master welder nor fabricator and it is my lacking in both these areas that I feel has failed me in this case.

To give a little history, when I bought this tank it had no mounting points at all, I welded a couple of bungs on the underside and went for a straight tab mount for the rear of the tank.

I would suggest that the tank wall thickness will be 1mm or there abouts and I welded on a 3mm thick tab to this.

You can see from the picture the specific area that is leaking as I pressure tested the tank today.

So I have some questions that someone may kindly be able to shed some light on who has far more experience than me in this field:-
  1. Is welding a 3mm tab to a 1mm piece of steel going to immediately weaken the thinner part?
  2. Has this area now suffered metal fatigue and repairing it again is pointless?
  3. Should I be looking at a larger weld area on a thinner tab to give more strength to the mounting point?

I should point out that the tank tunnel does not sit flat on the back bone.

I do want to get this fixed as soon as possible because I just want to ride but I don't want to be doing this again at the end of the summer.

If the advice is that I should get a pro welder to weld a tab on then I am happy to go with that also.

Thanks for reading, Dan.
Attached Thumbnails
Click image for larger version

Name:	DSC_0558.jpg
Views:	82
Size:	275.6 KB
ID:	254326  
__________________

https://www.jockeyjournal.com/forum/signaturepics/sigpic21807_5.gif

Blown Triple Build
Dan Boy is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 04-21-2019, 11:53 AM   #2
joe49
Senior Member
 
joe49's Avatar
 
Join Date: Apr 2009
Location: Tonica Il
Posts: 1,745
Default Re: Advice for tank mount tab that repeatedly fails please...

More pictures showing more of the tank and area would help.
But right off I'd say leave the welding to some one more skilled.
If you want long term success, the tank mount and all frame mounts need to be mated square to each other. No pulling them tight to make them mate with the fasteners.
My go to method is before paint to mount it and heat the tabs to cherry red to allow them to stress relieve.
__________________
OLD MOTORCYCLE ENTHUSIAST
joe49 is offline   Reply With Quote
Old 04-21-2019, 01:06 PM   #3
richbob
Senior Member
 
richbob's Avatar
 
Join Date: Sep 2011
Location: Toscana
Posts: 2,215
Default

Now that’s a top bit of advice cherry red
__________________
Rush Rush to the Yayo. Blondie

"Ultimately were all dead men"(Oliver Reed.Gladiator)
richbob is offline   Reply With Quote
 
Old 04-21-2019, 06:37 PM   #4
KCgran
Senior Member
 
Join Date: Dec 2011
Location: kentucky,USofA
Posts: 1,352
Default Re: Advice for tank mount tab that repeatedly fails please...

Yes , on the bigger pics of the area so we can better see what you are doing, please. I have some advice but I’m going to wait for better pics. I want to see where that tab is welded on to the tank. I recall that you have a tig welder and showed some of your welds before and were becoming pretty proficient with it. I think you can do it yourself, you may need some advice on the design of the tab to make it robust enough to stand the test of time. Being able to able to lay a bead is only one small aspect of fabrication. The design of the joints and layout of the welds is the more important I think. So please more pics
__________________
I buy all my groceries and pharmaceuticals at Circle K
KCgran is offline   Reply With Quote
Old 04-21-2019, 07:13 PM   #5
hammerweight
Senior Member
 
hammerweight's Avatar
 
Join Date: Oct 2013
Location: Canada
Posts: 128
Default Re: Advice for tank mount tab that repeatedly fails please...

Dan,
Toss us a couple more pics...too bad you’re not a little closer...lol, I’d fix it no charge...
__________________
www.marshallmetalshaping.com
hammerweight is offline   Reply With Quote
Old 04-22-2019, 02:11 AM   #6
Dan Boy
Senior Member
 
Dan Boy's Avatar
 
Join Date: Sep 2009
Location: Norfolk, UK
Posts: 2,444
Default

Thanks for the replies, here are some more pictures. Hope this helps. You can see the area where I have removed the paint around the weld.

Thanks, Dan
Attached Thumbnails
Click image for larger version

Name:	DSC_0559.jpg
Views:	61
Size:	292.7 KB
ID:	254336   Click image for larger version

Name:	DSC_0560.jpg
Views:	63
Size:	315.4 KB
ID:	254338   Click image for larger version

Name:	DSC_0561.jpg
Views:	57
Size:	277.3 KB
ID:	254340  

__________________

https://www.jockeyjournal.com/forum/signaturepics/sigpic21807_5.gif

Blown Triple Build

Last edited by Dan Boy; 04-22-2019 at 02:33 AM. Reason: Damn pics wouldn't load up from my phone.
Dan Boy is offline   Reply With Quote
Old 04-22-2019, 03:04 AM   #7
Ducbsa
Senior Member
 
Join Date: Jan 2009
Location: Virginia
Posts: 683
Default Re: Advice for tank mount tab that repeatedly fails please...

It looks like a butt joint, a lap would be better. Fitting it to the frame as mentioned above would go a long way.
Ducbsa is offline   Reply With Quote
Old 04-22-2019, 05:39 AM   #8
KCgran
Senior Member
 
Join Date: Dec 2011
Location: kentucky,USofA
Posts: 1,352
Default Re: Advice for tank mount tab that repeatedly fails please...

As Ducbsa say a lap weld is in order. Remake the tab a 1/2” longer and let it extend into the tunnel. Weld it on the end of the tab in the tunnel and where it exits the tunnel.this will have much more structural strength than a butt weld. Now instead of the butt weld vibrating and wearing the tank metal, the flex will most likely be happening between the end of the tank to the bolt on the tab where the metal is thicker.
__________________
I buy all my groceries and pharmaceuticals at Circle K
KCgran is offline   Reply With Quote
Old 04-22-2019, 11:27 AM   #9
joe49
Senior Member
 
joe49's Avatar
 
Join Date: Apr 2009
Location: Tonica Il
Posts: 1,745
Default Re: Advice for tank mount tab that repeatedly fails please...

As said a lap joint is the way to go. Cherry red is viewed in shade not in sun light. The weld should not be continuous, it should be 3/4 of the length of each of four sides, with no craters at the ends.
__________________
OLD MOTORCYCLE ENTHUSIAST
joe49 is offline   Reply With Quote
Old 04-22-2019, 11:28 AM   #10
Dan Boy
Senior Member
 
Dan Boy's Avatar
 
Join Date: Sep 2009
Location: Norfolk, UK
Posts: 2,444
Default Re: Advice for tank mount tab that repeatedly fails please...

Quote:
Originally Posted by hammerweight View Post
Dan,
Toss us a couple more pics...too bad youre not a little closer...lol, Id fix it no charge...
Quote:
Originally Posted by KCgran View Post
As Ducbsa say a lap weld is in order. Remake the tab a 1/2 longer and let it extend into the tunnel. Weld it on the end of the tab in the tunnel and where it exits the tunnel.this will have much more structural strength than a butt weld. Now instead of the butt weld vibrating and wearing the tank metal, the flex will most likely be happening between the end of the tank to the bolt on the tab where the metal is thicker.
Quote:
Originally Posted by Ducbsa View Post
It looks like a butt joint, a lap would be better. Fitting it to the frame as mentioned above would go a long way.
Hammer - if only distance were not a problem

Thanks Duc for pointing that out and KC, I will do the lap welded part as you suggest. I wonder if the thickness has any bearing here. Should I go for a thinner tab or is using 3mm OK for this application?

Thanks again for all the interest, Dan.
__________________

https://www.jockeyjournal.com/forum/signaturepics/sigpic21807_5.gif

Blown Triple Build
Dan Boy is offline   Reply With Quote
Old 04-22-2019, 02:33 PM   #11
VonWegener
Senior Member
 
VonWegener's Avatar
 
Join Date: Nov 2009
Location: Apple Valley
Posts: 3,223
Default Re: Advice for tank mount tab that repeatedly fails please...

I think a 3mm tab is fine if it extends into the tunnel. You have to consider that a full tank of gas is a lot of weight and if the tank can rock from side to side it will stress the weld no matter what. How is the front mounted? Can you keep the tank from moving around?
__________________
*
Your friendly neighborhood W&W Cycle Germany, Paughco and V-Twin dealer

VonWegener is offline   Reply With Quote
Old 04-22-2019, 04:31 PM   #12
KCgran
Senior Member
 
Join Date: Dec 2011
Location: kentucky,USofA
Posts: 1,352
Default Re: Advice for tank mount tab that repeatedly fails please...

Honestly the thicker the tab the better in this case. Think about how gravity will “ load” this joint, and the exponential increase in downward force when you hit bumps in the road that are trying to force the bolted end of the tab up, while gravity is still forcing the tank down.
The tab welded on top where it goes under the tank becomes a lever point, but because you’ve extended the tab under the tank ( the farther the better, btw, IF you weld some stitch welds along the side of the tab in the tunnel) it can’t pivot there like it could with the butt weld , so the tab has to either deform the back of the tank( not likely) or bend between the end of the tank and the mounting bolt. Also the shorter the distance between the end of the tank and the mounting bolt the better.. hope this helps and is understandable.
__________________
I buy all my groceries and pharmaceuticals at Circle K
KCgran is offline   Reply With Quote
Old 04-23-2019, 11:39 AM   #13
Dan Boy
Senior Member
 
Dan Boy's Avatar
 
Join Date: Sep 2009
Location: Norfolk, UK
Posts: 2,444
Default Re: Advice for tank mount tab that repeatedly fails please...

Thanks for your input VW, I have two bungs under the tank that is holding the front steady. No problem from those.

KC, thanks - as always - for you detailed explanation. I will get to it and be riding again soon.

Dan.
__________________

https://www.jockeyjournal.com/forum/signaturepics/sigpic21807_5.gif

Blown Triple Build
Dan Boy is offline   Reply With Quote
Old 04-28-2019, 07:10 AM   #14
jsaw
Member
 
Join Date: Oct 2008
Location: Geneva N.Y.
Posts: 60
Default Re: Advice for tank mount tab that repeatedly fails please...

I have strips of rubber between the tank and frame on my bike in order to cushion / isolate the tank from vibration
jsaw is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
taillight mount advice Concrete B The Board 9 08-06-2010 10:27 PM
Fab advice needed: Welding mount bungs onto gas tank Miker The Board 3 07-29-2010 03:39 PM
Broken Motor Mount Advice... MotorBike Mike The Board 9 08-03-2009 10:57 PM
Advice regarding 49 Pan Misalighned Motor Mount Holes ElkCreek The Board 7 07-13-2009 02:13 PM
Ironhead rear motor mount broken..... rukwikenuf The Board 3 05-07-2007 01:23 AM


All times are GMT -5. The time now is 05:26 PM.