Tag bracket broken; weld? replace? substitue solution?

[p6x]

As I got the Le Mans out to start my South Padre Island trip early this morning, the tail light turn indicators  number plate assembly fell off....

The bracket holding the assembly broke. The culprit seems to be item 11.

I looked at the Guzzi spare parts catalog, I don't know if I am going to be able to find one of these number plate support. Also, the assembly was held by a plastic tie, so this looks like the entire mudguard was chopped off at some point.

I am looking for suggestions, ideas before I decide what to do. The entire tail assy held by this flimsy bracket and happily vibrating produced the obvious result. I am not sure the top part of the bracket is not integral of that support which I am indicating with the arrow. This part is not shown on the Guzzi catalog.

 

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[p6x]

I have just finished to remove it. It broke at both corners.

I am still going to get it welded.

 

[p6x]

3 hours ago, docc said:

Perhaps a history of undisclosed collision?

Perhaps; but the place where it broke makes perfect sense. This is just close to the two welds, where the heat weakened the carbon steel. The mount plate was solidly screwed to the frame, leaving the tail end free to vibrate. All the weight of the tail end is there.

I will take a picture of the other side tomorrow; you will understand right away why it broke where it did.

I am going to go to a welding ship tomorrow. We need to grind the weld out on the other side, make a chamfer and weld it again.

I was lucky this incident happened at home while maneuvering by hand. If this had happened while on the road....

[p6x]

You can see the plate broke close to the welds on both sides. All the weight and the vibrations are concentrated there.

You can see that when the plate is bolted on the chassis, you got that cantilever part holding the tail light and turn indicators, and it is only supported by what, 1.5 cm of steel.

[p6x]

The mud guard is broken too.

The right side may have happened when I dropped the bike last year. The left side, I had never noticed it before.

 

[docc]

There are two studs that extend downward at the rear aspect of the long mudguard that carries the lights and license tag. These are capped with two nuts. This adds two more fasteners at the rear and eliminates the cantilever effect.

These are obscured by the inner cover.  Do you see this part of the retention system?

[docc]

Looking back at your first image, @p6x, we’re there any actual bolts or screws (there should be six fasteners) holding this assembly or just the plastic “zip-tie?”

[p6x]

22 minutes ago, docc said:

Looking back at your first image, @p6x, we’re there any actual bolts or screws (there should be six fasteners) holding this assembly or just the plastic “zip-tie?”

Just the plastic zip tie.

I don't think the tail assembly is original. The entire assembly is supported by the bracket that broke. I did see some unused holes when I took it apart. I think I am missing item 7, number plate holder.

 

[docc]

2 hours ago, p6x said:

Just the plastic zip tie.

I don't think the tail assembly is original. The entire assembly is supported by the bracket that broke. I did see some unused holes when I took it apart. I think I am missing item 7, number plate holder.

 

Both #7 and #18 are called "number plate holder" in the diagram. I believe you are missing #11 and your #7 has been shortened/ cut off below the number plate.

The original fastener system might still be usable. Let me mark up an image, host it, and post it for you . . .

 

[docc]

Alright, here is my best shot.

The image below is of #7 that I will refer to as the "Fender" (what the tail light and turn signals are bolted to).

@p6x's modified #7 has been cut off below the tail light, the #11 "Number Plate Holder" and the Tag Light (not pictured) are both removed from the modified "fender."  I am not yet convinced there is enough left of the modified #7 "Fender" to properly re-use.

edit: [-> So, upon close consideration, not likely collision or impact related. The broken Support Bracket is not the source of the failure, IMO - it stems from the inexpert modification to the #7 "Fender" which is the mounting structure for the tail/brake light, license tag/number plate, tag light, and turn signals.<-]

 

The image is looking rearward from the front (tire side) of the "Fender" hanging down a few inches from the mounting points. 

Three pair of fasteners hold this assembly to the #1 Rear Subframe and the #11 Support Bracket.

1) The vertical red lines represent where horizontal #7 "Fender" holes fit over vertical threaded studs extended down from the #1 Rear Subframe  and nutted from below (later V11 may have hex-drive bolts installed upward, from below). If these holes are cut off the modified #7 Fender, this is a problem and whole assembly will "cantilever" and fail as described.

2) The blue lines represent the pair of hex drive fasteners that that are engaged from behind , beside the Tag Light (which is likely missing on the modified fender), and are nutted from in front of the support bracket lower tabs through the lower two holes of the #28 "Rear Splash Guard". [This image shows the braces of the 1st Generation Tekno pannier mounts slightly obscuring the lower support bracket tabs.)

3)The yellow arrows indicate the "Nut-Certs" on the upper tabs of the support bracket that are engaged with two screws from the front of the top two holes of the #28 "Rear Splash Guard" (not shown in this image, but shown five posts back as the "The mud guard is broken too.")

[docc]

Looking back now, I see that assembly in failure mode. I am sorry I did not see it before and say something . . .

[p6x]

I agree with you. #7 has been shortened. The modification and the reduction of fasteners has properly made the support failure prone.

Once I manage to find a welding shop I will check if we can add some support beams so I don't experience that same issue again.

I am so bummed to be immobilized again. I was looking forward to that South Padre Island excursion. I also have to listen to people telling me I should purchase a bike that works...

 

[p6x]

6 minutes ago, docc said:

Looking back now, I see that assembly in failure mode. I am sorry I did not see it before and say something . . .

Well, I was lucky that it did not happen while I was traveling.

I am going to do a bit of engineering on that support, to make sure it does not happen again.

[docc]

6 minutes ago, p6x said:

Well, I was lucky that it did not happen while I was traveling.

I am going to do a bit of engineering on that support, to make sure it does not happen again.

Yessir. #7 is a structural member together with the #11 Support Bracket and #28 Splash Guard.

Nothing wrong with repairing the Support Bracket, it is not the issue.

It is the chopped up #7. Unless you can find all of those attachment points and re-fasten them properly, a replacement #7 is in order.