Rear sub-frame cracks

I'm starting a new thread to re-emphasize the importance of limiting the load placed in a top box! Feel free to combine it with the other threads on the issue.

I have a 2006 FJR1300a (gen II). I have a Yamaha top trunk (with recall upgrade). 20,000 miles.

I had the rear sub-frame replaced under warranty last summer. The cracks were discovered by the service manger when the trunk recall was being performed. I had less than 10000 miles on the bike and it was less than a year old.

Unfortunately, I did not research this problem on this forum until after the new sub-frame was installed. If I had known the problem that others have had, I would've had the new sub frame welded/reinforced before installing it. It would have been so easy then. However, hoping to avoid a repeat, I severely limited the weight I carry in the top trunk. For example all I carry in the trunk on a daily basis: 4 bungee cords, a small hand towel, Geza Gear MC cover, gloves (winter), baseball cap and a 20 oz bottle of water. This has to be less than 7 lbs!

All this caution for nothing! Yesterday I noticed when I closed the trunk before going to work that it "bounced" up and down more than usual. I quickly removed the pillion seat, peered at the sub-frame and saw what I knew was going to be the case....Both side cracked! Same spot as last time!

IMHO rear sub-frame is seriously under engineered.

I can't imagine how someone could avoid this problem, especially if they ride two-up (my wife doesn't ride with me).

Needless to say I am very disappointed by this. :angry: :dribble: I will repair/reinforce the cracks this winter.

EDITED to add photos





LC

Could you please get some pictures of the location of your cracks. If you were so diligent to avoid overloading the box I don't see how it keeps cracking. Maybe there is something more involved?

Bummer man.

While I might go so far as to say that the rear subframe design could be much stouter, I am not so sure the sky is falling as of yet. What happened to you seems to be an anomaly. If the problem was as bad as you suggest, there would be all kinds of peeps around here with cracked rear subframes and that just hasn't happened. Why it has happened twice to you is very interesting.

The only others that I am aware of are from Gen I bikes with a totally different rear subframe, and that were hard core LD bikes and loaded pretty heavily back there.

My own Gen I did experience a rear subframe crack. But I don't think having the FJR doing cartwheels down the road after a highside would be considered reasonable use in the design parameters.

Are you absolutely positive about the weight? If you had it crack in the far tail area using the factory mount and only had 7 pounds....then that's very odd. My subframe cracked because I was using a custom mount that only used three of the 5 securing points and was running more like 30 pounds.

Also, the subframe has two distinct components to it. The area that a pillion sits on is different than the area that force is exerted with a Top Case. That area of the subframe is a cast unit of marginal quality metal that's then welded to other part that is square tubing. The square tubing is much better quality and fine.

I wonder if the stock Givi rack helps at all considering it mounts in several places instead of just the very rear?

I only ask this because I have a Givi, and I've had it loaded to the hilt for roughly 6000 of the 12000 miles the bike has.

All good points. Things I've taken into consideration. I will try to get some shots of the cracks and post them here.

Also, while I'm certain of the weight....I'm also a recent member of the crash club. A high side which subjected the bike to, let us say, extreme stresses. While I checked for sub-frame cracks afterwards, it is entirely possible that the sub-frame sustained damage which was not visible, but would eventually become full blown cracks...

At any rate, when I'm done I'll be able to put anything (reasonable) I want to in the top case!!

LC

Last Chance said:

... I will try to get some shots of the cracks ...

Click to expand...

Does this help Loren? :lol:

(from bergs' trip report!)

Hmm, that's not a crack I'd try and weld up... :huh:

Last Chance said:

I'm also a recent member of the crash club. A high side which subjected the bike to, let us say, extreme stresses. While I checked for sub-frame cracks afterwards, it is entirely possible that the sub-frame sustained damage which was not visible, but would eventually become full blown cracks...

Click to expand...

Ahhhhhh-Haaaaaaa!

You failed to mention that little gem the first time around. I wouldn't go blaming Yamaha's subframe design quite yet.

SkooterG said:

Last Chance said:

I'm also a recent member SNIP d damage which was not visible, but would eventually become full blown cracks...

Click to expand...

Ahhhhhh-Haaaaaaa!

You failed to mention that little gem the first time around. I wouldn't go blaming Yamaha's subframe design quite yet.

Click to expand...

Because I knew YOU would jump all over that.....I expect my machine to be able to handle a little "stressful" somersaults!!! After all doesn't the saying go, "It's not if, but when!"

Mike, your mind works in really unusual ways, which I will not comment on! :dribble:

LC

A high side can really stress the rear sub-frame. The weight of the bike hits that area, that's pretty darn stressful. I'd say you just answered your own issue.

SkooterG said:

Last Chance said:

I'm also a recent member of the crash club. A high side which subjected the bike to, let us say, extreme stresses. While I checked for sub-frame cracks afterwards, it is entirely possible that the sub-frame sustained damage which was not visible, but would eventually become full blown cracks...

Click to expand...

Ahhhhhh-Haaaaaaa!

You failed to mention that little gem the first time around. I wouldn't go blaming Yamaha's subframe design quite yet.

Click to expand...

I've added photos. While I can't claim it is a design problem, these cracks are identical to the ones on the original sub-frame which was replaced after only 2000 miles. Since I had a couple tip-overs while stationary prior to that and since this isn't a "common" problem I would guess that anyone that has had a tip-over with the top trunk should check the rear sub-frame for cracks.

If need be, I could reweld and strengthen it. PM me if you wish to pursue...

Garauld rocks! Other forums don't have guys like this. We're lucky!

garauld said:

Hmm, that's not a crack I'd try and weld up... :huh:

Click to expand...

You need some of this?????

https://www.youtube.com/watch?v=ruFp4Tj3RjU

My Shad 48 has been heavily loaded on every long trip I've taken. While my bike only has 7k on the clock, the topcase is always on and, when not on a long trip, it ususally has about 10 lbs of gear in it. No cracks so far.

Do you have the stock platform and grab rail, or have you had some kind of custom moount installed? If the grab rails are gone, then you're getting what you would expect, as the rails form a triangulation brace for the rear bulkhead of the subframe. That's what Iggy referred to when he said his mount used 3 of the 5 mounting pounts. I have the Givi E52, which replaces the stock platform and rail with a steel rail, ups the "allowable" weight to 13 pounds, and I regularly carry about 15 to 20 pounds.

wfooshee said:

Do you have the stock platform and grab rail, or have you had some kind of custom moount installed? If the grab rails are gone, then you're getting what you would expect, as the rails form a triangulation brace for the rear bulkhead of the subframe. That's what Iggy referred to when he said his mount used 3 of the 5 mounting pounts. I have the Givi E52, which replaces the stock platform and rail with a steel rail, ups the "allowable" weight to 13 pounds, and I regularly carry about 15 to 20 pounds.

Click to expand...

Stock platform and Yamaha Top box.

LC

In that case I would chalk it up to playing tumbleweeds with the bike. . .

It occurs to me to wonder if something in the subframe is bent, causing the parts at the back to not line up right. Maybe that bulkhead is just a titch forward or above where it ought to be, causing the grab rails to not have the correct bracing tension. Just kinda wondering out loud.

Again, if the bike has tumbled, an impact on the tail would seriously overload that bulkhead, even a glancing blow.