Broken Rear Bulkhead.......


OneLapper

"You don't *really* need the water pump...."
Forum's Sponsor
Likes
781
Location
Connecticut
#1
This past weekend I did the GP and Sprint Enduro at a JDay Offroad event at Hemonds in Maine.

On the second to last test for the Sprint Enduro, I low-sided the MX. It was non-event. I picked the bike up and continued on. At some point I realized the rear brake wasn't working. After the test I got back to the trailer and noticed the lower mounting tab on the bulkhead was cracked and missing. This allowed the master cylinder bracket/guard to pivot on the top bolt, preventing the rear brake from functioning.

Alta IMG_7289.jpg Alta IMG_7290.jpg Alta IMG_7291.jpg Alta IMG_7293.jpg Alta IMG_7307.jpg
 

rayivers

Well-known member
Likes
238
Location
CT, USA
#4
It looks like the lower large Torx screw on the boot guard is still tight - is the broken-off piece still being held by it? If so, you could try JB Welding it back on and hoping for the best (I did something very similar on one of my vintage bikes; alignment was critical, but after the JB Weld cured I just chased out the threads with a tap & it worked fine). If it were my bike I'd also JB Weld on a large fender washer behind it, for a larger glue area & also to add some steel into the mix (there's enough swingarm clearance on my MXR to do it, hopefully the same on yours).

If you really want to be sure it'll hold up long-term you could install a 12.9 screw into the top-hole threads from the rear (red LocTite on the final threads near the screw head) and torque it down to about 8 ft/lbs, then use that as a stud along with an M6 flange nut (you might need a 1/4" drive socket to install it in the tight boot-guard tunnel). This would allow you to really torque down the top of the MC for added holding power and twist resistance, without risking damage to the bulkhead threads.
 

OneLapper

"You don't *really* need the water pump...."
Forum's Sponsor
Likes
781
Location
Connecticut
#5
Yeah that’s a mega-bummer. Weld repair would scare me without totally tearing it apart. I’d go LHRB and forget about the foot brake.

Nice trailer BTW!
The LHRB is just waiting for me to get the time to install it. I've had so many projects going on it was a challenge to just get to this event.

Thanks on the Airstream! We spent 4 years looking for the right deal. So many losers and scammers trying to sell them, you almost lose faith in humanity. This one was in TN it's entire life, we're the third owners. Still lots to do to get it 100% but the plan is to do the work in small sections so we can continue using it.
 

OneLapper

"You don't *really* need the water pump...."
Forum's Sponsor
Likes
781
Location
Connecticut
#6
It looks like the lower large Torx screw on the boot guard is still tight - is the broken-off piece still being held by it? If so, you could try JB Welding it back on and hoping for the best (I did something very similar on one of my vintage bikes; alignment was critical, but after the JB Weld cured I just chased out the threads with a tap & it worked fine). If it were my bike I'd also JB Weld on a large fender washer behind it, for a larger glue area & also to add some steel into the mix (there's enough swingarm clearance on my MXR to do it, hopefully the same on yours).

If you really want to be sure it'll hold up long-term you could install a 12.9 screw into the top-hole threads from the rear (red LocTite on the final threads near the screw head) and torque it down to about 8 ft/lbs, then use that as a stud along with an M6 flange nut (you might need a 1/4" drive socket to install it in the tight boot-guard tunnel). This would allow you to really torque down the top of the MC for added holding power and twist resistance, without risking damage to the bulkhead threads.
The lower bolt is still there, but the threaded portion of the case is not.

I'm hoping Alta will look at this design and compare it to the KTM 250 I took pictures of and sent to them. The boot guard/MC mount acted like a shovel in the soft dirt when I low-sided, unlike the KTM which tucks the MC behind the right frame upright, making it near impossible for the MC to be hit.

Alta suggested I weld the case. If I am forced to go that route, Alta will have to make available the tech manual so I can safely disassemble the bike, remove the motor and electronics, all without getting electrocuted. The other option they offered is to purchase a new bulkhead, but I'm in the same scenario of needing to completely disassemble the bike and remove the motor.

Either way, it's going to be better than original when I'm done with it.
 

rayivers

Well-known member
Likes
238
Location
CT, USA
#7
it's going to be better than original when I'm done with it.
This is the way I've always tried to do things too, but the electric experience has forced me into 'plan B mode' so many times it's now become plan A. :)

Just to get you back up for now... you could also do two of the JB Welded screw/studs I mentioned, using what's left of the lower threads for a guide if possible. If you use enough JB Weld around the screw head it should be plenty strong for anything short of another crash, and can be easily removed with a torch later on. That way you can ride while working out the logistics of your surely-much-better repair, which I predict will take far longer than you think.
 

Similar threads