EVO tank bag sticky latch

tjhiggin

R.I.P. - 2022/06/11
Rest In Peace
Joined
Jul 6, 2016
Messages
327
Location
North Alabama
Bike
2004 ST1300A
My tank bag (SW-MoTech EVO DayPack) isn't waterproof, just water resistant. So on days when I ride to work, if there is a chance of rain I put the tank bag into the top box for protection.

I just beat the rain to the office this morning. The pull wire for the bag latch won't move, so the bag won't come off the tank ring. Argh! I'm standing there as the rain starts. After several seconds I give up and put the rain fly on the tank bag. Good thing I didn't have to stop for gas this morning.

Once the rain moves through, I go out and take a look. Fortunately the screws to remove the bag from the latch mechanism are easily accessible from inside the bag, under a velcro flap.

IMG_20200528_104000.jpg

After unscrewing the bag, it still takes a minute or more of fiddling with the latch to release it from the ring. Once removed, it takes great effort to pull the latch wire with enough force to move the mechanism.

Upon disassembling the mechanism, all the pieces are hard plastic except the pull wire and the return springs. There is a wheel inside that turns a small amount when the wire is pulled. The turning of the wheel causes 2 plates to slide away from each other, releasing the latches from the tank ring.

IMG_20200528_105435.jpg IMG_20200528_105448.jpg IMG_20200528_110551.jpg

It's hard to see in the next picture, but I've moved the wheel with my right thumb. You can see that the 2 plates are separated by a few millimeters; compare it to the picture above that shows the plates close together.

IMG_20200528_110933.jpg

This last picture shows the mechanism disassembled as far as I cared to take it. On the underside of each plate is a tab that fits into a slot in the wheel. It's hard to visualize, but when the wire is pulled and the wheel turns, the tabs slide in the slots and move the plates to release the latches. The springs then push the plates back together when the pull wire is released.

IMG_20200528_114308.jpg

There doesn't appear to have ever been any grease or other lubrication in the mechanism. This mechanism has worked flawlessly the entire time I've had it, over 3 years. I've ridden in the rain some lately, but it has never been a problem before, even when I was caught in a big storm in Wyoming in 2018 where the rain was blowing horizontally. There doesn't appear to be any signs of wear or friction on any of the parts. I wonder what caused it to start sticking.

I used some Molykote 111 grease we have here at the office to lubricate the mechanism and now it operates smoothly. The product sheet says it has "excellent water resistance" and is "compatible with many plastics and elastomers." Fingers crossed that the lube doesn't harm the plastic of the mechanism. If so, new mechanisms are available for about $53.
 
Great write up! Thanks for sharing! I too had the same issue and disassembled, cleaned and lubed. I used Vaseline to lube the assembly. I even put a dab in the channel that the cable slides through. Works as expected now.

I did not note any burs or defects, and very little wear on the various surfaces. I expect the problem to return in the future, but know what to do if it does!
 
My tank bag (SW-MoTech EVO DayPack) isn't waterproof, just water resistant. So on days when I ride to work, if there is a chance of rain I put the tank bag into the top box for protection.

I just beat the rain to the office this morning. The pull wire for the bag latch won't move, so the bag won't come off the tank ring. Argh! I'm standing there as the rain starts. After several seconds I give up and put the rain fly on the tank bag. Good thing I didn't have to stop for gas this morning.

Once the rain moves through, I go out and take a look. Fortunately the screws to remove the bag from the latch mechanism are easily accessible from inside the bag, under a velcro flap.

IMG_20200528_104000.jpg

After unscrewing the bag, it still takes a minute or more of fiddling with the latch to release it from the ring. Once removed, it takes great effort to pull the latch wire with enough force to move the mechanism.

Upon disassembling the mechanism, all the pieces are hard plastic except the pull wire and the return springs. There is a wheel inside that turns a small amount when the wire is pulled. The turning of the wheel causes 2 plates to slide away from each other, releasing the latches from the tank ring.

IMG_20200528_105435.jpg IMG_20200528_105448.jpg IMG_20200528_110551.jpg

It's hard to see in the next picture, but I've moved the wheel with my right thumb. You can see that the 2 plates are separated by a few millimeters; compare it to the picture above that shows the plates close together.

IMG_20200528_110933.jpg

This last picture shows the mechanism disassembled as far as I cared to take it. On the underside of each plate is a tab that fits into a slot in the wheel. It's hard to visualize, but when the wire is pulled and the wheel turns, the tabs slide in the slots and move the plates to release the latches. The springs then push the plates back together when the pull wire is released.

IMG_20200528_114308.jpg

There doesn't appear to have ever been any grease or other lubrication in the mechanism. This mechanism has worked flawlessly the entire time I've had it, over 3 years. I've ridden in the rain some lately, but it has never been a problem before, even when I was caught in a big storm in Wyoming in 2018 where the rain was blowing horizontally. There doesn't appear to be any signs of wear or friction on any of the parts. I wonder what caused it to start sticking.

I used some Molykote 111 grease we have here at the office to lubricate the mechanism and now it operates smoothly. The product sheet says it has "excellent water resistance" and is "compatible with many plastics and elastomers." Fingers crossed that the lube doesn't harm the plastic of the mechanism. If so, new mechanisms are available for about $53.
I was on a solo ride and dangerously low on gas. I found an open station and low and behold, my SW-Motech tank bag release mechanism wouldn't budge. It was installed by the previous owner so I was pretty unfamiliar with how it latched. I Googled the problem and was led to your post. Thank you so much! Your pics and description saved me. After a cleaning and lubing, it's working great.
 
I would opt for a dry lubricant - a silicone spray with teflon or something similar. I would think grease would hold dust and gum things up eventually. Maybe that Lock-Ez stuff that sprays colloidal graphite deep into locks and the carrier evaporates? Come to think of it, why not just powdered graphite?
 
I would opt for a dry lubricant - a silicone spray with teflon or something similar. I would think grease would hold dust and gum things up eventually. Maybe that Lock-Ez stuff that sprays colloidal graphite deep into locks and the carrier evaporates? Come to think of it, why not just powdered graphite?
Good advice. Thanks.
 
Just recently I cleaned the SW MoTech mounting base on my larger tank bag and sprayed the mechanism with Silicone. The pull-release was becoming a bit cantankerous (ha!) and now works smoothly.
I didn't imagine the mechanism could ultimately become locked though - nasty! A periodic clean an lube would seem a sound preventative action.
D
 
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