Seat locked down

[PitchlerBrick]

This seems very un-German, how could a seat lock fail before even 60K miles are on the clock? I have done many searches on this site and on Google. After trying LockEase, Kroil, twists, turns and pouring stale beer on it, the under-seat lock remains inhospitable to its key.

Next, I removed the two 8mm bolts and the two Philips screws which hold the pushbutton and lock assembly in place, to see if I could slip the entire detached lock upwards through the frame by lifting up the seat. Nope, not enough clearance, the lock bumps against the nearby fender so you cannot push the button in through its housing to get clear.

Really, I hate to destroy OEM parts, but has anyone found a way to bust one of these boogers open? Thanks for any tips and advice.

I had two recent trips, one 7 hours and one 10 hours, all highway with high TX posted speed limits (85 posted on one two-hour stretch, each way!); I ran 5.5-6K+ rpm most of the time. The bike never complained and was solid and smooth as could be. Maybe speed caused enough vibration on those little internal lock parts to put them out of sorts, but dang, that's slower than the Autobahn!

[PitchlerBrick]

The Catch.png (47.35 kB . 768x512 - viewed 109 times)

Could The Catch post turn over time, just enough to make it impossible for the lock to release? Has anyone heard of that? Did the factory use blue threadlocker when assembling the post into the seat mount? Maybe the lock is fine!

When I get this thing apart that is definitely a step I will take, to prevent that possibility in the future.

Really appreciate the fische links, super helpful!

For now though, I'd like to figure out how to get in and saw that catch post, to get this sitz offen.

[frankenduck]

Post (part 8) turning will not impact the key being able to turn. That's not how the lock works.

No Loctite. That post has a washer(6) and lock nut(7) on it to keep it from turning.

[The Mighty Gryphon]

I had an issue once with the helmet lock messing up the button.

Try wiggling the latch for the helmet lock while putting light pressure on the key.  Avoid pulling on the seat while you do this.  It worked for me, but I have no idea what made it finally let go.

[Laitch]

Try wiggling the latch for the helmet lock while putting light pressure on the key.  Avoid pulling on the seat while you do this.  It worked for me, but I have no idea what made it finally let go.

Good vibes. 

[frankenduck]

It helps if you understand the mechanics of how the seat lock works.

Turning the key: When you insert the key it flattens the tumblers along the sides which allows the lock core to rotate within the lock cylinder.



At the base of the seat lock lock core is a pseudo rectangular block of metal.



1 - When the key is in the vertical position that metal block aligns with the base of the pivoting locking bar with the hook at the top.

2 - When you push the lock in the locking bar pivots

3 - The hook at the top disengages from the rectangular hole (4) in the end of the seat post rod

[frankenduck]

Get the key in the vertical position. Try pushing down on the seat before/while pushing in the seat lock to make it easier for the hook to disengage.

[PitchlerBrick]

All of this is really good stuff and Frankenduck, those pictures are great. I will try these suggestions and appreciate each one.

[PitchlerBrick]

Any ideas getting the seat open?. The lock is stubbornly shut regardless of a variety of approaches. Therefore, I'm trying to remove the latch post mount that's attached to the seat pan. (As expected, spinning the center locking nut down doesn't do anything.)

The two outside Nylock 10mm nuts need to come off, tricky, since the Corbin seat is locked down. The nut on the left is free, the nut on the right, despite trying 3 different types of 10mm wrenches, is in an odd place which doesn't allow a wrench to get on it properly. There's a slanted wrench angle which connects only part way, and it's starting to round off the nut. You cannot come up from underneath with a socket, there is metal in the way.

The lock itself is hanging free but will not lift out when disconnected from the frame, due to clearance issues.

My next move is to put some protective painter's tape on the tube frame and slide in a SawzAll metal blade and cut the latch post itself. In anticipation of this least desired option, I ordered a new latch post so I can reinstall, after rebuilding the lock. Any ideas are welcome, otherwise out comes the saw.


K75 Under Seat Lock Latch.jpg (45.73 kB . 577x576 - viewed 61 times)

[frankenduck]

Needlenose pliers on rear nut? There are needlenose Vise-Grips.



You could pry the seat up but that will probably break the hook before the post hole breaks.

[frankenduck]

If you can't get a good angle on the post with the Sawzall then a hacksaw blade holder would work. Tedious and slow but good for cutting metal in tight spaces.

[PitchlerBrick]

Needlenose pliers on rear nut? There are needlenose Vise-Grips.

You could pry the seat up but that will probably break the hook before the post hole breaks.

It's a good idea; I have one of the little needlenose vice grips and will give it a go. Clamping it on is one thing, having space to turn it is another! But it just needs to be broken loose then things will get a bit easier.

The blade on my cordless SawzAll just slides in there. I'd duct tape or painter's tape everywhere the blade might slide / touch on the frame, etc. to not booger up the adjacent areas. I hate to cut the latch post because like the hard to find under-seat locks, someday the latch posts too, will be unavailable.

[Laitch]

It's a good idea; I have one of the little needlenose vice grips and will give it a go. 

Try padding the jaws of a needlenose vice grip, spraying Freeze Off to the screw shank of the latch eye to perhaps allow it to rotate, grabbing it with the vice grips and turning it ≈20º one way then pushing the button, followed by turning it the other way and pushing the button. You'd be attempting to loosen the hook's hold; however, sawing through the post will definite change the game.
 
Good luck!

[frankenduck]

What position is the lock's key slot in? If it's vertical then the tab on the lock core can push on the locking bar. If it's at the 10:30 position then pushing it in will never do anything.

[PitchlerBrick]

Thanks, at the moment life is getting in the way of time for my hobby! I appreciate the ideas and am trying them all.