1978 R100S Seat pan latch issues

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1978 R100S Seat pan latch issues

Post by dannyleo »

'78 R100S seat won't unlatch when you press the release so we went in and removed the latching mechanism to see what the issue was. Everything looks okay, but my buddy (remotely) said that maybe the seat pan was deformed a little so that the pin that sticks down from the seat is at a slight angle when it engages the lock. It doesn't appear deformed on first glance. Anyone have any experience with this? I could just remove the latch I guess, but I'd prefer to make it right. If the seat pan is deformed, that will be next to impossible I would think. ? I could try to insert a thin, flat piece of metal into the latch to keep the seat pin from engaging. It's not like I'm worried about anything under the seat so it would just be free to raise.
Let's settle this the old-fashioned Navy way, first guy to die; loses.
1978 R100S, MOTUS (delayed my retirement), 2014 F800 GSA, 2010 R1200 GSA, 2013 Triumph Thuxton, from my friend, Randy Lusk. USMC, Motor Officer, SF... Been there, done that, got the t-shirt, then got too fat to wear it. :( Rode Prudhoe Bay to Key West, no room for a t-shirt on that 30 day, 13,500 mile odyssey.

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Didn't Clint Eastwood say

Post by Twocams »

Didn't Clint Eastwood say "Improvise adapt & over come" I got one of those T shirts like yours. Stopped smoking after 45 yrs....gained 45 lbs. Cant ware anything I Retired in, in 1989. ( USAF).
My 92 seat maybe, most likely different. But I can look if it will help.
92 R100RT/69 R69S
2004 Aprilia Atlantic 500cc single cylinder Scooter
83 Honda V65 Magna, fastest production bike in1983

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A little way down this page

Post by schrader7032 »

A little way down this page is a pictorial by Brook Reams when he served the seat latch:

https://brook.reams.me/bmw-motorcycle-r ... eat-latch/

Another bike on this page:

https://brook.reams.me/bmw-motorcycle-r ... eat-locks/
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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Post by lauffer6996 »

These are tricky, and sometimes just need a bit of frustrating fiddling to get right. Often the pot metal housing is failing and must be replaced, The seat pin is also adjustable (at least on replacement seats), sometimes the hinges of the seat are failing or missing the circlips (some models) holding them in place, often the rubber bumpers under the seat are missing or worn out which can lead to failing seat hinges, sometimes you just have to push down on the seat (while pushing the button) to get it to release, there are also 2 positions of latching...could be a combination of above. You just have to be persistent and you will figure it out.
Good luck,

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Re: 1978 R100S Seat pan latch issues

Post by srankin »

I can't remember if I had any problems with a stock seat and stock latch mechanism but, I have had problems with Corbin seat pins. For some reason, they will not stay in adjustment leading in my case to looseness or failure to latch at all.
Perhaps it is the fiberglass base causing the problem. Anyway, it does take a bit of fiddling around to get them adjusted properly so they latch properly.

In my worst case episode, due to the pin not latching, I had one of the seat hinges tear out requiring the seat to be sent back to Corbin. They were nice enough to repair it.

I can imagine the stock metal seats are far better for the pin staying adjusted. St.
Owner of a 84, R80RT and 78, R100RS

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