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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: beemuker on June 18, 2021, 11:08:10 AM

Title: Broken seat hinge repair?
Post by: beemuker on June 18, 2021, 11:08:10 AM
Seat felt loose and I identified the cause as a broken forward seat pin.  It appears it was welded to a plate that is bolted (and / or ) welded to the frame. The pin in question is pictured . I looked at max part catalog but I don’t see this particular part as available . Has anybody had to repair this and if so how did you do it I also came across a way to modify the rear pin so it’s easier to remove but now can’t find it.
(http://www.motobrick.com/gallery/3/2839-180621104458.jpeg)
Title: Re: Broken seat hinge repair?
Post by: beemuker on June 18, 2021, 11:28:51 AM
Update : the plate comes off but it doesn’t look like there’s much to weld to, hoping I can find another Plate with attached pin? I circled the area where I think it broke off but it doesn’t look like it fits very well
(http://www.motobrick.com/gallery/3/2839-180621113741.jpeg)
Title: Re: Broken seat hinge repair?
Post by: Martin on June 18, 2021, 03:31:29 PM
PO has bodged that one up. The side cover should have a rearward protruding pin that pushes into the hole in the tail unit. Your picture shows it being plugged and covered with a bit of hose. What's on the other side?
Regards Martin.
Title: Re: Broken seat hinge repair?
Post by: The Mighty Gryphon on June 18, 2021, 03:45:00 PM
Martin, the photos are of an 1100 which I think has a different arrangement for attaching the battery covers.  The pin on the tail cowl in the pictures is correct. 

As far as the seat hinge, it should be welded to the frame.  I'm guessing that the fix is to get a chunk of 5 or 6mm rod and weld it to the frame.  No need for the clip on it, the seat portion of the hinge isn't going to slip off as long as the rear hinge is in place.
Title: Re: Broken seat hinge repair?
Post by: beemuker on June 18, 2021, 07:31:04 PM
Martin, the photos are of an 1100 which I think has a different arrangement for attaching the battery covers.  The pin on the tail cowl in the pictures is correct. 

As far as the seat hinge, it should be welded to the frame.  I'm guessing that the fix is to get a chunk of 5 or 6mm rod and weld it to the frame.  No need for the clip on it, the seat portion of the hinge isn't going to slip off as long as the rear hinge is in place.
It does look a little "buggered up" whynot weld it to the plate and bolt it back on ?
Title: Re: Broken seat hinge repair?
Post by: beemuker on June 19, 2021, 09:34:42 AM
Here is what it looks like off the bike but it really doesn’t fit together very well.
(http://www.motobrick.com/gallery/3/2839-190621093116.jpeg)
Title: Re: Broken seat hinge repair?
Post by: Laitch on June 19, 2021, 10:42:30 AM
This post is to lessen toggling for interested readers.


Title: Re: Broken seat hinge repair?
Post by: beemuker on June 19, 2021, 12:05:37 PM
Laitch, thanks for the toggling assistance . Looks like I may have to try to fabricate a replacement. Maybe use a screw/bolt and a piece of angle iron.
Title: Re: Broken seat hinge repair?
Post by: Laitch on June 19, 2021, 07:44:40 PM
Looks like I may have to try to fabricate a replacement. Maybe use a screw/bolt and a piece of angle iron.
That looks like a homegrown assembly anyway, unless the bolt in it was sold by BMW for $50.  :laughing4-giggles:  Maybe a member with a K1100 will post a photo of an 1100's stock seat hinge pin assembly.
Title: Re: Broken seat hinge repair?
Post by: frankenduck on June 19, 2021, 08:17:23 PM
That looks like a homegrown assembly anyway, unless the bolt in it was sold by BMW for $50.  :laughing4-giggles:  Maybe a member with a K1100 will post a photo of an 1100's stock seat hinge pin assembly.

It's exactly the same as K75s and K100s and seats are interchangeable among K75s, K100s and K1100s.

Title: Re: Broken seat hinge repair?
Post by: The Mighty Gryphon on June 19, 2021, 10:28:52 PM
It's exactly the same as K75s and K100s and seats are interchangeable among K75s, K100s and K1100s.

While I've never owned an 1100, every one of the 5 K bikes I have owned had the pin the seat attached to welded to the frame. 

I am pretty sure the part in the photos was fabricated by a previous owner.  If it was my bike i would weld a replacement to the frame.
Title: Re: Broken seat hinge repair?
Post by: daveson on June 19, 2021, 11:07:19 PM
Here's a photo from my '84 RT.

Title: Re: Broken seat hinge repair?
Post by: Laitch on June 20, 2021, 06:59:58 AM
It's exactly the same as K75s and K100s and seats are interchangeable among K75s, K100s and K1100s.
Verily, as the Duck and Gryphon giveth forth, so ever it were, hinge-pin–wise. It wouldn't take too much money to bend some appropriately-sized round rod then gas weld it to that gusset.


Title: Re: Broken seat hinge repair?
Post by: beemuker on June 20, 2021, 03:34:51 PM
Verily, as the Duck and Gryphon giveth forth, so ever it were, hinge-pin–wise. It wouldn't take too much money to bend some appropriately-sized round rod then gas weld it to that gusset.
thanks. I think I’ll try to make one like the (un)original as I’m not a welder. APiece of angle and a bolt may work.
Title: Re: Broken seat hinge repair?
Post by: RobP on June 20, 2021, 04:13:50 PM
Yeah, when I did an R&R on my "barn find"  K100RS that part was broken off and I fabbed one up with some rod stock and I welded it on.
Title: Re: Broken seat hinge repair?
Post by: Laitch on June 20, 2021, 05:17:05 PM
APiece of angle and a bolt may work.
I believe we already have empirical data concerning that method.  :laughing4-giggles:  Come on, beemuker; it's time to meet to new people (who weld) and learn new skils, to spread your wings and fly, fly, fly!
Title: Re: Broken seat hinge repair?
Post by: johnny on June 23, 2021, 03:52:38 PM
greetings...

1/4 20 threaded rod coupling + 1/4 20 allen head bolt...

j o


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Title: Re: Broken seat hinge repair?
Post by: Laitch on June 23, 2021, 07:49:03 PM
See what can happen when a well-organized, well-fed and well-lubricated design team is put to the task, beemuker?  112350