Author Topic: Broken seat hinge repair?  (Read 5345 times)

Offline beemuker

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Broken seat hinge repair?
« 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.
  • Panama City, FL
  • '00 R1100RT,’92 K75 RT,past tense:'83 R80ST, '93 K1100LT,,94 R1100RS K75s, Honda NC700, Suzuki Bandit 1200, bmw R75/5 Honda 750

Offline beemuker

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Re: Broken seat hinge repair?
« Reply #1 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
  • Panama City, FL
  • '00 R1100RT,’92 K75 RT,past tense:'83 R80ST, '93 K1100LT,,94 R1100RS K75s, Honda NC700, Suzuki Bandit 1200, bmw R75/5 Honda 750

Offline Martin

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Re: Broken seat hinge repair?
« Reply #2 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.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline The Mighty Gryphon

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Re: Broken seat hinge repair?
« Reply #3 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.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline beemuker

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Re: Broken seat hinge repair?
« Reply #4 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 ?
  • Panama City, FL
  • '00 R1100RT,’92 K75 RT,past tense:'83 R80ST, '93 K1100LT,,94 R1100RS K75s, Honda NC700, Suzuki Bandit 1200, bmw R75/5 Honda 750

Offline beemuker

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Re: Broken seat hinge repair?
« Reply #5 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.
  • Panama City, FL
  • '00 R1100RT,’92 K75 RT,past tense:'83 R80ST, '93 K1100LT,,94 R1100RS K75s, Honda NC700, Suzuki Bandit 1200, bmw R75/5 Honda 750

Offline Laitch

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Re: Broken seat hinge repair?
« Reply #6 on: June 19, 2021, 10:42:30 AM »
This post is to lessen toggling for interested readers.


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  • 1995 K75 89,000 miles

Offline beemuker

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Re: Broken seat hinge repair?
« Reply #7 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.
  • Panama City, FL
  • '00 R1100RT,’92 K75 RT,past tense:'83 R80ST, '93 K1100LT,,94 R1100RS K75s, Honda NC700, Suzuki Bandit 1200, bmw R75/5 Honda 750

Offline Laitch

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Re: Broken seat hinge repair?
« Reply #8 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.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline frankenduck

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Re: Broken seat hinge repair?
« Reply #9 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.

Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
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Offline The Mighty Gryphon

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Re: Broken seat hinge repair?
« Reply #10 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.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline daveson

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Re: Broken seat hinge repair?
« Reply #11 on: June 19, 2021, 11:07:19 PM »
Here's a photo from my '84 RT.

  • Victoria, Australia
  • Current; '85 K100RT~100,000km; four other bricks. Past; Vulcan 1500, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline Laitch

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Re: Broken seat hinge repair?
« Reply #12 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.


  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline beemuker

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Re: Broken seat hinge repair?
« Reply #13 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.
  • Panama City, FL
  • '00 R1100RT,’92 K75 RT,past tense:'83 R80ST, '93 K1100LT,,94 R1100RS K75s, Honda NC700, Suzuki Bandit 1200, bmw R75/5 Honda 750

Offline RobP

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Re: Broken seat hinge repair?
« Reply #14 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.
  • Driftwood, TX
  • 1985 K100RS

Offline Laitch

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Re: Broken seat hinge repair?
« Reply #15 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!
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline johnny

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Re: Broken seat hinge repair?
« Reply #16 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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  • :johnny i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin  :johnny

Offline Laitch

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Re: Broken seat hinge repair?
« Reply #17 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
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

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