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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: jayman_k75 on February 01, 2021, 11:15:10 AM

Title: Seat issue - Missing tank pad or something else?
Post by: jayman_k75 on February 01, 2021, 11:15:10 AM

So this is a corbin seat on this bike. It did not come with the factory seat. This bike was passed down from father-in-law as is. Is it just missing the tank pad piece for a low seat? I'm not sure what to do here. Any help would be appreciated.
(http://www.motobrick.com/gallery/3/7265-010221111111.jpeg)
(http://www.motobrick.com/gallery/3/7265-010221111036.jpeg)

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Gio on February 01, 2021, 11:36:09 AM

Hi jayman ... when I converted to low seat option on my K75 it came with the tank-pad attachment (BMW # 16.11-2.3?8.?60 - ? character hard to read ... will try to post a pic) [ Invalid Attachment ]

Title: Re: Seat issue - Missing tank pad or something else?
Post by: jayman_k75 on February 01, 2021, 11:39:41 AM

Yeah. I am assuming that's what I need. I guess that will fill that space and make a place for the corbin seat to sit on? The lock latch works and there is a little tab on the right hand side of seat that fits under the rear seat fairing. Other than that I don't see anything else that holds it in place. Do you need yours, or is it for sale?

Title: Re: Seat issue - Missing tank pad or something else?
Post by: mw074 on February 01, 2021, 11:47:24 AM

This.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Gio on February 01, 2021, 11:48:31 AM

Sorry - no experience with the Corbin seat - bike had the oem ("high") seat when purchased, and now the optional "low" seat ... which I'm using now.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: mw074 on February 01, 2021, 11:50:07 AM

And this.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: jayman_k75 on February 01, 2021, 11:57:37 AM

Thanks for the diagrams. I have searched those on Bike Bandit. This bike doesn't have any of the seat parts other than the rear seat fairing/fender, the storage tray/jetronic holder, and the relay box cover.  The seat itself just has the latch pin and little bracket on right hand side that rides under the fairing. It had a Russell seat on it prior to this seat. but the Russell seat had the same issues. Just not sure what all I need to buy for it..

Title: Re: Seat issue - Missing tank pad or something else?
Post by: mw074 on February 01, 2021, 11:58:56 AM

And this.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Chaos on February 01, 2021, 01:24:43 PM

you might be better off looking for a Corbin or whatever for a non-low seat K75 or 100. 

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Laitch on February 01, 2021, 01:59:23 PM

Quote from: jayman_k75 on February 01, 2021, 11:57:37 AM

This bike doesn't have any of the seat parts other than the rear seat fairing/fender, the storage tray/jetronic holder, and the relay box cover.  The seat itself just has the latch pin and little bracket on right hand side that rides under the fairing.

Without viewing the seat in place with a full side profile of your moto, it's too difficult for me to tell what you've got. Please post a photo of that arrangement. I can tell you that a low-seat assembly does not have a toolbox/Jetronic holder combo. It has only the Jetronic holder as indicated by the arrow in the attached diagram.

(http://www.motobrick.com/gallery/3/1601-010221135046.png)

Furthermore, a low seat assembly uses hooks on each side of the tail cowl's opening to stabilize the seat. Those are parts #6 with #7, #8, and #9 for attachment to the cowl. View them within the diagram in Post #3.

Motobrick member rcgreaves made an excellent comprehensive video about the low-seat attachment mechanisms. Here it is.
https://www.youtube.com/watch?v=2NEQrMfiVkI&feature=emb_logo

Title: Re: Seat issue - Missing tank pad or something else?
Post by: The Mighty Gryphon on February 01, 2021, 02:25:23 PM

Please post more photos of what parts you have and where they are on your bike.  From the photos you have posted so far, I can't tell if the Corbin actually is a low seat and if you have it installed correctly with the proper hardware.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: jayman_k75 on February 01, 2021, 02:56:21 PM

(http://www.motobrick.com/gallery/3/7265-010221145155-3604286.jpeg)
(http://www.motobrick.com/gallery/3/7265-010221145154-3603135.jpeg)
(http://www.motobrick.com/gallery/3/7265-010221145150-36012397.jpeg)
(http://www.motobrick.com/gallery/3/7265-010221145153-3602365.jpeg)
(http://www.motobrick.com/gallery/3/7265-010221145148-3600271.jpeg)
(http://www.motobrick.com/gallery/3/7265-010221145144-35871561.jpeg)
(http://www.motobrick.com/gallery/3/7265-010221145144-3587834.jpeg)
(http://www.motobrick.com/gallery/3/7265-010221151109-3608764.jpeg)
(http://www.motobrick.com/gallery/3/7265-010221151107-3607254.jpeg)
(http://www.motobrick.com/gallery/3/7265-010221151105-36061172.jpeg)
p://www.motobrick.com/gallery/3/7265-010221151105-3606281.jpeg[/img]

Title: Re: Seat issue - Missing tank pad or something else?
Post by: jayman_k75 on February 01, 2021, 03:03:24 PM

I meant to add that. I do not have any mounting parts on the frame or tank side. I have the seat and the brackets that are attached to it (see above pics). Not sure what I need to make this seat fit correctly at this point. I am attempting to mock up a home built wedge piece to fit in there so at least it will have some sort of seat for now..

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Laitch on February 01, 2021, 04:00:34 PM

That is not a low seat; it's a standard profile, custom seat. If it had all its hinges it would open from the left. One of your photos shows a rusty prop hinge on the underside of the seat. A low seat would dip down into that frame triangle. Look at the bench seat hinges in the classic fiche at MaxBMW (https://shop.maxbmw.com/fiche/DiagramsMain.aspx?vid=51739&rnd=09082020). They're what you need to buy or fabricate.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Gio on February 01, 2021, 04:02:42 PM

Further and with reference earlier reply from Laitch - your pics clearly show tool tray with those parts inside (above Jetronic) ie regular or "high" seat config ... there is also lid for this tray (not seen in your pics). My guess would be that you have a Corbin seat from a different bike (?) in which either a spacer as you suggest, or keep an eye out for a standard / high seat ..?

Title: Re: Seat issue - Missing tank pad or something else?
Post by: The Mighty Gryphon on February 01, 2021, 07:22:47 PM

There is pretty wide interchangeability between seats over all the years and models.  The only problems are with the very early seats that had the grab handles as part of the seat pan rather than the the rear cowl.

Almost any seat will work on any classic K(75,100, or 1100).  The main difference is that some of the seat pans sit further down on the frame and interfere with the under seat tool tray.

You have a Corbin touring saddle and it will work on your bike.  It will not interfere with the tray.  There are three separate parts to the hinges that hold the seat on the bike.  The first part is a "strap" that is mounted on the rear cowl in front of the the cubby hole in the cowl.


DSCN3938.JPG (61.14 kB . 768x576 - viewed 574 times)

The other two parts are mounted on the bottom of the seat.  One at the rear that attaches to the "strap" on the cowl,


DSCN3937.JPG (49.73 kB . 697x576 - viewed 564 times)

and the other is near the folding support and attaches to a pin on the right side of the frame near where the battery cover attaches to the rear cowl. 


DSCN3936.JPG (55.91 kB . 642x576 - viewed 578 times)

The other seat hardware you need is a hinge pin for the rear hinge, and three "C" clips to secure the hinge pins and the seat support. 


DSCN3939.JPG (52.31 kB . 660x576 - viewed 564 times)

You already have the support and the latch pin that goes into the seat lock located on the left side of the frame near the handle used to put the bike on the center stand.


DSCN3934 (2)_LI.jpg (29.07 kB . 768x427 - viewed 596 times)

All of the parts are adjustable to allow positioning the seat in the center of the frame, and to some extent adjust it's position fore and aft.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Martin on February 01, 2021, 09:50:40 PM

I fitted a Corbin to my K75 when one fell into my lap as part of a package deal. It took a bit of wangling with the hinges to get it to align properly especially the rear hinge. I had to slightly twist the rear hinge and move it around. But once finally adjusted it actually fits better in the nose area than any of my stock or modified seats.
Regards Martin.
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Title: Re: Seat issue - Missing tank pad or something else?
Post by: Laitch on February 01, 2021, 10:10:13 PM

Quote from: Gio on February 01, 2021, 04:02:42 PM

My guess would be that you have a Corbin seat from a different bike (?) in which either a spacer as you suggest, or keep an eye out for a standard / high seat ..?

If by "different bike" you mean different manufacturer, that's unlikely because the rear slope of the seat matches the tail cowl of his Brick. It could be from a K1100 but the prop hinge is definitely classic Brick hardware. If he follows Martin and Gryph's guidance he's likely to get it usable on his moto.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Martin on February 01, 2021, 10:40:38 PM

For some weird reason I've ended up with five Brick seats. Three OEM, one with stock padding and two modified padding and a K1100 comfort seat that required different hinges and the under seat tray being cut down slightly (now sold), and the Corbin. The three OEM were the easiest to fit, the K1100 seat after trimming down the tool tray went pretty much straight on. All four have varying gaps at the nose. However the Corbin required a lot of adjusting and a bit of force, as in taking off the rear hinge the part that attaches to the seat and twisting it. The rear hinge strap that attaches to the bike also required loosening and adjusting. When I first tried to fit it on it didn't look like it was close to fitting, after a lot of stuffing around it now fits like a glove. With patience and persistence you should get there.
Regards Martin.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: The Mighty Gryphon on February 01, 2021, 11:12:56 PM

Going back and looking closely at his photos, I can see that all the hinge parts are present.  Can't tell about the hinge pin or the "C" clips. 

Like Martin, I've dealt with a number of K's including five bikes and 9 seats, including a K100 Russell, a K1100 Russell, 3 BMW comfort seats, 2 BMW bench, A Corbin/BMW dual Canyon, and a Corbin dual touring seat. 

I have been able to mix and match seats with bikes and they are all interchangeable with the exception of the K1100 and K75 comfort seats which had a pan that interfered with the tool tray.  Those seats also have slightly different hinges, but if you have the hinges, they will go on any classic K bike if you remove the tool tray. 

It might take a little fiddling with the hinges, especially on the Corbins, but they can be moved from bike to bike with no major difficulty.  I like to "tune" the seat for how far I plan on riding.  The bench is good for commuting and afternoon rides.  The OEM Comfort seat is nice for touring and doing 4-500 mile days on a trip.  The Russell Day Long is the choice when I'm doing 7-800 mile days to go coast to coast as fast as possible.  The Corbin Canyon seat is a really nice looking seat that is too hard for more than short rides of a hundred miles or less.  Their Touring seat is nice, but IMO the BMW Comfort seat is slightly more comfortable.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Martin on February 02, 2021, 01:29:58 AM

Gryph there is no need to discard the tool tray, it only needs to be trimmed down. I used a white marker to mark anything above the frame rail  and continued it through to where the frame kicks up and trimmed it off. Although I didn't reuse the lid, it might have been possible. I just used a thick cloth to retain the articles in the tray, and didn't loose a lot of storage. There were no hinges around at the time but it wasn't that hard to make them using basic hand tools and an arc welder. Pictures of cut down tray.
Regards Martin.
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Title: Re: Seat issue - Missing tank pad or something else?
Post by: jayman_k75 on February 03, 2021, 09:39:35 AM

 112350 - Thanks for all the responses. I am ordering the extra strap that I am missing and bolts / pins. I've still need to figure out why it's so far from the gas tank, but may be the tool tray or maybe the gas tank is too far forward somehow (it's in the rear pin seats). All the feed back has made it better in that I now understand how the seat should be installed. Thanks again!

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Laitch on February 03, 2021, 10:50:15 AM

Quote from: jayman_k75 on February 03, 2021, 09:39:35 AM

I've still need to figure out why it's so far from the gas tank ...

I think you'll discover some forward adjustment is possible using the seat hardware. My moto's oem seat has a gap there which allows clearance for the strap buckles of my aftermarket tank bag.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: The Mighty Gryphon on February 03, 2021, 10:55:35 AM

Without the rear bow, you can't really position the seat to know where it is on the bike.  Get all the parts and get back to us.

Speaking of parts, I have a rear bow with the pin and the c-clip.  I also have a tool tray cover here as well.  You can have them all for $25 plus shipping. 

Title: Re: Seat issue - Missing tank pad or something else?
Post by: jayman_k75 on February 03, 2021, 12:32:13 PM

Okay. So I just made an interesting observation.. It seems the seat has a bend in it maybe from sitting too long on it's end. I strapped down the back end of the seat to the tail fairing where it belongs and if I apply force to the front of the seat, it bends down to touch the rubber feet to the frame and the front of the seat lies against the tank like it should..

So, I have strapped the front and rear of the seat down into the correct position and will leave it that way while I restore the rest of the bike.. Maybe by then it will be more back to the normal position and the new brackets and hardware will have arrived. I have to say that I may not have figured this out without all of the guidance here!!

Title: Re: Seat issue - Missing tank pad or something else?
Post by: The Mighty Gryphon on February 03, 2021, 01:46:11 PM

If indeed you need to straighten the seat base, you might want to hit it with a heat gun to get the fiberglass almost too hot to touch and applying a little force to straighten it.  Just letting it sit with the bend straightened will let it snap back to whatever shape it's in now.  Again, I would wait until I had all the hardware to mount the seat before I made any attempts to make it fit.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: jayman_k75 on February 03, 2021, 02:22:18 PM

Agreed. Will do. Parts have been ordered.

Title: Re: Seat issue - Missing tank pad or something else?
Post by: jayman_k75 on February 05, 2021, 11:28:42 AM

 112350 112350 So heating the seat pan and bending it... Worked PERFECTLY! Seat now fits as it should. My only guess is that whoever had it before kept it stored with something stacked on it's end. Thanks for all the input. I also have all the brackets on order!

Title: Re: Seat issue - Missing tank pad or something else?
Post by: The Mighty Gryphon on February 05, 2021, 01:17:33 PM

 icon_cheers

Title: Re: Seat issue - Missing tank pad or something else?
Post by: Gio on February 05, 2021, 04:51:24 PM

Good job jayman ... am glad to hear all worked out in the seating dept!