Corbin seat hackabout

[Lord Stig]

After a painful ride up to the BMF this year I decided action to improve the comfort of my Corbin seat was definitely required. Much of the problem seems to have been caused by the slope of the seat - I was using a nice plush sheep skin at the time, so it was certainly soft enough. Anyway, I decided in the first instance to try remodelling the seat to remove some of the slope, and to narrow it slightly so getting my feet down on the ground would be easier.

First, some things I discovered about the Corbin. 1) The upper panel of the seat cover is actually made from stiff 1.5 - 2.0 mm thick leather, with a waterproof patterned upper surface. The sides are more flexible vinyl. 2) The cover is glued to the foam (other seats I've re-covered weren't). 3) the foam is one piece and all of the same density - not sure what the Corbin "comfort cell" is all about, as there doesn't seem to be anything new there. No gel or memory foam here. The black line you can see around the seat in the second photo below is just where the piping was positioned. 4) The combination of gluing the cover to the foam, and using such stiff unyielding leather is probably why the seat feels so firm, and why it isn't that comfortable.

First I drilled out the rivets to remove the cover at the rear, leaving the forward rivets in place because they fit flush. My plan was to use self tappers to hold the refitted cover on, and these could rub against the tank, so leaving the rivets in place here is a better plan.
http://www.xrv.org.uk/forums/%5Bimg%5Dhttp://www.xrv.org.uk/photopost/data/500/medium/Seat_1.JPG%5B/img%5Dhttp://www.xrv.org.uk/photopost/data/500/medium/Seat_1.JPG

This is the cover pulled back, showing the glued surface:
http://www.xrv.org.uk/photopost/data/500/medium/Seat_2.JPG

Using a specially sharpened carving knife I sliced the foam to remove the overhanging sides, cut more level steps into the foam (to be rid of that slope), and to level off the convex front of the seat which can be painful to the 'nads with a pillion sliding into you and pushing you forward. The front was also made narrower. The result isn't perfectly flat, but better than it looks here. A sheet of softer foam over the top would cure this.
http://www.xrv.org.uk/photopost/data/500/medium/Seat_3.JPG

The cover was then refitted using self tappers in the holes left by the rivets.
http://www.xrv.org.uk/photopost/data/500/medium/Seat_4.JPG

The leather cover is too stiff to lie flat after years of having been glued to foam with a different (concave) profile. As a result, there is a lumpiness to the finish, though this isn't a result of the cutting of the foam. It might get better with being sat on, and at least it's slack enough to let the foam compress properly.
http://www.xrv.org.uk/photopost/data/500/medium/Seat_5.JPG

So far impressions are good - It seems more comfortable, and foot to ground contact is better. I will let you know more when I've tried it on a long journey (next weekend). The seat is amazingly soft now, especially considering how firm/hard it was before. In retrospect this seems obvious - the raised outer parts were the only parts of the seat that had enough leather to allow the foam to compress - the leather that you actually put weight on is almost in tension before there is any weight on it, and since it's glued and the leather doesn't stretch it was like sitting on a drum skin. Odd design....

So, before (smooth, but damned uncomfortable):
http://www.xrv.org.uk/photopost/data/500/medium/Seat_before_3.JPG
http://www.xrv.org.uk/photopost/data/500/medium/Seat_before_2.JPG
http://www.xrv.org.uk/photopost/data/500/medium/Seat_before_1.JPG

After (more wrinkly but nice and soft):
http://www.xrv.org.uk/photopost/data/500/medium/Seat_6.JPG
http://www.xrv.org.uk/photopost/data/500/medium/Seat_7.JPG
http://www.xrv.org.uk/photopost/data/500/medium/Seat_8.JPG

I may make some further changes - this is a work in progress.....

[gerry]

It took determination to chop a Corbin seat.Looks like a good job too.:thumbright:

[Lord Stig]

Hi Gerry - well, it was more a case of having nothing to loose so long as it didn't make it worse! As it happened it took until last weekend to take it for a proper run. I was in the saddle for most of the day, but with breaks. The longest stint was a little under two hours. Verdict? MASSIVELY better. It's firmer than I thought it might be considering how soft it felt after the modification, but no numb bum whatsoever. It's not often a mod that cost nothing but bravery makes so much difference....

[stageonesimmo]

I've got to get round to sorting out my Touratech pain in the arris - I've got the plastic sheet I need to waterproof it and some tent seam sealer to be on the safe side, but I want it to be a bit softer - just need to find the foam to do it......

[Lord Stig]

I can recommend memory foam for softness; I bought a sheet of 2" stuff for under a tenner (I think) from a shop in Taunton for doing this. I didn't fit it, and in the end used it folded as a pillow (recommended!). However, I can't recommend the shop in Taunton - I ordered via eBay, and the postage was almost as much as the foam, plus it took far too long to arrive. Probably there are closer sources to you.

One thing I think I'd avoid when fitting the sheeting is gluing the cover to the foam like Corbin did. With a cover that doesn't have much 'stretch' in it (like leather), the foam simply can't deform. I think if I had simply pulled the cover off and refitted it as it was I would have had the same soft effect. Granted, the wrinkles would have still been there, and the leather would no longer have fitted the concave seat area, but who cares, it's just cosmetic. On the plus side, cutting down the Corbin has meant that I can get my feet flatter on the floor, and that helps a lot on rough ground!

[chAos ego]

i have justed hacked out original foam from my dommie seat and stuffed in a memory foam pillow bent double bit better than standard but still room for inprovement ha :p