Ripple in seatpan

My Interstate seat has an underside ripple that prevents it from sitting level on the frame, making contact with the rear mudguard.

I don't know what caused it, but I've tried to get a few photos to give you an idea of what I mean.

Any ideas on how best to repair it? Walloping it with a FBH was my first thought, but may not lead to success.

Dismantle seat back to bare pan, then dolly and hammer.

OEM seat?
Or reproduction?

99% sure it's OEM.

AN sells new seat pans now. I am not sure of the front buckles, but the rear ones are typical for shear buckling. Plate extension and deformation over a large area took place. Even if you succeed in hammering out the buckles, the seat pan has lost much of it's stiffness.

- Knut

No buckling in the AN latest seat pans.

Does the ripple show through to the surface of the seat ?
Can you feel the ripple through the seat of your pants ?

If no I'd be tempted to leave alone for as said above the ripple will help provide rigidity.

While the seat was apart, I reinforced the pan on the top side with some with some 18ga sheet metal in the shown weak areas.

Has stood the test of time, 40,000 miles.

Grandad said:

Does the ripple show through to the surface of the seat ?
Can you feel the ripple through the seat of your pants ?

If no I'd be tempted to leave alone for as said above the ripple will help provide rigidity.

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The ripple can't be spotted or felt in use, however it pitched the seat a little higher against the tank on the right and just looks wrong.

Madnorton said:

No buckling in the AN latest seat pans.

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I have to admit, they look a million, gadzillion times better than the originals...

(me, exaggerate?, never )

cliffa said:

I have to admit, they look a million, gadzillion times better than the originals...

(me, exaggerate?, never )

View attachment 112372

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The wrinkles in the OEM were simply mass production tell tales.
Fast
Cheap
Simple

Didn't hinder function, and hidden from view.

Bonzo said:

My Interstate seat has an underside ripple that prevents it from sitting level on the frame, making contact with the rear mudguard.

I don't know what caused it, but I've tried to get a few photos to give you an idea of what I mean.

Any ideas on how best to repair it? Walloping it with a FBH was my first thought, but may not lead to success.

Click to expand...

I know its a bit of a bodge but... would doubling the thickness of the rear and middle/rear rubbers give adequate clearance? Could super glue on rubbers that have the "spike" trimmed off.
Could test the workability with a few small bits of insertion rubber (sheet)
It is unlikely to be a structural issue - so I would try this first (but I am a bit rough - and a curmudgeon)
Cheers

RAID a builders scrap heap .

panel forming was leather sand sacks & a lot of hammers , in Italy .

4 x 4 or 6 / 8 x 2 , one each side on the ' V ' . find a Galv. Pipe - same diameter . and get a really big hammer or a heavy brick .
A really cool guy would get 3/4 x 6 cut to fit under each side , but on top as its inverted . Throw a plank across and get the
neigbours kids to stand on it each side . To keep it flat . Or Nail ( tack ) and clamp , if youve lots of big clamps .
dont let the wife see if you use the Grand Kids to stand on it .

SO , the genral principle is SUPPORT IT , and give it a few whacks at the appropriate place , ON a ' form fitting ' drift .

Tease out the ripples later . Tecnically , heat , wait till dull red , then quench , to shrink .

Yep , a couple of 1 in x 1/8 steel straps across under the cover somewhere might help . BUT if the Seat Base is contured to FIT the frame rails ,
the loads directed into them near directly . BLUEPRINTING the seat to frame fit !

That chip foam is high density , a layer / wedge , under ( 3/4 or 1 inch thick ) if the ass bottoms out ( accidental pun ) can avoid pressure points
on old collapsed Triumph Seat inlays , ANYWAY .

Took a look at the AN page and the seat pans are there for the Interstate but none for the Roadster. Perhaps in the Days to Come.

Looking into it, Roadster seat pans should be back from paint very soon

How similar, or different, are the various years of Roadster seat pans?

Blimey! This one (described as new) looks worse than mine

Bonzo said:

Blimey! This one (described as new) looks worse than mine

Norton Bare Seat Pan Interstate 750 850 MK1 MK2 Pre-MK3 06-3183/P 06-5382/P | eBay

This is a correct fit to ALL Interstate models except 1975 MK3 From Andover OEM.

www.ebay.com

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"Manufacturing" is not a dirty word.

Start looking over the (hidden) formed sheet metal on any vehicle.

What's the procedure for stripping the seat down to bare seat pan?

Pull the trim first, then clips off and the cover & foam can then be removed from the pan?

Bonzo said:

Pull the trim first, then clips off and the cover & foam can then be removed from the pan?

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Exactly in that order, the foam might be glued to the pan but that will be the only difficult bit other than rusted clips and hardened trim.