Best MK3 Seat Covers / Install

It doesn't look like I'm going to find a unribbed (seamless) squared one.


Any thoughts on this cover (at almost half the price of Andover who is out of stock)?
It looks like the same one to me.

elefantrider said:

Norton Roadster MK2/MK3 850cc (Square top)

Norton Roadster MK2/MK3 850cc (Square top) Years: 1974-75 Complete with sprag clips and trim, Colour: Black Made in England *Please note that the cover in the images was fitted onto a universal model, and will fit perfectly tight on the models it is

www.classicbikeshop.co.uk

Any thoughts on this cover (at almost half the price of Andover who is out of stock)?

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At half the price, this cover is an Asian import. You get what you pay for. You should enquire about thickness of the cover before placing an order.
Leighton's price is at the same level to what AN charges.

- Knut

Their web page says Made in England though.

There's a MK3 Leighton seat posted in the classifieds. Sadly, it doesn't have either side seam.

elefantrider said:

There's a MK3 Leighton seat posted in the classifieds. Sadly, it doesn't have either side seam.

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The ad says 1974 seat. No hinge and it has a seat strap.

"It was the incorrect seat for the 1975 Commando (no seat hinge for 1975 mounting) when I recieved the restored bike so I replaced it with the correct seat."

elefantrider said:

Their web page says Made in England though.

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Not trustworthy.

- Knut

Looks like Andover sells Viper- branded covers which also say "made in UK".

Actually, I believe there is only one manufacturer of these covers, all re-sold under various brands.

Here is one sold by JRC , which also says made in the UK! Conventry Spares sells the same.


All these covers look like they are made with the same materials, no difference in manufacture!

Seeing how the original UK manufacturer is such a mystery, I'm beginning to doubt all these Made-in-UK assertions also!

Hi guys, I am doing a Mk3 Roadster seat upholstery using a new AN seat pan and new foam and cover supplied by Leighton.

The original seat foam was encapsulated by a PE (Polyethelyne) bag (I know because I took an original seat apart, which revealed the seat pan was beyond repair at a sensible cost, while the foam was in remarkably good shape).
I think the new foam looks denser than the original foam. Is it advisable to install it in a PE bag, or can I dispense with the bag? Your advice is appreciated.

- Knut

mdt-son said:

Hi guys, I am doing a Mk3 Roadster seat upholstery using a new AN seat pan and new foam and cover supplied by Leighton.

The original seat foam was encapsulated by a PE (Polyethelyne) bag (I know because I took an original seat apart, which revealed the seat pan was beyond repair at a sensible cost, while the foam was in remarkably good shape).
I think the new foam looks denser than the original foam. Is it advisable to install it in a PE bag, or can I dispense with the bag? Your advice is appreciated.

- Knut

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I just did my Dominator seat with a kit from Leighton’s - first time for me and I didn’t use any bag over the foam . I think if they thought it necessary they would have included it in the kit. My original foam did not have a bag over it .

When I redid my B25 seat I added a bag to cover the foam as otherwise being garageless water soaked into the foam when left outside. Overnight in Winter on frosty nights the foam frooze. You then had to sit on a solid seat on the commute to work. I have never found one on any seat I have rebuilt and I must have rebuilt nearly 10 over the years, with the bikes all garaged I never rebuild with one either now.

I think use of a PE bag depends on the foam acting as a sponge or not (open cell vs. closed cell structure). I need to do a test! If it acts like a sponge, it will strongly promote corrosion of the seat pan, and the foam should be fitted in a PE bag, IMO. There are always instances of outdoor parking.

The fact that Leighton didn't include a PE bag shouldn't be seen as a recommendation not to fit a PE bag. Leighton will only deliver what they have and what's ordered. It's the buyer's responsibility to assemble as required. There was no sheet from them explaining the installation.

The seat foam of my modern BMW m/c has no PE bag, and the PUR foam looks similar to what Leighton offers. Thinking about it, the seat foam and cover came in a shipping box originating with a German PUR foam supplier, so it seems likely the foam supplied by Leighton is of similar quality to that used by BMW today. I believe it is of the closed cell type. Humid dissipation of the seat covers could be very different though.

Kommando: The inclusion of a PE bag by the factory may have been a development to prolong life of the seat, mitigating a spongy seat foam.

- Knut

What the PE bag does do is reduce the friction between the cover and the foam making the pulling of the cover over the foam on assembly a lot easier.

I have a '72 ribbed seat. Cover and foam is Leighton. Well made, but has the wrong number of ribs for picky people. I found after a few years the rear edge of the cover had come out of the clips. When you sit on the seat the air inside has to go somewhere. (No plastic bag). There is no venting (on the fiberglass base anyway). I added 4 holes 3/4" diameter in the base to allow any air to escape. These are protected from water by the rear fender. I used vented plastic hole plugs made by Heyco to dress it up under there. It is close in area to what Matchess did on their seats - just a big 2" or so hole in the middle of the base ('66 G80CS).
Just something else to dick around with...
Russ

I asked Leighton for their opinion on using a PE bag draping the foam.

" I think the PE was used to try to water proof the seat foam. You can try it if you want I don't think they make a lot of difference. The water will still get through (to) the bottom of the seat base and lie between the foam and seat base.

Thanks
Andrew"

I then made an absorption test of the foam. Turns out the PUR foam supplied by Leighton is of the closed cell type, i.e., it will not absorb moisture. However, the upper surface is somewhat rough, and will hold on to moisture until heated. The seat cover's underside will do the same, so a PE bag will have no function, other than perhaps ease installation of the cover. I will dispense with the PE bag.

As for venting, AN's new seat pans have 6 venting holes, allowing air and moisture to escape.

- Knut

batrider said:

I have a '72 ribbed seat. Cover and foam is Leighton. Well made, but has the wrong number of ribs for picky people.

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I agree, and I'm one of those picky people. The 1972 seat had 14 full and 2 end pleats and a strap like in these pictures from one of Roy Bacon's books (and the one I bought new in 1972):



Do you know if Leighton would duplicate this exact seat? Whereas I do like the look of my current rear hump seat (see avatar), it's not very comfortable and I like the OEM look better.

Probably will if you ask and wonder why nobody else has mentioned it.

Onder said:

Probably will if you ask and wonder why nobody else has mentioned it.

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Good question, and I've searched for one many times on the internet over the years with no success.