Norton Commando frame / gas tank / seat lengths

What are the lengths of the seat and tank for the Norton Commando Interstate compaired to the Commando Roadster? Are the frames of these bikes the same from 1972-1975?

The gas tank and seat do not seem to be interchangeable between bike models of different years. (1972 Interstate Fiber Glass, and 1974 Roadster Steel)

I apologize in advance for this lazy and probably already answered question.

The frames are essentially the same and any of them can become an Interstate or Roadster pretty much at the owners whim. I don't have exact lengths at hand but a roadster tank is about 3-inches shorter than the interstate. The Interstate seats are pretty big for two-up riding so are probably longer than the roadster seat but the tabs that secure under the knobs on each side are set farther forward in relation to the seat, so the net result is that the interstate seat sits farther back. I made a solo seat for my Interstate by taking a Roadster seat and cutting the front of it back.

Hope that helps.

Russ

"The frames are essentially the same and any of them can become an Interstate or Roadster"

Or a Fastback!

But of Course . When is a FASTBACK ( L.R. ) Not a Fastback ? probly when its a ex Interplod .



QUOTE " Don’t know if you have come across my blog, http://nortonsnortons.blogspot.com/ ?
Hope you like it…. Attached is (I think) a really atmospheric shot of me on my newly bought ’75 Commando taken in the back streets of Newcastle upon Tyne in 1988. "

Wow a bike built with similar philosophy and 'upgrades' of my 920 Ms Peel.
The Fastback style is definitely in your face Brit sassy-ness to surprise the moderns no end. I find I'm faster more secure with IS tank than Roadster as most tank better placed to grip knee against which goes against the knee hanging out new age style. Seat info already covered but do note the big King Queen IS seat is a real treat on Iron Butt runs, if ya can stand your special that long as I can mine.

I have both IS and Roadster tanks and seat, It's a straightforward change on my 72 : less than 5 minutes, the biggest part being spend to move the grab rail. I keep the roadster side panel anytime as I think they look better.

Even mudguards(fenders) are the same on IS and Roadster , with the fastback rear one shorter with a different numberplate

No changes in frames impact the ability to mount any tank and seat , excet the 850 MKIII with different seat hinge and lock.

JRD said:

No changes in frames impact the ability to mount any tank and seat , except the 850 MKIII with different seat hinge and lock.

Click to expand...

I was going to ask the same question as the original poster until I found this thread. Do I understand this correctly - an Interstate seat/tank can be installed on a Roadster, but the seat and tank would have to both be from an Interstate? I am interested in obtaining an Interstate tank for my Mk3 Roadster, but I am using a Corbin Gunfighter seat currently. The Corbin seat does not use the original hinge and lock. But I'm guessing I would need to change the seat or modify the mount somehow due to the difference in the length of the IS tank.

Has anyone done this already?

Thanks in advance!

I was going to ask the same question as the original poster until I found this thread. Do I understand this correctly - an Interstate seat/tank can be installed on a Roadster, but the seat and tank would have to both be from an Interstate? I am interested in obtaining an Interstate tank for my Mk3 Roadster, but I am using a Corbin Gunfighter seat currently. The Corbin seat does not use the original hinge and lock. But I'm guessing I would need to change the seat or modify the mount somehow due to the difference in the length of the IS tank.

Has anyone done this already?

Thanks in advance![/quote]

Your Corbin seat will not fit an Interstate tank, correct. Corbin mad a few seats that will fit the Interstate, but not really any production of this. You will need to get a custom made or use an original Interstate seat with that tank. Alternatively as has been mentioned....Fastback. That tank holds more fuel than a roadster and the seats from RK Leighton are very comfortable. The downside is you need to find a metal tank as fiberglass isn't a viable option any longer with current pump gas.

As you can see below a Roadster tank will work just fine on an Interstate. Of course you have a small gap between the tank and the seat (about 4 inches). However, if you are into looks you better get yourself a Roadster seat to match the tank.

Then again an Interstate fuel tank will not work with the Roadster seat unless you can figure out a way to deal with the tank and seat overlap (about 4 inches).

Roadster tank on the Interstate

PeterJoe said:

As you can see below a Roadster tank will work just fine on an Interstate. Of course you have a small gap between the tank and the seat (about 4 inches). However, if you are into looks you better get yourself a Roadster seat to match the tank.

Then again an Interstate fuel tank will not work with the Roadster seat unless you can figure out a way to deal with the tank and seat overlap (about 4 inches).

Click to expand...

I see very clearly, yes. My Mk3 is 165 miles away at the moment so I can't check the Corbin seat mount. But 4 inches is probably too much of an adjustment even though the mount is a simple bracket.

Well, this answers my question. I'll stop wondering about it. I love my Corbin seat too much to cast it aside. :lol: