1100 Plastic to steel tank swap

[MattW]

I'm finally getting round to fitting a brand new steel tank that I've had for a couple years to my '94 plastic tanked 1100.

As far as I understand, the only bits I need to make it fit and take care of this gap (the black stuff is duct tape to protect the tank):

are the steel tank specific black rubber trim jobbies. I've just ordered these (along with a new fuel filter, tank neck and fuel pump plate o-rings.

Anyone done this and can tell me what I haven't thought of?

Cheers
M

 

[Dr Bones]

I think the plastic tank has a separate earth wire that might need to go somewhere when you put the steel tank on?

 

[MattW]

I think the plastic tank has a separate earth wire that might need to go somewhere when you put the steel tank on?

Thanks Dr B

I did wonder about this but as it just earths the pump access plate, I'll just reconnect it as before. Arguably the steel tank probably doesn't need it but an extra earth can't hurt.

 

[Bob_Johnson]

Just found this forum and just registered so I could post a reply. I just replaced the plastic tank on my 1100GS with a new steel tank from an 1150GS, and from the photos your steel tank looks like it might be from an 1150. If that is the case, and as you found out the tank fits the frame but it does not fit the front plastic.

The front sub-frame and plastic "fairing" pieces on an 1150 are different from an 1100 (and expensive, obviously). What I did was to glue the original 1100 rubber pieces to the lower part of the front plastic with a pretty strong adhesive. I then installed the lower plastic back onto the bike and used RTV to glue the rubber pieces to the upper plastic (in case I ever needed to remove the plastic "fairing" pieces again....). If you loosen the lower plastic mounting screws when you install the tank you can squeeze the plastic inside the front of the tank with the rubber pieces installed. This leaves the top flange of the tank exposed as in your photos. It's not beautiful but it is functional. I am going to try to source some black trim to cover the exposed flange on the tank, but for now the questionable "workmanship" of Behr is still on display....

Sorry I don't have photos but my trusty Olympus camera decided to die yesterday.

All the best from the desert southwest,

Bob Johnson

 

[MattW]

Just found this forum and just registered so I could post a reply. I just replaced the plastic tank on my 1100GS with a new steel tank from an 1150GS, and from the photos your steel tank looks like it might be from an 1150. If that is the case, and as you found out the tank fits the frame but it does not fit the front plastic.

The front sub-frame and plastic "fairing" pieces on an 1150 are different from an 1100 (and expensive, obviously). What I did was to glue the original 1100 rubber pieces to the lower part of the front plastic with a pretty strong adhesive. I then installed the lower plastic back onto the bike and used RTV to glue the rubber pieces to the upper plastic (in case I ever needed to remove the plastic "fairing" pieces again....). If you loosen the lower plastic mounting screws when you install the tank you can squeeze the plastic inside the front of the tank with the rubber pieces installed. This leaves the top flange of the tank exposed as in your photos. It's not beautiful but it is functional. I am going to try to source some black trim to cover the exposed flange on the tank, but for now the questionable "workmanship" of Behr is still on display....

Sorry I don't have photos but my trusty Olympus camera decided to die yesterday.

All the best from the desert southwest,

Bob Johnson

Bob,
Many thanks for taking the time to reply to my thread
I've ordered some of the black trim pieces which I believe are for the steel tanked 1100. They should arrive today so I'll find out if they work. I guess it'll depend on whether my new tank is from an 1100 or 1150 and whether the tanks are the same... If not I think I'll have to 'create' something from what I have in a similar fashion to you

I'll let you know what happens.

Cheers
Matt

 

[motobiker]

Bob,
guess it'll depend on whether my new tank is from an 1100 or 1150 and whether the tanks are the same...

Unless its a recon tank - it will be from an 1100 as there wasn't a RED 1150.

Aside from that - they are identical. My 1100 has what was originally a graphitan 1150 tank - it was a straight swap - zero difference between the two.. The rubber buffers were swapped over too.

The reason for the swap was the original tank had shed its internal lining.

Its no longer Graphitan.

 

[MattW]

They are. My 1100 has what was originally a graphitan 1150 tank - it was a straight swap - zero difference between the two.. The rubber buffers were swapped over too.

The reason for the swap was the original tank had shed its internal lining.

Its no longer Graphitan.

Thanks - good to hear.

I'll see what transpires when my new steel tank rubber bits arrive. Looking at your pic above, there doesn't seem to be such a big gap as I've got at the top of the silver side pieces on your bike. Time will tell...

 

[MattW]

Unless its a recon tank - it will be from an 1100 as there wasn't a RED 1150.

Just seen your edit.
Very good point - hadn't thought of that

My new tank is brand new, never been fitted - still has the little sleeves on the access plate studs which protected the studs during spraying.

 

[MattW]

I'm pleased to report that the 1100 steel tank specific rubber trims fit perfectly and close up the gap shown in the picture above

The steel tank also fits much better than the old plastic. I've a feeling that age and fuel had swollen and distorted it such that it always had a slight lean to the left. The steel tank sits perfectly square.

So, for anyone searching for this issue in the future (not that there are probably many of us left who have a plastic tanked 1100), you just need the correct trims (about £4 each from Motorworks)

 

[Bob_Johnson]

Well, now that I look at the part numbers the 1100 and 1150 tanks are the same - guess I shouldn't have used that "permanent" adhesive on the old rubber parts.......

Fortunately it looks like the correct rubber pieces as shown in your pictures will cover any collateral damage to the plastic fairing. I'll be ordering those today. They may be the least expensive BMW parts I've ever purchased.

Thanks a lot for the information and photos - I'm glad that there was one other GS left on the planet that still needed the plastic tank replaced. The original owner of my bike (a good friend) never bothered to have the plastic tank replaced under warranty and after 18 years the only thing holding gasoline inside my tank was the white paint.

All the best from the desert southwest,

Bob Johnson