Question: Is it possible to upgrade the fuel bladders on a 185 from the smaller 65 gallon to the 84 gallon or are there issues with the spars and ribs that prevent one from doing so? Thanks in advance for anyone who might have experience with this.

Different construction in the wings... fuel tank bays are larger therefore can’t just install one or the other..

Brian

Thats the answer I am looking for and my fear. Thanks for the help.

Granted that there are two different structural configurations. But how hard is it to modify the smaller bay to accept the larger bladders? Has anyone done this? I would think, it would be a matter of removing the parts ffrom the standard bay and installing the larger bay Cessna parts. It is an interesting objective that I have thought about in the past!

buck_justice wrote:Granted that there are two different structural configurations. But how hard is it to modify the smaller bay to accept the larger bladders? Has anyone done this? I would think, it would be a matter of removing the parts ffrom the standard bay and installing the larger bay Cessna parts. It is an interesting objective that I have thought about in the past!

Having taped all the rivets in a tank bay, I feel confident that switching the parts would be a major undertaking. Probably just cheaper to buy a different set of wings.

There's always the Hartwig/Monarch kit

https://backcountrypilot.org/forum/monarch-hartwig-tanks-21252?p=303532&hilit=monarch%20tanks#p303532

And the internal Flint tanks.

There was also a mod that added additional bladders in the next two outboard bays......can’t remember the name.

MTV

I’m in the process rebuilding my wings and incorporating LR tanks. I’m attaching the list of parts that are required to be changed. Not on the list are the rear inboard spars. The location of the ribs on the spar are not the same resulting in extra holes. I replaced both spars. The panel assemblies are difficult to find or manufacture.