If the cars have NEM coupler pockets, you can swap for Roco NEM couplers. Roco has three types, all compatible with Marklin Loop couplers. (Some problems with close couplers, but you get that with Marklin also[}:)])

Hi Bill, all,
Once you´ve been advised about couplers, I want to tell you something about Fleischmann (and other DC) rolling stock. If you plan to run them on an AC layout (Märklin) and will use now or in future train detection tracks, you´d better change their wheels, cause AC ones are isolated and AC aren´t. (Maybe you knew this)
Regards

Thanks for the help! I was aware of the wheel isolation difference so I'll change em when necessary. But isn't it the DC wheels which are isolated and the AC that are not? Anyway, I probably should've stuck with Marklin only which is what I've been trying to do up till now.
Bill

Hi Bill, about 65% of my Locos and 70% of my wagons are Non-Märklin (Brawa, Fleischmann, Kato, Liliput, Roco).
I use only C track, with R3, R4 and R5 radii and R9 turnouts, and I know this is a great advantage.
All my rolling stock has NEM couplers, either factory installed or adapted by myself. I didn´t change the wheels since I don´t use track contacts. I use both Märklin and Roco couplings. I have no derailments at all, DC rolling stock negotiates very well the turnouts.
In the past, when I was an M-track victim, I've adjusted the gauge of some wheels to 14,0mm internal and this brought some relief. After installing C-track I adjusted the gauge back to 14,3mm and now all my problems are gone.
Have a Happy New Year!!!

I beg your pardon ladies and gentlemen,
it´s true, AC is not isolated and DC is. It was so late at night.....Christmas celebrations (untill next Jan-6-04)... and so on, you know....

Hi Roland, I have a Fliegender Hamburger from Kato and have Märklinized VT25s too. The pickup shoe I've for my Fl.Ham. is an original Kato. For the ET25s, you have alternatives: the Kato shoe, M* 7164 or Fleischmann 69.2009 could do the trick, but I don't remember which one I've used... sorry. For every product for which Kato offers an AC version, you have a pickup shoe available. I don't have any experience with US Kato models, only German ones. Both SVT877 (Fliegender Hamburger) and ET25 are excellent models.
In regards to Brawa BR06: mine is an original DC model adapted to 3R, but this was quite simple: a M*7164 installed under the movable bogie in the tender and a change in connections, done by simply re-arranging the wires at the board in the tender. Wheels and flanges are the same for both DC and AC versions. It runs perfectly in my layout, but I have only R3, R4 and R5 curved track and R9 turnouts.
Brawa says that this loco will run on R1 track at half speed, having removed some pieces to free the bogies from being catched by those pieces under the boiler.
I've tried this in a layout of a friend of mine but the results were not conclusive since his layout was not properly set and some derailments could have occurred due to bad installation of track. What I can assure is that you need at least a half section of right track between both tournouts.
Hope this could help you.
Regards,

The only change you need for R3-4-5 is the front lateral piece on both sides, to allow the wheels of the first axle to go out of the loco body. The loco comes with those parts for your choice.
Regards,