Linhof 6x9 Rollex back problem

For my 6x9 Linhof I have an older 6x9 Rollex back. I have a problem with overlaping frames. The overlaping occurs when I don't shot the whole film but carry on maybe one or two weeks later. I never wind until just before I hit the trigger. The "old" frame is then overlapped by approx. 8mm. I can't figure out what causes this. I don't think the film "rewinds" during time by this 8mm. But it seems that the winding of the first frame is to short after a period where the back has not been used?

Someone knowing what is going on?

The problem is that you have a Rollex back (with the knob wind), and it can't be fixed. They advance the film by a fixed number of turns of the takeup spool, and older films and film backings were evidently thicker than some of the modern ones. You may find that some films aren't a problem (Ilford films are a good bet), while some (color transparency films usually have this problem) are particularly prone to overlapping frames. You might try things like starting past the start point or winding some tape onto the takeup spool to see if it helps, but ultimately, this is a design flaw (or at least a design anachronism) in the back.

Super-Rollex backs (with the lever wind) don't have this problem, because they meter the actual film distance traveled.

OK!
But I think if I just shot the whole film at the same session it will be ok. I can see that in bewteen some frames the spacing are very small. But the 8mm of overlaping seems to occur between and old and new frame if the time gap between these frames is 1 or maybe 2 weeks. But thank you very much for the advice. I will try them out. The film I was using was Fuji Velvia 100F.

Yes, when I had a 6x6 Rollex back, I always had overlap with Fuji transparency film.

I sent the back to Frank Marshman, who cleaned and inspected it thoroughly, and realized it was a design issue, and very generously didn't charge me for the work. I then posted about it here and on the Large Format forum, and others reported similar problems with older Rollex backs, and Bob Salomon, the US representative for Linhof, acknowledged that these backs are obsolete.

Still, they seem to work with some films, and when they work, they're fine. Try FP4+ or HP5+.

Think I should try to get a Super Rollex back then.....for the Fuji's. I will try to take all frames in the same session and see how things looks like. My old Rollex back has been re-made so it has got the very thin rollers the Super-Rollex back has which does that the film are more flat. The film plane has also been adjusted by 0.1 - 0.2 mm so it lays exact vere the ground glass has focus.