I need to use some older 3 rail bridge and ramp sections on my layout. I just do not have enough stud/puko sections to complete what I want to do.

Whatever I do my locos run slower on three rail than they do on stud track. Both are in good condition and clean etc, loco pick ups correctly set.

Any suggestions? Is this a known phenomena?

Hi Michel

I believe this has to do with increased friction slider-thirdrail is bigger than slider-studs because of the surface.
Usually M rails are easy and cheap to find (unlike curved bridges with stud) so why not use a Faller bridge-5100 curved units?
Cheers
Jean

Hi Michael
It is all a matter of choice and taste.
Indeed, early post-war M tracks were of high quality, even starting with brass, profiled, blackened rails. The rail bed was made of a thicker steel metal plate and "Kontaktlaschen" (contact tongues) were of a much higher quality. This came at a moment (1951-1955) when Märklin embarqued into a cost-cutting war to increase its market share.
On the other hand M track with studs appeared in 1956 and was really of a reasonnable quality (when new, because one can find many with abused rails and joiners).
There was a new generation of M track which appeared in the 1980s with:
- a fantastic precision manufacturing
- more coimpact turn-outs motors and lanterns
- invisible clips to fasten the contact tongues

The last M tracks were so well made that detecting were the rail joined was only possible by seeing the joiners

So, just my opinion, it is a matter of finding recent M track in near new condition, rather than using the old 3 rail track pieces
Here is a photo comparing the 3600 early track (1950) with the latest M track (1980-2000)

Spoon pick-ups wear rapidely and are expensive to replace

I went the other way by adapting a "normal" slider on a 1951 DL800 loco, of course without modifying any original part nor applying epoxy glue to those

Cheers
Jean