Which track code

[Roy L S]

I know zero about Unifrogs so am grateful to have been corrected by @chrism
All my points are code 55 small or large.

Code 55 tends to be stronger as part of the rail is buried in the sleeper webbing.
Whichever you plump for please don't mix codes.
There is no insulfrog in code 55. All the points are electrofrogs so wiring can be a little more tricky but the better running is worth it.

In my experience there is absolutely no problem mixing codes in terms of rail heights, personally I have code 55 on my scenic section and Code 80 in the fiddle-yard. HOWEVER I think the geometry of points may be slightly different and from that perspective mixing might cause a few headaches, and I can understand advice to avoid mixing from that point of view and a visual one.

That aside Code 55 is essentially Code 80 cleverly disguised with rail part-buried in the sleeper base instead of having functioning chairs, to give the visual impression of being finer. This approach still allows even old pizza-cutter wheels to function on it. The inner chair is the merest impression to allow the necessary clearance. The illusion is pretty convincing, but look at things like point blades and you will see they are little different to Code 80 in design and depth.

Joining the two, there is a miniscule discrepancy of about five thousandths of an inch in rail-height which in my experience causes no issues at all. My advice would therefore be to stick to one type or another on any given section of your layout, but there is (for example) no problem if (say) you want to use Code 80 in your fiddle-yard and 55 on the scenic side.

Roy

I cannot agree with Roy as, according to Peco's own diagram there is a 0.6mm difference in height between the two codes and the two are very different in shape. Certainly enough to cause derailments on lighter weight stock e.g. Dapol rolling stock
Never be tempted to file that difference in height off

Mick

With respect, the diagram you are showing illustrates the VISIBLE rail height, in Code 80 all is visible, with Code 55 a significant percentage is buried in the sleeper-base. If you attach the two with standard rail joiners at the bottom of the rail (which let's face it is where they go rather than the dummy ridge half way up) the height difference at the rail top is practically zero and the difference is so insignificant that there is no need to file anything. I have done this numerous times, I am not being theoretical or making assumptions, I have done it in practice.

Also worth mentioning that on my Whitrope Siding layout I used a Code 80 catch point amongst otherwise Code 55 track because Peco do not make one in Code 55, there was no tangible difference in rail height at the top of the rail and with a bit of careful ballasting and painting it never stood out as visibly different.

Honestly, I would not have posted what I did without being sure of my facts.

Roy

[Belly]

Good morning everyone,

We at the NGS Western Australia Area Group have decided to use Code 55 as we experienced the rail popping out of the sleeper chairs on the new Code 80.  It's just not as robust as the older version which used oversized chairs so has to be treated with a fair amount of respect while laying and positioning it.

Additionally, and this may not present a problem in the UK, but expansion through heat also played a part in our decision, after a couple of layouts experienced the rail leaving the chairs after a hot day or two.

All the best,

Geoff

[Graham]

Similarly we also chose code 55 over code 40 for Mid Albion, robustness and in the case of code 40 cost, whilst we looked at it the timescales we had to work with meant it had to be "off the shelf".

[Mr Sprue]

My feelings are, is that code 55 is the best compromise if you want your layout to look more to scale. Code 80 is too large, meaning that your stock will be running on bullheads that are a foot high!

Code 40 looks the best, but is really for the people with good modeling skills that want to achieve a layout that represents detail and true scale.

[Roy L S]

My feelings are, is that code 55 is the best compromise if you want your layout to look more to scale. Code 80 is too large, meaning that your stock will be running on bullheads that are a foot high!

Code 40 looks the best, but is really for the people with good modeling skills that want to achieve a layout that represents detail and true scale.

All very true.

The further issue that may still attract people to Peco Code 80 over their Code 55 is that their extremely long-established Set Track sectional track range range has only ever been available in Code 80.

[Newportnobby]

I have done this numerous times, I am not being theoretical or making assumptions, I have done it in practice.

Honestly, I would not have posted what I did without being sure of my facts.

Roy

@Roy L S Roy, you are a better modeller than I'll ever be and I would never doubt what you say.
I'm only going by my many years experience of a small step difference in heights of code 55 and code 80 and the subsequent derailments that ensued. The 'bobbing' of stock going over such joints also ruined many a video made at the time.
No one has to act on what I say as I can only provide personal recommendations. I would never mix codes knowing what I know

The diagram in my post above is lifted from the sheet Peco put in with every point/crossing they sell

[Portpatrick]

I have used code 55 on Allanbrae and Cromarty.  In my view it is a worthwhile visual improvement over code 80.  I have used code 80, in part because I had a load in hand,  in the fiddle yards.  Allanbrae was my first time doing this.  I jacked the code 55 up with a slither of styrene sheet to even the rail surface.  On Cromarty I have not bothered.  Like Roy I have not found the tiny step creates problems.  On termin us to fiddle yard layouts, speeds are low which doubtless helps. 

I adopted code 80 in the fiddle yards in part because I use setrack points in them.  Two reasons for that.
1) the points are much shorter which is important when, as for me, length is at a premium.
2) The wider track centres makes handling stock in the yard easier, eg when moving locos from one end to the other. 
3) I had experimented with cassettes for Allanbrae,  which was my first use of code 55, using electrical trunking as done on a layout in the NGS Journal a few years ago.  But they were not popular with my regular operating team.  So I went back to the fan of sidings I had adopted for Cromarty.
When building Cromarty - during lockdown - Unifrog was just starting.  I laid in a stock of Electrofrongs.  I dislike the sight of the plastic on Unifrog and for me, the fact they are not self isolating straight from the box, and need extra switching/wiring, was a big negative.  Wiring is my most unfavourite occupation.  So I keep it as simple as possible.  Cyril Freezer basics from the 60s/70s!!

[Nbodger]

Newton Kyme has a mixture of 55 and 80 with no packing between the two with no running or visual problems whatsoever.

This is also my experience on a couple of club layouts.

When code 55 first came out, I bought a length to see what it was like, used it in Hillsden's fiddle yard again directly connected, with no running problems. At the time I am fairly sure it was advertised as a like for like connection.

[njee20]

But there's clear air between the bottom of the sleepers on the code 55 if you join it to code 80? I guess if you're ballasting it then you can fill in the gap with that, inadvertantly packing it.

[ntpntpntp]

... the height difference at the rail top is practically zero and the difference is so insignificant that there is no need to file anything.

"practically" but not exactly, and the difference IS significant in my experience - too much to be acceptable and as bad as loose Unitrack joints where I've had low slung snowploughs and brake gear catch on the joints.   I only ever have the two codes meet (but not physically join) at board joints between scenic and fiddleyard parts of the layout.