Improving the LS Models
NMBS i4 coaches (1)

Original page created on 10/06/2023.

NMBS I4 A4B6 coach

LS Models NMBS I4 A4B6 coach.


When you take the coaches out of the box, you get the feeling that they’re heavy — too heavy! The weighing confirms this: around 170 g against a NEM value of between 116 and 154 g.

The first visual impression is very good, with one drawback: LS Models has once again seen fit to show weld seams on the roof, where they are almost invisible in reality. The bogies are very detailed. Of course, LS Models has respected the difference in length between the two coaches.

Electric jumpers

An oddity: the heating jumpers are inclined, whereas they are vertical, at least in the few photos I’ve found.

Comparison of jumper positions

On the other hand, the assembled jumpers are shortened, while others, whole, are supplied as spare parts. But why, when they in no way interfere with the movement of the drawbar? All the more annoying in that they are difficult to replace, hidden as they are behind the buffers.


Rare enough to be noted, the couplings are practically horizontal and at the right height.

Face-to-face view of the buffers

But as I take this photo, I notice that the buffers are taking a nosedive, especially on the A9 coach. The problem isn’t with the buffers themselves, but with the way they’re housed in the buffer beam.


The coaches acquired in 2019 each have a “braking” bogie. This is due to the brass bearings not being properly seated in their housings.

Bogie braking due to incorrectly inserted bearings


Separating the body from the chassis is easy: there are just two small studs and two small stops per side. All you have to do is spread the body a little at these points, using plastic cards, then gently lift the chassis by the buffer beam.

View of the assembly clips: on the enlarged photo, in 1), the stud to be snapped into the chassis; in 2), the stop resting on the chassis underside.

Dismantling the chassis

Click on the photo for a better view of the clips.

Removing the roof

To remove the roof, carefully insert an X-Acto blade just far enough to create a small gap, then unclip it by sliding a fingernail along the entire length. The clips are not deep.

The structure of these coaches is the same as for the VSE coaches, with a false roof not perforated at the compartment pitch, and a supposed light diffuser. This diffuser is removed by pressing down on its fixing pins from above.

Dismantled coach

Hover over the photo to see the details.


As these coaches are too heavy, you may want to remove the ballast, which weighs 40 g. To do this, you need to dismantle the interior fittings by releasing all the clips on one side, not forgetting those at the ends.

To remove the ballast, first insert a flat-bladed screwdriver to spread the parts, then continue with a steel blade (I used a ruler). Heating the metal with a hairdryer will make the removal much easier.

Mechanical preparation for lighting

Wire routing

A ⌀ 2 mm, 1 mm deep countersink is made into the chassis, between the pivot hole and the drawbar spring housing. The same is possibly done underneath the interior fittings.

Chassis after wire routing

A ⌀ 2 mm hole is drilled obliquely towards the toilet.

Oblique drilling, bottom view

Oblique drilling, top view

Milling a toilet cubicle

I milled the toilet cubicle at end 1 to accommodate the anti-flashing capacitor, keeping it on the interior fittings. But it was finally ejected, fortunately without any damage. It would have been better to remove it. For the following coaches, I dismantled it, breaking off the positioning pins in the process, which were very well glued in place.

Is’s possible to just remove the inner partition, but the best thing would be to level everything down to the ground.

Milled toilet

Note: the electronic circuit visible in this photo is no longer used, as all the electronics are now housed in the lighting strip.

Machining the double roof

My lighting strip has LEDs at the exact pitch of the compartments, so the double roof needs to be drilled again. Start by levelling the ridges on the roof with a scalpel or, better still, with flush cutters.

Next, prepare a machining shim. This is made of 10 mm plywood, 30 mm wide. Notches are made to go around the inside clips of the body. My shim doesn’t run the full length of the body, so I turn it over after half the machining.

Shimming the body

For machining, the body is clamped in the vice of the milling machine, with several layers of paper towel interposed.

Here you can see the ⌀ 4 mm holes for the LEDs, as well as the end milling for the insertion of the capacitor.

Machined body