FAQ & More

Q: How I recognize the compatibility and replaceability of spare parts ?

A: Look for the Alfacode. The Alfacode is the second and third letters of the component identification number. The same Alfacode means compatibility and/or replaceability. The only exceptions are the components coded “ZZ9xxx”. We do not dedicate these parts to a specific model, but they are for general use.

e.g. The Inner Chassis WAB1215 is:

a) replaceable with the WAB1202 Inner Chassis, and vice versa

b) compatible with the WAB1301 Main Chassis.


Q: How do I choose the right screws ?

A: Check first the head diameter not interfering with the receptacle. Then, once the screw is in the ultimate position, the body has to float sliding freely along the not-treaded portion of the shank.


Q: What are for the two posts at the back end of the Inner Chassis ?

A: Screws may be tightened or unscrewed for limiting the vertical excursion of the Inner Chassis back end. This tuning is fully independent and has no effect on the suspension springs installed at the side rear and forward posts.

Q: How do I set the chassis clearance to the ground to

a minimum ?

A: One Spacer should be installed between the pickup and the

inner chassis as a minimum to lower friction allowing the Pickup

to rotate freely.

A: We design All Core Chassis for a track featuring the metal

contact and the track ground being co planar. Someone may

install more washers to compensate for any mismatch between the two planes as with a wooden track.

Q: How do I correctly install the ball bearing/bushings in the Inner Chassis receptacles ?

A: Single flanged. Light pressure is enough to insert the bearing/bushings into position. However, the inherent tolerances of round holes 3D printed may require, in a few cases, very light chamfering of the hole's outward edge.

A: Double flanged. Gently snap the bushings into their receptacle. 


Q: How do I choose the correct pinion and crown couple for their best match ?

A: We sized The Inner Chassis for Pinion/Crown diameters coupling of 7.5/16.8 mm, (NSR) 6.75/17.5 mm (NSR) 6.5/18.0 mm (Slot it). The NSR crowns are angle winder.

A: After extensive track testing and 24 h Endurance Races no significant pinion or crown-wearing, nor we have detected loss of transmission smoothness when using a straight pinion mating angle winder crowns


Q: How do I install the crown in its correct location ?

A: Install the Crown with the flat side toward the motor.

A: Use a spacer 0,5 or 1.0 mm maximum spacer between the

crown and the bushing. The spacer locates the gear in the

right position, clearing the screws fastening the motor to

the Inner Chassis.

Q: How do I manage the tire to tire width at the rear axle ?

A: This issue applies mostly to the left-hand side only. Use a

standard Stopper or a spacer. Be aware of a rear axle too long,

colliding with the wheel inserts.

Q: How do I use retainers to hold the inner on the Main chassis ?

A: The Chassis Full Kit has four retainers to be used with springs at the side rear and forward posts. The two no-spring retainers are an alternate solution at the front side posts only.


Q: How do I manage the front wheel touching or clearing the track ?

A: Use grub screws in the lower and upper holes of the front axle supports.


Q: How do I choose where to install suspension springs ? Rear only or forward too? soft, medium, or hard sprigs? Maybe no spring is “the” solution ?

A: Sorry, I can’t help this time. I raised this question many times to myself, not finding a reliable answer so far. It looks like any setting works perfectly when the driver is well above the average. If you are smiling, you are one of them.

Design references 

The rear axle Outer Diameter (OD) diameter must match the ball bearing and /or bushing inner diameter (ID). Pay attention to the axle diameter. The 3/32” OD means 2.37 mm. for (NSR) and 2.38 mm.for (Slot it).

Motor. We sized the Inner Chassis to host either the "small can" Slot it MX type or the NSR Shark latest version with two fastening holes, despite its bigger size. The older type has one hole only on top of the shaft and is not suitable to be assembled into the Posillipo Inner Chassis.


“Versatile Plastic” is the best choice when selecting the 3D printing material. Posillipo Slot based the design on flexibility/stiffness and manufacturing tolerance of this type of material.

Brush out any residual powder from the 3D printing process.

Use a primer to coat the white “Versatile Plastic”. The material is porous by nature. The coating is not for the appearance but for sealing the 3D printed material to preserve stability and mechanical characteristics.


Sacrificial sprues join the Full Kits components. Do not remove them by bending, as you may damage the part. Use a sharp blade to cut the sprues in the middle, then cut the residual material and flush the area of the last cut by sanding.

The 3D-printed “Versatile Plastic” has a slightly grainy surface. We recommend sanding of mating surfaces.


The 3D printing process of “Versatile Plastic” produces a dimensionally stable product. However, should a Chassis be slightly nonplanar, it can be easily conditioned by soaking in hot water. Constrain the Chassis in a plain condition and let the hot water do the job. Make the cooling process slow; an overnight stay would be perfect. The result is stable, there is no experience of any significant spring back after the treatment.


Pre-tread the Retainers before the final assembly to align the screw with the holes axis. A tilted screw would constrain the Inner Chassis free-floating despite the accurate design.



The chassis doesn’t fit well the Body posts.

We based the Design of the Posillipo components on the original model size dimensions. A misfit is mostly because of the body's out of shape. Sometimes, we’ve experienced out-of-the-box deformed bodies, leading to a mismatch up to 1 mm, even when mating their original chassis.

The Inner Chassis does not slide freely inside the Main Chassis

Check for any residual material because of the sprue cuts.

Check screws if they are well fit in the retainer/forks

To ease the relative motion, lightly sand the mating surfaces.



If You have any other extra Questions, please, write to:


Posillipo Slot Car will answer to questions of general interest on this website.

Posillipo Slot Car will do their best to give a personal answer to the other questions.

Managed languages:

English, French, Italian, and, of course, Neapolitan. 

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