|Basics of Mini 4WD|
|Part of the chassis|
|Basics of Grade-up Parts|
|Intermediate and expert customizations|
A Custom Stay (Japanese: 自作バンパー, Jisaku Banpaa) refers to the customized stays that can be used on a Mini 4WD car.
What are Custom Stays?
Custom stays are stays that provide one or more functions that benefit a Mini 4WD car. They are usually made from Tamiya's reinforced plates, and other Tamiya GUPs. Custom stays are usually only possible on cars with bumperless setup.
Types of Custom Stays
There are multiple types of custom stays, and each of them has their pros and cons.
Custom sliding damper
This type of custom stay provides the same functionality as the stock sliding dampers sets, where the main plate slides left and right when the car being pushed against the fence during cornering. This type of bumper is recommend for tracks with Digital curves.
The Anchor stay has the main plate holding down against the base plate by a single or two spring-loaded screw(s) with rubber/plastic paddings (Usually the underside stabilizing head), typically bolted in between the chassis and the main plate. Stoppers are used to prevent the main plate from rotating horizontally. There are three types of Anchor stays: The single-point anchor, sliding anchor and the dual-point anchor.
The main purpose of the Anchor stays is to change the stay's thrust angle when being pushed upward while it is grinding on the fence of a track. In addition, the main stay can be rotated vertically when being pushed upward on one side, forcing the car to slide back down onto the track lane. On the sliding anchor stay, the plate can slide sideways when the car is being pushed against a fence, providing some shock absorption.
However, the main plate being held down by only a single spring-load screw means that the Anchor stays are structurally weak, as the screw will bend if the impact force is much greater than the screw can handle. This is more apparent when normal screws are used and as such, It is recommended to use stronger screws (likes the stainless steel screws) when making an Anchor stay. The dual-point Anchor stay, being having the main plate held down by two spring-loaded screws, doesn't have the same problem that plagues other types of Anchor stays, though using the stronger screws are still recommended.
Due to how it is constructed (particularly on using the long screws and spacers for stoppers), this type of custom stays are generally used as a rear stay.
The Autotrack stay (also known as an "AT Stay") is similar to the Anchor stay, but with two spring-loaded screws holding down the main plate instead of one.
Unlike the Anchor stay, the main plate can only move upward and rotate vertically, thus, only providing the track returning function. Because there are two spring-loaded screws, stoppers are generally not needed.
While Autotrack stay doesn't slides sideways that the Anchor stay do, the additional spring-loaded screws means that the Autotrack stay is more durable than the Anchor stay.
Due to how minimal the stay is designed, the Autotrack stay can be used as the bumper and rear stay. It can be combined with the pivot design to create the Pivot Autotrack stay.
The Pivot stay's design is similar to the Progressive Down Thrust Rollers, but without the angled roller plates. The stay has 2 smaller, independent roller stays, held into position by screws and either springs or wrapped rubber rings.
The Pivot stay absorbs the shocks caused by hitting the fence. Small stoppers are used to prevent the small roller stays from rotating too far.
Similar to the Autotrack stay, the Pivot stay can be used as the bumper and rear stay due to its minimalistic design. It can also be combined with the autotrack design to create the Pivot Autotrack stay.
The LG stay is similar to the Anchor structurally, but instead of being held down by the spring-loaded screws, the main plate is usually held down by a pair of rubber rings, wrapped to the screws and spacers on the main plate and the base plate. Just like the Anchor stay, stoppers are used to prevent the main plate from rotating horizontally.
The way the rubber rings hold down the main plate creates an interesting way on how it works; The main plate can move upward and rotate both vertically and transversely when being pushed upward, while it can move sideway while pushing against the fence, far more than what an Anchor stay can do. However, getting the LG stay right is tough, as the main stay will unintentionally change its roller thrust angle. Furthermore, the rubber rings that holds down the main plate will eventually snap under stress.
The use of the rubber rings, as well as long screws and spacers, means that it can be only used as a rear stay.
Because custom stays contain moving parts (which causes friction), it is recommended to periodically grease them up with the anti-wear grease.
For the Anchor stays, it is recommended to check the screw's condition once in a while, and replace the bend screw(s) if found. The rubber rings on the Pivot stay and the LG stay has to be replaced periodically, as the rubber deteriorates over time.