Tether Bolts

A tether bolt is designed to anchor the top part of a car seat to the chassis of the car. Bolts can be located in various parts of the car, though they are most commonly found on the parcel tray of sedans and on the seat back, or boot sill of wagons and other vehicles.

A top tether strap attaches to the bolt, and when the seat is installed correctly the seat should not move more than 2.5cm (1 inch) in any direction.

tether bolt

Black connector plate to which the tether strap hook connects.

Bolt and nut to secure tether bolt to the car.

2 different sized spacers used when the bolt needs to sit higher up so not to sit in a recess.

Bolt reinforcement plate to be used in cars that do not have pre-drilled holes.

Factory Installed:
The tether strap needs to attach to a tether bolt (shown below). Some cars have a tether bolt pre-installed, this may be under a plastic cover, in the boot area, or attached directly to the seat back.

Make sure you do not use cargo hooks as tether bolts as they are not strong enough to hold your child and seat during an accident. cargo hook

Pre-drilled hole:
A pre-drilled hole may be found under a rubber bung, or screw off cap, this hole must have a screw thread, if there is no thread track the reinforcement plate MUST be used on the underside of the bolt. You are then able to fit a bolt by screwing the bolt into the hole. You must fit the bolt in this order: Bolt, washer, tether attachment hook then spacers if require (these fill any gaps under the attachment hook). The large metal ring is not required nor is the nut.

Manually drilled hole:
If there is no pre-drilled hole you will need to drill a hole, this must be fitted in line with the car seat position. Check first that there are no gas lines or wires in your drill path. With a non pre-drilled install the tether bolt needs to be fitted as: Bolt, attachment plate, reinforcement plate (large metal ring), washer and then the nut. Spacers to be used if required to fill any space where the bolt is fitted.
It is vital that bolts be installed in the correct place. They must pass through the metal structure of the cars chassis.


Above image shows where to drill a hole on the parcel tray in the back window of a sedan if not pre-fitted with tether bolts and no holes have been drilled, check under rubber or plastic bungs for pre-drilled holes.

Top right shows installation for cars without pre-installed bolts. It is important to ensure the washer is fitted at the bottom of the bolt as this prevents the bolt from pulling through in an accident.

Opposite image shows how to install a bolt into a pre-drilled hole. The washer and nut are not required. There is a nut fitted on the underside of the hole.

Below Left, Vehicle with modern bolt bar behind vehicle seat. Right, Older car with installed bolt on boot sill.

drilled hole



tether bolt
Images property of Britax

seat back boot bolt

Use the links below to find out more:

| Essential information
| Knowing the type will help achieve a correct install
| Find out what one is and how to use it
| Find out what to do with the tether strap
| Lower tether system to use in place of the seat belt
| External link to technicians list by area
| Why wont my seat install correctly? Help!