How To: Improve Seat Belt Retraction
Not sure if this is the right section. Did this a while ago, but only just got around to writing something up that might help others.
A common problem with older cars is the seatbelts no longer retract strongly. This can be annoying, is a safety issue, and can be picked on by roadworthy checks. In some cases it may be worth sourcing replacements, but there are a couple of things you can do to improve their performance.
Disclaimer: Seatbelts are extremely important safety devices. Incorrect operation may result in serious injury or even death. This is designed as a guide to improve useability. If your seatbelts are damaged, have them replaced by a professional.
The example is based upon an ADM SW20 MR2, although it should be applicable to many other cars.
Step 1: Remove the entire assembly. This will differ slightly from car to car, but should be fairly straightforward. In the MR2, removing the side plastic cover allows access to the three bolts securing the spool assembly, with a single bolt at the shoulder and the ground.
Step 2: Remove the belt from the spool. Extend the belt completely. This will require the spool assembly to be held upright. The belt itself has a loop at the very end, with a small piece of plastic inside to stop it from pulling through the spool. This plastic can be pushed out, allowing the belt to be pulled through and removed completely.
Step 3: Inspect the belts for damage. My drivers side had a very small amount of fraying, which I carefully trimmed to avoid further damage. If there is any significant amount of damage, get the belts replaced. They are interchangeable side to side, so I ended up using the better condition one on the drivers side.
Wash the belts in soapy water. You’d be surprised how disgusting they are, and being clean helps them slide through easier. Mine were actually blue, not the black they looked like.
Step 4: Make sure all the buckles are facing the correct direction before you try putting it back together, especially if switching sides. Trial fit it to make sure, then check again. I stuffed this up more than once.
If you need to change their orientation, just make a fold in the belt and feed it through the buckle.
Step 5: Wind back the spool against the spring by hand. Keep turning until it will not turn any more and the spring has binded. While holding the spool with one hand, feed the belt back through the centre and replace the plastic rod in the end of the belt. Once released, the belt should retract back into the assembly, hopefully a little faster than before.
Step 6: You can get a bit more preload on the spring, but it will sacrifice how far the belt can extend. With the length of my belt, this was acceptable. The spring itself is housed within the brown plastic on the side. It is secured with two screws, and two locating tabs.
(Gloves and eye protection recommended)With the belt fully retracted into the spool, remove the two screws holding the spring housing on. Make sure you keep it pressed against the housing. You need to lift it away from the spool just enough to free the locating tabs, which are about 5mm long. If you lift it much more than this, the spring will basically explode into a tangled ball of metal. It would be very impressive if it wasn’t so annoying.
Once the tabs are free, the spring will try to rotate the housing. You want to rotate it against the spring, to increase the force it has on the belt. I found 4-5 rotations was the most I could do before it affected the length of the belt. After the rotations, locate the tabs and screw the housing back on.
Step 6.5: If you didn’t stuff up the spring, then congratulations and skip this step. If you currently have a huge tangled ball of spring, then locate an end and begin to straighten it out. It will naturally try and go into a coil shape, but it needs to actually be coiled in the opposite direction to provide any force.
Start by locating the external tab, and make sure it is orientated in the same direction. Then wind it out around the housing working towards the middle. Again it will want to come out of the housing, so be very careful or you’ll have to start again. Once you’ve finished winding it back up, a small amount of grease wouldn’t hurt.
Step 7: Install the entire assembly back in the car. Check the bolts are all tightened properly. Test out how strongly the belt retracts.
Hopefully you have seen an improvement. Mine was fairly significant, and the belts will no longer hang loose under any circumstances.