twotone's Seat Belt Upgrade

[twotone_ra64]

DISCLAIMER: This guide contains potentially dangerous modifications to a motor vehicle. Please check with your local authorities to ensure this type of occupant restraint modification is legal and conforms with all motor vehicle safety laws. This guide is provided as reference only. DO NOT attempt any modifications of any kind on your vehicle without seeking advice from a professional and certified mechanic FIRST. You proceed with this modification at your own risk.

Introduction

Are you tired of your Celica's floppy seat belts? As it is often found in classic cars, the seat belts tend to cease to retract or even lock when pulled. In 3rd-generation Celicas, the belts' retractor springs wear out over time and the clasps can hang loosely. The clasp can end up in the door jam, and the unaware driver or passenger will close the door, breaking the plastic on the clasp. Poor design of the upper hooks on model year '82-'83 cars cause the seat belt to bind in the hook, further preventing the belt from retracting properly. Lack of locking under high-G deceleration can be extremely dangerous, as it won't hold the occupant in the seat in a front crash.

This modification utilizes newer seat belts, retractors, hooks, and buckles from the model year '94-'99, 6th-generation Celica. For the model year 2000, and the beginning of the 7th-generation Celica, explosive pre-tensioners were added for further crash safety. This, however, makes the retractor assembly too bulky for use in the 3rd-generation cars. Thankfully, Toyota kept all the fasteners the same, save for the buckle design, which is bolted to the seat. It otherwise makes this a nearly bolt-on mod! This will work for both liftbacks and coupes.

A huge thanks to Lone.mincer_ for investigating the mechanism and doing some initial testing, and @707_matt on Instagram for helping out at the Fairfield Pick n' Pull, where we pioneered the mod! Prepare yourselves for a write-up with high quality, DSLR images!

The Parts List

Here's a very short list of what you'll need:

• 1994-1999 Celica seat belt assemblies with buckles & all hardware

• The two lower 14mm bolts from the donor car that held in the retractor assemblies

• An extra pair of belt finisher trims from a 3rd-gen car

From your local junkyard, these should cost no more than $75 USD.

The Seat Belt Mechanism

The 6th-gen belts contain a few useful safety features, including fast-pull locking, to hold your body during a crash, and inertia-reel locking, to hold your body during braking. To ensure your safety using these belts, DO NOT remove the following components from the retractor mechanisms.

This is the passenger side belt mechanism. It contains a few more gears and things than the driver's side. Please note: do NOT interchange left & right side belts, or use two right side belts, etc ad infinitum ad nauseum. They will not work!



These little pins must be removed in order to access the retractor internals:



Popping the cover off, we can see two features: the fast-pull locking ratchet on the left, and the inertia-reel ball bearing ratchet on the bottom right corner.





The inertia-reel system alignment is crucial. The ball bearing sits in a concave pit, and disengages the ratchet. Lateral and longitudinal forces on the car cause the ball to roll out of the pit, pushing up on the ratchet, locking the seatbelts. We'll take special care to make sure the retractors are aligned properly for this to function.



This is the driver's side mechanism.



Not nearly as much to see underneath, but it still functions the same way. The inertia-reel ball was removed in this image.



The Removal Process & Preparing the New Hardware

First, grab the seat belts from an appropriate car in your local junkyard! My victim was a 1994 liftback:



Remove the seats, pop off the seat side trims on the inside of the seat bracket towards the transmission tunnel, and unbolt the buckles. Snip off the wires for the buckle sensors. Then, remove the rear quarter inner trim panel's speaker grilles with a trim removal tool, and remove the one screw you see by the speaker. That's all you need to remove in order to pop off the panel enough to reveal the bolts for the seat belt retractor. The top bolt is a 10mm, bottom bolt is a 14mm. All the rest of the hardware for the upper hooks and end of the belts are 14mm. An electric ratchet or impact makes this super easy!

Now that you have the donor seat belt hardware, there's s few things you need to do to in order to get the new stuff ready to bolt in.

First, start at your own car and remove the seats. 14mm bolts hold down the rails.



This will give you access to the buckle. Two 14mm's to remove there.



Don't forget to disconnect the seat belt warning plug on the driver's side. I omitted connecting anything to the open plug, as it didn't throw any warning lights or cause anything to stop working.



Notice how even though both bolts were 14mm, the forward-most bolt has a smaller diameter thread? We are actually going to use that bolt for the new buckles. A couple washers will solve the diameter difference.







The next thing you need to do is bend the metal tabs on the buckles. Otherwise, they'll fowl on the center console. It'll go from this:



To this:



Finally, as shown in the parts list above, the finisher trims need a slit cut into them to come off the original belts in order to slip them onto the new ones:





Old Belt Removal

With the seats and buckles already removed from the previous step, you're already 20% there!

First, remove the upper and lower hooks. Both are 14mm.





Next, remove the single screw from the finishing panel and pop it out:



The rear quarter trims need to come out in order to access the retractors.



The rear speaker panels must come out first, two screws there.



Then, the armrests. These just pop out and hinge at the back.



The back seats might hold the panels in place, so unlatch them and move around to pop out the panels. Careful not to tear that 35-year old cardboard.





Now there are two bolts to remove the retractors. Much like the 6th-gen car, it's one 14mm on the bottom:



...and a 10mm on top.



And voila! Just like that, the retractors can be extracted.



New Belts Installation

A quick initial note - in case you forget which belt is for a particular side, here's an easy way to tell:

The driver's side belt end has a small plastic trim, while the passenger side has a longer, rubbery plastic trim!



First, install the new buckle with the bolt and washers. To cover up the unsightly hole left by the unused bolt, I used some Dum Dum strip caulk and stuck it over the hole.



Next is to put in the new retractor! Make sure to use the 14mm donor car bolt. The top bolt will be left unused. Now, here's where that crucial alignment comes into play for the inertia-reel ball - especially on the driver's side, when you're tightening up the bolt, the retractor will want to pivot towards the front of the car. Push it back with your hand so that the plastic side cover of the retractor touches the sheet metal towards the back of the car. Seriously, if it tips forward too much, the inertia ball will roll out of its stay. This is not an issue for the passenger side, where the retractor will naturally pivot to the required position.



With that nerve-racking part over with, bolt on the upper hook. Slip on your cut finisher trims over the belt, too.



Bolt in the lower belt end to the floorpan. Keep in mind the seat belts needs a 180 degree twist from the hook to the bottom end in order to align properly when you put the seat belt on. Play with it, and you'll see what I mean.



To button up, pop in the rear quarter side panel trim, speaker cover & screws, finisher trim and its screw. And that's it! Rinse and repeat for the other side. Test everything before you bolt up the seats!

[twotone_ra64]

Afterword

It really is nice that, despite a decade difference, the newer belts and buckles work with our cars. A test drive confirmed the inertia-reel functionality under hard braking. It's really nice to have locking, retractable seat belts again. And I'm sure your passenger will appreciate it, too!

Now, there is one area where a variation may occur. The buckle can be attached with the bolt I showed you above, or to the OEM buckle bracket, or to a custom metal piece of your own design that uses the two original bolt holes. Just bear in mind, the stock buckle is attached to its bracket with a non-removal fastener (and for good reason!), so how you tackle modifying it is up to you. The bolt method puts the new buckle in the correct position for my seat setup.



In case you need a shorter buckle for your seat configuration, 7th-gen buckles also work with the 6th-gen clasps and have a shorter metal tab on them.



----------

That's it! Best of luck with this mod, everyone! I hope this guide helps to show that your seat belt experience no longer has to be a flaccid mess. Let me know if you have any questions.

[patwhac]

Awesome write-up man! 

Sticky???

[twotone_ra64]

Thanks man! I'll probably move it to the Write-Ups section after a little bit in case there's more discussion to be had or there's anything I need to add on (for instance, a seatbelt solution for 'vert owners).