Apologies for what are probably some very silly questions.

My car is fitted with Britax Auto-Lok type seatbelts. I am not sure if they were factory fitted original but if they weren't they must presumably have been fitted not long afterwards, they appear to be of the era. The thing is, if you pull on them they do not lock. I have seen it suggested that these cannot be tested in that way as they supposedly work differently to modern seatbelts (something about forces caused by swerving /heavy braking causing a ball bearing to move triggering locking) and that the only way to test them is to tilt them and see if they lock. Is this true? I would like to keep the car authentic but this is safety critical equipment, if they are no longer functioning they ought to be replaced.

Also, the anchoring points for the receiver and the end of the belt (ie down near the reel) are eye hooks rather than the standard fittings which are bolted into place. Do you know of anyone supplying reasonably unobtrusive inertia reel seatbelts with the correct fittings to attach to eye hooks rather than bolts?

Thanks

 

What I did with my car was use the seatbelts from a Series III XJ6. The upper anchor point is already there, I added some metal to the lower side of the B pillar and mounted the reel there. The other end bolted to the holes in the floor that were existing.

I'm not aware of an inertial type belt that could attach to eyebolts.

 

If they are Britax they are original.

 

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Pictures credit Primaz ~ California.


And they have many other options to mount on the B pillar. They also do Daimler buckles.

 

I think and it is the way mine work, that if you pull the belt slowly it unreels itself but if you pull fast and sharp then there is a centrifugal clutch mechanism that kicks in and locks the belt up. Have a look on you tube there are plenty of videos explaining it.
There are a couple of methods of bolting the inertia reel to the floor or rear parcel shelf.
This the original type of bracket for attaching the initial reel block to the rear parcel shelf. It is a plate with a single bolt going through the factory fitted threaded hole in the rear shelf and on top of that is a swivel plate onto which the inertia reel is bolted. It allowed the inertia reel to have some slight sideways movement for comfort. Ignore the condition of the reels these are not ones I have used. I also only fitted standard belts in the back as the inertia reels on the rear parcel shelf looked really ugly and blocked a lot of your rear view.




For the front seats there was also a bracket made. When I first fitted my inertia reels in the front I noted there was not enough room for the inertia reel block to sit between the side of the seat and the "B" pillar so I mounted it on the floor just behind the seat. Problem with this is that it got in the way of people getting in the back seat as they were hitting their toes on t all the time. No good for a wedding car. So I was at a show one day and saw another S type with inertia reels fitted to the front seats but they were mounted on a bracket which sat over the top of the sill adjacent to the "B" pillar. I went home and made a couple of brackets to fit my car which are both bolted to the floor via the eye bolt and to the "B" pillar upon which the inertia reels sit out of the way. The only thing I had to do was remove the recline handle on the side of the seat as this interfered with the reel stopping the seat from sliding back or forth. The handle is in the glove box now if I ever needed to recline the seat.

 

As I recall, the non-original Britax that I installed in my Mk2 locked under inertial load (any acceleration, deceleration, or cornering forces) or tilt load (car on slope or unfortunately inverted). I don't think they lock up under ******. They work beautifully and are extremely effective; they saved me from any injury when I had a rather serious off road excursion.

 

Correct Cass ~ Inertia Reel Belts.

 

B Pillar Mounting ~ very neat. Inertia reel belts. Seat Belt Services will provide to mount to the proper reinforced mounting point. No brackets required. You can have in chrome if you want. They will do anything you wish. They will even re-chrome your original parts & mounting bolts.

 

The set up in mine looks very similar to your final two photos, they are the same sort of seatbelts and a virtually identical bracket arrangement (although the bracket looks factory made rather than bespoke).

 

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Am i overcomplicating things? If the eye bolt is the same thread could i unscrew it and bolt a new seatbelt in place? Or use (suitably robust) bolts which are the same thread as the eye bolts?

 

So can these be (safely) tested by unbolting the reel box and tilting it ?

 

Yes or by jacking the car. You might also try slowly extending the belt with one hand and give the reel box a heavy thump with the other (might be easier with an assistant). I think (I've never tried it) you should feel a momentary block on the belt. However, unless the belt has been stored in a pretty awful environment, it's very unlikely to have a problem. They are very reliable.

For fitting, I'm pretty sure all the nuts and reinforcement plates were already in place in my 1962-3 car. We made a plate and cut a corner off the reel box of the belt to make it fit between the Mk2 seat and the bottom of the B/C post. The belts we used were the type BL were fitting on most of their cars in the mid 1970s.

 

if you want new belts have a look at the MG owners club website. similar inertia belts were used on a lot of the BL and the MG owners club stock them. Cheap as well being MG rather than Jaguar and SNG Barrett. I bought some not so long ago for a friends MGR V8. They come with different coloured webbing and I am sure they would fit the Jaguar.

https://www.mgocspares.co.uk/search?...Code=RELEVANCE