Four Point Harnesses - (Maybe NOT) Successful fitment!

[theslayyer]

Thought you guys might be interested in this job I've just completed :-

It wasn’t too much work (once I’d worked out how I was going to do it) and it’s proved to be very successful.

I purchased a pair of Recaro seats - Recaro Sport Trendline Seat in Black Ambla Leather / Black Dinamica Suede (these seats are identical to the seats fitted by Renault to some of the other Clio models so I knew they'd fit), along with matching bases to fit the original sliding rails and the elelctric kit to sort out the airbag wiring.

After fitting the Recaro seats and sorting out the seat airbag wiring (fairly straight forward), I ended up cutting out little rectangular bits of a steel plate from behind the seats to allow access to a decent bit of steel, drilling holes into the 50mm box section brace (that holds the engine up), tapping a thread, then TIG welding on some nuts for strength (after removing the annoying zinc coating!).

Finished the job off with some paint (to stop any rust) and modification of the soundproofing / carpet.

With the main trim panels sorted, it looks pretty neat and provides a massive amount of strength.

Lap belts are fitted into identical eye-bolts drilled into the Recaro seat bases.

It’s transformed the car on the circuits, and lets me use my other tuning modifications properly (more power, more brakes!).

Fitment of the 7/16ths UNF nuts to the steel box around the engine bay (painted) :-

Soundproofing and Carpet trimmed to fit :-

Engine covers drilled to match hole locations and eye-bolts fitted :-

Sabelt harnesses fitted and ready to go - awesome! :-

[smilie=icon_cheers.gif]

If anyone wants to know any more about part numbers etc etc, let me know.

P.

 

[clarkeeuk99]

Looks great, well done!! :approve:

 

[Mike T]

Just a thought - are the eye bolts longer than the depth of the box section and there's another nut in the engine bay?

Tig welding a nut on one (upstream) side of a really thin (2mm I think) box section will give you a large headache in a crash as with he best will in the world the weld will hold but the box section will rip.

You need to go to the other side with spreader plates at least.

If you have I'll shut up if not don't find out the hard way with your passengers head.

Worried

Mike

 

[theslayyer]

Mike - Thought about all the options regarding strength already - obviously ... yes - 2mm - which is lighter than a standard 50mm box (which would be around 3mm of steel).

However, imperial 7/16th eyebolts at more than 1.5 inches with the correct eye size just aren't available.

More importantly, drilling through both sides of this box in FOUR places would weaken the box too much (11mm holes!). It would bend very easily when put under strain. I was concerned about lateral impact strength too - it would probably crumple very easily.

After much discussion on strength with various engineering friends, we reckoned you'd need a fairly serious front end collision with a heavy driver (I'm not!) to tear this box in both places.

Mind you, it's all relative - bear in mind is that the recaro seats come with a SINGLE nut, welded with 3 TINY spot welds (and not with any added metal from a rod either) onto 2mm steel. Granted, the forces are in a different direction, but if they consider this design adequate to cope with the standard seat belt mount ... Hmm.

With this method. the body load is spread across FOUR mount points, with these two behind the driver welded all the way around.

However, for passengers that are concerned, the standard belts are still in place which should be worn under the harnesses (which is suprisingly practical), as the harness sets are NOT road legal (FIA approved only).

The harnesses were fitted purely to add stability to the upper body in the seat.

In a serious head on collision ??? Hmm ... who knows. Both would have to fail simultaneously to be disasterous, but you still have the lap belt and the air bag.

And hey ... If I worried about such things I wouldn't ride 180bhp motorbikes ... which I do. A lot. :badgrin:

Actually, come to think of it, I probably wouldn't drive this car either ... it isn't the safest vehicle out there! (And the side impact airbags are gone now too).

The jurys open on this one! I'm not about to head-on impact it to test it, but if I do ...

P.

 

[Matt]

Looks good.

 

[TRW1]

Mine was drilled through both sides with a full length tube section inside to strengthen............
You can see a couple here to get the idea...........

 

[theslayyer]

Hiya ...

What do you mean by a TUBE section ?

Someone else suggested that this morning ...

To quote "A remedy is to remove the nuts and insert tubes through the box section, welding to both sides of the box and put a reinforcing plate on the back of the box where the nut will pull down" but I'm not sure what he means by this.

What sort of tube ???

This is driving me nuts - I thought I'd got this cracked! I've been on this project in my (very little amount of) spare time now for about 2 months.

Without grinding off my welded nuts it's going to be very hard to drill right through now - and grinding these nuts off is going to weaken the bar further I reckon.

I've spoken with a manufacturing company this morning about trying to get some specially made 7/16th UNF long collared eye bolts but I'm struggling to come up with something compatible.

Also, they are talking about £40 + vat EACH!!!

AAARGH!

[smilie=icon_aaargh.gif]

P.

 

[theslayyer]

OK CHAPS!

Opinions please!

I've come up with this idea now :-

Sort of a combination of all the other ideas.

The idea being that I can use my exising 7/16th eyebolts (there's lots of reasons for this) and NOT have to damaged to box section by grinding off my existing welded on nuts.

Internally threading the tube should provide a lot of strength.

Do you think the BACK END (engine side) of the tube will be sufficently strong with just a weld on protuding tube ???

Any more advise much appreciated.

P.

 

[TRW1]

Tube section through the box and bolted at each end with another tube inside that the eye bolt threads into............

dodgy diagram

Yours is a nicer pic than mine!! :wink:

Back end weld is fine if the steel is quality and a good size and welded properly.

 

[GTTurbo]

Good work Paul, but the thought of chopping the plastic covers (unless you have spares?) would put me off a bit

 

[Mike T]

Tims solution - which I've seen and is better than mine - is very robust

As to you being a lightweight

If you weigh 10 stone standing - you'll weigh 200+ stone in a head on - thats a very fat bastard!!!

Keep working on it as these ones are the ones that take the majority of the load at impact.

the sleeved solutions are the answer

Remember, the oak tree always wins in these fights

 

[theslayyer]

Thanks for all this everyone.

The diagram provided by TRW1 makes perfect sense but this is one hell of a thing to engineer for someone like myself.

I'm just thinking of using the "middle bit" of his diagram - ie, a threaded tube with a large plate at the back, through a 12mm hole, inserted into the exsiting nut at the front of the box (then welded to hold it in place there).

The eyebolt will screw into this threaded tube - when it's pulled, it will pull on the tube and hence the backplate "spreader".

IE - a bit like my diagram, but doing it this way will mean I don't have to weld at the back of the box section (it's a little tricky with the engine in the way).

I can also then manufacture the "tubey" bits with the back spreader plates on OUTSIDE the car - making things a bit easier.

P.

PS 200+ stone if I hit a tree ... if I eat any more cakes in Amsterdam this weekend I'll be that WITHOUT hitting the tree. :wink: