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So, i was putting my new bucket seat in yesterday (thanks Ajay!), and I was screwing in the last bolt for the seat/rails, AND IT SNAPPED AT THE HEAD!!!

The head of the bolt was only just starting to touch the rail... ...and it wasnt even tight yet. And I was using a good torque wrench, and I was bolting it straight... so I cant see how a bolt that hold the seat can be so weak!!!!!

I was reusing the original bolts... which is scary... I kinda want to replace them all now...

So now ive gotta get some nifty little thing from an auto shop to get the rest of the bolt out of the seat...

It must have picked up the thread on the way in. Nasty. Hopefully the thread on the captive nut isn't to damaged.

Whhaaat?!?!

YEP!

...and considering that the seat belt buckle is attached to the seat itself in NB+ models... if your in a nice accident and these bolts sheer, you'll get pinned between the seat and the steering wheel... FUUUN!!!
And your seat belt is practically useless in that scenario... at best it will hold on the right, great pivot point there... and as you 360 across the road, you and your seat 360 within the car...

Who needs theme parks?

now THAT makes me worry.

yeah it concerns me too because i was not putting much pressure on, I wasnt putting it in on an angle, the head wasnt even touching the surface it was being screwed into...

I guess in a crash the base of the chair mustnt have too much forward force anyway cause the teeth on the lever mechanism (the bits that stop the chair sliding back and forth on the rails) couldnt be thaaaaat strong right? Tho they may be hardened steel... dunno!

On the other hand, i plan to change all the bolts over now.. but i probably wont... laziness

i think you should contact mazda about the problem and show them the bolt.

it's possible that there was a manufacturing fault or something - if it's serious enough may even spark a recall and save someone's life.

or they might just shrug it off - it would be interesting to see their reaction either way.

is it still in the car or have you removed it?
if its still in the car can you take some pics I and others might beable to give you some tips on how to remove the rest of the bolt without costing too much

metris wrote:On the other hand, i plan to change all the bolts over now.. but i probably wont... laziness

Going for a Darwin Award, are you?

sabretooth wrote:

metris wrote:On the other hand, i plan to change all the bolts over now.. but i probably wont... laziness

Going for a Darwin Award, are you?

I dunno sabretooth, you changing all yours now are you?
Ive used the original bolts for now so that I can use my car but will be shopping around for some hardened ones this weekend...

AZNTieN wrote:if its still in the car can you take some pics I and others might beable to give you some tips on how to remove the rest of the bolt without costing too much

Thanks so much for the helpful offer AZNTieN!
I managed tho to remove it yesterday veeeeery carefully with an easy-out kit.. read some nasty things about them, but it worked!
I have the bolt thread and head and will be calling mazda for sure.
Im pretty sure tho that they will just tell me that the bucket seats thread must have been buggered or something like that... (even tho the thread on the bolt looks perfectly intact)...

Will give it a try and I'll let you know how it goes...

Please do keep us informed.
Do some digging and googling and see if this is a common occurence, if so, I can feel a nation-wide dodgy-day happening post-haste.

I shall post a query on the Miata.net forum. *shudder*

You will probably find that they are a single use bolt
IE once you remove them you are sopose to throw them away

this goes for suspension nuts as well they will usually have a punch mark on three sides (spaced) around the nut which when screwed on get cut into the thread preventing them from undoing.

bolts are the same but have a patern that works its way down the thread and get tight as the bolt penetrates the other side of the nut.

It is defantly not a once off bolts are only so strong and if the method you were using i.e. if you use a big breaker bar then they don't stand a chance.
(it probably didn't feel tight but lubrication is the key)

and screwing a bolt in is probably the most strenuous task that it would have to endour!

Hmm okay thanks.
I'll still contact Mazda and hopefully they will confirm that its a one use bolt!

It sounds to me that the bolt may have suffered a failure due to hydrogen embrittlement. All self tappers for example are hardened and treated to avoid embrittlement. One of the way they test product is to screw them into a plate and leave them for a set time- if the screws are faulty the heads will drop off.
If its an OE bolt you would not expect to see it fail. One of the OE screw and bolt makers or even a distributor( not many manufacturers left sadly)could give an informed comment. Another suggestion talk to the QA mgr at Autoliv - they know all about seat belts and anchorage

Well im please to let everyone know:

None of the other bolts broke last night when i crashed into a 4wd that decided to take a left from the right lane right in front of me who was in the left lane..!!!

Yay for bolts..!

Well the accident wasnt actually that bad cause I managed to wipe of a crap load of speed a yank the steering wheel to the left at the last second before impact... still hurt poor car tho...