understanding seat bolt threads

[trd_st184]

hey all,
Was just checking over the Caldina (all the interior is out) and noticed that the inner most rear seat threads were a bit dirty, the 1 bolt that came out of the drivers side hole had a few sections of the threads that were "squashed" together.

I used the correct size tap to clean the threads but i've heard I should have used a thread cleaner instead?

Only the inner most rear seat rail bolts required cleaning with the tap. I was able to wind in the tap with my fingers most of the way with only a few small areas which required a bit of extra force with the tap handle (which i only wound in slightly and then unwound)

Should I have anything to be worried about? The threads are still fine and I tightened up the bolts nicely and there was no difference. The threads themselves also looked fine.

I read up that a thread chaser is used to realign the "damaged" thread, where the tap may have taken too much off?

I wonder if I could take it to an engineering place to replace the nut on the under side? Not that I think it needs it, I only did a very light clean of the threads but my mind just keeps thinking about the "what if".

[JustenGT8]

It'll be fine mate, don't stress it.

[trd_st184]

It'll be fine mate, don't stress it.

Thanks for the reply mate. If I could no doubt do the bolts up more than what they would normally be tightened to they would no doubt have adequate force holding the rails in place?

[dnegative]

Yeah nothing to worry about, running a tap through wont cause any damage worth caring about.

[trd_st184]

Yeah nothing to worry about, running a tap through wont cause any damage worth caring about.

There was a small amount of metal in the tap that I cleaned out after the tap, the actual threads look like any of the other threads. I just get really paranoid about these sort of things. I heard that using a tap would no doubt cut the top of the threads slightly lower (if the tap catches at any point).

[Supra967]

wind the bolt into the treads fully, but don't clamp it down. shake it around. If it really moves, you might have problems. Do the same with a brand new nut and bolt if you need to compare. Little bit metal off the tap isn't going to do anything.

Get new bolts, it's often the bolts that cause the problem in the first place. Running a stuffed bolt into a repaired thread is asking for trouble. I wouldn't advise over torquing a repaired thread either.

[trd_st184]

Good point actually, I tried doing that with the other thread and I struggled to find any difference between the 2. I think I may have noticed a VERY slight amount of movement extra back and forth (so small a difference it was hard to actually detect) but this was with the bolt 1/2 out of the thread. With the bolt in fully I couldn't get any movement different.

Hypothetically could an Engineering place remove the nut (if it was accessible) and weld in another one with the same grade steel in its place? Would you trust the replacement welded in nut or the original one retapped with a bit of the material missing.

The other thing I thought of was getting the car up on the hoist and putting another nut on the end of the bolt once it was all threaded through. That would be a bit of extra precaution.

Thanks for your help.

[Supra967]

Bugger the hypothetical mate, sounds like you're good to go with the one you've got

[trd_st184]

Bugger the hypothetical mate, sounds like you're good to go with the one you've got

Haha thanks man. I just worry about these sort of things way too much. I'd prefer a tyre to blow out than my seat (and me) to fly through the windscreen lol

On a similar topic, Would a decent set of ADR aftermarket seat rails be as good as a set of Genuine seat rails? I would love to chuck in a set of aftermarket seats but always worry in the back of my mind they may not be as safe.

[TERRA Operative]

If they have the ADR stamp, they have passed the same tests that an OEM item is required to pass, so they will be fine to use, no worries.
Just use the right rail for your car and you'll be fine.

[allencr]

Sure, any metal removed from threads weakens them, and if was in tension, being pulled, it would fail sooner but most likely that bolt is in shear, being pulled from the side, so the strength is still there.
The captive nut & sheetmetal is way weaker then the bolt anyway.
Put a nut & thick or double fender washer on the other side if you're worried & it's accessible. I wouldn't be.

[trd_st184]

Thanks for the info. Should I have used a Thread cleaner instead of a thread tap?

[TERRA Operative]

Doesn't really matter. I always just use a tap.

[lexsmaz]

Agreeing with what has been already said in regards to checking the loosness of the bolts in the nuts is going to be your biggest tell tale as to wether to much metal has been taken out, some slight side to side movement is normal / ok, but you shouldn't be able to feel very much movement at all if you try to pull the bolt up & down ( obviously this is with the bolt threaded into the captive nut & screwed in making sure the depth of the nut has bolt thread in it & making sure it is not bottomed out as it will give you a false feeling...

Also dont over tighten the bolts as it just makes them more susceptible to stripping pulling out of the threads in the case of a heavy impact ..

[trd_st184]

Great info there everyone thanks

Moving up and down there was barely any noticeable movement out of it. It actually took me a few goes comparing to the other one to get any distinguishing differences between them. In the back of my mind its the one thing that is still stressing me in the back of my mind. I know I didn't apply any more pressure than required and backed off each time it got "tight" when winding in. I could hand wind in the tap about 2-3 turns before there was any catching.

In the back of my mind i'm always going to be thinking "what if it wasn't strong enough" in the case of a heavy impact. I would say most people would find it quite difficult to detect any differences between any of the other nuts visually.

Would it cost much for someone at a workshop to look over it for me? I know i'm being hugely paranoid but I know it'll keep bothering me even if I know its nothing to worry about.

I wonder if any of the metal I saw could have been from the actual bolt itself or likely to be the edges of the thread on the nut.