My rear left bolt on drivers seat is ballsed up, after removing the bolts and seat to fit the drivers seat cubby and clean up under there.

I was having problems with it, screwed in at first by hand and it was going in, then added further pressure with what I thought was torx/hex but was getting resistance and it wasn't tightening all the way in (subsequently on the other bolts they went in fine but I used a tiny bit of oil spray just to add a bit of lube - I still used threadlock on the bolts too though).

I have to admit I then succumbed to a feeling of urgency because I did need the bolts back in the car to drive the next morning ! I should have sat back and took a deep breath before my stupidity - in fact I should have looked carefully before applying the incorrect tool but it was dark in the back of the car too.

Well I now know it wasn't torx and now even bought a spline kit with M10 in there. Trouble is, the damage is done and I can't get it out even with spine which is spinning !

I've been trying with grips similar to monkey wrench to grasp on and see if I can free up a bit and

Even thought of maybe whacking a socket around it but don't suppose that would work....or maybe hammed it anti clockwise with a chisel ?? Dunno what next...how do I loose this one bolt from inside the car ?

Welding a socket on might be an option except I don't have any welder !

Any one able to help ?? Anyone prepared to help anywhere near me (Northants) I can drive to you - if you have welder ?

Its not really urgent as I can push the seat over the bolt and its still fairly secure (the bolt ain't going anywhere yet) but don't like the idea of the play in because the bolt isn't fully tight yet

I feel like such a numpty !

You could try some special sockets designed to remove rounded off bolt and nut heads I have some as I'm found of buggering up bolt and nut heads and they work well. Tap socket over your round headed spline bolt then hey presto. Not sure how much room you have though?

http://www.amazon.co.uk/Irwin-Bolt-Grip-Remover-Expansion/dp/B000QW6K8I/ref=sr_1_1?ie=UTF8&qid=1362769674&sr=8-1

Cheers dude, its about 1/2 cm from the nut to the runner so not too bad...more room along the length of the runner itself so thats the only limit - and obviously makes mole grips etc very limited.

Hmm may have to look into that then thanks for that....not really rounded off though, they are rounded by design lol, as they are internal drive via the spline bits

So maybe something like this then ( need to check size )

http://www.ebay.co.u...=item4d041f059f

Irwins should sort this easily. Every toolkit should have a set.

I can check in a bit whether one of the standard set fits the bolts in question, if you like?

Yes I know the spline bit you rounded off is internal but those sockets should grip the round by design outer part of the bolt. I've had problems with those bolts in the past by using a torx bit instead of a spline bit like you lol!

Irwins should sort this easily. Every toolkit should have a set.

I can check in a bit whether one of the standard set fits the bolts in question, if you like?

This is true! Especially if your a hamfisted DIY mechanic like me lol!

I think you'd be better off with the tools that grip on the outside. I've got a set that has saved me on quite a few occasions. Seeing as the splines are no good now and the bolts possibly not that tight, it might worth having a go at hammering a larger torx or allen key socket into it first.

use a smallish drift and hit the centre of the bolt or the whole bolt if you have the correct size drift .... do this a couple of time to try break the thread lock

Thanks for those good ideas...only thing I think I have close would be allan keys for trying from the inside, I do have hex, torx and NOW spline (lol) but they got up from 10 to 12mm I think, it would probably be more like 11mm....so I may need to invest in the rounded bolt extractor

Mmmm, this might be trickier than I thought. How far from 'all the way done up' is the bolt in question?

Just tried with both standard set and extended set of Irwins, and it looks like the 13mm one from the extended set may just bash on OK. Trouble is, the rolled-over edges of the runners are just too close for the hex part of the Irwin socket to turn inside. So may not work without either damaging the seat runner, or grinding off some of the Irwin tool.

If you're a couple of turns or more from being fully tightened down, this shouldn't be a problem, 'cos the Irwin's hexagonal part will be high enough to be above the rolled edges.

I can experiment a little more if you like, by loosening one off a couple of turns with the spline bit, then checking that the Irwin can take it from there?

Alternatively...something I once had success with...is to find a (flat ended) Allen Key or other similar tool that just fits into the rounded inside of the head, then lean it over at an angle from the vertical (so the end corners of the bit dig in) before attempting to turn it. It's cowboyish, but got me out of trouble once when all else failed.

Nah dont damage your car or tools please....I'll see what I can do

Worst comes to worst maybe I could even manage to get some kind of lever in there and then use an adjustable wrench to turn it around ?

Is there enough space to get a small angle grinder in there?

If so, you could cut a flat spot (or 2) onto the outside of the spline head and then the mole grips will grip it nicely and free it.

if it came to it you could always use a small grinder / hacksaw lengthways and cut a slot on to the head and use a screwdriver that you can get a spanner on to turn it

OK, best of luck with it.

Dremel style cutter disk to make a slot head? Maybe use an impact driver (gently).

I had the same problem when changing a door lock mechanism. Previous owner had damaged one spline bolt. I drilled off the head using increasing diameters of drill bits until head of bolt was removed. Starting at 5mm and working up. You will need good quality HSS bits. Once head is removed you can remove seat and then should be able to remove remaining threaded portion. Hope this helps.

Thanks all - turned out to be much easier than I thought (despite taking a few half hours faffing to work out how to get it off)

Irwin substitute - 13mm socket from an old set banged on, came off with a little force after that.

Even salvaged the old socket by banging a driver through the centre onto the bolt into the void of a brick which didn't damage the threads on the old bolt either - not that I need it but I'm gonna probably struggle to get a replacement at this time so need to work out the PCD, to see if I can get a substitute to work temporarily

I'm a bit confused why the bolt got stuck which led to the problem with not being able to get it fully in tight to be honest - I was struggling because it didn't seem so square anyway when I offered the seat up and started the thread by screwing it slowly in by hand - not with tools - it did go in a hell of a way before its got stuck

So I wonder if the factory managed to thread it and just managed to bodge the bolt in regardless? So its not the end of my faffing yet.

I might just see if I can get a shorter bolt in that will still tighten it for now as a temporary bodge

run a tap down before putting new bolt in? can help check treads are ok and depth under nut then buy new bolt from dealer

Edited 9 March, 201313 yr by Holmesie

Should have picked up that set that was Aldi recently lol

Should have picked up that set that was Aldi recently lol

Maybe take care, VAG, and probably other car marques, tend to use what you might call "alternative" thread pitches (not PCD as that refers to Pitch Centre Diameter of hubs/wheels), and using cheap crappy taps could end up with a tap shearing in that hole, cheapish tap and die sets are okay if they are not too cheap - to use only to clean up threads, no really cheap ones are like the ones you get at markets - and in my case, of no use at all (been there done that - just hope I binned them!).

Maybe you, me or someone else out there with access to a VAG parts cat could check the thread size - just don't buy and fit something that kind of looks okay.

BTW, Screwfix used to sell an extensive kit in a wooden box, that set, if still available covers most of the thread variations (fine/coarse) that you might "bump" into on VAG cars, and from my experience, it is good enough to clean up threads, though I would never consider using it to form new threads.

Edited 9 March, 201313 yr by rum4mo

You are right - its a very specific bolt and not something I can just put a standard bolt in

You are right - its a very specific bolt and not something I can just put a standard bolt in

looks like its a case of just run the new bolt in then and hope not to do same again lol

I would put the new bolt in as far as it will go by hand, then tighten it a small amount then undo it again with plenty of lubrication. Keep doing that. If it won't tighten further down without excessive force the thread is b******d lower down and you need to tap it out properly.

The part number of these bolts is/was N908 921 01 and it is an M8 x 28mm (with a multi spline socket head), now, as I said before, there is more than one standard M8 thread, just check the tap against the old bolt, do Halfords or Machine Mart not sell a kit for cleaning up threads - that you would be allowed to check against first?

Standard ISO metric M8 threads are 1.00mm and 1.25mm pitches - that is fine or coarse.

You need to aim as high as the Laser Tools one in Machine Mart before you find an honest statement as to what is in the kit, it is £59 inc VAT. (all the others just give "normal" thread pitches, in the case of M8 that would be 1.25mm pitch)

Screwfix sell a kit for £25 that includes both fine and coarse threads.

Scrub Halfords from that list as they only seem to carry one thread per size.

Edited 10 March, 201313 yr by rum4mo