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The old steel bolts seized in aluminium housing challenge


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Hello Gents, 

And merry lockdown season's greetings!

This is a long shot - and I apologise to admins if out of place - but probably relevant to tackling similar tasks on our Defenders and a challenge I'm sure others have faced. Whilst in the process of rebuilding my 1999 TD5, a regular vehicle check on the family 2011 Passat  required the replacement of its front suspension lower arm bushes which VW call 'console bushes'. It seemed a simple enough task  (for which VW wanted to charge nearly £400!) - three bolts each side (1 x 18mm head and 2 x 16mm head) through an aluminium bush bracket into an aluminium underbody beneath the engine - so I jacked up and hit the gravel. Using my air impact wrench the two 18mm's came out quite easily, as did one of the 16mms (10mm body). Despite plenty of a well-known penetrating oil, heat from my plumber's butane torch and gentle to-ing and fro- ing with a hand socket wrench, the remaining three bolts sheared!  Removing the brackets over the remaining studs themselves proved another challenge: they certainly couldn't be slipped off their retaining arms and I had to drill rubber and cut and pry them off in the end. It's clear that whoever fitted these components on that unhappy Friday in Germany had decided to use no grease or anti seize on either bolts or brackets.  %^$$£*%! My dilemma now is that until I can remove the sheared bolts I can't slip on the replacement brackets/bushes and the car is unusable. Ridiculous. I've tried various methods learned on my Defender to free the sheared bolts but to no avail and I'm hoping someone might be able to point me to the trick I've missed. So far I've tried the following: welded nuts onto the stubs - nuts torn off; drilled into bolts (as centred as possible, but imperfect) , then welded on nuts hoping for greater grip - nuts torn off; built up  'blobs' on the stubs and tried grabbers for rounded nuts - blobs torn off; bolt extractors - seemed to expand remaining stub and tighten against thread with no bolt movement; left-handed drill-bits - after biting, they simply go on removing metal, so I stopped before damaging threads... So I'm now getting lost for swear words. I've yet to try one idea seen on youtube - applying jump leads from a good battery to built-up blobs to seriously heat up the bolts to release any corrosion - but I had hoped welding might do that! And I watched one jolly American cousin applying induction heat to seized bolts using an induction gun which costs a mere £600!! I should add that the sheared bolts (all now sheared to the surface of the plate in which they are seized) point directly downwards so I have to weld blobs and nuts directly upwards; using first 0.6mm and now using 0.8mm wire - my welder is turned up to just below maximum amps and  fairly fast wire speed. I use quick bursts to tack or fill nuts or make blobs  but still wonder if I am getting good penetration or how else this might be ensured. I imagine that completely drilling out the sheared bolts would be a nightmare and would almost certainly lead to damaged threads and helicoils... but am I missing something? Once again, apologies if this appears off-piste but any suggestions or new swear words gratefully received.   

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My thoughts are that if you can thread the remains of the seized bolts you can then screw in new (smaller) screws.

This gives you greater access to heating the new screw and thus the old bolt directly, rather than heating up the whole area.
Yes, I would use an inductive heater because there isn't any of the surrounding heat you get with a flame device.

Inductive bolt removers are cheaper from 'China' than from the UK, but take longer to arrive.
Your profile doesn't say where you are, but have you asked about hiring or 'borrowing' from a local garage, or enthusiast?

Regards.

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Thank you for that idea David which is worth considering. The problem I envisage is that the actual bolts are below surface (currently with welding blobs suspended like stalactites) and just 10mm diameter; I've used a 4mm  drill so far (not always perfectly centred) so any new screws would seem rather flimsy. As it is, when using bolt extractors (a bit like smaller screws) there is no movement and I reach a point where I'm concerned that they might snap. Although the idea of using the new screws to get deeper heat penetration might offer a window. I did see one youtuber weld on a bolt in preference to a nute - which might allow a similar approach - especially if an induction heater was available. I'm up in the wild (currently snowy) North West Highlands, but I'll ask around to see if anyone has an induction heater. (What a cost though!!). Thank you so much for pitching in. :) 

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A picture may help, but i'd probably end up drilling out gradually to size of bolt with some cobalt drills then hopefully being able to collapse the thread remains into the hole created by winding the tang in on itself and tapping? if that fails you may be left with the option of helicoiling. Depends a lot on the application. If it's load bearing/alignment safety critical a new bracket or component may be the only way forward.

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Thank you Pete. Yes, I think it's time I invested in some decent cobalt drills for sure... and probably a helicoil set too... if only to prepare for a possible endgame. I'd like to try to avoid that if at all possible though, but the options do appear to be narrowing greatly. This is such a common problem it's an infuriating design issue I fail to understand, just as I fail to understand why induction heater guns should be so ridiculously expensive when by all accounts they do seem to offer a pretty good way out. Thanks for your thoughts. :) 

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Thanks to both Bowie and landroversforever. The youtube video you've shared Bowie is the one I mentioned I hadn't tried - attaching a good battery via jump leads to the bolt (positive) and body. In the video the bolts appear to get red hot and break the corrosion. I wonder if you or anyone else had actually tried that method: a hell of a lot cheaper than an induction heater gun!

And yes, landroversforever, I think you must have a point. I've been a bit wary about welding directly upwards. I've got the welder running pretty hot and the wire feed quite fast to try and push the wire up to where it needs to go to adhere to the bolt and fill the nut. But I've tried to avoid gravity causing my blobs to sag or drip and distort the sides of the nut - hence the quick bursts! But I think you're right - I'm not sure I've struck the right balance - perhaps I'm trying to make it too neat rather than give it real welly. I think I'll have to wrap myself in welding leathers and try again. 

Really useful pointers lads - much appreciated. :)    

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Hi Vulcan Bomber,

In theory the component - which is a kind of plate beneath the engine - could be removed, but realistically not unless the vehicle was high up on ramps in a workshop (luxury!) rather than on axle stands on gravel. Recovery to a workshop will be the very last option, I hope. I don't know if there is any kind of portable drilling jig to ensure accurate drilling out in tight spots. So I suppose if hand drilling is the only option, cobalt drill bits and  even more patience will be needed. 🤞

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13 hours ago, Cluaran said:

Hi Vulcan Bomber,

In theory the component - which is a kind of plate beneath the engine - could be removed, but realistically not unless the vehicle was high up on ramps in a workshop (luxury!) rather than on axle stands on gravel. Recovery to a workshop will be the very last option, I hope. I don't know if there is any kind of portable drilling jig to ensure accurate drilling out in tight spots. So I suppose if hand drilling is the only option, cobalt drill bits and  even more patience will be needed. 🤞

The problem you have is free hand drilling a steel bolt surrounded by Aluminium will never end well. Where are you located?

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18 hours ago, vulcan bomber said:

The problem you have is free hand drilling a steel bolt surrounded by Aluminium will never end well. Where are you located?

Yes, that's why I would love to avoid this if at all possible... not least because I'd be doing it on my back on very cold gravel! 😱 

I'm hoping that repeatedly welding nuts or stubby bolts onto the sheared ends plus somehow belting heat into them will break the corrosion and let me waggle them out. So far, however, I keep tearing these off with no movement from the stuck bolts. But as landroversforever commented above, I may need to longer bursts of weld to get both heat and penetration... which is my next move when the danger of frostbite or electrocution passes! Also, I'm going to try welding plain steel rather than zinc plated nuts on in the hope of better adhesion.   

If, with great reluctance, I do try drilling, I saw a useful video on youtube where a combination of self-centering hinge drills, a centre-drill, and cobalt drills were used to get to the point suggested by Pete above where the remains of the bolt threads might be removed with a tap. Careful stuff but unless I throw in the towel and opt for recovery my options seem very limited. But thank your for suggesting a Bridgeport... that really would be the Rolls Royce route! :)

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Note that the heating unit shown is only half the story.
The purchaser will need to buy a power supply and a cooling system (pump, coolant resevior).
The voltage of the power supply has a significant effect on the heating power available.
Coolant pumps are often 12v so two power supplies might be required, 36v or more to run the inductive heater, the other to run the coolant pump.

Regards.

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A alternative to FF's suggestion is an ordinary drill bit, a left hand tap and matching die, all small enough diameter to not jeopardise the original thread.  Once the stuck bolt is tapped, make a left hand bolt and thread it into the stuck bolt.  Then use the method posted by Bowie69, above.  The left hand bolt should be made long enough for you to make a reasonable electrical contact on it as well as get a spanner on it.  The left hand threads allow you to attempt to undo the bolt without screwing the smaller bolt out of the stuck bolt.  I know that left hand taps and dies are not cheap, but neither is a recovery to a commercial workshop.

Mike

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On 12/29/2020 at 10:41 PM, ballcock said:

If you have to drill it out can you clamp a plate over the bolt position with a starter hole to centralise your drilling? Would an arc welder be better for putting heat into the bolt rather that a mig?

 

5 hours ago, Troll Hunter said:

A alternative to FF's suggestion is an ordinary drill bit, a left hand tap and matching die, all small enough diameter to not jeopardise the original thread.  Once the stuck bolt is tapped, make a left hand bolt and thread it into the stuck bolt.  Then use the method posted by Bowie69, above.  The left hand bolt should be made long enough for you to make a reasonable electrical contact on it as well as get a spanner on it.  The left hand threads allow you to attempt to undo the bolt without screwing the smaller bolt out of the stuck bolt.  I know that left hand taps and dies are not cheap, but neither is a recovery to a commercial workshop.

Mike

These are really great straightforward ideas, lads, well worth trying. Thank you! On the heat front - the induction heater would be great to try, but currently out of my budget and waiting for it - or components suggested by Soutie and commented on by David - to arrive would be too much of a delay. I've really got to get a move on now. Ballcock: I'm not sure if an arc welder (I assume you mean using sticks) would make much difference; I haven't got one and I've seen many migs used with success on youtube (albeit welding downwards!).

Fridge Feezer: thanks for mentioning the left-hand drill bits. Yes, I've tried them, as described - however, similar to a point made by landroversforever about not welding aggressively enough, I suspect I chickened out too early after they just seemed to cut. I suspect I should let them carry on cutting for quite a bit longer to reduce the mass of the seized bolt(s) such that they might then break loose. I feel more hopeful now that some combination of the ideas suggested here MUST work.  

It's absolutely brilliant to get this kind of advice from guys who have clearly wielded (not welded!) a spanner or two. I will try to post some kind of update to let people know how this tale of challenge and adventure ends!  Thank You! :)

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Just a thought Cluaran, have you tried a decent amount of pre-heat from the plumbers torch right before migging on full power?, this might allow more sticking of the weld if that makes sense. Use a heat shield or plate with a hole in to avoid burning any delicate bits as much as you can.

I used a rothenberger mapp torch to great effect when fabbing some trailer lower shock plates this year. The weld went on like butter, albeit it was downwards so appreciate the difficulty in welding upside down.

Pete

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Pete and Bowie: see, these are tricks I've definitely missed. Pre-heating before welding and a non-weldable shield! Brilliant ideas! Of course they make sense. I will definitely do this! Many thanks again. 

And happy Hogmanay when it comes gentlemen! 👌

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The warmer you dare get the aluminium, the better, as it expands more than steel. Ideally, hot aluminium, cold steel. So preheat a great idea. You might even try quenching the steel once you have welded onto it. And also try tapping the stud cold with a hammer if you can, not ridiculously hard, but you are trying to break the corrosion bonds. We are all willing you on.

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