rob_bell

rob_bell

Well-Known Member
Hope everyone is enjoying the weather! A bit hot in London to be working on cars: even beating a stubborn screw with a hammer brought be out in a sweat over the weekend!

This particular screw happens to be on an MGF rather than a Freelander, but I thought I'd see if the wisdom of this forum might give me some inspiration before going down the destructive route of drilling and retapping...

The bolt in question is the M6 bolt that retains the ABS sensor in the MGF's hub carrier. It has a 8mm head and these bolts almost always seize in place and either round off or snap.

I practiced a number of techniques on a scrap hub and ABS sensor screw. I tried cleaning up the area extensively (the head of the screw, just 8mm in diameter was actually in great condition, with minimal corrosion). I sprayed with penetrating oil. I tried rocking the screw tighter/ looser. I tried tapping it with a hammer.

Nothing.

Then I tried heat. Because of the close proximity of the plastic sensor, I decided to put a blob or two of weld on the screw head to get some heat into it.

Still nothing.

Then I took a cutting disc to the head and then used a impact driver.

Nope, that did not work either.

I think I'll probably end up cutting or shearing the head of this screw off and then welding on a new nut or simply drilling the old one out and re-tapping the hole - but is there something else I can try before resorting to this?

This is now the definition of straw clutching - but in case of something really obvious, it is worth a punt to ask!!! :)
 
That’s always a possibility - but as a new Bosch OEM sensor is only £15, then so long as I can get the old one out, everything ought to be golden :D
 
I'd give the hammer and chisel trick a go before resorting to snapping it off, re-drilling and tapping a new thread.
 
Forgot to mention this - but tried that (hammer and chisel approach) too!

I wasn't having a great day yesterday... heat and frustration! lol
 
Thanks - yes, I ordered an equivalent kit of bolt extractors from Amazon earlier this morning.

I directed all the heat (with a weld) to the bolt itself, rather than the hub. I could try heating the hub, but would rather avoid this if possible (rubber bushes/ rubber gaiters/ grease in wheel bearing) - but I may be over-thinking the risks...? Not sure my butane torch would be man-enough to adequately heat such a large mass of cast iron - but worth a shot if all else fails!
 
Can you get to the rear of the screw, does it go all the way through? I changed the front calipers on my Defender earlier this year and the bolts did not want to come out. I tried the bolt extractor as the head was rounded, penetrating fluid and heat where I could (but that's not easy on a caliper. None would work and I broke the (screwfix) bolt extractor trying.

I ended up cutting the caliper in half so I could get to the back of the screw. I tried more penetrant but could see it was making no difference. I decided before I tried again I would do as much as I could and decided to drill out the centre of the bolt (from the back) as I was hoping it would relieve some stress from the threads - mine were M12 screws so I drilled it almost to the head at about 5mm, then something like a 7mm drill to about half way - my thoughts being I needed more strength near the head.

As I didn't want to fail on the next attempt I also used heat around the bolt (not on it) and then quickly applied penetrant to the bolt - my thought here was it may cool the bolt quicker than the surrounding steel and hopefully it may contract and brake the binding of the rust.

I did this with both (one at a time) and it worked on each. The big difference between my situation and yours is the size of the bolt. M8 and under are notorious for snapping the head off so you need to be really careful, but also be prepared to drill it out.

Good luck with it, I hope all goes well.
 
Arctic2 said:
Hi Rob.
Is it just the fact that the 8mm bolt as rounded off or it's seized up, if rounded do you have a set Irwins removal grip sockets, when you tried the heat did you direct it onto the bolt or onto the hub where it fits into, try heating up the hub around the bolts area.

IRWIN Bolt Grip Fastener Remover Expansion Set, 5 Piece | eBay
Click to expand...

+1 for those irwin things, they are a godsend....

Try one of these impact drivers with a suitable socket / bolt extractor on it's 1/2" square drive:
 
Jayridium said:
+1 for those irwin things, they are a godsend....

Try one of these impact drivers with a suitable socket / bolt extractor on it's 1/2" square drive:
Click to expand...

That was 1 of the very first tools I bought, way back when my dancing strides still fitted. It worked well.
 
Thanks guys!

I already have and have tried the impact driver @Jayridium - these are great and wish others would use them rather than rounding off disc brake location screws... Regarding the Irwin style extractors, I have a set of similar off Amazon to try. It may snap the screw/bolt - but so long as I can get the old sensor and its plastic mount off, I can use more heat and force without fear of breaking it!

I've not seen that particular tool before @Nodge68 - I might put that on my Christmas list :D

@Dr Strangeglove - sadly, the tapped hole is into the hub casting, with no sight of the screw thread on the other side. The hub is a great lump of cast iron - so it'll take a lot of heat to make a difference [or so I would have thought] - but as a matter of course, I may give it a go!!!

I'll have another stab at this at the weekend and let you all know. Once the old sensor is removed along with its retaining screw, putting a new one is a doddle! (I can't believe this is becoming such a mission - I thought the Hippo's ABS sensors were a pain!!!)
 
Update: success! The Irwin-style bolt extractor tool did the job.

I initially gave it some love with the extractor on my impact driver and then simply applied some elbow grease with a ratchet on the extractor socket and it came away nicely.

The unthreaded shoulder of the screw had corroded within the brass insert of the ABS sensor mount, which is made of plastic on these cars. The brass insert came out - and after some penetrating fluid + heat from a torch, I got the old screw out.

Interestingly, this ABS mount has been damaged in the past and I had to use a thin M6 washer to space the sensor away from the trigger wheel. It’s now 0.9mm clearance - a little more than the 0.75mm clearance of the other sensors, but the ABS ECU seems to be happy for now!

thanks everyone - simple job really, just the usual challenges of working with old fasteners… ;)
 
rob_bell said:
Update: success! The Irwin-style bolt extractor tool did the job.

I initially gave it some love with the extractor on my impact driver and then simply applied some elbow grease with a ratchet on the extractor socket and it came away nicely.
;)
Click to expand...

Hi Rob.
Great tool i have a few different sets some shallow for confined places.
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i really rate aviation spanners as well more leverage when you need it.
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5
 
Agree with the aviation spanners. Someone gave me a set to 19mm and these have often been my go-to spanners. I wish I had the 22/24 one as well as that would have been really useful doing the radius arms.
 
@rob_bell Congrats on the result. @Arctic2 Those silverline low profile ones look handy. I've been hankering for a set of aviation spanners for a while, but I keep buying other things instead of them, like spunking heavy gold on the mother of all engines and gearboxes for my range rover classic... I must grow a pair and buy them AS WELL AS the other stuff, as well to get hung for a sheep as a lamb. I've also seen you can get aviation ratchet spanners, which will go nicely with the e-torx ratchet spanners I bought recently.
 
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