An M8 bolt with two filled flats could at largest be 6mm AF.
Given the head has already twisted off, molegrips just chewed the top off, I can imagine that spanner just spinning/rounding off the flats.
[Guide] Adjusting B14 Ride Height With H&R ARBs
- Thread starter andys
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An M8 bolt with two filled flats could at largest be 6mm AF.
Given the head has already twisted off, molegrips just chewed the top off, I can imagine that spanner just spinning/rounding off the flats.
That was one of the first things I tried, it just chewed more of it off. There’s not enough of it left to grip now, I don’t see I have any choice.
I’m going to test my theory by putting the other bolt in the vice and drilling into it in an easier position. If it goes in ok I’ll know that a piece of the cobalt drill bit is indeed stuck in it, and also be able to find the best size and type of drill bit for the job before trying again for real.
Ahh bugger! Have you got any plusgas to soak the remaining part of the bolt?
Yes I've tried that, trouble is it's upside down so runs off, plus it's actually jammed solid in the thread. I'm worried it's never coming out
Another evening with no progress. No drill bit I've got is making a dent in the bolt, with 3 different drills. I've ordered another set of cobalt bits and a set of titanium bits and I'll go again. Just baffling how trying to grab it with mole grips tears bits off the side like chewing gum, but going in end on with a drill and it's invincible
B
I’ve had similar experiences with titanium drill bits. It’s best to dull the cutting edge on a brand new cobalt drill when drilling soft material to avoid it ‘biting’, jamming and snapping. This can be done by using it on a relatively hard material for a short time.
If there is a piece of broken drill bit in the bolt it will have to be removed first, depending on how deep it is it might be best to try and break it out with a spring loaded centre punch.
The best way to get it drilled precisely is to make a guide on a lathe or less likely find a bush of the correct bore. This can then be tack welded in the correct position and will prevent the drill bit wandering off centre. The bush / guide bore should be approx’ 0.5mm smaller than the core diameter of the thread as no matter how careful it won’t be welded up absolutely dead centre to the bolt.
No idea what the thread size is but:
M10 standard thread core diameter is 8.5 so make the bush bore 8.0 and drill 8.0.
M8 standard thread core diameter is 6.8 so make the bush bore 6.3 and drill 6.3.
After drilling, the remains can be picked out with a scriber and tapped to clean up the thread.
I’d avoid using a tapered extractor as it will probably expand the snapped bolt in the hole.
A real pain in the ass but a fixed drilling guide will work as long as it’s centred correctly and tack welded on flat.
Good luck.
Another evening with no progress. No drill bit I've got is making a dent in the bolt, with 3 different drills. I've ordered another set of cobalt bits and a set of titanium bits and I'll go again. Just baffling how trying to grab it with mole grips tears bits off the side like chewing gum, but going in end on with a drill and it's invincible
I’ve had similar experiences with titanium drill bits. It’s best to dull the cutting edge on a brand new cobalt drill when drilling soft material to avoid it ‘biting’, jamming and snapping. This can be done by using it on a relatively hard material for a short time.
If there is a piece of broken drill bit in the bolt it will have to be removed first, depending on how deep it is it might be best to try and break it out with a spring loaded centre punch.
The best way to get it drilled precisely is to make a guide on a lathe or less likely find a bush of the correct bore. This can then be tack welded in the correct position and will prevent the drill bit wandering off centre. The bush / guide bore should be approx’ 0.5mm smaller than the core diameter of the thread as no matter how careful it won’t be welded up absolutely dead centre to the bolt.
No idea what the thread size is but:
M10 standard thread core diameter is 8.5 so make the bush bore 8.0 and drill 8.0.
M8 standard thread core diameter is 6.8 so make the bush bore 6.3 and drill 6.3.
After drilling, the remains can be picked out with a scriber and tapped to clean up the thread.
I’d avoid using a tapered extractor as it will probably expand the snapped bolt in the hole.
A real pain in the ass but a fixed drilling guide will work as long as it’s centred correctly and tack welded on flat.
Good luck.
Thanks, but I don't have a welder or lathe. I've had a closer look tonight and couldn't see any remnant of drill bit left in so didn't grind it flat as I'd originally planned. I'll have one more go at drilling when the new bits arrive and after that I'll just have to take it somewhere.
Turned out it wasn’t a piece of broken drill bit, I found the missing part under the van and on closer examination the “gold” I saw was just the reflection of the phone screen in the centre punch holeThis sounds like a plan.
Plus you'll probably end up with a good starting point for your next drilling operation.
I tried drilling into the broken off head of the bolt in the vice, and the other one and got nowhere too so I’m hoping that the problem is the drill bits I’ve been using and that the ones that are on the way will cut better. Also ordered some cutting fluid just in case it’s lubrication or temperature, but I’m clutching at straws there, I can’t see it being vastly more useful than 3in1.
Fingers crossed on the new drill bit, make sure when your drilling your not at full speed, you want it quite slow and steady. Really you need a carbide drill bit as the bolt sounds quite hard but that'll cost a few quid. Just take your time and have patience, an hour drilling is better than a full strip downTurned out it wasn’t a piece of broken drill bit, I found the missing part under the van and on closer examination the “gold” I saw was just the reflection of the phone screen in the centre punch hole
I tried drilling into the broken off head of the bolt in the vice, and the other one and got nowhere too so I’m hoping that the problem is the drill bits I’ve been using and that the ones that are on the way will cut better. Also ordered some cutting fluid just in case it’s lubrication or temperature, but I’m clutching at straws there, I can’t see it being vastly more useful than 3in1.
Thanks but there's no way I'm taking the arm off! There isn't enough of the bolt left to grip anyway. No, if the new drill bits don't work it's going to a pro to sort.Heat. Frees all seized fastenings, always. get a torch on there, the bolt will come out with pliers.
(You might have to take the arm off again, and do it on the bench though, save setting fire to the van).
I am happy to report the little fecker is out!
New drill bits arrived today so third night in a row straight out to the garage after work without eating, not something I do lightly. They were definitely better, this time I could just see tiny particles of metallic dust falling out, but 20 mins later the hole was still only 4mm. It took another half an hour of constant drilling, with changes of hand and battery when it got tired to get through, though it did look as if it was in a bit of an angle. Miraculously though, I got a screw extractor halfway in when it went loose, and pulling it out, the bolt came out in two pieces. Cleaned up the thread with a tap and all sorted. Thank f*ck for that!
The new bolts haven't arrived so the ARB is not going back on yet, but all the threads have been cleaned up ready and I'm going to take the opportunity to drop the springs another 5mm at the back just to get it absolutely level.
New drill bits arrived today so third night in a row straight out to the garage after work without eating, not something I do lightly. They were definitely better, this time I could just see tiny particles of metallic dust falling out, but 20 mins later the hole was still only 4mm. It took another half an hour of constant drilling, with changes of hand and battery when it got tired to get through, though it did look as if it was in a bit of an angle. Miraculously though, I got a screw extractor halfway in when it went loose, and pulling it out, the bolt came out in two pieces. Cleaned up the thread with a tap and all sorted. Thank f*ck for that!
The new bolts haven't arrived so the ARB is not going back on yet, but all the threads have been cleaned up ready and I'm going to take the opportunity to drop the springs another 5mm at the back just to get it absolutely level.
I am happy to report the little fecker is out!
New drill bits arrived today so third night in a row straight out to the garage after work without eating, not something I do lightly. They were definitely better, this time I could just see tiny particles of metallic dust falling out, but 20 mins later the hole was still only 4mm. It took another half an hour of constant drilling, with changes of hand and battery when it got tired to get through, though it did look as if it was in a bit of an angle. Miraculously though, I got a screw extractor halfway in when it went loose, and pulling it out, the bolt came out in two pieces. Cleaned up the thread with a tap and all sorted. Thank f*ck for that!
The new bolts haven't arrived so the ARB is not going back on yet, but all the threads have been cleaned up ready and I'm going to take the opportunity to drop the springs another 5mm at the back just to get it absolutely level.
Victory!
Must admit, I was getting close to giving up and paying someone to do it. Very satisfying feelingVictory!
Must admit, I was getting close to giving up and paying someone to do it. Very satisfying feeling
Good work for sticking with it!
I still have to swap mine out for new bolts too (got them sat here) but waiting till I an get the time to tweak the rear height.
Yes it's a shame my ARB and lower shock bolts haven't arrived, I could have got it all done and dusted on Sunday. It's certainly taught me to be more careful with torquing exterior bolts and making sure the bolt goes cleanly into the thread.Good work for sticking with it!
I still have to swap mine out for new bolts too (got them sat here) but waiting till I an get the time to tweak the rear height.
It's worth replacing them if you can, the stretch bolts can end up a weird shape even if only used once!
Check out the shape of front damper pinch bolts:
