GolfGTIforum.co.uk
Model specific boards => Golf mk2 => Topic started by: hobbiniho on 07 January 2008, 18:23
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right this is really starting to piss me off :angry: :angry: :angry: iv replaced the rear bushes with powerflex ones and when tightening the bolts with a torque wrench to 60nm (according to the haynes book of lies) they just SNAP now as i am a bit of a novice mechanic is there something i could be doing wrong??? i mean how hard is it to tighten a nut, this is the second bolt that has done this and it is starting to get expensive at £1.09 for each bolt :grin: and more so it is holding up the progress of my project, and iv been waithoing since before christmas for this bolt only to go and snap it :cry: :cry:
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How accurate is your tourque wrench, i dropped mine and now its completely out of calibration and only clicks when it wants too, causing the snappage of one of my flywheel bolts.
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i dropped mine and now its completely out of calibration
Using it as a breaker bar and a hammer probably contributed to that too :grin:
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well i borrowed it off a mate and its pretty much brand new it doesnt click it vibrates :rolleyes: :rolleyes:
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ditch the torque wrench, using a sensible sized bar or a big decent rachet and just do it till its tight.
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yeh tried that first time and it was no where near tight and it snapped thats why i borrowed this fancy torque wrench from my mate, is it possible that the haynes is speaking sh!t and that 60nm is far to tight, im sure that iv done things up tighter than that before, the front subfame bolts havnt snapped and i torgued them up to the right setting with the torque wrench
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are they shoulderd bolts are you running out ov thread and this causing them to snap
persuming there 17mm head and nuts .they will take a good 150nm
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It's perfectly possible that haynes are wrong, i know they have the torque ratings for a fair few bolts on the mk2 wrong. By as much as 20nm.
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right well im going to buy a new bolt tomorrow and ask the stealers what the correct torque rating is, as i hope that it is the haynes that is wrong well anyway iv taken a couple of pics of the offending bolt
are they shoulderd bolts are you running out ov thread and this causing them to snap
persuming there 17mm head and nuts .they will take a good 150nm
ok so sorry for being thick but whats a shouldered bolt??? no they are not running out of thread, and how the hell am i managing to snap them with the torgue wrench set at 60 if they can take 150 :laugh: :laugh:
(http://i147.photobucket.com/albums/r301/hobbiniho/07012008001.jpg)
(http://i147.photobucket.com/albums/r301/hobbiniho/07012008002.jpg)
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A shouldered bolt is referring to the collar around the top, just below where you put the socket.
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ahhh right the fat bit at the top, and its purpose is???
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acts like a washer and puts the shear load on the stronger part of the bolt as the metal is formed thicker. When you get your new bolt, try tightening the nut onto the bolt, don't screw a torque bolt into a nut, the torque is on the pull(nut) not the twist(bolt) when a nut is used. Try going in stages, do 20nm, 40nm 50nm then if feels good to go higher try, if that fails again, god knows why though on a 10mm thread, they should take 120nm no probs, get a bolt the same length from a proper supplier with a higher torsion number stamped on it, like 10.8 or 12 instead of 8.8. The size of the head on the bolt only matters if the area it sits is likely to be fouled by something. Hope you sort it!!
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sorry to piss on your parade but this is a m12 bolt from the stealers and it is a 10.9 not a sh!tty little 8.8 :grin: :grin: ok so i was tightning the BOLT could this cause them to snap even with the torque wrench set to 60nm :shocked: :shocked:
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hold on am minute when i was putting my front bumper back on i torques the BOLTS up to 82nm and they didnt f**kin well snap so what the f**k is goin on here then :cry: :cry: :cry:
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:shocked:
you need to get another torque wrench, a m12 bolt will shear of course,!!! :rolleyes: but it takes some force, I doubt it could be done with a 3/8" ratchet and spanner easily just to give you some idea, try taking the bolt back and and asking them to get it tested, could be a bad batch!
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as i said the torque wrench is brand new, and what kind of pressure are we talking to snap said bolt 150nm?? more it just doesnt make sense ok if the torque wrench is f**ked i can understand snapping the bolt with it as its 600mm or so long but not with a normal sized t bar is it possible to exert that amount of force????? :shocked: :shocked:
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I'm with Herbster on this one. A 10.9 M12 can take around 80 kN ultimate strength in tension. So you could hang 7 or 8 Golfs off one bolt before it actually broke!! Temsile strength is not the same as applying torque of course - if there is too much torque applied then the bolt could break by twisting - shear off. Shear failure looks different to failure in tension. If you break it in tension then it will 'neck' i.e get smaller diameter just where it fails.
It is always better if possible to apply the torque from the nut end but 60Nm is relatively small for an M12 - as aleady said.
I would suspect a bad bolt or batch. I have had problems recently with nuts stripping threads. Could be poor quality imports from India or China.
You could try greasing the threads and also make sure the nut runs freely right up the bolt before you put it on the car.
Good luck.
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your right, with a normal t bar your on the verge of severe knucklelitis to snap a m12 bolt especially as its a 10.9 !!!! Put all the pull on the nut, this pulls the bolt through the hole to tighten, worst that should happen is the threads on the nut will go, good luck
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Just a tip, only use oil if torque not grease, as the grease gets older it wastes away leaving a void thus potentially loosening! Sorry :nerd: But a steel bolt thru an alloy head into a cast case needs no lube just for reference, only oil if the head is cast too!!
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Just a tip, only use oil if torque not grease, as the grease gets older it wastes away leaving a void thus potentially loosening! Sorry :nerd: But a steel bolt thru an alloy head into a cast case needs no lube just for reference, only oil if the head is cast too!!
Wrong thread by any chance!? :smiley:
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No! :sad: just adding to dadrathers tip! Feel free to use it though!! :laugh:
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I didn't read it properly :embarassed:
I'll get my coat........
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If you break it in tension then it will 'neck' i.e get smaller diameter just where it fails.
like this :cry: :cry: dodgy batch, cos iv just been out and tried tightning the one i got today and it has torqued down to 60 nm and hasnt snapped :rolleyes:
(http://i147.photobucket.com/albums/r301/hobbiniho/07012008004.jpg)
(http://i147.photobucket.com/albums/r301/hobbiniho/07012008006.jpg)
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sorry for crap pics iv only got my phone :wink:
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Yeah that looks like tension failure to me. That is gobsmacking - even a lowly mild steel bolt should take half the load of a 10.9 before breaking. So the material that those bolts are made of must be sh@@te.
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yeah i went back to the stealers and they are refunding the cost of the new bolt and getting me a new one free of charge, as they said that it was proably a dodgy batch of bolts so they are going to report it anjd that batch should have been taken out of cirulation a while ago these were just ones that still had in stock :grin:
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Good - glad to hear they accept responsibility - sounds like you are sorted now but what a lot of messing about!!!!!
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yeh f**kin pain in the arse the new bolt wont arrive until monday :shocked:
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Hope they've got better quality control on their cylinder head bolts... Christ be'zeesus!!!