Crushed Nuts... August 10, 2021, 02:28:53 PM Found this set up on a few different areas of my car.Said before I think very little's been changed from new on it and I'm confident a lot of what I'm finding is factory fitted.This is one of the retaining nuts that holds the brake servo in place, they're on the inside of the bulkhead.Hopefully you can see in the photo's that it's been pinched at it's top, causing the thread to be slightly oval and presumably 'lock' it in place.That serrated mark is also on the opposite face of the hex.One of the other places I found this feature was the rear shock lower securing nuts (they fit into that clip that's the first post on the 'test your knowledge' thread).Seems to be limited to what you'd maybe consider safety critical items - are they a precursor to nylock nuts?
Re: Crushed Nuts... Reply #1 – August 10, 2021, 11:18:27 PM ""Seems to be limited to what you'd maybe consider safety critical items - are they a precursor to nylock nuts? "" No not at all just designers / company's idea, as apposed to nylocs try google search for prevailing torque nuts , Inloc, aerotight, https://www.mscdirect.com/industrialtools/threaded-zinc-lock-nut.html
Re: Crushed Nuts... Reply #2 – August 11, 2021, 10:42:33 AM Cheers - Always a good day when you learn something new - 'prevailing torque nuts', one to remember.Nuts - Yet another massive subject if you're inclined to get into it and once again umpteen different views / opinions / differing facts if you're using Google to check.Just to use that particular nut as an example - 7Zap gives it as a 'M8 Hex nut, self locking', even has a part number N 90074404 and an aftermarket alternative - Contitech V31213.So a pretty specifically specced item and presumably for a reason, otherwise VW would be unlikely to take the extra cost needlessly.One thing I didn't think of, but makes sense when I read it was this type of lock nut will resist heat when nylon lock nuts could melt - don't see that being the rational using them at the servo though.I'm wondering too are the all metal types single use, if they're pinched before or even after fitting might they not expand again when unthreaded?
Re: Crushed Nuts... Reply #3 – August 11, 2021, 09:35:55 PM Quote from: L90E on August 11, 2021, 10:42:33 AMCheers - Always a good day when you learn something new - 'prevailing torque nuts', one to remember.Nuts - Yet another massive subject if you're inclined to get into it and once again umpteen different views / opinions / differing facts if you're using Google to check.Just to use that particular nut as an example - 7Zap gives it as a 'M8 Hex nut, self locking', even has a part number N 90074404 and an aftermarket alternative - Contitech V31213.So a pretty specifically specced item and presumably for a reason, otherwise VW would be unlikely to take the extra cost needlessly.One thing I didn't think of, but makes sense when I read it was this type of lock nut will resist heat when nylon lock nuts could melt - don't see that being the rational using them at the servo though.I'm wondering too are the all metal types single use, if they're pinched before or even after fitting might they not expand again when unthreaded? God i could bore you silly with nuts and bolts, but why bother. Anyhow, you can use metal ones again although the recommendation is always to replace as the thread will reshape the nut after few uses (cutting own thread) on the servo the engineer has decided that brakes are important and therefore has picked method /type of lock nut to ensure where that the parts are unlike to come loose unless tooling used.(service)Nyloc nuts can be used quite safely in those positions, but are definitely use once, as the thread is cut into the plastics, and useful tip when removing such nuts heat the plastics to melting, and the bolt should turn straight out.Another one to fry your mind is what is the torque setting for such parts as ISO standards have set specific torque ranges for bolts and materials, so if 1 designer says go higher than material spec do you follow designer or material specs. http://www.chapmanssfs.com/torque-tightening-values-structural-steel-bolts/maybe i mentioned before but i was meachnaical technician/advisor for Siemens, Alstom, Mitsubishi, and only time we changed from ISO was lower torques, never increasing. for example due to heat expansion, 5" diameter bolts over 1000mm in length would lengthen and snap, if torques too high and the elasticity of the bolt is lost. ive torque tightened bolts in BA,BW, BSF,BSP,UNC,UNF Metric, coarse/fine, using heat, spanners ,hammers, hydrolics ,induction and now i play on cars where i can undo everything with 1/2" drive... nothing heavy at all 1 Likes
Re: Crushed Nuts... Reply #4 – August 11, 2021, 09:53:44 PM Not boring at all, never apologise for being well informed... wish I was more like you and knew more.I had one of those 'Oh F+++' moments a while back... was looking into replacing some bolts and when I started to delve into the basics it scared the life out of me just dangerous getting a simple bolt spec. wrong could be. That's why I probably fixate on making sure I've the correct ones VW stipulate - can't put a price on safety.
Re: Crushed Nuts... Reply #5 – August 14, 2021, 07:07:44 PM I have a situation now where one of my TREs is firmly stuck, I’m at the point where I’m considering slitting the lock nut. Then I worked out I’d have the issue of spec’ing and appropriate replacement.It’s good to have such info and knowledge on here.
Re: Crushed Nuts... Reply #6 – August 15, 2021, 10:27:33 AM Hopefully Kenny'll be along soon and clarify certain things about nuts in general, I'm keen to know myself.The nut you're after, if I've understood correctly which one you're considering cutting is N 90321302 (No. 4 on the first schematic).Not sure if it is model / year dependant or PAS / Non-PAS - you'll have to confirm that for yourself.If it is the one shown you're after then it's an M12 self locking, hex nut with a 1.5 pitch. One of the things Kenny could particularily clear up is - bolts are marked with their tensile strength, but I'm finding nuts aren't.If a certain tensile strength bolt is specced, surely a similarly specced bolt (and material) would be needed to compliment it?The engine mount bolts - again if I've looked up the ones you're referring to they are -N 10087403 (No. 23 on the second schematic)It is M12 with a 1.5 thread pitch and the length is given as 74 (mm?) though I'm assuming that's for the entire shaft and not just the threaded part which will be shorter.N 90445801 (No. 34 on the second schematic)It is M10 x 95mm with 32mm of thread? Doesn't mention the pitch.Any original mounting parts like these that are under heavy load I'm finding are 10.9 (at a minimum) and not the regular 8.8.If I've read things correctly, stainless steel isn't suitable either as it can break more readily, but again I'm sure Kenny will know.
Re: Crushed Nuts... Reply #7 – August 15, 2021, 02:35:10 PM Quote from: L90E on August 15, 2021, 10:27:33 AMThe nut you're after, if I've understood correctly which one you're considering cutting is N 90321302 (No. 4 on the first schematic).Think Tim's on about part no 20, no 4 usually gets supplied with the the tie rod end
Re: Crushed Nuts... Reply #8 – August 15, 2021, 07:52:38 PM Yes no. 20My windy gun got no.4 off and my splitter separated the tre form the hub carrier without smashing up the boot which is a first for me. I usually find the shaft just spins and I cut through it. I consider TREs are sacrificial parts. I have no need to change it other than I have a new one and want to know everything is new and good. Plus if I don’t solve this now it’ll only be a problem when I come to get tracking done. Tempted to put it all back and get the shop to do tracking and supply the new TRE if they need it. They’ll be able to get a long bar on it from under the car. I only have a spanner’s length and driveway access.
Re: Crushed Nuts... Reply #9 – August 16, 2021, 12:15:48 PM If you have access to heat like a blow torch heat the nut and try to undo it that often works.scs
Re: Crushed Nuts... Reply #10 – August 16, 2021, 12:54:44 PM Could it be reverse threaded on one side only (if it's function makes it act the mirror image of the other side) so as to stop it coming undone in use?
Re: Crushed Nuts... Reply #11 – August 16, 2021, 01:15:34 PM Finally found my own and they're not different...
Re: Crushed Nuts... Reply #12 – August 16, 2021, 02:05:04 PM Quote from: scs on August 16, 2021, 12:15:48 PMIf you have access to heat like a blow torch heat the nut and try to undo it that often works.scsTried it. Lots of heat!!!Quote from: L90E on August 16, 2021, 12:54:44 PMCould it be reverse threaded on one side only (if it's function makes it act the mirror image of the other side) so as to stop it coming undone in use?Had this thought and confirms both sides are normal thread. During a moment of doubting myself I put some effort into the opposite way too so I think I've just managed to tighten it further.I'm also now sporting a bruised chin, tried locking one spanner in place under the jack mount bobble and put all my effort into the other spanner and 'ping' 22mm spanner in the face. I was wearing safety glasses, that's one thing I've got in the habit of doing recently especially under but didn't anticipate the need for a full face shield.
Re: Crushed Nuts... Reply #13 – August 16, 2021, 04:28:32 PM I typically use 2 spanners and squeeze them together, ensuring fingers are out the way - you only do that once.I presume the end is still secured to the hub even just loosely. If it's that bad is it worth changing the arm, I know that's a pain with just a spanner and lying on your back?
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