nick 3 Posted August 17, 2008 I have been using high tensile pinch bolts on the hubs for a while now and would just like to give a warning. The car started wandering around as though one of the bushes had gone, so I crawled underneath to investigate. This is what I found.. I think that you can go too tight with the high tensile bolts (it's very tempting to just bollock them up as tight as you can) which then put undue strain on the clamp. Nick Share this post Link to post Share on other sites
welshpug 1,626 Posted August 17, 2008 they should be HT bolts of 8.8 grade, thats what the factory fits. but only done up to 26 lbfts Share this post Link to post Share on other sites
nick 3 Posted August 17, 2008 I am using the 12.8 (or whatever it is..) cap heads... done up fooking tight!! Nick Share this post Link to post Share on other sites
welshpug 1,626 Posted August 17, 2008 ah, that be the problem then!! 26 lbfts feels like they're only just nipped up with a 1/2" ratchet Share this post Link to post Share on other sites
Gentrix 2 1 Cars Posted August 17, 2008 The crack already got rust and dirt on the surface - so it didn´t happend just yesterday, did it? andi Share this post Link to post Share on other sites
Chris H 10 Posted August 17, 2008 Strongly recommend you invest in a half decent torque wrench....some parts have torque settings for a reason Get one from halfords or similar for about £40 and you'll be able to avoid things like this happening. Share this post Link to post Share on other sites
Batfink 201 Posted August 17, 2008 torque wrenches save wheel bolts too. Share this post Link to post Share on other sites
pug_ham 242 3 Cars Posted August 17, 2008 I'm also dubious it was the bolt material that caused this nick & not just the torque setting you used (FT!) IIRC Anthony said he has been running these for a while on his car including runs to (& round) The Ring & various trackdays without any issues so far. Graham. Share this post Link to post Share on other sites
Paintguy 0 Posted August 17, 2008 I'm also dubious it was the bolt material that caused this nick & not just the torque setting you used (FT!) I'd agree. I think it's more a case that you can wind even more excessive torque on with the higher grade bolt. Share this post Link to post Share on other sites
markw 1 Posted August 17, 2008 i had exactly the same failure,even hag the rust in some of the crack before it completely failed,unfortunately i was on my second practice run at curbrough and end up in the ditch on the first corner oops Share this post Link to post Share on other sites
nick 3 Posted August 17, 2008 Agree that a torque wrench is a good idea... and yes, I do own one..... What I'm saying is, is that the high tensile bolts easily allow you to take them way above the torque limit (way more than a lower tensile bolt which would strip first) and be honest, how many people use a torque wrench on wishbone bolts and hub pinch bolts?? Yes I have over tightened them, but with a thread in the "for sale" section" for higher tensile bolts than std for this application, I would just like to wan people of what might happen. Nick Share this post Link to post Share on other sites
mrswampy 0 Posted August 18, 2008 It wont be due to useing a bolt with a higher tensile grade yes you can wind on more pressure with a higher rated bolt prior to thread stripping but if done up correctly with a good well calibrated torque wrench it will be just fine all bolts with in the steering and suspension area should be done to the correct pressure haveing the bolts too loose is as bad as over tight as this can lead to wear and premature failure of items Share this post Link to post Share on other sites
nick 3 Posted August 18, 2008 FFS!! will people stop going on about bleeding torque wrenches!!! Yes, I do own one, yes, I do know how to use it, yes, I overtightened them.... People are missing the point of this thread, forget the high tensile bolts.... go out and check your hubs!! The night before I found this I was doing an indicated 120mph with it weaving like a bastard... the only thing stopping me from visiting the mortuary that night was a high tensile bolt holding the clamp together!! (so they maybe are a good idea after all.....??!!) Nick Share this post Link to post Share on other sites
brianthemagical 1 Posted August 18, 2008 If a higher tensile bolt is used at the same torque there will be a possibility of less clamping force due to less stretch of the bolt. Share this post Link to post Share on other sites
Paintguy 0 Posted August 18, 2008 Chill Nick, you're amongst friends here I for one appreciate you giving us this heads up, and I'll certainly be checking that area next time I have my wheels off. I'm also glad that you're ok after what could have been a catastrophic event! It's just that your thread title seemed to imply that you thought the bolt material itself was the cause of the problem, and some of us were just trying to point out (to others reading this thread) that it wasn't. I suppose we should have read your final sentence more carefully: I think that you can go too tight with the high tensile bolts (it's very tempting to just bollock them up as tight as you can) which then put undue strain on the clamp. which basically says exactly what the rest of us have been saying. Share this post Link to post Share on other sites
davepug205 7 Posted August 18, 2008 The night before I found this I was doing an indicated 120mph with it weaving like a bastard... the only thing stopping me from visiting the mortuary that night was a high tensile bolt holding the clamp together!! (so they maybe are a good idea after all.....??!!) Its amazing what speeds you can reach on a private runway Share this post Link to post Share on other sites
nick 3 Posted August 18, 2008 I'm cool!! was all said tongue in cheek.... It's just I know you should use a torque wrench and I don't for stuff like that (I bet a lot of others don't either...) and I still think that the high tensile bolt has allowed me to put undue strain on the clamp AND IT'S ALL MY FAULT!!!!! Nick Share this post Link to post Share on other sites
Pugnut 9 1 Cars Posted August 18, 2008 that could easily be an old fracture from a bump or hitting a kerb in the snow or anything. i've seen a few that have been overtightened till the two halves are flat against each other and the holes have ovalled out without any signs of breaking. I guess theres a good chance you could have over done it but it's just as easy to close the two halves with an 8.8 Share this post Link to post Share on other sites
James_R 3 Posted August 19, 2008 I've also been using 12.8 cap heads for a few years after Miles recommended them having bent/stretched the std 8.8 on big kerbs on track (particularly the top section at cadwell) and have no problems since. Infact having been across Adenau Forst nearly sideways twice at over 90mph I think they stopped a premature end to my weekend (dispite me trying my best) and actually managed to oval the hub (mildley) at about 8 O'clock position (if the split is 12) shows they work rather well. Looking at that it could also be down to the gap being over prized open to remove the wishbone (not saying you've done that) but flexing the section backwards would induce a weaker area like that and potentially snap. But alwasy worth checking as Nick says. Share this post Link to post Share on other sites
