PDA

View Full Version : I'm being thick - torquing bolts


Iain
03-03-12, 03:59 PM
I have had my rear beam off to sort the bushes out.

I'm trying to torque the main pivot bolts to 105nm as per Haynes, however before I get anywhere near that the bolt seems to stretch and the nut spins and won't come off, meaning I have to grind the head off to get it out.

Tried this with a couple of new 8.8 tensile bolts now and its happened a few times.

Wtf am I doing wrong.
Iain
03-03-12, 04:12 PM
Only thing I can think of is crap bolts, but I built the whole car with these bolts and never had this issue.
Adam
03-03-12, 04:23 PM
105 aint that much so its a bit of a weird problem :wtf:

Daft question but you arent damaging the bolt threads when putting the bolt through the hole? Is the bolt going straight through or are you having to "persuade" it through?
Iain
03-03-12, 04:50 PM
I didn't think 105 was phenomenal either, even cheap 8.8 bolts wouldn't have this problem three times would it?!

The last one went in with my fingers so no thread damage, and I've just spent half hour grinding the head off it to get it out.
Minikidx14
03-03-12, 05:08 PM
Have you got your torque wrench set to 105Nm and not 105 lbf ft?
Iain
03-03-12, 05:12 PM
Yeah! Tried it on the front knuckle-to-strut bolt and it clicked immediately.
Royston
03-03-12, 05:14 PM
Has your torque wrench been calibrated / checked recently, I ruined a set of conrod bolts on my range rover V8 as my wrench was incorrect
scott.parker
03-03-12, 05:15 PM
Are you sure it's not clamping it tight enough for the bush to be turning?
Iain
03-03-12, 05:19 PM
Royston the wrench is probably a year or two old and not had a huge amount of use. How do you calibrate them?

Scott not following what you mean?
scott.parker
03-03-12, 05:22 PM
Well could it be that once it gets to a certain tightness and you have smeared grease all over it that the metal bush is turning inside the polly part, or the lot is slipping round etc??
Iain
03-03-12, 05:29 PM
I'm holding the bolt in place with a spanner and torquing up the nut so nothing should be spinning, just clamping.

Just had a look at one I felt "start" to go and its started bending the threads over and chewing them up, the other two I had to grind off have properly stretched the threaded section before the nut.

Just messed with the torque wrench on a front knuckle/strut bolt too, set it to 130nm and it undid without clicking and turned quarter turn, then set it to 110nm and it clicked after quarter turn so its not too far off to what it was a year ago? Not very scientific I know lol
scott.parker
03-03-12, 05:31 PM
**** bolts then dude, need to go an get some OEM ones from vaux dealer.
Iain
03-03-12, 05:33 PM
Worrying as I've built up the whole car with the same bolts...
scott.parker
03-03-12, 05:35 PM
Humm best to replace the one's you think might be under stress then mate, as i wouldn't trust them after finding this out!
Mieran
03-03-12, 06:46 PM
beam, tca, pinch bolts etc dont cost that much from vauxhall
Royston
03-03-12, 06:57 PM
[QUOTE=Iain;1999447]Royston the wrench is probably a year or two old and not had a huge amount of use. How do you calibrate them?/QUOTE]

I'm lucky as i can check them at work, can you compare your wrench with someone elses, know anyone who could check it? Mine was also fairly new and unused but was under reading the actual torque by a significant amout, resulting in damaged fasteners!!