I'm about to change my front discs and pads on a peugeot 107, I see on you tube, that you have to set the torque for the bolt on the disc to 5nm and the calliper bolts to 89 mm, the question is do you have to use these settings as I have changed pads before and never used any torque settings, and I don't possess a torque wrench
Replace front discs and pads
- Thread starter carlbhoy
- Start date
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If you have done a reasonable amount of DIY - ing you know how tight a bolt or nut needs to be by its size and function, if that's the case do them up as tight as you normally would. They seem to specify torque for practically every nut and bolt on a modern car, I've been repairing my own cars for 60 years and the only thing I use a torque wrench for is cylinder head bolts.
That's my opinion - others may think differently.
Peter
That's my opinion - others may think differently.
Peter
Thanks Peter I have done minor jobs on cars and garden machinery before and never used torque settings
Yea me too, though I'd add hub and flywheel bolts to the list.
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When you get the old disc off, spend some time with some emery cloth to get the hub spotlessly clean 
then apply some clean coppaslip / ceramic grease thinly. The disc to hub screw needs to be just finger tight - its only for location.
John
then apply some clean coppaslip / ceramic grease thinly. The disc to hub screw needs to be just finger tight - its only for location.John
It has been said that a good mechanic can generally do a bolt up to about 80% of it's yield stress just by feel. I think that's probably true. Much of the enthusiasm for torquing everythig to a particular value just comes from using robotised production lines. You need to set the robot to "something". Also in the current litigious climate, it's the first thing any compensation lawyer would ask in the case of a failure and subsequent lawsuit. Pretty much everyone knows that as long as the bolt was "tight" it will have been fine, but it dosn't take much for a lawyer to "cast reasonable doubt" and then the manufacturer is in trouble! If you specify a numerical value, then you can have a quality control check point that can audit that value on the production line, and that will allow a box to be ticked. If you just specify "tight" then the guy doing the QC check has to make a subjective decision as to whether it was or not.
Not just head bolts but fasteners round a big gasket (like a sump, cam cover or timing chain cover) benefit from being torqued because often, long before the bolt is in any danger of snapping or the thread in any danger of stripping) you can overdo them and cause the gasket to leak by making the cover "bulge" between fasteners. With big, gasketed joints like these, often "less is more" when it comes to tightening the fasteners. Also things like whel bolts, where over-tightenng (and you've got to be a really insensitive gorilla to do it!) can cause the hub and disc to distort and cause an effect like "warped brake disc".
Like Peter, I rarely use a torque wrench on my own cars, but I can see the reasons why it's a good idea!
Not just head bolts but fasteners round a big gasket (like a sump, cam cover or timing chain cover) benefit from being torqued because often, long before the bolt is in any danger of snapping or the thread in any danger of stripping) you can overdo them and cause the gasket to leak by making the cover "bulge" between fasteners. With big, gasketed joints like these, often "less is more" when it comes to tightening the fasteners. Also things like whel bolts, where over-tightenng (and you've got to be a really insensitive gorilla to do it!) can cause the hub and disc to distort and cause an effect like "warped brake disc".
Like Peter, I rarely use a torque wrench on my own cars, but I can see the reasons why it's a good idea!
