The spec for the three nuts that secure the ball joint to lower control arm is 60Nm if the arm is cast steel, but 100Nm is the arm is steel sheet. Can anyone explain this? 100Nm seems like a crazy torque for a M10 thread. I have the pressed sheet steel control arms.

Probably to do with embedding of the nut's mating face (and that of the balljoint if textured) being different on the two types of wishbone, together with the fact that when a fastener is tensioned by torque alone, a very high proportion of that torque is used in overcoming friction, rather than actually extending the screw.

There's a lot of techy stuff about pre-tensioning threaded fasteners, and the general trend towards using a lower torque followed by an angle tightening stage is mostly about reducing the variability impact of this friction.

Ok then. Let's hope the studs are made of some pretty amazing steel to take that torque without snapping.

100Nm not for the three nuts but ball joint to knuckle.

for the three nuts 20 Nm + 90°

20Nm + 90° sounds like the workshop manual info for mk1 Fabia with M8 fasteners.

Please show your source for this information in relation to mk2 Octavia @kokosal

Hmm Indeed could be for M8 bolt. It is hard to find reasonable torque. I looked at my ball joint M10 and definitely I'm not going tight it for 100Nm. At least not with nyloc nut provided by Febi in the kit.

What I have found so far is this 40Nm +45deg. I keep looking.

Edited 2 hours ago2 hr by kokosal

From memory our Roomster, with same M10 studs and nuts shows 50Nm + 45° turn in the workshop manual.

It would be quite interesting (so I may well do it in the next few days) to do the above method on a new genuine nut and then see what torque the wrench has to be adjusted up to to move the nut any further.

Or to do it up to 50Nm, mark nut and wishbone and then see how much of a turn is done by going to 100Nm.