Diff / diff carrier spanner check help

[james.c]

Hi all,
I'm spanner checking my 620S before a track day at Silverstone on Tuesday. I had a total failure of the diff carrier this year because I had not been checking the diff and carrier bolts every track day (the carrier sheared off and I had to be rescued from the west coast of Wales!).

I'm new to this so just wanted some help to identify the correct bolts so I get the torque right. I couldn't get everything in one photo (sorry!) so I've labeled the 4 bolts in the two images below. 

My best guess are:
1 = Rear carrier bolt (so from build guide "x2 M10 plain on rear - 47Nm")

2 = Upper differential mounting (??) so 54Nm

3 = Forward carrier bolt (so from build guide "x2 M12 caphead on either side - 81Nm)

4 = Lower differential mounting (??) so 54Nm

I'm obviously just worried that I could be completely wrong here and do some damage if I under / over tighten the wrong thing!

Thanks for any help you can give.
J

 

[Jim 123]

Looks correct to me.  On my build the carrier frame mountings to the chassis were specified at 60Nm but this has probably been revised. You might want to consider paint marking the bolts heads etc for quick visual checks that things are not going anti clockwise with use

[james.c]

Thanks Jim,

Much appreciated. I got confirmation from a couple of friends earlier too so went for it (and I've used a marker for a quick check next time!). I've done 2 track days since it all collapsed and nothing was loose this time. Long story but I have my suspicions that it was not torqued up properly in the factory. But the manual does specifically say to check them on the 620 so can't really complain! 

J

[ChrisC]

The upper diff bolt (the long one) in my S3 metric kit was a imperial 1/2” x 11” therefore it’s a 3/4 socket you need

[jamesclarkson]

I'm pretty sure that some of these are 'wire locked' on the race cars to help prevent a total failure.  Might be worth looking into.

[7 wonders of the world]

Or use Schnorr locking washers