Rear suspension torque specs

[Dr J]

Hello guys. I need help with three torque specs for 79, 911 SC as I am finding contradictory information.

1) the bolt going from trailing arm to body (item 40)
2) spring plate to trailing arm (item 42) and
3) the camber/toe eccentrics in the spring plate (items 41 and 41a) in the diagram below from the 78-83 Bentley manual. According to Bentley, the values are:

1) 72 ft lb
2) 90 ft lb
3) 61 ft lb

But according to the small tech spec booklet, 78-81, the values are:
1) Control arm to cross tube 60NM (44 ft lb)
2) Spring strut to control arm -hex bolt 95 NM (70 ft lb)
3) Spring strut to control arm -eccentric 60 NM (44 ft lb)

Am I confusing the terminology in the tech spec? What gives?

Here is Bentley:



Here is the tech spec

[GG Allin]

Item 40 is a *****, at least on a G50 car. I paid a pro to do mine.

[DaytonaCoupe66]

Torque values were updated as was the hardware size in 1984, with a suggestion that the new values be applied if the trailing arm is removed and reinstalled. These apply to my 1982 930. Trailing arms are slightly different on the 930, but you should check on whether these changes apply to the SC. Photos in next post...techno-turd.

[DaytonaCoupe66]

[Dr J]

I don’t have other manuals to tell if there are updated specs for the SC.

I’m sure someone has these numbers memorized.

[Dr J]

Well, looks like I wasn’t the only one with this problem. I found the exact same confusion for 74 specs according to this post.

Suspension Torque Specs?

[Gretz]

I’m having exactly the same issue. I am putting my rear suspension back together and I am bolting in the trailing arms. The bolt that goes through the upper trailing arm mounts is specced at 60 NM in the tech specs book but 100 NM in the Bentley. I am replacing the bolts and nuts with the updated parts, which include a slightly longer bolt and a much beefier nut which is 22 MM instead of 19 MM. I assuming I should go with the 100 NM torque value but Bentley is notoriously unreliable with torque values. Does anyone have a picture or link to the actual shop manual with the updated values?

[TxGerman]

I ran into this exact same issue on my '82 SC when I was going through an entire suspension refresh (and more). I deferred to a tie-breaker resource. I went online and found a torque sheet based upon fastener material/plating, type, diameter, pitch and grade. When in doubt, I used that as my target torque. It was not uncommon for the torque chart to be close to either Bentley's or the small Porsche book.

An example of one website is: https://www.imperialsupplies.com/pdf/A_FastenerTorqueCharts.pdf

Or Fastenal: https://www.fastenal.com/content/merch_rules/images/fcom/content-library/Torque-Tension%20Reference%20Guide.pdf