any volvo Torque spec's with/w.o. lubrication

[JimBee]

Before re-torquing the subframe mounts on the 850, I looked up specs and came across the following post:

http://www.cycleworld.com/2014/07/25/as ... ng-torque/

Does anyone have an official opinion about this? If lube (not just threadlock) is used, should both the threads and the underside of the bolt head be lubed, or just the threads?

What's the best way to get an accurate torque?

[jimmy57]

Torque plus angle, no adjustment for dry , lubed, or locking chemical. The torque is low and the affects of any of those things is negligible at low torque.

Torque only it can make a difference.

By the way, Kevin Cameron is da man! His column is always god and every once in a while he delivers one that is legendary.

[JimBee]

Okay, jimmy57, thanks.

So you're saying 77 ft lbs. + angle on the subframe main mount bolts. The angle must bring the total to around 90 to 100. Those are hefty bolts, but what if one of them snaps? Nightmare. Would the car be junk?

[bctom]

I can't remember where I saw it written down. I think it was another vehicle where the manual gave torque spec's for dry and lubed.

Reduce the dry spec by 10%.

I mostly use this for lug nuts and bolts as the torque spec is high; 81 ft.lbs.

[jimmy57]

subframe bolts new from Volvo have plastic locking compound on them and are put in at factory dry but into pristine threads.
If the bolt is rusty and the shank has lost diameter due to rust then you are at risk.
If the bolt is healthy then you will not break it. I think the rotating force goes to 150 lb-ft (maybe 200) at the end of the angle. It is 77 lb-ft plus 120 degrees.
Torque only fastener tightening is very unpredictable and lubrication does affect final clamping force.
The torque plus angle will have the first step torque at a value that is dependent on the size of the fastener. The torque sets a minor preload to fastener and the angle goes to a predictable elongation for the fastener that sets it clamping load very predictably.
I use a cheap penetrating oil spray in the hole and then blow it out so it is very lightly lubed and clean before I install the fastener. The effects of oil are slight once the load on threads is high unless you are using some special molybdenum or other metal enhanced lubricant that tolerates the extreme pressure.
The other consideration here is that dry corroded threads makes a fastener hard to turn which makes the clamp load low for torque only fasteners and makes torque plus angle fasteners very hard to turn to get the angle. When you are turning the fastener and it chatters (bind and release cycles) that twist as bind occurs is very stressful on the bolt and is often when they break.
Yes, broken subframe bolts can be removed but it is not easy.