99 boxster clutch

[truegearhead]

Originally Posted by maytag

Always, always always use the torque setting provided by whoever supplied the fasteners. If they didn't tell you, I'd default to the factory manual. (and if you're reusing fasteners, then you're on your own.... I wouldn't in this application)

And don’t use any lubricants. They’ll change the torque value of the hardware drastically.

[JFP in PA]

Originally Posted by truegearhead

And don’t use any lubricants. They’ll change the torque value of the hardware drastically.

Nonsense. USING the proper lubricant will give you the most accurate torque readings.

[Boxstard]

Originally Posted by JFP in PA

Nonsense. USING the proper lubricant will give you the most accurate torque readings.

It depends on how the torque spec was originally designed, with lube or dry.

For example, Porsche does not specify any lube on wheel lug bolts, so lube would cause actual torque above the spec.

[JFP in PA]

Originally Posted by Boxstard

It depends on how the torque spec was originally designed, with lube or dry.

For example, Porsche does not specify any lube on wheel lug bolts, so lube would cause actual torque above the spec.

I would suggest you read ARP’s white paper on the subject of reproducible torque levels and how they cannot be achieved without proper lubrication. The random scatter of torque readings without lubricant demonstrates why ANY fastener with a torque setting needs to be correctly lubricated in order to achieve the desired clamping loads.

[Boxstard]

Originally Posted by JFP in PA

I would suggest you read ARP’s white paper on the subject of reproducible torque levels and how they cannot be achieved without proper lubrication. The random scatter of torque readings without lubricant demonstrates why ANY fastener with a torque setting needs to be correctly lubricated in order to achieve the desired clamping loads.

It does not take much imagination to predict relatively poor gage R&R with dry torque vs lubed... My point was to clarify if the spec is meant for lubed or dry condition.

If you lube and torque to the dry spec., it will be over tightened, it's the fact. Still you may have no issues if the clamp force is still under the material yield, which could be the most cases where components are designed with safety margin, especially Porsche.

[JFP in PA]

Originally Posted by Boxstard

It does not take much imagination to predict relatively poor gage R&R with dry torque vs lubed... My point was to clarify if the spec is meant for lubed or dry condition.

If you lube and torque to the dry spec., it will be over tightened, it's the fact. Still you may have no issues if the clamp force is still under the material yield, which could be the most cases where components are designed with safety margin, especially Porsche.

The entire point of the ARP paper was to demonstrate that you cannot reproduce the intended clamping force without proper lubrication. The torque spec is to get that clamping force level, which you may, or more probably may not get when applying torque to dry fasteners. In their research, ARP looked at the actual achieved clamping load vs the observed torque readings; when the fasteners were torqued dry, the clamping load was all over the place; sometimes high, more often too low. When lubricated, the specified torque readings uniformly produced the expected clamping loads.

[Boxstard]

Originally Posted by JFP in PA

The entire point of the ARP paper was to demonstrate that you cannot reproduce the intended clamping force without proper lubrication. The torque spec is to get that clamping force level, which you may, or more probably may not get when applying torque to dry fasteners. In their research, ARP looked at the actual achieved clamping load vs the observed torque readings; when the fasteners were torqued dry, the clamping load was all over the place; sometimes high, more often too low. When lubricated, the specified torque readings uniformly produced the expected clamping loads.

Again the point is if the spec was designed for dry or lubed condition. Dry spec can be developed to statistically assure the min clamp force for the application and still under material yield. It is risky to torque with lube when the spec really meant for dry...

I’m sure ARP as a fastener company advocates lube that reduces variations and achieves clamp force intended as consistent as possible for their optimal design without overengineering.

It was just not clear to me if Porsche spec. was based on dry or lubed, as I have not seen factory document specifying to lube.