wheel bolt torque

[Rocky997]

Can anyone clarify something for me please.
I am just in the process of removing my wheels and giving the the hubs a rub down and clean before sealing the wheels and calipers.
I have also cleaned up the slightly tarnished wheel bolts.
I have found two different torque settings in the porsche imanuals. 2009-2011; so I am assuming correct for me (997.2) says 130nm and to grease the threads with aluminium paste...so wet torque settings. Later manual says 160nm and dry. I am just checking as I was always told although it would seem common sense that greasing wheel bolts is a no no.
Any advice please folks.
Thanks in advance.

 

[tscaptain]

Optimol paste on the thread only, not on the face of the bolt, and 130 nm.[] (Well, that's what I do anyway!)

 

[Rocky997]

Thank you for that. It would appear that wet torque values are usually 25% less than dry torque settings. Perhaps thats why Porsche have now gone up to 160nm dry.
I have used copper grease not aluminium. Anyone know any reasons why I shouldn't.
Thanks again.

Dave.

 

[tscaptain]

Don't Porsche mention Optimol in the manual? I think copper can react with any aluminium it comes into contact with.

 

[Lancerlot]

Coppaslip and similar are anti-seize, not lubricating compounds and should not normally used for wheels fasteners. Also, I believe there have been cases where the copper element in this compound has caused corrosion to adjoining aluminium wheel/hub/brake components.

Optimol paste on the other hand, is a torque retaining lubricant that controls friction.

Friction during torqueing can cause galling, seizing and fastener wear. The lubricant prevents these problems by reducing overall friction during the assembly process. It assists with applying the correct tension. Even when following the prescribed torque, unexpected thread factors can reduce the fastener preload and you end up with an assembly that is insufficiently tightened.
The paste will reduce/prevent corrosion that can wreak havoc on your fasteners. It prevents moisture and chemicals infiltrating the assembly by setting up a lubrication barrier.
It will also assist with disassembly later as a bolt assembled with lubricant is easier to break-out - even years later. It will reduce thread stretch and damage by ensuring a correct and even clamping force.

Regards,

Clive.

 

[tscaptain]

ORIGINAL: Rocky997


I have used copper grease not aluminium. Anyone know any reasons why I shouldn't.

Dave.

Better get them off again quick then![]

 

[Rocky997]

Thanks all. Wheels now removed again and threads wiped clean.
Just to chuck a spanner in the works. Manual for 997.2 states 130 nm with titanium grease as discussed. I have checked with an OPC tech who says the manual has changed and they now torque all studs to 160nm dry. Tried 160nm on one wheel and 160nm seems a lot.
I guess that if a dry torque setting should be reduced by 25% for a wet (lubricated) setting then this logic is why they are now suggesting 160nm with no grease.
Who would of thought bolting a wheel on would be so confusing.

 

[Chris_in_the_UK]

COPASLIP® prevents seizing and galling and gives quick and easy breakout of threads, gaskets and packings even after long exposure to high temperature, corrosive conditions or extreme surface pressures. It also reduces wear in areas of high friction. By protecting against seizure, maintenance work requiring routine or infrequent assembly and dismantling is made much easier and less costly.

 

[tscaptain]

I still wouldn't put it on my wheel bolts....[]

 

[RJKflyer]

The right answer, as said by Dr. Porsche:

"Always apply a thin coat of Optimoly TA (aluminium paste) on the thread of the wheel bolts, on the shank and between the bolt head bearing surface and spherical cap ring (under the head) −arrows− . Do not grease the spherical cap bearing surface −X− of the wheel bolts that face the wheel."

From Castrol: "OPTIMOLY PASTE TA for screw connections up to + 1100°C/+ 2012°F. It is used as assembly paste and prevents seizing, welding or scaling. OPTIMOL PASTE TA ensures a good separating and sealing effect in high temperature and wet environments as well as under the influence of aggressive media."

The 'wheel coming off' issue sometime reported (irrespective of aluminium or copper slip) is that greasing the thread risks over-tightening if torque is not reduced by appropriate amount (as noted above 130Nm wet, 160Nm dry) - which can stretch the material, and I suppose might exceed its elastic limit - meaning it will not stay tight.

I believe that although Copper-based anti-seize can be used as a (perfectly good) assembly paste, it is more likely to cause seizure ('welding') with steel and aluminium components? (Hence the use of aluminium anti-seize...).