H2

As I put a new water pump on yesterday, with Hylomar on both sides of the gasket, I had to torque it about 3 times to get a torque reading that would "stick" ..w/three minutes between each tightening.

Then I puzzled...was the apparennt loss of torque between tightenings due do the gasket seal settling in...or the anti-seize on all the bolts I put in? If just the former, that's fine.

However, if the anti-seize on bolts fools the torque wrench and you just keep on torking, that's bad. Has anyone ever proved this one way or the other? I'd hate to have WP bolts start stripping just because they were overtorqued. All appears well...just checking.

Harvey
"Keep on Torking"

69gaugeman

they have a reducing factor when you use anti sieze. Just don't ask me what it is.

Randy V

Applying any type of material to the threads that reduces the friction load between the threaded surface and the bolt will definitely affect the torque setting.

I'm betting there is a standard correction factor - probably increase torque value 10-20 % or thereabouts. Try googling for a correction factor.

JKelly

Yes. It can fool the torque wrench. I use anti-seize on everything and usually use the minimum amount of required torque without any problem. This is what happens if you glob a bunch of anti-seize on the threads and aren't careful:



Also, different anti-seizes use different carriers(?) or oils in them, so that might make a slight bit of difference.

JKelly

You would want to decrease the torque value to compensate for the loss of friction in the threads.

Edit: I see what you mean. The anti-seize itself probably increases the torque value.

glork98

The torque is the same!

Lubing the threads changes the tension on the bolt. Most of the torque is friction under the head anyways. Torque ratings assume new and clean thread for the nut/hole and bolt/stud as well.

If you use antiseize, or loctite, just torque to the given specs.

The strength of the bolt will accomodate the difference. In 98% of the cases the torque is intended to make sure the bolt stays in place anyways. It's not a case of a precision effect like for heads and rods.

If it's a special situation, then do it as the manual suggests.

SharkSkin

Usually, torque specs assume lightly oiled threads, so adding anti-seize won't affect it much. You'll be close enough that it's not worth worrying about.

BrianG

The following excerpt from ARP (the auto-racing engine fastener manufacturer) clearly indicates that different thread lubricants result in different torque values to attain their 75%-of-tensile-strength desired clamping force. I also provided some of their other notes, just for interest sake.


PART NUMBER / TENSILE STRENGTH / TORQUE-OIL 30 wt / TORQUE-ARP LUBE
Rod Bolts
BEB-08..................220,000 PSI...............65 ft lbs....................45 ft lbs
BEB-09..................220,000 PSI...............65 ft lbs....................45 ft lbs
BEB-1...................190,000 PSI................55 ft lbs....................38 ft lbs



The following notes are important!

* ALWAYS wash the fasteners with cleaning solvent prior to installation. They come coated with a "protective" coating, this is NOT a lubricant.

* Choose correct torque from the chart.

* Note the difference in torque settings depending on the thread lubricant used.

* The method to follow for applying lubricant:

* Coat the fastener with lubricant as evenly as possible (especially important with the L99 lube).

* Pull up the fastener so that it is 'snug'.
Do this three times, on the third time torque in the recommended order to the torque as shown in he chart opposite.

* The above method no doubt seems strange, but does ensure no metal to metal contact that increases friction between the threads.

* The torque figures shown will give a preload equal to 75% of the yield strength of the fastener.

* Use a generous chamfer on all stud holes.

* Screw studs into the block using 4 ft lbs only. (Basically hand tight).

* If you feel you have to use a thread locking compound for studs (not bolts or nuts) then be sure to do the final torque before the compound sets up.

* We do not recommend the use of lock tabs which are made from a material which is too soft, and as it squeezes out, the fastener preload is lost.

* Due to leverage differences a fine thread will produce a greater preload for a given torque than will a coarse thread of the same diameter.

* Tap all female threads before installing bolts or studs. (Best not to use a new tap)

* ARP lube, part number L99 is recommended over 30 wt oil if possible, as its superior lubricating properties produce the correct clamping preload for less torque.

* For all connecting rods check that the chamfer required to clear the bolt under head radius is adequate - this is VERY important.

SharkSkin

Should have stated that I was talking about general hardware -- on critical applications like head/rod/bearing bolts/studs, obviously more care is needed.

jon928se

As a general rule somthing like 50% of the applied torque is just to overcome friction/galling under the bolt/nut head and in the threads, for a bolt specified as not lubed. Apply a perfect lubricant that eliminates all the friction and the bolt will have twice the clamping force than specified.

In an alu block this probably means that a lubed bolt (that shouldn't be lubed) torqued to WSM value will pull the threads out of the block.

BrianG

A dry steel bolt in an aluminum block is asking for trouble. Does this mean that the given torque setting contemplate use of an anti-seize compound?

SharkSkin

FWIW, the big bolts around the bellhousing and at both ends of the TT have copper anti-seize on them -- most other bolts that have not been disturbed(when you find them) have copper anti-seize as well. I'd think that Porsche figured this into the torque spec.

jon928se

Any thing crucial like head bolts or crank ladder bolts the torque spec and wether installed dry or lubed (and lubed with what) gets specified in the WSM, the less important stuff doesn't specifically get mentioned . I guess you have to search hi and low for some one liner that says all other bolts - x Nm, lube with zzzzzz. I haven't searched - anyone else found some reference like this ?

Daniel Dudley

I have seen lots of suspension nuts and bolts stripped out over the years from too much antiseize and over tightening. Big but few threads per inch. I have seen antiseize put on sparkplugs in such copious quantities that the plugs jammed halfway and stripped out the top of the hole. This would be in aluminum heads. A little goes a long way, and you can slather it on the exposed threads later if so desired. A classic example would be when the alignment guy stripped out the two excentric bolts that align the rear wheels on my OB. TONS of antisieze, NO brains. It costs a lot to buy those suckers new, not to mention the exquisite driving feel you get with loose excentric bolts on your rear wheels. In this case the loose nut was not behind the wheel for once.

SharkSkin

Jon, I seem to recall something like that in the tech docs but I don't have time to go looking for it.

Daniel, alignment guys tend to get lazy IMHO they tighten and loosen so much that they often don't bother with a torque wrench. I think that a hamfisted tech will strip stuff with or without antiseize.