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Old 16th October 2016, 14:59   #11
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Between the face of the hub and inside of a brake disc is one place never to apply copper grease, I cringe when I see it on the drive flanges when a disc is removed.

Basically if you see a bolt which has traces of blue or red on the thread form, these are Patchlok bolts, and if reusing them, a spot of anaerobic threadlock should be employed, ie loctite 243 or similar, similarly nut and bolts with nyloc nuts should not be lubricated

In the case of rear wheel bolts in particular, they should not be slathered in anti gall grease, as this has a propensity to distribute itself inside the handbrake drum area, a case of less is best in this case.

If any lubricant is employed on a fastener which has been previously used, the torque settings should be reduced by 5% from specification.

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Last edited by marinabrian; 16th October 2016 at 15:02..
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Old 17th October 2016, 11:43   #12
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Quote:
Originally Posted by marinabrian View Post
Basically if you see a bolt which has traces of blue or red on the thread form, these are Patchlok bolts, and if reusing them, a spot of anaerobic threadlock should be employed, ie loctite 243 or similar, similarly nut and bolts with nyloc nuts should not be lubricated
I support this one!

I have noted that traces of blue or red threadlocker are seen on a lot of bolts that basically not need it. I suspect this is not for locking them in place, but to seal the threaded area from the environment to avoid seizing due to corrosion. Brake caliper carrier bolts for example...

I talked with one of the old school guys a couple of years back, and their best advice was to use underbody sealant (tectyl/dinitrol i.e.) to the threads prior to assembly as this keep the threads protected from the environment and do not dries out like grease i.e. over time.
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Old 17th October 2016, 19:48   #13
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Coincidentally, today I got the current edition (Nov 16) of Car Mechanics magazine it has an article on this subject. Basically it mirrors this thread.
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Old 17th October 2016, 21:09   #14
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Quote:
Originally Posted by beinet1 View Post
I have noted that traces of blue or red threadlocker are seen on a lot of bolts that basically not need it. I suspect this is not for locking them in place, but to seal the threaded area from the environment to avoid seizing due to corrosion. Brake caliper carrier bolts for example...
I think this is to do with bolt sizing vs torque requirements - the maximum torque a small bolt can handle is actually quite low, even in high tensile form. As such threadlock is used as a way of increasing the effective tightness without requiring more torque on the fastener - I think at least!
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Old 17th October 2016, 21:09   #15
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Highly overloaded bolts like that can also fail in use.----

Your wheel, Sir, went thataway-------
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Old 17th October 2016, 22:07   #16
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I wonder why MarinaBrian doesn't like copper grease there. I always use it like you do Mr MG John.---
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Old 17th October 2016, 22:11   #17
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Just about all of them except-------------------those the manufacturer says put Thread Lock on.---

If you do lubricate your wheel bolts DON'T lubricate the taper section that buts against the wheel itself.

Otherwise you might hear somebody say--Your wheel went-- ---thataway.
I have done this now for past 20 years, after having had to stuggle with wheel bolts. I have never had a wheel bolt loosen. Never did it for steel wheels. Only with alloy wheels after struggling to remove when they seized at the flange. I do get your reasoning, but I am smearing the remnants of the line smeared onto the thread.

I do also smear a little onto the face of the wheel/hub where they meet and flange of the hub (elsewhere though, invites trouble as centrifugal force could splash residue onto the discs ) . And this comes after having to give the wheel a more than is safe thump to remove from the hub.
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Old 17th October 2016, 22:20   #18
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There is a good reason why the flanges and disc faces should be very carefully cleaned and bolted together dry.

Unless the coat of grease is completely uniform without any specks of grit or dirt (highly unlikely) you will introduce run out to the disc (extremely likely).

When I fit discs, I always check them for run out with a DTI, and if excessive I will remove and recheck the surfaces, and even rotate the disc on the flange irrespective of whether the retaining CSK screw is in alignment to obtain the best figures.

Brian
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Old 18th October 2016, 05:28   #19
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Quote:
Originally Posted by marinabrian View Post
John, there is a good reason why this is bad practice, the flanges and disc faces should be very carefully cleaned and bolted together dry.

Why is this I hear you ask?, the answer is simple unless the coat of grease is completely uniform without any specks of grit or dirt (highly unlikely) you will introduce run out to the disc (extremely likely).

When I fit discs, I always check them for run out with a DTI, and if excessive I will remove and recheck the surfaces, and even rotate the disc on the flange irrespective of whether the retaining CSK screw is in alignment to obtain the best figures.

Brian
While we all agree that the disk must run true, I can assure you that the presence (or not) of grease behind the bolts is not going to affect that aspect one iota. It would have some effect on friction however, but that is another story.
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Old 18th October 2016, 09:15   #20
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I'm not very good at explaining things but basically I use grease on exterior bolts (such as exhaust hangers etc) to prevent them from seizing due to environmental exposure and use Copperslip on what could be considered critical (such as suspension bolts, wheel bolts etc) and between the faces of dissimilar metals to prevent them fusing together. Thread lock is to be used when advised (mounting bolts such as seats etc) but on its own and not put on then anything else used over it.

Heat is another reason to use Copperslip, for example heat causes metal to expand and results in faces seizing together so when replacing injectors they get a light coat of Copperslip (around the body and NOT on or near the nozzle) as this will prevent the injector seizing in place and aid future removal (granted we do this on ships as injectors are removed every few thousand hours and there is a lot more heat and carbon build up but can also be beneficial on other engines).
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