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General Category => General Discussion => Topic started by: robebop on September 20, 2020, 02:01:27 PM

Title: nylocs on exhaust studs?
Post by: robebop on September 20, 2020, 02:01:27 PM
Any reason not to use Nylocs on my exhaust??
Title: Re: nylocs on exhaust studs?
Post by: rtbickel on September 20, 2020, 02:08:19 PM
On the manifold studs?  Those little plastic inserts would probably melt and/or catch fire in short order.
Title: Re: nylocs on exhaust studs?
Post by: Burkslaw on September 20, 2020, 02:17:59 PM
Nyloks are not effective above 250F. Here's an excellent article on fasteners, if you want some rainy afternoon reading:   https://www.hotrod.com/articles/how-to-use-aircraft-fasteners-on-a-hot-rod/?wc_mid=4035:19899&wc_rid=4035:762138&_wcsid=61AF3CB1CCA6571117BB8C1165E9A09A0BF55682539CA0CE
Title: Re: nylocs on exhaust studs?
Post by: Bert Remington on September 20, 2020, 02:21:02 PM
Nord-Lock washers https://www.nord-lock.com/nord-lock/products/washers/
Title: Re: nylocs on exhaust studs?
Post by: Guzzistajohn on September 20, 2020, 02:35:12 PM
metric lock tite
Title: Re: nylocs on exhaust studs?
Post by: Roebling3 on September 20, 2020, 03:19:59 PM
Any color loctite is on the fringe of worthwhile on exhaust studs. I'd use a split lock washer. They have some history.  R3~
Title: Re: nylocs on exhaust studs?
Post by: John A on September 20, 2020, 03:51:04 PM
I just use schnoor washers and silver antisneeze with domed nuts. silver is usually nickel based but the reason I use that is the color blends in better than copper based antisneeze.  I tried heat resistant lock nuts but it would pull the studs out too frequently.  I check them after a few hot-cold cycles and after that they don't change.
Title: Re: nylocs on exhaust studs?
Post by: Muzz on September 20, 2020, 04:00:48 PM
There are things , I think they are called crush nuts.  The top of the thread is tighter at the top.  They work well but can sometimes undo the stud out of the head instead of actually undoing.
Title: Re: nylocs on exhaust studs?
Post by: Guzzistajohn on September 20, 2020, 04:14:54 PM
There are things , I think they are called crush nuts.  The top of the thread is tighter at the top.  They work well but can sometimes undo the stud out of the head instead of actually undoing.

I've also heard them called stover nuts
Title: Re: nylocs on exhaust studs?
Post by: Muzz on September 20, 2020, 05:03:54 PM
I've also heard them called stover nuts

Ya learn something every day!.  Thanks John. ,sadly I will probably forget by tomorrow and go back to crush nuts. :rolleyes:

edit: just did a search and you are 100% correct John. :thumb:
Title: Re: nylocs on exhaust studs?
Post by: lucky phil on September 21, 2020, 07:29:22 AM
A properly torqued plain nut lubricated with anti seize compound wont loosen off in an exhaust header installation.

Ciao
Title: Re: nylocs on exhaust studs?
Post by: Guzzistajohn on September 21, 2020, 07:36:10 AM
Ya learn something every day!.  Thanks John. ,sadly I will probably forget by tomorrow and go back to crush nuts. :rolleyes:

edit: just did a search and you are 100% correct John. :thumb:

Used them in overhead lift equipment for handicapped patients. Gotta be for sure X2  :thumb:
Title: Re: nylocs on exhaust studs?
Post by: mechanicsavant on September 21, 2020, 07:45:23 AM
+1 on the article from “Hot Rod” . I got it in my “Special 411”folder  :thumb:
Title: Re: nylocs on exhaust studs?
Post by: roadventure on September 21, 2020, 09:30:17 AM
Any reason not to use Nylocs on my exhaust??

Where, in particular on the exhaust system?
Title: Re: nylocs on exhaust studs?
Post by: Groover on September 21, 2020, 10:34:59 AM
Would these be a good alternative?

https://www.aircraftspruce.com/catalog/pnpages/AN363-720.php?gclid=EAIaIQobChMIhbCnj8n66wIVRNbACh0oagmdEAQYAiABEgKz0PD_BwE
Title: Re: nylocs on exhaust studs?
Post by: Old Jock on September 21, 2020, 10:43:07 AM
I often find that these nuts will loosen after initial application, I'm just not as meticulous as Phil

I use Aero Nuts as posted by Groover, Nord Locks are also excellent as mentioned by Bert

Definately not Nylocs they'd just melt and make a mess
Title: Re: nylocs on exhaust studs?
Post by: acogoff on September 21, 2020, 02:14:56 PM
    Plain nut with schnoor washers and a retorque once a week for a couple weeks or so. 
Title: Re: nylocs on exhaust studs?
Post by: lucky phil on September 21, 2020, 05:18:59 PM
I often find that these nuts will loosen after initial application, I'm just not as meticulous as Phil

I use Aero Nuts as posted by Groover, Nord Locks are also excellent as mentioned by Bert

Definately not Nylocs they'd just melt and make a mess

Maybe I should preface my previous comment John. After initial tightening you need to go back after a short while/heat cycles and tighten them up again. Its not the nuts backing off its the header gasket compressing so they need a re torque like a composite head gasket. After that they will stay tight without the need for some abominable thing like a schnor or spring washer.

Ciao
Title: Re: nylocs on exhaust studs?
Post by: ridingron on September 21, 2020, 10:58:12 PM
Quote
There are things , I think they are called crush nuts.  The top of the thread is tighter at the top.  They work well but can sometimes undo the stud out of the head instead of actually undoing.     

I think crush nut is shop slang term. I think Stover is a brand name like Crescent for adjustable wrench. I have also heard the term prevailing torque nut for the crush/Stover nut.

They do have a tendency to tear threads on the bolt/stud. I have seen anti-seize spec'ed as an attempt to prevent that and to increase the accuracy of the torque. The anti-seize would probably melt away after a few heat cycles, in this application.
Title: Re: nylocs on exhaust studs?
Post by: lucky phil on September 21, 2020, 11:11:14 PM
I think crush nut is shop slang term. I think Stover is a brand name like Crescent for adjustable wrench. I have also heard the term prevailing torque nut for the crush/Stover nut.

They do have a tendency to tear threads on the bolt/stud. I have seen anti-seize spec'ed as an attempt to prevent that and to increase the accuracy of the torque. The anti-seize would probably melt away after a few heat cycles.
I used them in aviation for 40 years and just used to get them out of free issue. We just called them pressed metal nuts as opposed to your usual AN or NAS fastener. Ducati have used copper nuts with crimped ends on their exhaust manifolds for the last 20 years or so. I've never had an issue with exhaust flange nuts coming loose on bikes or cars but like I said I check them once after initial torquing down to account for the gasket creep.

Ciao