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French Locks
Posted by: JimBrandberg ()
Date: July 09, 2019 05:45AM

I've just about always used french lock tabs on exhaust manifold clamps. What's the reasoning behind GM using them for this application? The times I've used lock washers I can't remember them loosening up.

While I'm at it, how did they make the screws with captured lock washers like those used on carburetor tops? Were they hot when installed and shrunk when cooled or did they install them and give a little squeeze or...?
Maybe I've been watching "How's It Made" too much.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: French Locks
Posted by: jjohnsonjo ()
Date: July 09, 2019 06:24AM

Its exhaust, why risk a law suite?

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa


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Re: French Locks
Posted by: vairchet ()
Date: July 09, 2019 12:12PM

I've had good luck using GR5 lock washers and self locking nuts.

Chet in Ramona

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Re: French Locks
Posted by: Timothy Shortle ()
Date: July 09, 2019 12:25PM

It is not uncommon for exhaust parts to "vibrate" loose. I am sure that is the reason for F Locks. I also have wondered how they made the carb. screws with washers. Not recently though.

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Re: French Locks
Posted by: junkman ()
Date: July 09, 2019 01:02PM

The lock washers were installed prior to the threads being rolled or cut onto the screws.

---------------------------------------------------------------------------------------------------------------
Woodstock CT... Located on the Connecticut / Massachusetts border, approximately 6 miles from the center of Southbridge MA. About 45 minutes from Hartford CT. 1 1/2 hours West of Boston MA. Woodstock CT to Los Angeles CA 2,937.1 miles. 1 Mile as the crow flies to Big Bird's nest.

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spinning smiley sticking its tongue outRe: French Locks
Posted by: jcorvair ()
Date: July 09, 2019 01:23PM

That looks like a Grade 8 lock washer to me Chet

James
West Kelowna, BC

1965 Corvair, Corsa, Convertible 180/4 - Artesian Turquoise w/ white interior
1966 Corvair Corsa Coupe, 140/4 - Aztec Bronze w/ black interior
2013 Hyundai Santa Fe Turbo
2016 Dodge 3500 Crew Cab 4x4 (for hauling cars, trailers, fifth wheels, quads, etc.)
2013 Victory Car Hauler (enclosed)
2019 Express Car Hauler (Aluminum, Enclosed)
2015 Polaris 570 EPS
2016 Polaris 570 SP
2017 Corvette Z06 Convertible

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Re: French Locks
Posted by: momach ()
Date: July 09, 2019 01:35PM

What Junk said. Washer is located on shaft before threading. Thread rolling displaces material with form dies, doesn't cut the threads.

Wet side of Washington State

one too many cars,(maybe)

multiple Corvairs.
1962 Buick Skylark
1967 Datsun 2000 roadster

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Re: French Locks
Posted by: JimBrandberg ()
Date: July 10, 2019 05:58AM

So as an example using round numbers a 1/4" bolt starts with .25 material and ends up at .26 after the threading die operation?

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: French Locks
Posted by: momach ()
Date: July 10, 2019 08:49AM

You will still end up with .25 outside diameter. When the thread is formed, the material get displaced, not cut away. No material is removed. Some material is pushed into a smaller diameter and the rest displaces to a larger diameter. The starting, or original diameter would be under .25, depends on pitch, but I'd guess around .230 to get a 1/4-20 thread.

Wet side of Washington State

one too many cars,(maybe)

multiple Corvairs.
1962 Buick Skylark
1967 Datsun 2000 roadster

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Re: French Locks
Posted by: JimBrandberg ()
Date: July 10, 2019 12:17PM

So if you want a 1/4" bolt with a captured lock washer you would start with .23 material and the lock washer would be .24 ID using round numbers as an example.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: French Locks
Posted by: junkman ()
Date: July 10, 2019 06:37PM

Can't ever remember ever seeing a 1/4" bolt with a captured lock washer. Most times, the lock washers are the star type, and I have seen them used many times on small screws. Also have seen them on nuts, but with those, there is a part of the nut that holds it on by swaging.
The only thing that I know about French locks is what my former French girlfriend taught me. Damn, I sure do miss her!

---------------------------------------------------------------------------------------------------------------
Woodstock CT... Located on the Connecticut / Massachusetts border, approximately 6 miles from the center of Southbridge MA. About 45 minutes from Hartford CT. 1 1/2 hours West of Boston MA. Woodstock CT to Los Angeles CA 2,937.1 miles. 1 Mile as the crow flies to Big Bird's nest.



Edited 1 time(s). Last edit at 07/10/2019 06:39PM by junkman.

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Re: French Locks
Posted by: JimBrandberg ()
Date: July 10, 2019 07:37PM

I just used 1/4" as a numerical example since #10 is an odd size.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: French Locks
Posted by: Frank DuVal ()
Date: July 10, 2019 08:11PM

1/4-20 socket head cap screws can come with integral split lock washers.

McMaster Carr has them.

I have seen various hex head bolts on cars with integral split lock washers, but i have no examples here right now.

Frank DuVal

Fredericksburg, VA

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Re: French Locks
Posted by: corventure Dave ()
Date: July 12, 2019 07:48AM

Back to French Locks. I have had a few exhaust studs turn out of the head because someone used self locking jam nut's when installing the exhaust. I know some of these nuts hold better than others, but in this case French locks could have make disassembly a lot easier.

I have even seen where someone used lock nuts with the nylon locking insert!!!
At least it held for a few minutes!eye popping smiley

Corventure Dave

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Re: French Locks
Posted by: Rcelt75 ()
Date: July 14, 2019 09:17AM

I know that the drill size for 1/4" is #7 when you drill a hole to tap threads in it, so I must assume that the stock would be the same diameter before the threads are rolled on. #7 drill diameter is 0.201

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