What did you LEARN today?

[JollySipper]

Recently learned that they used to fill the Porsche 917 endurance racer frames/chassis with nitrogen so they could tell when a crack had occurred.......... Probably common knowledge to some folks, but it was new to me!

[peteski]

Ok, I'll bite.  Why nitrogen and how exactly it would indicate a frame crack?  It is not like nitrogen is a liquid die which would seep out of the crack. It is a gas.  Or was the gas pressurized in the airtight frame and they would check if the pressure dropped after a race?  The ambient air is 78% nitrogen. Why not just use plain atmospheric air?

[stitchdup]

6 minutes ago, peteski said:

Ok, I'll bite.  Why nitrogen and how exactly it would indicate a frame crack?  It is not like nitrogen is a liquid die which would seep out of the crack. It is a gas.  Or was the gas pressurized in the airtight frame and they would check if the pressure dropped after a race?  The ambient air is 78% nitrogen. Why not just use plain atmospheric air?

the nitrogen freezes and shows the cracks as lines of frost

[peteski]

So  it must be pressurized inside the frame, correct?

[stitchdup]

I used up the sum of my knowledge on nitrogen. I could say they use it in the nissan gt-r r35racecar tyres as its a stable gas that doesn't go up and down in pressure like air does but that doesn't really help the answer. At a guess I'd say it doesn't need to be pressurised as it will still freeze on contact with the air but the chassis should be sealed and not have open bolt holes. My basis for that little bit of knowledge is from seeing it used to remove sound deadening on car tv shows when it wasn't pressurised and still froze so it should be the same with the chassis

[JollySipper]

46 minutes ago, peteski said:

So  it must be pressurized inside the frame, correct?

From what I was reading about this, the nitrogen WAS pressurized inside the frame........ There was a gauge that alerted the driver when the frame lost pressure, thus telling of a stress crack or cracks from fatigue.....

[peteski]

That makes sense.

[Ace-Garageguy]

18 hours ago, JollySipper said:

From what I was reading about this, the nitrogen WAS pressurized inside the frame........ There was a gauge that alerted the driver when the frame lost pressure, thus telling of a stress crack or cracks from fatigue.....

Correct. 100%

EDIT: And nitrogen is used because for all intents and purposes in this application, it's an inert gas.

So no oxidation (rust) inside the frame tudes from the presence of oxygen in "atmospheric air".

FWIW, race-car and light aircraft fuselage-frame tubes have been internally coated with linseed oil to guard against oxidation in the past as well.

 

Edited March 14 by Ace-Garageguy

[Ace-Garageguy]

19 hours ago, stitchdup said:

...when it wasn't pressurised and still froze so it should be the same with the chassis

Maybe you'd like to explain how that can be, considering 78% of "atmospheric air" is nitrogen.

Edited March 14 by Ace-Garageguy

[stitchdup]

Just now, Ace-Garageguy said:

Maybe you'd like to explain how that can be, considering 78% of "atmospheric air" is made up of nitrogen.

hence why i started that statement with the words AT A GUESS, and began my entire post with i used up the sum of my knowledge. at least quote the whole statement. This isn't the joe rogan show

[Ace-Garageguy]

36 minutes ago, stitchdup said:

...This isn't the joe rogan show

Who?

[JollySipper]

Recently learned what a garden-path sentence is..............

https://en.wikipedia.org/wiki/Garden-path_sentence

 

Edited March 22 by JollySipper

[LennyB]

11 minutes ago, JollySipper said:

Recently learned what a garden-path sentence is..............

https://en.wikipedia.org/wiki/Garden-path_sentence

 

Sometimes I think Wikipedia just makes this 💩 up.  

[JollySipper]

I learned of it first, then looked it up on wiki............

[Ace-Garageguy]

2 hours ago, JollySipper said:

Recently learned what a garden-path sentence is..............

https://en.wikipedia.org/wiki/Garden-path_sentence

 

Best to understand what one is so you never use one. They are usually not clear communication.

[89AKurt]

I pretended to know how to bend tubing today.  Yesterday I had replaced a 3/8" hose, but it was kinked at both ends.  First thing today was a trip to Home Deephole, hoped 10 feet of copper refrigerant line would be enough.  Got the bender too, sure makes life easier!  Took only 4 tries.

[espo]

17 hours ago, 89AKurt said:

I pretended to know how to bend tubing today.  Yesterday I had replaced a 3/8" hose, but it was kinked at both ends.  First thing today was a trip to Home Deephole, hoped 10 feet of copper refrigerant line would be enough.  Got the bender too, sure makes life easier!  Took only 4 tries.

Make some good-looking headers. 

[espo]

I was reminded that today is the end of the month. How you may ask. While driving on the freeway this morning I noticed at least one recliner chair beside the roadway and in another area a box spring mattress also. Seems to be an unwritten law around here when someone is moving their own furniture to forgo and type of rope or other type of security devices for furniture or even an occasional box of belongs. Since most people relocate at about this time of the month, I was reminded, it's the first of the month tomorrow.    

[ksnow]

Button head screws and nylon lock nuts do NOT like to come apart after 30 years of Wisconsin weather (and road salt). Its a good thing I am working on this project because I want to , and not trying to make money.

[stitchdup]

47 minutes ago, ksnow said:

Button head screws and nylon lock nuts do NOT like to come apart after 30 years of Wisconsin weather (and road salt). Its a good thing I am working on this project because I want to , and not trying to make money.

burn the nylon with a lighter, it wont take much heat to melt the nylon then it wont catch on corrosion.

[ksnow]

15 minutes ago, stitchdup said:

burn the nylon with a lighter, it wont take much heat to melt the nylon then it wont catch on corrosion.

Yep, started with that, wire wheeled the exposed part of the screw, and still managed to strip the head out on the screw. Vice grips worked in one application. Can't get them on the 2nd spot, going to have to cutting wheel or sawzall that one.  Have to be careful with heat, lots of plastic parts close by.

[89AKurt]

16 hours ago, espo said:

Make some good-looking headers. 

Yea no kidding!  I've done that for a Honda model, been there done that. 😬

[Bugatti Fan]

What did I learn today?  

   Not to go shopping with my wife!    I can live with food and essentials shopping.

But !   Never sit it out when they go into a clothing store. Typical scenario. Will take two dresses for example and ask which I like best. When given a answer she will immediately ask what's wrong with the other one ! A lose, lose situation.

[SSNJim]

On 3/31/2025 at 6:22 PM, espo said:

While driving on the freeway this morning I noticed at least one recliner chair beside the roadway and in another area a box spring mattress also.

I was riding my scooter on a state highway headed to Santee, CA many years ago. The car a ways ahead of me had a mattress attached to his roof, until he didn't. It flew through the air tumbling end over end. It was a beautiful and graceful thing. Fortunately I was far enough behind that it wasn't a hazard and easily avoidable. What a sight.

[johnyrotten]

47 minutes ago, Bugatti Fan said:

What did I learn today?  

   Not to go shopping with my wife!    I can live with food and essentials shopping.

But !   Never sit it out when they go into a clothing store. Typical scenario. Will take two dresses for example and ask which I like best. When given a answer she will immediately ask what's wrong with the other one ! A lose, lose situation.

Anytime I'm asked that, I tell my wife know that I'm not the one wearing it. If i was, I'd have some questions to answer. She's used to my smart --- remarks, so its a quick laugh.