Thermo Housing Bolts: Old and New?

[Bingster]

Below is a photo of the original thermo housing bolts on my '47 Desoto and a new one.  The parts book says it's 2" and the new bolt is a 2", but the new one is a bit longer.  I can cut it down to match or is there a replacement that I don't know of?

[knuckleharley]

If it were me,I'd just cut it to the same length as the one that came out,and use it.

Put a nut on it all the way up to the head before you cut the bolt,and then cut it and grind a slight bevel on the end so it's easy to start,and unscrew the nut. That will almost always clean up the thread where you cut and ground it so the bolt will start like it should.

 

Edited June 26, 2017 by knuckleharley

[Bingster]

Thanks.

[Plymouthy Adams]

its not a blind hole, if nervous, set the housing on the head, use your depth gauge or mock up dowel rod and test your overall room you have before bottoming out on the head............what is the grade on that bolt...look like hardware store special grade 2, three at best....

[Bingster]

I got them at the auto parts store.  If YHC means anything. I can go to Fastenal and get a harder grade bolt.

[knuckleharley]

1 hour ago, Plymouthy Adams said:

its not a blind hole, if nervous, set the housing on the head, use your depth gauge or mock up dowel rod and test your overall room you have before bottoming out on the head............what is the grade on that bolt...look like hardware store special grade 2, three at best....

Grade 3 to 5 should be fine for a thermostat housing. It has no real pressure on it to speak of.

Providing it's not a Chinese bolt,that is. Grade 3 in China means Grade -3

BTW,for those who don't know,you check the grade of a bolt by looking for straight lines on the head of the bolt. All bolts start at Grade 2,so the heads on these are unmarked. I am assuming a Grade 3 will only have one mark but I have never seen one. Grade 5,which I have always called "hardware quality bolts" will have 3 marks on the heads. Grade 8 will have 5. Grade 8 are machinery bolts like head bolts. The threads fit much tighter,and they are made from harder steel.

It does you no good at all to use grade 8 bolts if the bolt goes all the way through to the other side and you use grade 5 or lesser nuts on it. Always try to match the nuts with the bolts.

Edited June 27, 2017 by knuckleharley

[Plymouthy Adams]

grade two or three are inferior bolts I would not use on anything other than maybe a mudflap....there is no real protection against corrosion as they normally have no Zinc or Cadmium plating..their poor metal also allows for almost immediate galling of the threads instead of accepting/displacing the torque applied..do as you wish..but in my book not worth it less than 5 grade...

[Bingster]

These are a grade 5.  I'll go to Fastenal. They were very good last year matching my old bolts to new ones. Thatnks for the education.

[knuckleharley]

23 minutes ago, Plymouthy Adams said:

grade two or three are inferior bolts I would not use on anything other than maybe a mudflap....there is no real protection against corrosion as they normally have no Zinc or Cadmium plating..their poor metal also allows for almost immediate galling of the threads instead of accepting/displacing the torque applied..do as you wish..but in my book not worth it less than 5 grade...

I have honestly never seen anything less than Grade 5 sold in any of the local hardware stores. I had never even heard of Grade 3 before your post.

[Young Ed]

9 minutes ago, knuckleharley said:

I have honestly never seen anything less than Grade 5 sold in any of the local hardware stores. I had never even heard of Grade 3 before your post.

my good local hardware store that has the best selection has grades 2 5 and 8. I rarely waste my time with 2.

[knuckleharley]

17 minutes ago, Young Ed said:

my good local hardware store that has the best selection has grades 2 5 and 8. I rarely waste my time with 2.

Same here.

[Andydodge]

Here in Oz, both UNF and UNC which is what the thermostat bolts are, are only available as high tensile bolts, grade 5 or 8....I've never seen UNF or UNC in a grade 2..........but because we have the damn Metric system and have also had to deal with the mongrel British Whitworth sizes very few general hardware store carry UNF/UNC bolts, these have to be obtained thru specialist engineering supply retailers.............in the US you guys seem to refer to the UNF/UNC threaded bolts by the SAE or AF sizing, does anyone refer to them by the thread design like I have?...........for me these are a UNF or UNC bolt which is the thread design as mentioned but when I am working on the car I refer to various bolts and spanners via the AF, (Across Flats) or SAE size, ie, the head size........lol....it gets confusing don't it.........lol .................andyd      

Edited June 27, 2017 by Andydodge

[Plymouthy Adams]

most drop the UN and call them fine or coarse thread 

[Bingster]

Found some grade 8 bolts at Menards and cut them down and tapered ends. Perfect fit.

[chrysler1941]

On 6/27/2017 at 2:49 AM, knuckleharley said:

 

BTW,for those who don't know,you check the grade of a bolt by looking for straight lines on the head of the bolt. All bolts start at Grade 2,so the heads on these are unmarked. I am assuming a Grade 3 will only have one mark but I have never seen one. Grade 5,which I have always called "hardware quality bolts" will have 3 marks on the heads. Grade 8 will have 5. Grade 8 are machinery bolts like head bolts. The threads fit much tighter,and they are made from harder steel.

 

Well all bolts in my 1941 are without these markings. Chrysler made their own hardware.

Don't know what year they started. Maybe someone can clarify when they where added?

As I'm into the original look, the few bolts I had to change, markings where removed on a lathe. The unpainted ones had them zinc plated.

Edited July 1, 2017 by chrysler1941