C1 exhaust insulator screws - which is it?

[Keith R.]

For years, the 4th edition TIM & JG said "Each insulator is attached to the bumper with two flat head slotted cadmium plated screws from the bottom. Replacement screws are often phillips head stainless steel." Now, the new 5th edition reads, " Each insulator is attached to the bumper with two Phillips flat head cadmium plated magnetic screws. Replacement screws are often slotted head stainless steel." So, which is it? slotted or Phillips?

[David B.]

Re: C1 exhaust insulator screws - which is it?

If the part # is 156253 it is 1/4-20 x 3/4 cad or zinc flat head cross recess machine screw (sae 1010 - 1020 steel)

[Keith R.]

Re: C1 exhaust insulator screws - which is it?

Thanks David. According to the AIM, it is indeed part # 156253 however a cross recess machine screw is not a Phillips head as it is described in the TIM & JG. It does have a photo of what could be an original car with Phillips head screws. I think I'll just go with Phillips head.CrossEdit


A cross or double-slot screw drive has two slots, oriented perpendicular to each other, in the fastener head; a slotted screwdriver is still used to drive just one of the slots. This type is usually found in cheaply-made roofing bolts and the like, where a thread of 5 mm (0.20 in) or above has a large flattened pan head. The advantage is that they provide some measure of redundancy: should one slot be deformed in service, the second may still be used and the tool can not slip out.

If the part # is 156253 it is 1/4-20 x 3/4 cad or zinc flat head cross recess machine screw (sae 1010 - 1020 steel)

[Bill M.]

Re: C1 exhaust insulator screws - which is it?

Keith:

I definitely have the originals for my '59. They are Phillips.

Bill

[Keith R.]

Re: C1 exhaust insulator screws - which is it?

Thank you for responding Bill. That confirms things then.

Keith:

I definitely have the originals for my '59. They are Phillips.

Bill

[Loren L.]

Re: C1 exhaust insulator screws - which is it?

Does anyone else find it sad that the 58-60 Judging Team does NOT respond to these questions? Back in the '70s & '80s when I was part of THREE of these teams, DISCUSSION was the Byword, not to mention "what was the source?".

[David B.]

Re: C1 exhaust insulator screws - which is it?

Thanks David. According to the AIM, it is indeed part # 156253 however a cross recess machine screw is not a Phillips head as it is described in the TIM & JG. It does have a photo of what could be an original car with Phillips head screws. I think I'll just go with Phillips head.CrossEdit


A cross or double-slot screw drive has two slots, oriented perpendicular to each other, in the fastener head; a slotted screwdriver is still used to drive just one of the slots. This type is usually found in cheaply-made roofing bolts and the like, where a thread of 5 mm (0.20 in) or above has a large flattened pan head. The advantage is that they provide some measure of redundancy: should one slot be deformed in service, the second may still be used and the tool can not slip out.

Keith,
Your description is not even close to GM Engineering Standard specifications re: Flat head cross recess machine screw.
TRUST THE AIM! If I was computer smart I would post the print description. It's a small item so I guess it's easier to follow the crowd.

[Keith R.]

Re: C1 exhaust insulator screws - which is it?

Thanks David but I was just responding your initial thread response where you said that part #156253 (depicted in the AIM) was a cross recess machine screw which is basically a double slotted screw used with a flat blade screwdriver. Rather than trust the AIM (which was not how the cars were assembled in many cases), I'd rather trust Bowtie or original cars like Bill's which actually show what was used - a flat head Phillips head zinc or cadmium screw in the insulator.

Keith,
Your description is not even close to GM Engineering Standard specifications re: Flat head cross recess machine screw.
TRUST THE AIM! If I was computer smart I would post the print description. It's a small item so I guess it's easier to follow the crowd.

[Keith R.]

Re: C1 exhaust insulator screws - which is it?

I hear you Loren. It would be nice if the Judging Team would be more responsive to these kinds of questions particularly when a new TIM & JG has been issued so as to work out the bugs and mistakes. There is a section on the forum where errata sheets are posted but it doesn't appear that anyone is maintaining it or posting corrections to the Judging Guides. In fairness to John Tidwell however, who helped author the 5th Edition, he did response to another mistake in this latest edition regarding the position of the seat separator lock when locked and unlocked. It is wrong in the 5th edition which caused me a lot of time, effort and minor paint damage in pulling the compartment lock and molding apart once again to determine why my lock wasn't functioning as it was described in the 5th edition. If this were posted to the Errata page, it would probably save others a lot of time and trouble with regard to their cars.

Does anyone else find it sad that the 58-60 Judging Team does NOT respond to these questions? Back in the '70s & '80s when I was part of THREE of these teams, DISCUSSION was the Byword, not to mention "what was the source?".

[Joe M.]

Re: C1 exhaust insulator screws - which is it?

I have judged at least six '59 and '60 Bowtie cars and all had Philips head screws. My 1960 also has Philips head screws.

[Keith R.]

Re: C1 exhaust insulator screws - which is it?

Thanks very much for confirming that Joe. Looks like they got it right in the 5th edition TIM & JG. Now, I have to pull off the rear bumpers AGAIN to replace the slotted screws with Phillips head - bummer...

[David B.]

Re: C1 exhaust insulator screws - which is it?

I have judged at least six '59 and '60 Bowtie cars and all had Philips head screws. My 1960 also has Philips head screws.

Just to clarify what appears to be some misunderstanding #156253 described by GM as a flat head cross recess machine screw by appearance looks like what we commonly refer to as phillips head.
J

[Keith R.]

Re: C1 exhaust insulator screws - which is it?

Yes, that seems to be the consensus David. Thanks for the clarification.

Just to clarify what appears to be some misunderstanding #156253 described by GM as a flat head cross recess machine screw by appearance looks like what we commonly refer to as phillips head.
J