Rag joint bolt on 68

[Rich G.]

I noticed the bolt is missing that holds the clamp that clamps down on the spline shaft of the steering column. I don't have an AIM, so the question is first, would it be the same as a 67 (no tele) and if not where should I look? If it is the same as 67 I have a source, I think. I have no idea how long it has been gone. I was trouble shooting a horn issue and when checking the ground at the rag joint I saw it.

Rich

[Jim S.]

Re: Rag joint bolt on 68

The 12 point 7/16 pinch bolt that secured the steering column detachable flange to the steering column shaft was 5686553. This bolt was released for production sometime around 1957. This bolt was used until the 1969 model year. The same bolt was also used to attach the bow tie flange on the flexible coupling to the steering gear input shaft. In July 1968 pinch bolt 7817271 was released for production. It was the exact same bolt as 5686553 except that a nylon patch was added to the threads. This was to insure that an assembly person could not just screw the bolt finger tight into the flange. With the patch, a wrench was required to tighten the bolt after the first one or two threads. Both bolts had a phos and oil finish.

There are no head markings called out on either the original 5686553 drawing or the 7817271 drawing. When the bolt is installed there is no indication as to the nylon patch. So the bolts would appear the same.

Please do not drive your car without a pinch bolt in place. Its a testiment as to how tight the bolt pinches the flange around the mating shaft such that it is a very secure connection. The bolt also sits in a slot in the mating shaft such that the flange cannot be pulled off with the bolt in place.

Jim

[Rich G.]

Re: Rag joint bolt on 68

Jim

Thank you very much. The car will not move until the bolt is replaced.

Rich

[Jim S.]

Re: Rag joint bolt on 68

7807271 is no longer listed on the GM Parts Direct website so I assume it is no longer a service part through GM dealers. However, there should still be a large stock of them at various Corvette suppliers. Also, millions in salvage yards.
Jim

[Scott S.]

Re: Rag joint bolt on 68

Jim,

The presumed original 12-point pinch bolts (first two pictures) that were removed from my '67 (manual steering, non-tele) have "NL" headmarks, with no grade lines. I found a pair of what were described as NOS 12-point pinch bolts (last two pictures), and they have what looks like the patch of nylon near the end of the threads that you describe. The headmark is a small circle bisected by a line in the center, with three grade lines (Grade 5).

Do any of your blueprint drawings indicate the grade or strength of steel for these bolts?

My originals appear to be in good enough shape to replate (were originals black phosphate?) and reuse. Is there any reason not to, or is it always a better idea to use new bolts for the steering coupler?

[Rich G.]

Re: Rag joint bolt on 68

Jim

Yeah, I tried there too. Long Island has the ones without the nylon patch which I assume will work ok. My buddy says he may have one, but probably a mid year. I've been searching the internet in my spare time tonight.

Rich

[Jim S.]

Re: Rag joint bolt on 68

I don't think that you would need to replace the bolts after a couple uses. The material is GM 280M except hardness to be Rockwell C-27/34.
I am not a metalurgist so I can't equate GM 280M material and the special hardness spec to grade 5 or grade 8. The coating is black phosphate and oil finish. The small circle bisected by a slash mark was Fenton Heading as the bolt supplier. The plastic patch was yellow.

The same bolts without the plastic patch were used for over 10 years without problems. So I am quite sure that the plastic patch just prevented people from running the bolt into the flange and leaving it only finger tight. If the head wasn't all the way down, then an inspector could tell that the bolt wasn't tight. With the patch, a tool had to be used to run the bolt all the way down so that the head was flush with the flange. At that point you had to assume that it was also tightened to spec.

Jim

[Scott S.]

Re: Rag joint bolt on 68

I don't think that you would need to replace the bolts after a couple uses. The material is GM 280M except hardness to be Rockwell C-27/34.
I am not a metalurgist so I can't equate GM 280M material and the special hardness spec to grade 5 or grade 8. The coating is black phosphate and oil finish. The small circle bisected by a slash mark was Fenton Heading as the bolt supplier. The plastic patch was yellow.

The same bolts without the plastic patch were used for over 10 years without problems. So I am quite sure that the plastic patch just prevented people from running the bolt into the flange and leaving it only finger tight. If the head wasn't all the way down, then an inspector could tell that the bolt wasn't tight. With the patch, a tool had to be used to run the bolt all the way down so that the head was flush with the flange. At that point you had to assume that it was also tightened to spec.

Jim

Jim,

Thanks for the reply. 280M steel is Grade 5 (three grade lines) according to the standard parts section of the old GM parts books. I think the examples with the "NL" headmark are original, seems odd that they don't have any grade markings.


Rich,

I will send you an email via the Forum with contact info where you can get the NOS 12-point pinch bolts,

Scott

[Jim S.]

Re: Rag joint bolt on 68

This didn't copy very well. But Willcox Corvette Inc shows two different part number pinch bolts. This one is listed for 1963-67 and actually has a somewhat different picture than the 1968-82 pinch bolt.

42439

1963-1967

Steering Column Coupler Flange Screw. 63-67

$3.20

[Scott S.]

Re: Rag joint bolt on 68

This didn't copy very well. But Willcox Corvette Inc shows two different part number pinch bolts. This one is listed for 1963-67 and actually has a somewhat different picture than the 1968-82 pinch bolt.

42439

1963-1967

Steering Column Coupler Flange Screw. 63-67

$3.20

Jim and Rich,

The bolt Willcox shows for 63-67 (Willcox # 42439) is threaded the entire shaft. The bolt they show for 63-82 (implying C3 and backwards compatible with C2) looks the same as my NOS examples:

Steering Column Coupler Star Bolt. 63-82 $6.11

Part Number: 33330 Part Year: 1963-1982

[John C.]

Re: Rag joint bolt on 68

Jim

Yeah, I tried there too. Long Island has the ones without the nylon patch which I assume will work ok. My buddy says he may have one, but probably a mid year. I've been searching the internet in my spare time tonight.

Rich

Rich

If originality is what you are looking for you actually want the mid year version. The nylon patch wasn't used until the 69 model year.

John

[Jim S.]

Re: Rag joint bolt on 68

Scott, you are correct. That is not the correct bolt. I did not notice that the pictured bolt was threaded all the way to the head. With fine pitch splines on the input shaft on the gear, it was possible for the threads on a fully threaded bolt to match up with the gear shaft splines which could allow the flange to be pulled off. That is why the long smooth (0.372 dia) shank where the bolt passes through the input shaft notch on the special 7807271 and 5686553 bolts.

I took over responsibility at Saginaw Steering Gear Division, GMC for the flexible steering shaft coupling assemblies and the 7807271 pinch bolt just about the time that the patch was introduced back in the late 60s. Sure seems like a long time ago. Sure was a lot of engineering design that went into some relatively simple parts. I never did find out why the 12 point head on the bolt. Of course I was in 9th grade when it was released in 1957!

Jim

[Joe L.]

Re: Rag joint bolt on 68

All-----


These bolts are available in reproduction from AMK Products under their # B-12734.

[Gary B.]

Re: Rag joint bolt on 68

All-----


These bolts are available in reproduction from AMK Products under their # B-12734.

In the photo on the AMK website, the bolt does not look to me like it's black phosphate. When you add the bolt to the shopping cart, the description is:

"(II) 3/8-24 X 1 3/16 FLNG BOLT 12PT, PHOS/PATCH. 1 pk"

Could the "PHOS" in this description be other than black phosphate?

Gary

[Rich P.]

Re: Rag joint bolt on 68

The AMK bolt has a late 70's/service replacement headmarking.

Rich