67 Steering Coupler/Rag Joint Bolts

[Donald H.]

I'm restoring a couple of 67 rag joints with the kits from ZIP (which are from LIC inventory that ZIP purchased). I have the original bolts from an original 67 rag joint. The 5/16-24 bolt definitely had copper plating still on the threads when I took it apart, and the 5/16 bolt in the ZIP Kit is copper plated. I have also attached a link to a thread where Jim Shea discusses the copper plating and the reason for it. From what I have researched, Jim is the expert on C2 steering columns and components. So, I would tend to take what he said as accurate, and they were copper plated.

However, the 7th Addition 67 TIM&JG, page 167, states 'Both bolts are steel, not copper plated,'.

I actually found a process to do decent copper plating, but I'm not sure what I should do now. If they were copper plated and there is history from a regarded source like Jim Shea, how could the TIM&JG not agree?


67 rag joint standard column (ncrs.org)

Thanks,

Don

[Richard M.]

Re: 67 Steering Coupler/Rag Joint Bolts

Don, I always wondered about the copper bolts too. Here is a original 1967 coupler with the copper plated 5/16 thread bolt.

PC250025.jpgPC250031.jpg

What Jim said makes perfect sense now....

Originally Posted by Jim Shea (36737)
Here is a bit of trivia. Why was the 5/16-24 bolt copper plated?
Answer: The Vette assembly plant had a common nut driver for the two nuts that connected the flex coupling assembly to the steering column flange. Both 5/16-24 and the 3/8-24 zinc plated nuts had a common size 11/16 hex. Therefore a common driver was possible. But now you say, "Wait a minute, you have two different size threads, you cannot torque them to the same spec with a common driver." That is where the copper plate on the 5/16 thread comes into play. The plating on the threads change the torque-tension relationship between the zinc plated nut and the 5/16 thread. Therefore a common torque spec of 18 to 20 ft-lbs was possible.

Jim

[Gary B.]

[Donald H.]

Re: 67 Steering Coupler/Rag Joint Bolts

Something else interesting, if true. The 63-66 has two different sized 'pins', both however are as Gary noted 5/16-24 threads. The 67 has two same sized 'pins'; however, these are rivets and not bolts.

I've wondered the purpose of these pins (red arrow in the attached picture). I recently read that they are there so that if the donut starts to fail and pull apart the pins will help keep the joint somewhat functional. I have no idea whether this is true or not.

Don

[Stephen L.]

Re: 67 Steering Coupler/Rag Joint Bolts

Also in '67 there was an "insulator" on each stud, #7800470. Purpose???????

[Donald H.]

Re: 67 Steering Coupler/Rag Joint Bolts

The copper coating is clearly visible in Rich's post #2. When I took apart what I believe was the original on my 67 it looked much the same as Rich's example. No plating left on the head of the bolt or tip of the threaded end, i.e., the areas open to the environment. So, I'm assuming the comment that there should not be any copper plating per the TIM&JG is based on what has been observed, which would be areas of the 5/16 bolt installed and not as appears removed from an original.

I have three 67 rag joints I am restoring, but I'm making a few changes to the kit. the two bolts (5/16 and 3/8) in the kit are course thread bolts and do not have the shoulder as the original that are shown in Rich's post #2.

Also, the kit includes a 1/2" wrench sized nut on the 5/16" bolt (size for standard SAE bolt) and 9/16" wrench on the 3/8" bolt. On originals, both bolts used a nut that took a 9/16" wrench. I have purchased correct sized nuts that both use a 9/16" on the bolt heads.

I also purchased tubular spacers in 5/16" ID x 7/16" OD and 3/8" ID x 7/16 OD and cut them to length to make the 'shoulders' on the bolts. It seems to be the purpose of the shoulders is to prevent over tightening and crushing the rubber donut.


Don