Rag joint question for Jim shea
Thread Starter
Heel & Toe
Joined: Sep 2010
Posts: 19
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From: B.C
Rag joint question for Jim shea
I ordered a rag joint for my early 69. After reading just about all the threads on rag joints and all of Jim Shea's notes I still have a question.the new rag joint came from cc and looks identical to what I had except for reg bolts instead of shoulder bolts. So I used my old 3/8 shoulder bolts and put it together , problem is that to achieve a metal to metal contact with 20 ft lbs of torque it compresses and disfigures the rag horribly.The new rag is a Half inch thick and the shoulder on the bolt is 3/8. By the time the bracket on the shoulder is added the rag needs to compress almost 1/4 Any pictures I have seen of rags are not compressed that much.Should I not be tightening the bolts to have metal to metal contact?
Last edited by fozz; May 4, 2013 at 04:51 PM. Reason: Addition of question
Le Mans Master
Joined: Jul 2000
Posts: 6,001
Likes: 113
From: Saginaw Michigan
The original coupling disc was 0.35 inch thick. Too bad that foreigners can't even copy the thickness correctly.
The only thing I can suggest (if you cannot find an original GM NOS or used flex coupling assembly) is that you have some bushings machined that are basically about 0.030 shorter than the thickness of your roughly 1/2 inch replacement coupling disc. That is about the squeeze that we designed into original shoulder length of our special bolts.
Then you would use regular bolts and not shoulder bolts to compress the disc and then affect a metal to metal connection bolt to bushing.
Jim
The only thing I can suggest (if you cannot find an original GM NOS or used flex coupling assembly) is that you have some bushings machined that are basically about 0.030 shorter than the thickness of your roughly 1/2 inch replacement coupling disc. That is about the squeeze that we designed into original shoulder length of our special bolts.
Then you would use regular bolts and not shoulder bolts to compress the disc and then affect a metal to metal connection bolt to bushing.
Jim
Thread Starter
Heel & Toe
Joined: Sep 2010
Posts: 19
Likes: 0
From: B.C
Thank you Jim for your speedy response, you knowledge is very much appreciated , how would I have known without your responses on this forum. I will check with some machinists to see if they can make some bushings for me.
Le Mans Master
Joined: Jul 2000
Posts: 6,001
Likes: 113
From: Saginaw Michigan
Maybe in heaven people can copy better.
The engineering reasoning on using shoulder bolts or tightening metal to metal on a steel bushing:
You NEVER just make a bolted connection by just squeezing rubber. No matter how much you try to tighten your original nut and bolt, the rubber will relax with time and you will have a loose connection. The loosening will occur regardless if you double nut, use locktite, or use torque prevailing cinch nuts. The entire connection will be loose and you are steering your vehicle through this coupling assembly.
It really scares me as to the quality of these rebuild kits or the actual "copied" coupling assembly.
I tried in the past to write letters to several of the automotive outlets that were selling kits with common attaching bolts. A few said that they would contact their distributor/supplier on my concerns. As near as I could figure out; nobody has actually changed to shoulder fasteners. My letters went for nought.
A few Corvette owners have mentioned in the past that they used the shoulder bolts from their original flex coupling assembly. But up until this thread, nobody indicated that the coupling disc was way, way too thick so that the original shoulder bolts just would not work.
I sure hope that heaven is better.
Jim
The engineering reasoning on using shoulder bolts or tightening metal to metal on a steel bushing:
You NEVER just make a bolted connection by just squeezing rubber. No matter how much you try to tighten your original nut and bolt, the rubber will relax with time and you will have a loose connection. The loosening will occur regardless if you double nut, use locktite, or use torque prevailing cinch nuts. The entire connection will be loose and you are steering your vehicle through this coupling assembly.
It really scares me as to the quality of these rebuild kits or the actual "copied" coupling assembly.
I tried in the past to write letters to several of the automotive outlets that were selling kits with common attaching bolts. A few said that they would contact their distributor/supplier on my concerns. As near as I could figure out; nobody has actually changed to shoulder fasteners. My letters went for nought.
A few Corvette owners have mentioned in the past that they used the shoulder bolts from their original flex coupling assembly. But up until this thread, nobody indicated that the coupling disc was way, way too thick so that the original shoulder bolts just would not work.
I sure hope that heaven is better.
Jim
