Clutch bellcrank to push rod attaching bolt

[David H.]

Re: Clutch bellcrank to push rod attaching bolt

John, I saw that diagram and looking at it again on CC web site it does look clearer that the bushing in that diagram is going in from the engine side.
We had a CC rep post on another thread about this that it goes from the wheel side tho. And I called Paragon and their tech support says they put them in from the wheel side.
Dan, I'll do some precise measurements tomorrow and we can compare things.
Jerry, All my parts are brand spankin' new NOS except the push rod. The push rod does not appear worn and does ride on the threaded portion of the bolt. It goes up against the larger bushing support journal of the shouldered bolt as you call it that sticks out beyond the bushing about 3/16". I was wondering if this is the problem? I will take a picture tomorrow and post it so you can see what I mean.

[David H.]

Re: Clutch bellcrank to push rod attaching bolt

OK, here is what I have for measurements.
See pictures.
I'm sorry to keep beating on this but I want it correct before I go on to other things. And it just doesnt seem correct with this much play. Again, is it suppose to be tight against the rubber bushing or is there suppose to be some space between it? and how much? Someone must know this. I cant be the only one that has questioned this assembly.
The thickness of the bellcrank where the bushing goes in is 1/4" which I suspect is correct as this is a NOS new assembly.

[Dan D.]

Re: Clutch bellcrank to push rod attaching bolt

Dave, my bushing is .690 wide. The bolt shoulder is .743, making clearance .053. Your measurements are close. At .730 shoulder and .680 bushing, that yields .050 clearance, which is all but exactly what I measured. So where you are getting .106 I don't know, except in your photo it looks like you have clearance between the threaded part of the bolt and the push-rod. That should be tight. The wife is at a luncheon with our camera so I cannot post any photos yet. -Dan-

[David H.]

Re: Clutch bellcrank to push rod attaching bolt

Dan, you are correct of course, that the difference in these measurements is .050, however when I tighten it up and tried to measure with a set of calipers it seems more like the .106. Probably not accurate tho, so disregard it. Even so the .050 seems sloppy to me. A thin washer under the head of the bolt head would take up some of it. I just wish I knew how much play there "should be" here if any. I think the tendency would be to try to tighten it up against the rubber part of the bushing but that can't be correct. Ken posted earlier that his play is 3/32" (.093) so that is even more than ours is. This really seems like a very weak link in this whole assembly to me. I would like it to be right the first time out so I don't end up pushing her home!

[Dan D.]

Re: Clutch bellcrank to push rod attaching bolt

Hi Dave, I think you are golden. There should be some end play, the question is how much. I think .05 to .06 is fine, and that is what we both have. You need some clearance to compensate for temperature and humidity.
I installed my bushing from the engine side. No reason for this except it is easier to get apart if you have to. If installed from the wheel side you have to remove the push rod to get the bushing out. How St.Louis installed it is apparently anyone's guess. I suppose it could have been random, depending on how much hangover the operator was suffering from on that particular day.
As far as wear goes, this is a weak design for sure, as is evidenced by the almost yearly changes made during C1 production. Make sure you have seals at both ends of the z-bar and pack it well with grease. The General added a grease fitting to the z-bar in 1963 but that doesn't do us any good.
It bothers me that your friends bushing failed in only 100 miles. I will be watching this for sure, but something had to be wrong. No way it should be gone in 100 miles.
I would not worry about it stranding you though. Wear will be gradual, giving you time to notice it. Even if the rubber goes away completely it should still function and not leave you sitting. And it can be fixed easily if required.
I take it you got the mighty spring on okay. I made a simple tool and it worked like a champ. Took 1/2 hour to make it. -Dan-

[David H.]

Re: Clutch bellcrank to push rod attaching bolt

Just came across this link on another web site and thought it interesting.

http://www.ecklers.com/catalogsearch/result/?search_year=1961&q=clutch+rod+bushing&x=0&y=0

Urethane version of the original bell crank bushing for the clutch rod.

fyi

also found this thread on another site, very interesting...be sure to read all 4 pages.

http://forums.corvetteforum.com/c1-and-c2-corvettes/2651683-1961-clutch-push-rod-bushing.html

[Dan D.]

Re: Clutch bellcrank to push rod attaching bolt

Hmmmm Dave, the plot thickens. A lot of discussion on the CF thread - not all of it correct, but they were trying and I think I may understand it better now myself. One thing I did not notice is the second shoulder on the bolt. That centers the push rod on the bolt. You might want to make sure yours is not hung up on the shoulder. That might explain the extra clearance you are seeing.
It also appeared to me that some of the CF responders did not understand that the bolt has to be tight against the push rod. Some of them seemed to think that it should be free to rotate. Not so. If that connection is tight the bolt will always be perpendicular to the bushing and the z-bar. That insures that the bushing will not be side loaded. In the pics that show bushing failure, the rubber appears to be torn. That tells me there is side-loading that is cutting the rubber. The first rule of troubleshooting anything is to visually study the evidence. A failed part can usually tell you why it is sick, if one just takes the time to look at it in detail and study it.
If the durometer is too soft service life will be decreased if the loading exceeds the yield strength of the rubber. That may or may not be the case here. I certinally can believe that aftermarket has the wrong rubber compound, as they have plenty of other things wrong with their parts in general.
You also have to believe that the design works, if implemented correctly. It certainly has survived the test of time in thousands and thousands of Corvettes and pass cars. It is not a matter that the design is poor, or the design is good. Rather it is the design is sufficient. It certainly had to be fully life tested before GM released it for production, and while changes were made over the years, the design basically lasted over a couple of decades. If some of us are seeing problems now, that is 50 some years later and things do wear out, especially rubber products.
Dave, your NOS bushing will have the correct rubber compound, but you may have another problem with it. 50 year old rubber will be dried out and harder that when it was new. It may or may not last either. I don't know if the Urethane version is stronger or not, but it would be worth a try if replacement becomes necessary. It looks just like the original type in the pic and so it should pass judging. One thing I learned on the CF thread is those folks don't seem to care anything about correctness, they will do whatever it takes to make it work.
Too many words - time to go. -Dan-

[David H.]

Re: Clutch bellcrank to push rod attaching bolt

Thanks Dan, good post.
I decided to use what I have and see how it works. NOS bushing and bolt. Looks like it is bolted up correctly and will work. My concern was the gap between bolt head and bushing. About .050, which seems a bit much but now that I better understand the mechanics of the assembly it may be fine. I think the ones that destroy the rubber end of the bushing dont have enough of a gap and are rubbing the bushing till they are destroyed.
Thanks for your input. It really helps to "talk it over" on things like this.

[Dan D.]

Re: Clutch bellcrank to push rod attaching bolt

I agree Dave, go with it and see how it does. That is what I am going to do with my repop set-up and bushing. Just watch it for a time.

Make sure you grease the inter bushing surface and bolt shoulder. This is what rotates when the pedal is pushed. -Dan-

[David H.]

Re: Clutch bellcrank to push rod attaching bolt

Dan, this is what I ended up with. The bushing seemed to fit better going in from the wheel side as Paragon suggested.
Thanks again for your input.
What is this gorilla spring installation tool that you made?

[Jim D.]

Re: Clutch bellcrank to push rod attaching bolt

What is this gorilla spring installation tool that you made?

No need for any special tool. The ST-12 outlines how to do it. Takes only a few seconds to install it.

[Dan D.]

Re: Clutch bellcrank to push rod attaching bolt

The procedure in ST-12 should work. I did not realize it was in there. It might be difficult for one person to do.
Keep in mind the body has to be on the frame to do this as the clutch pedal and push rod is the end stop for the spring. Dave, not sure you have your body back on yet. Anyhow, I attached some photos on how I did it. -Dan-

[Larry B.]

Re: Clutch bellcrank to push rod attaching bolt

Dave, The reason your friends bushing is torn up already is because of the soft, poor quality of the rubber. My self and others have also torn up the new repops. Get the urethane bushing and you will not have any future problems.

[David H.]

Re: Clutch bellcrank to push rod attaching bolt

I have seen in posts that grease may be detrimental to the rubber in the bushing. Should I avoid greasing the bolt because of this?