MOXIE62

Have some arthritis in my left ankle so hoping this setup will make the clutch little easier to operate. I know they have the kits already made up but do not like the looks of them. The 1/2" shaft was purchased from Lowes and had the local trade school thread it. Next will be the shaft that goes from the swivel arm to the engine. That one I plan on purchasing a reproduction one and cutting off the swivel end and threaded it to accept the ball cap.

SS409

I tried one with the same spherical rod ends on my Impala and the difference was negligible.

TCracingCA

The clutch itself is what has to be changed.

vetrod62

The Rod ends will do nothing for relief for peddle pressure, but will make the life time of the joints last forever and be reliable, unlike the replacement joints that will fail very soon that could leave you stranded. I race my 62 and twice my day ended early because of them.

The next shaft you want to convert will do nothing. If you really need to reduce clutch peddle pressure and you car does not make a lot of power, try a really weak Diaphragm Clutch. Or if your car makes a little power, and I do not recommend this for most cars, put in a Ram #470 360 to 990 lbs. (yes, not 3600 or 2600 lb clutch, no misprint) and disc. It is racing clutch and disc. No marcel or hub springs. A bit sensitive on engagement for the street, but real easy to push. I have used its bigger brother 800 to 1680 lb clutch in my 600hp wheel standing car for 5 years. A bit grabby of the line, but works. Special problems, require special remedies. Jim

fogaley

Try this for your clutch linkage, it really works. Scott
https://www.corvetteforum.com/forums...some-pics.html

Qblue92

I have a different clutch return spring than the Gorilla spring. Mine is super easy to use.

Frankie the Fink

As you mentioned that piece is available along with the rod at the clutch fork from Speed Direct. (My '67 Chevelle kit is pictured)

I put that setup on the Chevelle and it did solve a slight geometry problem with the angles of the clutch linkage. It was an automatic converted to a 4 speed and so things were off a bit.
I can't say the clutch required less pressure to operate afterwards but some bothersome grinding was eliminated

jerry gollnick

What are you using?

hedgehead

although the gorilla spring is supposed to work as an over center spring and ease pressure, a milder spring eases initial pressure and the over center feel is fine. Plus your bushing will last longer.

Frankie the Fink

It is not "supposed to work" as an over center spring it IS an over center spring. Its purpose is to make the force over distance ratio of the pedal travel more consistent throughout and it works fine when installed and adjusted properly.

The adjustment for that spring is 6lb-9lbs of force - about the same amount as the trigger on a daily carry handgun. Thinking its ruining your knee cartilage because its in the car is a myth...

MOXIE62

I thought it's purpose was to bring the clutch pedal back to the staring point and take drag off the throw out bearing.. The spring to me just adds more force to overcome when pushing in on the clutch. That's why I was looking for a lighter spring.

Frankie the Fink

Its called an over-center spring in the ST-12 manual as its action is to reduce the force needed when the clutch Z-bar is at the apex of its swing and ensure it doesn't get "stuck" there. It's not simply a clutch return spring....

A good example of an over-center device is a wall light switch...it is designed to either snap "on" or "off" once pushed "over center" in one direction or another...

The over center spring provides "bistability" (yeah look that up). Folks first reaction when seeing the spring is to get fizzed up over its size (appearances are deceiving) or eliminate it because its adjusted wrong and giving them problems, or, they have worn clutch linkage (ball studs, Z-bar bushing) and blame it on the spring.

A typical (C2-style) clutch return spring has its max potential energy when the pedal is fully depressed and can only release it (making kinetic energy) as the pedal returns, and only in one direction. An "over center" spring has its max potential energy in mid-arc and can turn that into kinetic energy in EITHER direction - to help return the clutch pedal (engage the clutch) or to disengage the clutch.

Hence you only go through 1/2 the pedal arc to get the benefit of an over-center spring instead of going through a full arc to extend a return spring. That's why I tell people the gorilla spring smooths out the "force over distance" ratio.

People who remove the gorilla spring are clueless. If they really want to dwell on a problem in the C1 clutch geometry they should concentrate on the "single shear" bad design where the Z-bar top bushing resides..and engages the pedal pushrod.

stratplus

OK, call me stupid. I had to look up the word. Ya, well lets not get pugnacious about it

In mechanical systems:

https://upload.wikimedia.org/wikiped...et_example.gif

Bistability as applied in the design of mechanical systems is more commonly said to be "over centre"—that is, work is done on the system to move it just past the peak, at which point the mechanism goes "over centre" to its secondary stable position. The result is a toggle-type action- work applied to the system below a threshold sufficient to send it 'over center' results in no change to the mechanism's state.

As an example of a common over-centre device, a ratchet goes over centre as it is turned in the forward direction. In this case, "over centre" refers to the ratchet being stable and "locked" in a given position until clicked forward again; it has nothing to do with the ratchet being unable to turn in the reverse direction.

A ratchet in action. Each tooth in the ratchet together with the regions to either side of it constitutes a simple bistable mechanism.
Springs are a common method of achieving an "over centre" action. A spring attached to a simple two position ratchet-type mechanism can create a button or plunger that is clicked or toggled between two mechanical states. Many ballpoint and rollerball retractable pens employ this type of bistable mechanism.

Frankie the Fink

You should work at being less bumptious

MOXIE62

Thanks for your replies but as I see It the bottom line is it adds more force to over come in pushing the clutch down so I plan on finding a spring that will have enough strength to just bring the clutch pedal back to stop position.

hedgehead

Being clueless works for me.

Frankie the Fink

I wish people that had this attitude could drive my '61. The clutch action is as smooth and easy as my '63 clutch. Anyway, I've given my geometry lesson so folks can do as they see fit...

TCracingCA

I used to be a marathon runner for years and years, so i could depress any level of clutch, but then i nearly lost my leg in a motorcycle accident and essentially have an artificial type leg rod and knee/ankle attachments with the bones plated to support the ligaments and muscle, so the Doctors put it all inside my leg, but if you were to strip off the skin, it would be a big rod as the structure. therefore i get pain trying to drive my cars, but i have grinned and beared it. doing stair stepping etc. helps, but sometimes i stress the joint connections and get pain or soreness! A weaker clutch won't hold my HP levels so this thread has got me thinking. But then GM design was for the thought of a wide customer base and for mass production. so I could see how some engineering could help improve what we have. So thank you everyone for this thread. I took out our family 930 Turbo as the first car I tried, when I finally thought i could think about driving a clutch again. It was not pretty and hurt me, so i couldn't for years even get into the family Corvettes vice the lighter Porsche unit we have, but i eventually did. but they cause me discomfort, and i have to shift to neutral sitting at lights, and sometimes i just get nerve pain pushing on one and forget about any longer drives especially anything longer distances. So cool thread talk for me to follow! thanks

alexandervdr

probably the Nr1 parameter to look at is clamp load of the clutch , which is the pressure exercised by the pressure plate fingers through the clutch to the flywheel. From there on to the pedal it's a mater of how that force is 'de-leveraged' by changing the distance travelled (for the pressure plate, I read about .03") into several inches on the pedal (around 6"). The type of linkage in between is not much more than a rounding error to that (assuming it's mounted correctly), explaining why changing to ball link ends does not change a lot.
When I studied the problem (I wanted minimal force too, giving that I am the cruiser type of driver), I thought that looking for a clutch with the smallest clamp load while still able to deliver torque/power spec of my engine (say 300HP) would do it. Unfortunately, I discovered that very few clutch vendors publish clamp load, and when I asked they could not (or did not want to) answer. So the theory is fine, but in a real world does not help.
Many threads have been covering the topic, and there is a general consensus that the oem spec Lukes are 'light'. Whatever 'light' means.
Unfortunately highest gain is to be found where it is most work to get at. Changing a clutch is not something most would prefer spending their time on

Frankie the Fink

Precisely, absolutely correct - which is why most people screw around with the original linkage/springs as a first step instead of zeroing on the area that will give them the most 'bang for the buck' as far as the effort of operating the clutch.

"Never time to do it right; always time to do it over" as my old boss used to say...