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Discussion Starter #1 (Edited)
Experiment: Lighter clutch pedal spring for more linear & improved pedal "feel"

I'll try to keep this long story somewhat short:

Many of us are less than thrilled with the clutch pedal feel in the M6 cars. I live with it, and have gotten somewhat used to it, but I think there is room for improvement. The main issue, I believe, is the the pedal force is not consistent (linear) throughout it's entire travel path. This is due to the clutch pedal spring "assisting" during the lower 1/2 or 1/3 of the pedal travel toward the floor. When engaging the clutch (releasing from the floor) the force of the pedal changes right about at the point of clutch engagement. That is the point at which the pedal spring stops "assisting". Many of us here on the forum have speculated that if we could get a much lighter spring, it would improve the overall linearity of the pedal because it would be assisting that last 1/2 or 1/3 of the pedal much less. It would still have enough force to return the pedal all the way to the top, and it would take some more force to hold the pedal all the way to the floor.

Anyway, I found a spring manufacturer that is willing to make a small batch of springs, by duplicating the original clutch pedal spring at a much lighter spring rate (I'm thinking 30% of the original spring rate). If I have them make 10 of these springs, the cost to you would be $45 shipped to you (within the US). If I have them make 20 springs, the cost to you would be $30 shipped.

I have had a few forum members suggest having the company just make 1 prototype spring, so that I can try it out and determine if the spring rate is good. Unfortunately, I have asked, and the cost of just 1 spring would be $200. It makes sense, because I am sure most of the time is spent measuring the original spring, and machine setup. Once everything is setup, I'm guessing they can pump out a batch of spring relatively quickly.

With that said, I am looking for 10 people to sign up to be guinea pigs and test out a spring at 30% of the original spring rate. Cost of $45 shipped. I understand that you are taking a risk, just like me, and that it may not prove to be any better than stock. But, I think it is worth a try to improve overall drive-ability.

Please send me a PM if you are interested in purchasing a spring.

So far I have:

redwolf719 (myself)
Rick H.
grinchem
MichaelSS15
HanoverJoe

boiler (maybe)
good2go (maybe)
91RS (maybe)


Also, I started this information on page 9 of the thread below, but have since migrated it to this new thread. There is additional information on some things others have tried in the previous thread if you want to read thru.

https://www.ssforums.com/forum/how-forum/133522-how-remove-clutch-over-center-spring-9.html
 

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I removed the spring on mine entirely last week and it is much, much better, it's linear but definitely stiffer. The pedal is a little loose when let all the way out, which might bother some people as well; having a small spring would definitely help with that.

I like how mine feels now, but for anyone that isn't sure about going that extreme, I think this lighter spring would be a great option.
 

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Discussion Starter #3
I removed the spring on mine entirely last week and it is much, much better, it's linear but definitely stiffer. The pedal is a little loose when let all the way out, which might bother some people as well; having a small spring would definitely help with that.

I like how mine feels now, but for anyone that isn't sure about going that extreme, I think this lighter spring would be a great option.
There is quite a bit of information out there, as well as a TSB, that advises against removing the spring completely, as the bleed off port in the master cylinder will not be completely exposed if the pedal does not return absolutely 100% of the way. There are many differing opinions on that, as well as members who have removed the spring. But, I believe that is why many people, including myself, are weary of long term spring removal.
 

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Discussion Starter #4
Update - I have 6 people signed up (including myself) for the experimental clutch spring, and 3 maybes. Not too far away from being able to go forward with the order.

So far I have:

redwolf719 (myself)
Rick H.
grinchem
MichaelSS15
HanoverJoe
RRoberts

boiler (maybe)
good2go (maybe)
91RS (maybe)
 

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Cant wait to try it.

Like you said, Ive pretty much gotten used to it after 4 years, but any time ive let someone else drive the car, the firat thing out of their mouth is "Woah, thats a weird clutch pedal".... of course sometimes thats also a cover for when someone cant drive stick very well lol.
 

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Discussion Starter #8
Cant wait to try it.

Like you said, Ive pretty much gotten used to it after 4 years, but any time ive let someone else drive the car, the firat thing out of their mouth is "Woah, thats a weird clutch pedal".... of course sometimes thats also a cover for when someone cant drive stick very well lol.
That's usually what I tell people before they do drive it! I've learned to drive it pretty smoothly most of the time, but every once in a while it still trips me up. I'm hoping this spring will be an improvement!
 

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All of my cars except one (a company car in the distant past) have been manual shift. The SS is not the best feeling clutch I have ever driven, but also far from the worst. I had an E39 M5 for 12 years, and tried a half-dozen clutch fixes to solve a clutch slipping problem. Most of them did not have great clutch feel, and with some high-effort clutches I could feel the plastic clutch pedal flexing beneath my foot. The final fix was to machine the dual-mass flywheel flat and drill it for a larger diameter (stock was 9.45 in.) Corvette clutch. Pedal feel was always compromised by the externally-mounted slave cylinder and throw-out arm. As a result of all this I do not like a floppy clutch pedal. I am planning to install a Monster triple-plate clutch in my SS shortly, stimulated by learning that GM used a cheap, failure prone plastic spacer on the concentric t/o bearing slave cylinder. I figured that if I need to pull the transmission I might as well also install a better clutch while in there. Monster recommends removing the clutch spring, but I would greatly prefer to install a weaker spring instead.

Previous posts in the other thread mentioned the need to keep the master cylinder bleed port open when the clutch pedal is released, which requires the pedal to be in its rear-most position. Various reasons were cited but no one has mentioned the other reason for the bleed port, the fact that clutch (brake) fluid expands when it gets hot and contracts when it cools. This action requires free access to the fluid level in the clutch master cylinder to act as an accumulator.

A thinner diameter spring wire is the only way to obtain a reduced-force spring. The stock spring cannot be weakened as regards spring force, as steel has a constant Young's modulus (spring constant). Removing the heat treatment by annealing will simply allow plastic deformation when loaded. "Spring force" will be reduced, but it will no longer be much of a spring.

I encourage anyone interested in changing the SS clutch feel to jump on this deal. There are potential issues, as with any prototype, regarding dimensions, heat treatment, tooling mark stress raisers, etc., but this is not rocket science.
 

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Incidentally, a coil spring stiffness is proportional to wire diameter to the 4th power. If all other dimensions are the same, and the OEM clutch spring wire diameter is assumed (for example) to be 0.125 inch, a 30% strength spring will require a wire diameter of 0.0925 inch. Small differences go a long way at the 4th power.
 

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Discussion Starter #11
I have 7 people signed up for a spring and 3 maybes. I'll reach and to the maybes and see if they will commit.

redwolf719 (myself)
Rick H.
grinchem
MichaelSS15
HanoverJoe
RRoberts
SSSteve176M

boiler (maybe)
good2go (maybe)
91RS (maybe)
 

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Discussion Starter #13
Update - 9 committed to the prototype spring test:

redwolf719 (myself)
Rick H.
grinchem
MichaelSS15
HanoverJoe
RRoberts
SSSteve176M
6.2 SS M6
boiler

good2go (maybe)
91RS (maybe)

Little photo below of my shined up SIM and happy pooch!
 

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Update - 9 committed to the prototype spring test:

redwolf719 (myself)
Rick H.
grinchem
MichaelSS15
HanoverJoe
RRoberts
SSSteve176M
6.2 SS M6
boiler

good2go (maybe)
91RS (maybe)

Little photo below of my shined up SIM and happy pooch!

Yes, I'll go for it (if I have to), but . . . judging by how quickly you got 10 people to commit, I think it's entirely reasonable that you could come up with 20. You might want to seriously float that out there again before you jump at reaching the first 10 people. I bet there are enough people sitting on the fence at $45 that might be more than willing to jump at $30. I know that I am in no particular rush, so waiting another week or so to see them at the lower price is just fine by me. It's only been like 3 days so far! Think about it. :wink
 

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Discussion Starter #15
Yes, I'll go for it (if I have to), but . . . judging by how quickly you got 10 people to commit, I think it's entirely reasonable that you could come up with 20. You might want to seriously float that out there again before you jump at reaching the first 10 people. I bet there are enough people sitting on the fence at $45 that might be more than willing to jump at $30. I know that I am in no particular rush, so waiting another week or so to see them at the lower price is just fine by me. It's only been like 3 days so far! Think about it. :wink
I hear what you're saying G2G, and it is probably a good idea. My only rush is that I'm excited to get the spring and try it out before I have to tuck my SS away for the winter here in the upper Midwest (Minne-snow-ta). I am not sure why I live here, but unfortunately, I do for now. I figure I've probably got another 4 weeks, as I usually put it away near the end of October. There will be a 2-week lead time on getting the springs so I'll leave this out there a few more days and see if we can get some more folks on the list. If we can get 3/4 of the way to 20, I'll go ahead and order 20 of them.

Updated list (11):

redwolf719 (myself)
Rick H.
grinchem
MichaelSS15
HanoverJoe
RRoberts
SSSteve176M
6.2 SS M6
boiler
good2go
91RS
 

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I just sent you a pm for one.
 

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Discussion Starter #17
Updated list (14):

redwolf719 (myself)
Rick H.
grinchem
MichaelSS15
HanoverJoe
RRoberts
SSSteve176M
6.2 SS M6
boiler
good2go
91RS
billygoat
g8eraid
snoot
 

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I'm in for $30. That should be close enough to make your order. I'm positive you'll get 5 more by the time they come in. Now
Go Order Those Bad Boys!
 

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Are you having different "strength" prototypes made or just taking a wild guess ???
 
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