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  #441  
Old 01-12-2019, 04:59 PM
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69427 69427 is offline
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Originally Posted by Grampy View Post
Z bar in 6061 sounds reasonable. A little (very little) more deflection because of the lower modulus of elasticity but strength is similar to mild steel original. Might sleeve the linkage bar bearing surfaces with a sacrificial bronze insert (like shift levers) where the link bars attach. Don't think fatigue is a concern with current low use of car. IIRC the captured stud is held in place with a wire ring clip in a groove - replicate the OE pocket and reuse the stock ball stud and seats.
We're pretty much on the same wavelength here. I had envisioned putting bushings in the linkage arms and also one in the tube where it rotates on the ball stud on the engine block. The captured stud still has me thinking, as I'm not convinced yet that I'm talented enough to be able to fabricate the groove needed for the snap ring. I still have a bit of time to figure out how to "duplicate" that while I'm looking for the tube material (my favorite local metal place didn't have what I was looking for the other day).

I agree that fatigue shouldn't be a major issue if I correctly size things (I did do a bunch of torsional strength calculations to amuse myself the other week during down times at an extended family gathering). The clutch linkage doesn't get that much day to day use, and I'm curious (as I'm not a mechanical engineer) if the fact that the bar arms (and each finite area of the arms) are only stressed in one direction (just one half of a cycle, not a complete, reversing cycle) reduces the effects of any cycling. I welcome correction or clarification from any metals experts here.
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  #442  
Old 01-13-2019, 08:07 PM
Grampy Grampy is offline
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I'm out of the country so I can't make any measurements but much of the force multiplication will occur at the clutch fork. The pedal ratio is somewhere about 7:1 so I figure about 50# force at pedal and 350# applied to z bar lever arm. The Zbar lever arm is somewhere around 6" so I'd guess about 175 Lb-ft torque applied to the tube. Fatigue test machines do full reversal but with low cycles you should have no problems. I don't have any reference material here. I flew in a 1943 DC3 a few weeks ago so aluminum should be OK.

You should be able to grind or have ground a profile on a boring bar that matches the OE clip ring groove. IIRC there are plastic bearing cups for the ball studs.
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  #443  
Old 01-18-2019, 06:31 PM
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Kacyc3 Kacyc3 is offline
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I kno wyou are looking for ways to reduce the weight of your car but have you done anything with the gas tank? I know with my 79 the tank sits on top of the frame and believe this is the same for your car also. Lowering the tank to be flush with the top of the frame would help your center of gravity and allow you to carry more speed through the turns.
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  #444  
Old 01-19-2019, 12:26 AM
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69427 69427 is offline
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I kno wyou are looking for ways to reduce the weight of your car but have you done anything with the gas tank? I know with my 79 the tank sits on top of the frame and believe this is the same for your car also. Lowering the tank to be flush with the top of the frame would help your center of gravity and allow you to carry more speed through the turns.
Yeah, I've been trying to figure out my options with the fuel tank. I'm running stock location rear mufflers, so that gums up the works when trying to lower the fuel tank. So far the only decent option I've figured out is to fabricate a custom tank of about 8-10 gallon capacity versus the stock tank capacity (16-18 gallon range IIRC). The next thing I haven't figured out yet is if it would be better to make the smaller tank full height but narrow, and place it over to the right side to help get weight off the left side, or make the tank full width but shorter height to drop the c/g of the tank downward.

That's where I'm at currently. I appreciate your input here.

OBTW, anyone here know the weight of the early C3 fuel tanks?
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  #445  
Old 01-19-2019, 01:45 AM
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OZgreen69 OZgreen69 is offline
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I checked one for you : 1969 model, filler neck but no fuel sender :7.76 kg or 17.10 Lbs.
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  #446  
Old 01-19-2019, 03:24 AM
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69427 69427 is offline
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I checked one for you : 1969 model, filler neck but no fuel sender :7.76 kg or 17.10 Lbs.
I do appreciate it. Thank you very much.
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  #447  
Old 01-22-2019, 12:09 AM
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Originally Posted by Kacyc3 View Post
I kno wyou are looking for ways to reduce the weight of your car but have you done anything with the gas tank? I know with my 79 the tank sits on top of the frame and believe this is the same for your car also. Lowering the tank to be flush with the top of the frame would help your center of gravity and allow you to carry more speed through the turns.
Yeah, I've been trying to figure out my options with the fuel tank. I'm running stock location rear mufflers, so that gums up the works when trying to lower the fuel tank. So far the only decent option I've figured out is to fabricate a custom tank of about 8-10 gallon capacity versus the stock tank capacity (16-18 gallon range IIRC). The next thing I haven't figured out yet is if it would be better to make the smaller tank full height but narrow, and place it over to the right side to help get weight off the left side, or make the tank full width but shorter height to drop the c/g of the tank downward.

That's where I'm at currently. I appreciate your input here.

OBTW, anyone here know the weight of the early C3 fuel tanks?
Build your own that sits flush with the top of the frame, doesnt drop to hit the mufflers but still drops in the center shaped like a T

Last edited by Kacyc3; 01-22-2019 at 12:11 AM..
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