 Increasing clutch cable transaxle pulley diameter |
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| HalfMoon |
 Dec 23 2020, 07:55 PM
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#1
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Senior Member  Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region  |
Has anyone ever experimented with increasing the diameter of the transaxle clutch cable pulley?
Obviously the housing would have to be modified that much goes without saying. My wondering on this idea would be to shorten the "throw" at the pedal with the hope of increasing shift speed (I've converted to a cable shift). Direct experience with this modification very much sought. |
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| 914e |
Dec 23 2020, 08:15 PM
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#2
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Member Group: Members Posts: 497 Joined: 21-February 20 From: Arizona Member No.: 23,951 Region Association: Southwest Region 
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QUOTE(HalfMoon @ Dec 23 2020, 06:55 PM)  Has anyone ever experimented with increasing the diameter of the transaxle clutch cable pulley? Obviously the housing would have to be modified that much goes without saying. My wondering on this idea would be to shorten the "throw" at the pedal with the hope of increasing shift speed (I've converted to a cable shift). Direct experience with this modification very much sought. All the pulley does is change the direction. I don't see it changing the throw at all. |
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| windforfun |
Dec 23 2020, 08:17 PM
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#3
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Advanced Member Group: Members Posts: 2,097 Joined: 17-December 07 From: Blackhawk, CA Member No.: 8,476 Region Association: None
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Why bother? Get a life.
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| BillC |
Dec 23 2020, 08:17 PM
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#4
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Senior Member Group: Members Posts: 701 Joined: 24-April 15 From: Silver Spring, MD Member No.: 18,667 Region Association: MidAtlantic Region
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The clutch cable pulley doesn't do anything except change the direction of the cable pull. The rate at which the clutch is released or applied is controlled by the clutch pedal, not the pulley.
If you modify the clutch pedal, you'd need to make sure you still had enough throw to fully release the clutch, but still keep the throw short enough to not over-travel the pressure plate fingers. I'm willing to bet you're not going to find many people with experience modifying the clutch cable system, since there isn't really any advantage in changing it. Usually, the only change people make is to just replace the cable with a hydraulic system. |
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| GregAmy |
Dec 23 2020, 08:36 PM
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#5
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Advanced Member Group: Members Posts: 2,651 Joined: 22-February 13 From: Middletown CT Member No.: 15,565 Region Association: North East States
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All of the above. That's not how a pulley works...
If you want to shorten the "throw" of the clutch pedal you'll have to change the lever arm on the clutch pedal itself or on the fork at the throwout bearing. Or convert to hydraulic. |
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| HalfMoon |
Dec 23 2020, 10:04 PM
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#6
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
QUOTE(windforfun @ Dec 23 2020, 10:17 PM) Why bother? Get a life. Hey chum, what's your problem? If civility escapes you, maybe you should find a more suitable forum? Dickheads anonymous comes to mind... |
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| bdstone914 |
Dec 23 2020, 11:08 PM
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#7
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bdstone914 Group: Members Posts: 5,280 Joined: 8-November 03 From: Riverside CA Member No.: 1,319 |
QUOTE(HalfMoon @ Dec 23 2020, 07:55 PM) Has anyone ever experimented with increasing the diameter of the transaxle clutch cable pulley? Obviously the housing would have to be modified that much goes without saying. My wondering on this idea would be to shorten the "throw" at the pedal with the hope of increasing shift speed (I've converted to a cable shift). Direct experience with this modification very much sought. @HalfMoon A later 911 clutch arm in the pedal may be adaptable to accomplish that. It has a taller arm but requires more offset to not interfere with the accelerator cable. Attached thumbnail(s) 
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| porschetub |
Dec 23 2020, 11:15 PM
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#8
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914 Guru Group: Members Posts: 5,064 Joined: 25-July 15 From: New Zealand Member No.: 18,995 Region Association: None |
QUOTE(windforfun @ Dec 24 2020, 03:17 PM) Why bother? Get a life. You have got that backwards.....chill out man . |
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| Charles Freeborn |
Dec 23 2020, 11:26 PM
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#9
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Member Group: Members Posts: 321 Joined: 21-May 14 From: United States Member No.: 17,377 Region Association: Pacific Northwest |
QUOTE(bdstone914 @ Dec 23 2020, 09:08 PM) QUOTE(HalfMoon @ Dec 23 2020, 07:55 PM) Has anyone ever experimented with increasing the diameter of the transaxle clutch cable pulley? Obviously the housing would have to be modified that much goes without saying. My wondering on this idea would be to shorten the "throw" at the pedal with the hope of increasing shift speed (I've converted to a cable shift). Direct experience with this modification very much sought. @HalfMoon A later 911 clutch arm in the pedal may be adaptable to accomplish that. It has a taller arm but requires more offset to not interfere with the accelerator cable. This . Shorten one of the other levers. Much simpler. Plus, why? Are you bang shifting your 914? |
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| HalfMoon |
Dec 24 2020, 08:34 AM
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#10
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
QUOTE(Charles Freeborn @ Dec 24 2020, 01:26 AM) QUOTE(bdstone914 @ Dec 23 2020, 09:08 PM) QUOTE(HalfMoon @ Dec 23 2020, 07:55 PM) Has anyone ever experimented with increasing the diameter of the transaxle clutch cable pulley? Obviously the housing would have to be modified that much goes without saying. My wondering on this idea would be to shorten the "throw" at the pedal with the hope of increasing shift speed (I've converted to a cable shift). Direct experience with this modification very much sought. @HalfMoon A later 911 clutch arm in the pedal may be adaptable to accomplish that. It has a taller arm but requires more offset to not interfere with the accelerator cable. This . Shorten one of the other levers. Much simpler. Plus, why? Are you bang shifting your 914? Sbc wide body track car, so yes. |
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| HalfMoon |
Dec 24 2020, 08:35 AM
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#11
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
QUOTE(bdstone914 @ Dec 24 2020, 01:08 AM) QUOTE(HalfMoon @ Dec 23 2020, 07:55 PM) Has anyone ever experimented with increasing the diameter of the transaxle clutch cable pulley? Obviously the housing would have to be modified that much goes without saying. My wondering on this idea would be to shorten the "throw" at the pedal with the hope of increasing shift speed (I've converted to a cable shift). Direct experience with this modification very much sought. @HalfMoon A later 911 clutch arm in the pedal may be adaptable to accomplish that. It has a taller arm but requires more offset to not interfere with the accelerator cable. Interesting idea! Thanks for that. |
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| 914Sixer |
Dec 24 2020, 09:11 AM
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#12
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914 Guru Group: Members Posts: 9,453 Joined: 17-January 05 From: San Angelo Texas Member No.: 3,457 Region Association: Southwest Region
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Something else to ponder from Tangerine Racing
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| gereed75 |
Dec 24 2020, 09:14 AM
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#13
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Senior Member Group: Members Posts: 1,425 Joined: 19-March 13 From: Pittsburgh PA Member No.: 15,674 Region Association: North East States
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It is possible to change the pull ratio at the pulley. It would require the pulley to be some sort of cam lobe shape. The first example that comes to mind is the throttle cable cam/ pulley on a 944 throttle for those that might be familiar.
Lotta work for very little gain I suspect Boy this thread has been all over the map - must be a holiday thing! |
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| HalfMoon |
Dec 24 2020, 09:56 AM
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#14
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
QUOTE(914Sixer @ Dec 24 2020, 11:11 AM) Something else to ponder from Tangerine Racing Well that's got me thinking! Must have a look at the stock pulley housing. Perhaps it can be modified? Not sure if that would actually affect the "throw" though. Addendum-Nope, the housing itself can't be modified. But fabing up a new bracket (like what Tangerine has done) would be easy enough. Thanks for the tip! |
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| HalfMoon |
Dec 24 2020, 09:57 AM
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#15
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
QUOTE(gereed75 @ Dec 24 2020, 11:14 AM) It is possible to change the pull ratio at the pulley. It would require the pulley to be some sort of cam lobe shape. The first example that comes to mind is the throttle cable cam/ pulley on a 944 throttle for those that might be familiar. Lotta work for very little gain I suspect Boy this thread has been all over the map - must be a holiday thing! Hmmm. Interesting thought. |
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| old914dog |
Dec 24 2020, 10:46 AM
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#16
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Member Group: Members Posts: 74 Joined: 28-August 04 From: dallas,tx Member No.: 2,643 Region Association: None
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QUOTE(HalfMoon @ Dec 24 2020, 07:57 AM) QUOTE(gereed75 @ Dec 24 2020, 11:14 AM) It is possible to change the pull ratio at the pulley. It would require the pulley to be some sort of cam lobe shape. The first example that comes to mind is the throttle cable cam/ pulley on a 944 throttle for those that might be familiar. Lotta work for very little gain I suspect Boy this thread has been all over the map - must be a holiday thing! Hmmm. Interesting thought. I appreciate the disease of going faster. It is what makes cars go faster. With the 901 tranny, use caution. In a track only 914, I put a 5.5in clutch with a crazy lite flywheel, very close ratio gears.....thinking I could shift with the MGs and other competitors, which afterwards I learned had dog boxes. In one weekend I smoked 4 sycros. The box just was not designed for "bang" shifting. Just an old fart with his opinion. Merry Christmas |
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| Spoke |
Dec 24 2020, 01:06 PM
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#17
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Jerry Group: Members Posts: 7,370 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None
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QUOTE(GregAmy @ Dec 23 2020, 09:36 PM) Or convert to hydraulic. If you want to clean up the clutch mechanism, I think this would be the way to go. QUOTE(old914dog @ Dec 24 2020, 11:46 AM) With the 901 tranny, use caution...The box just was not designed for "bang" shifting (IMG:style_emoticons/default/agree.gif) My trans was recently rebuilt by Dr_Evil and shifts very well. When I get in a hurry going from 1st to 2nd, I'm either pushing the synchros hard and getting a grind or I'm nicking reverse. If you want to shift quickly, it might be prudent to look to a different trans. My 914 even with a 2056 is slow and no amount of shifting speed will help me out drag today's minivans and SUVs. |
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| Chris914n6 |
Dec 24 2020, 04:06 PM
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#18
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Jackstands are my life. Group: Members Posts: 3,528 Joined: 14-March 03 From: Las Vegas, NV Member No.: 431 Region Association: Southwest Region |
Change your technique slowfoot (IMG:style_emoticons/default/poke.gif)
*nothing is going to change the physics of syncromesh Also, raising the ratio will also raise the pedal force needed, so it's a wash |
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| wattele |
Dec 25 2020, 11:47 AM
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#19
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Newbie Group: Members Posts: 14 Joined: 17-November 19 From: Belgium Member No.: 23,651 Region Association: Europe |
I was thingking about converting to hydraulic.
My wife says the clutch is to hard to use. So hydrolic could solve this. Anyone did this before. (IMG:style_emoticons/default/driving-girl.gif) |
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| Mikey914 |
Dec 26 2020, 06:56 AM
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#20
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The rubber man Group: Members Posts: 12,772 Joined: 27-December 04 From: Hillsboro, OR Member No.: 3,348 Region Association: None
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Hey guys , just a thought. You are effectively shortening the cable length, so why not just tighten the cable to preload the clutch to the point you desire. Anything you would do would have a diminished rate of return.
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