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914World.com _ 914World Garage _ Clutch adjustment instructions
Posted by: Dr Evil Jun 13 2012, 01:47 PM
From my 31 pages of trans notes:
*Clutch cable
The clutch cable being too loose is probably one of the most common reasons that people’s shifting sucks. If your cable is too loose then you will not be able to fully disengage the pressure plate from the clutch disk and you will keep power to the transmission. If it is really loose then reverse will grind when shifting into it from a standstill. There is no way that this should happen if the clutch is fully disengaged. To properly adjust your clutch, you need to tighten the cable until the clutch disengages at about 1/4 to 1/3 pedal travel (See figure 1 in appendix). If the clutch disengages too early then it is too tight, too late then it is too loose.
Attached image(s)
Posted by: Dr Evil Jun 13 2012, 01:50 PM
If your clutch cable seems impossible to adjust, you may be suffering from a separated clutch tube. The clutch tube runs through the center tunnel and is welded near the front of the driver’s side of the tunnel and to the firewall where the clutch cable exits. Often, one or both of the welds brake causing your tube to shift when you clutch in. This will disable your cable’s ability to pull enough on your clutch and thus will not fully disengage your clutch. Repairs for this issue take many forms and are beyond the scope of this article. Searching www.914World.com , or other forums for information and advice on how to tackle this and other 914 related problems is a good start.
Posted by: Dr Evil Jun 13 2012, 01:51 PM
Also, it is often that the replacement cable is too long and thus you have run out of threads on the tranz end before you have adjusted it properly. I always put a small piece of tubing, about 19mm long, under the adjust nut. This also keeps you from having to tighten the damn lock nut 19mm onto the cable end.
Posted by: jim_hoyland Jun 13 2012, 01:53 PM
I was under the impression that the clutch should disengage the last 2 inches of pedal arc. If disingaging in the early part of the arc, it would cause damage to ( I forgot what) another part of the system.
Posted by: shoguneagle Jun 13 2012, 02:02 PM
Good job, Doc.
I do everything the Doc has said but also look at the appropriate angle the arm travels along with how close it appears to becoming to engaging the clutch disk; I adjust the clutch to where it appears to just engaging the clutch disk, and back it off always checking with the pedal for appropriate movement and engagement/disengagement. I also added a spring return to make sure the throw-out bearing is disengaging from the clutch pressure plate.
Always test drive and adjust accordingly
Posted by: Dr Evil Jun 13 2012, 02:09 PM
I was under the impression that the clutch should disengage the last 2 inches of pedal arc. If disingaging in the early part of the arc, it would cause damage to ( I forgot what) another part of the system.
You are worried about the TOB wearing out. It wont if you adjust this correctly. Too tight and it will wear the items, too loose and it will wear items. Just right and items wear slower and properly.
Posted by: jim_hoyland Jun 13 2012, 04:27 PM
So I need to tighten a little bit more so that the clutch is disengaging during the fist third of pedal travel ?
And, how does the floorboard clutch stop work or help ?
Posted by: Dr Evil Jun 13 2012, 04:52 PM
The floor stop is there to make sure you do not over stress the cable. With the stop adjusted correctly, the end of pedal travel with stop at the stop. If the stop is too short then you will stretch the clutch cable.
You can reason that, if the pedal engages at the lower part, you dont even need the stop as you will not make it pull all the way.
Posted by: tomrev May 20 2014, 03:04 PM
The floor stop is there to make sure you do not over stress the cable. With the stop adjusted correctly, the end of pedal travel with stop at the stop. If the stop is too short then you will stretch the clutch cable.
You can reason that, if the pedal engages at the lower part, you dont even need the stop as you will not make it pull all the way.
A quick question on this older thread: As I have read both opinions, Dr. Evil, are you OK with light contact between the TOB and plate fingers, when the pedal is not being used, to achieve the pedal engagement of 1/4 to 1/3 arc at pedal? I was of the opinion that the TOB did not want constant pressure, (nor the thrust bearings,) and always set the clutch up with a 1/16 in free play, but that will not work with my current, new clutch. I'm open to new methods! Thanks
Posted by: ClayPerrine May 20 2014, 03:13 PM
Just an addendum to the evil doctor's commentary:
If the clutch tube is welded back to the chassis wrong, then you can have a car that will never have a properly adjusted clutch.
Also, the throwout bearing arm can hit the transmission case if the flywheel has been ground down and the ball stud not shimmed properly.
Posted by: tomrev May 20 2014, 04:36 PM
Just an addendum to the evil doctor's commentary:
If the clutch tube is welded back to the chassis wrong, then you can have a car that will never have a properly adjusted clutch.
Also, the throwout bearing arm can hit the transmission case if the flywheel has been ground down and the ball stud not shimmed properly.
In this case all is new, flywheel disc and plate, and I am not hitting either end of the clutch arm opening. Bowden tube is fine at the firewall, but I do need to pull the carpet, and see if it is adrift up by the pedals. Thanks for the reply!
Posted by: buck toenges Jan 14 2019, 03:47 PM
Also, it is often that the replacement cable is too long and thus you have run out of threads on the tranz end before you have adjusted it properly. I always put a small piece of tubing, about 19mm long, under the adjust nut. This also keeps you from having to tighten the damn lock nut 19mm onto the cable end.
Can you expand on the 19mm long tubing. What is the tubing made of? Does the tubing back up to the trunnion piece in the tranny arm?
Thanks,
Buck
Posted by: JawjaPorsche Jan 14 2019, 06:56 PM
Most people use aluminum tubing and have seen people use several over sized nuts.
Yes it goes next to trunnion.
Posted by: Dave_Darling Jan 14 2019, 10:44 PM
One thing to note: The "helper" spring in the pedal cluster pulls the clutch pedal toward the floor. So the TO bearing will always be riding on the pressure plate fingers at least a little bit.
I have read that at least some of the free play that you measure is found by pulling up on the pedal.
--DD
Posted by: MikeM Jan 15 2019, 10:48 AM
Hi all...don't mean to hijack...
My clutch pedal feels light and springy. I checked the cable tube and it's very solid.
Now what?
Shifts OK, but clutch feels weird.
Mike
Posted by: Bartlett 914 Jan 15 2019, 02:24 PM
Hi all...don't mean to hijack...
My clutch pedal feels light and springy. I checked the cable tube and it's very solid.
Now what?
Shifts OK, but clutch feels weird.
Mike
Where and how did you check the clutch tube? It may be tight at the rear but loose near the front of the tube which it usually breaks free first. Later it breaks free in the middle then at the firewall. Another issue is with the accelerator cable. If installed improperly, it can be wrapped around the clutch cable causing issues
Posted by: MikeM Jan 15 2019, 04:58 PM
I removed the console, carpet and shifter. Tube in the tunnel is solid.
Solid also where the tube comes out of the firewall.
Mike
Posted by: Bartlett 914 Jan 15 2019, 05:17 PM
I removed the console, carpet and shifter. Tube in the tunnel is solid.
Solid also where the tube comes out of the firewall.
Mike
Were you able to look at the tube inside the tunnel with a mirror while moving the clutch? The tube is rather stiff. The cable pulls it away toward the center of the tunnel. Other than this I don't have anything for you. Lots of luck
Posted by: second wind Jan 15 2019, 11:11 PM
From my 31 pages of trans notes:
*Clutch cable
The clutch cable being too loose is probably one of the most common reasons that people’s shifting sucks. If your cable is too loose then you will not be able to fully disengage the pressure plate from the clutch disk and you will keep power to the transmission. If it is really loose then reverse will grind when shifting into it from a standstill. There is no way that this should happen if the clutch is fully disengaged. To properly adjust your clutch, you need to tighten the cable until the clutch disengages at about 1/4 to 1/3 pedal travel (See figure 1 in appendix). If the clutch disengages too early then it is too tight, too late then it is too loose.
Hello Dr. Evil.....could you please explain the color graph in more detail? I usually set my cable adjuster to just touching the clutch arm under the car by the transmission.....trying not to hurt the TOB but getting a good disengagement......I really appreciate it. I know a lot of things really well but I trust you and the brain trust more on certain things....like my 914.....thank you very much.
gg
Posted by: porschetub Jul 13 2022, 07:44 PM
From my 31 pages of trans notes:
*Clutch cable
The clutch cable being too loose is probably one of the most common reasons that people’s shifting sucks. If your cable is too loose then you will not be able to fully disengage the pressure plate from the clutch disk and you will keep power to the transmission. If it is really loose then reverse will grind when shifting into it from a standstill. There is no way that this should happen if the clutch is fully disengaged. To properly adjust your clutch, you need to tighten the cable until the clutch disengages at about 1/4 to 1/3 pedal travel (See figure 1 in appendix). If the clutch disengages too early then it is too tight, too late then it is too loose.
Hello Dr. Evil.....could you please explain the color graph in more detail? I usually set my cable adjuster to just touching the clutch arm under the car by the transmission.....trying not to hurt the TOB but getting a good disengagement......I really appreciate it. I know a lot of things really well but I trust you and the brain trust more on certain things....like my 914.....thank you very much.
gg
Kinda glad I'am not the only person that can't work out the colour graph ,presuming the green area is the sweet spot ??.
Have NOS clutch ,machined 911 flywheel (still in spec ) with re-shimed release arm ball pivot,new cable and 914 rubber cable roller,rebuilt pedal assembly and solid cable tube etc.
Prefer to make sure it is right as appears "free play" is less important than pedal height ???.
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