# Clutch adjustment



## Ohio66GTO (May 19, 2014)

So I swapped my 455 out for a 428 and everything is set except for the clutch. Looking in my restoration book it says to remove the lash at the clutch with the clutch pedal at the stop. It then says to turn the adjustment rod 3 1/2 + - 1/4. Is the lash between the rod and fork or the release bearing? I have tightened the rod until the point is seated into the fork with no movement back and forth. I then turned it 3 1/2 turns further into the fork which made it pretty tight to turn by hand. I could’ve turned it maybe another 1/2 to 3/4 by hand and that would’ve been it. Is that the correct way to set it?


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## PontiacJim (Dec 29, 2012)

Ohio66GTO said:


> So I swapped my 455 out for a 428 and everything is set except for the clutch. Looking in my restoration book it says to remove the lash at the clutch with the clutch pedal at the stop. It then says to turn the adjustment rod 3 1/2 + - 1/4. Is the lash between the rod and fork or the release bearing? I have tightened the rod until the point is seated into the fork with no movement back and forth. I then turned it 3 1/2 turns further into the fork which made it pretty tight to turn by hand. I could’ve turned it maybe another 1/2 to 3/4 by hand and that would’ve been it. Is that the correct way to set it?


Never used any book specs to adjust my clutch linkage. Just make sure the pedal is up against the rubber stop under the dash, ie clutch pedal fully released.

Position the clutch fork so it's about 1/4" from the bell housing opening and then turn the adjusting rod out until it seats into the clutch fork cup. There is a spring that hooks to the linkage and holds the rod into the clutch fork cup, not adjustment pressure.

You want some play in the clutch fork. You do not want the clutch fork up against the bell housing. You don't want a large gap between the clutch fork and bell housing opening - which typically indicates too short of a throw out bearing. You don't want the clutch fork being forced into the side/opening of the bell housing - which typically indicates too long of a throw out bearing. 

You do not want the throw out bearing pressed against the pressure plate diaphragm fingers - it'll burn up the bearing in a matter of time. The clutch fork/linkage must retract enough to keep the throw out bearing off and away from the pressure plate. You should be able to grab the clutch fork by hand and move it back and forth to "feel" when the throw out bearing hits the pressure plate. It does not have to come off much from the pressure plate, but it has to be off it. If the throw out bearing is adjusted too far from the pressure plate, when you go to push in the clutch, it will not release cleanly and you will clash gears during shifting. Manufacturers typically tell you to push in the clutch all the way to the floor and measure the air gap between the clutch disc and flywheel ( or pressure plate). Never did this. It either releases and I can pull a clean shift or it does not and needs an adjustment. 

You can shorten the rod to suite where the clutch grabs off the floor. Some like it low, while others like it high. I don't like it engaging right off the floor, nor way up high. Prefer something about mid-way as long as the clutch releases smoothly and clean for a good shift. So you can play with that if you choose. As the clutch wears, the pedal will get closer to the floor and you may even find the the gears clash a little when changing them, then you go back underneath and adjust the rod again to bring the pedal back up.

Now if you cannot get this gap/clearance from the fork/throw out bearing, you may have the wrong length throw out bearing. They come in 3 lengths, short, medium, and long. Sometimes a kit will supply the wrong one and you will have to swap it out or the parts guy gives you what the parts book says and it is wrong.


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## Ohio66GTO (May 19, 2014)

Thanks for the detailed response. I’ve never dealt with a manual transmission before so please bear with me. I’m working on a 65 and the only sping that I have is the return spring that goes around the fork and the other end of the spring is supposed to hook to the exhaust manifold flange. Since I switched to the Ram Air manifolds I had to rig something for the return spring that goes to the flange. Think I’ve got that figured out. When I pulled the engine and trans there was no boot on the opening of the bellhousing where the fork goes in. Since I saw them for sale I bought one and installed it. Seems like there is not much movement with it installed. Is it necessary to have that on there? I’m assuming its to keep debris out of there. So just to be clear, when turning the pointed end of the rod into the fork that is moving the bearing into the fingers and when turning it away from the fork it’s coming off the fingers?


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## PontiacJim (Dec 29, 2012)

Ohio66GTO said:


> Thanks for the detailed response. I’ve never dealt with a manual transmission before so please bear with me. I’m working on a 65 and the only sping that I have is the return spring that goes around the fork and the other end of the spring is supposed to hook to the exhaust manifold flange. Since I switched to the Ram Air manifolds I had to rig something for the return spring that goes to the flange. Think I’ve got that figured out. When I pulled the engine and trans there was no boot on the opening of the bellhousing where the fork goes in. Since I saw them for sale I bought one and installed it. Seems like there is not much movement with it installed. Is it necessary to have that on there? I’m assuming its to keep debris out of there. So just to be clear, when turning the pointed end of the rod into the fork that is moving the bearing into the fingers and when turning it away from the fork it’s coming off the fingers?


The boot is to keep water/dirt etc. out. Most of the applications I have had did not have the boot or it was torn up due to age and I pulled it off. I personally don't think it too necessary to have. If you get some water in there, it will drain down to the bottom, but I think you would have to hit a really big/deep puddle to do that. Without it, I'll give you some more room.

The adjustment rod sounds about right. One way will extend it and push it into/up against the clutch fork and towards the back of the car which moves the throw out bearing closer to the pressure plate fingers. The other way will shorten the rod and pull the fork toward the front of the car and move the throw out bearing further away from the pressure plate fingers.

There should be a spring (yours may be missing) that goes from the clutch fork (you should see a small hole for its attachment) to the lower arm of the counter shaft. This holds pressure on the clutch fork against the adjustment rod so it won't slip out as it gets lengthened or shortened for your clutch/pedal adjustments.

The other spring you mentioned sounds like the pedal return spring which you have made work. On my '68, the spring goes from a hole in the frame (although the book shows a body bracket which most do not have) to a hole found in the upper arm of the counter shaft to pull it towards the firewall, thus keeping the pedal up against the stop block - or fully released.


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## pontiachristopher (Jun 28, 2020)

PontiacJim said:


> The boot is to keep water/dirt etc. out. Most of the applications I have had did not have the boot or it was torn up due to age and I pulled it off. I personally don't think it too necessary to have. If you get some water in there, it will drain down to the bottom, but I think you would have to hit a really big/deep puddle to do that. Without it, I'll give you some more room. The adjustment rod sounds about right. One way will extend it and push it into/up against the clutch fork and towards the back of the car which moves the throw out bearing closer to the pressure plate fingers. The other way will shorten the rod and pull the fork toward the front of the car and move the throw out bearing further away from the pressure plate fingers. There should be a spring (yours may be missing) that goes from the clutch fork (you should see a small hole for its attachment) to the lower arm of the counter shaft. This holds pressure on the clutch fork against the adjustment rod so it won't slip out as it gets lengthened or shortened for your clutch/pedal adjustments. The other spring you mentioned sounds like the pedal return spring which you have made work. On my '68, the spring goes from a hole in the frame (although the book shows a body bracket which most do not have) to a hole found in the upper arm of the counter shaft to pull it towards the firewall, thus keeping the pedal up against the stop block - or fully released.


 appreciate your knowledge and willingness to share that in helping others. has guided me numerous times. have a 1971 and corresponding chiltons book. for normal wear adjustment. had a new clutch istalled a few years ago as the crossmember was welded before i got the car. so that was returned to bushing and bolts. anyway clutch has started needed feathering to start off sometimes, only on warm up and usage for the daily commute. says: clutch pedal adjustment 1.disconnect the return spring. 2. with the pedal against the stop, loosen the locknut to allow the adjusting rod to be turned out of the swivel (v8) until the throw uot bearing contacts the release fingers in the pressure plate. 3. turn the adjusting rod into the swivel or pushrod 3 and 1/2 turns, tighten the locknut to 30 lbs. for 69-72. 4. install the return spring and check the pedal lash; it should be approximately 1". so disconnecting the spring leaves the pedal resting on the stop, backoff the locknut, and turn the adjusting rod out of the swivel until the throwout bearing contacts the release fingers on the pressure plate. then, turn the adjusting rod into the swivel 3.5 turns. tighten the locknut. reinstall the return spring. pedal lash is the distance of travel backout from the stop where it starts to catch and engage? this is from underneath, spring on the fork and swivel is the seat indentation on the fork? think i got this from rereading and trying to understand, been awhile. again, thank you for your time and experience. also, happy holidays.


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## geeteeohguy (Feb 2, 2008)

Ohio66GTO said:


> So I swapped my 455 out for a 428 and everything is set except for the clutch. Looking in my restoration book it says to remove the lash at the clutch with the clutch pedal at the stop. It then says to turn the adjustment rod 3 1/2 + - 1/4. Is the lash between the rod and fork or the release bearing? I have tightened the rod until the point is seated into the fork with no movement back and forth. I then turned it 3 1/2 turns further into the fork which made it pretty tight to turn by hand. I could’ve turned it maybe another 1/2 to 3/4 by hand and that would’ve been it. Is that the correct way to set it?


In a word, NO. But it's a great way to wear your new clutch out in about 400 miles. 

Like most here, never used a manual to adjust a clutch. You want an inch or two of 'free play' at the pedal and you want NO TENSION on the clutch fork from the rod until you press the pedal. The rod sits there or is held in place in the divot on the fork by a small spring. You do NOT want it putting pressure on fork. 

That said, when you get it set, don't be like those guys on TV who rest their hand on the shifter as they drive. Unless you want to wear out your transmission syncros.


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## pontiachristopher (Jun 28, 2020)

geeteeohguy said:


> In a word, NO. But it's a great way to wear your new clutch out in about 400 miles. Like most here, never used a manual to adjust a clutch. You want an inch or two of 'free play' at the pedal and you want NO TENSION on the clutch fork from the rod until you press the pedal. The rod sits there or is held in place in the divot on the fork by a small spring. You do NOT want it putting pressure on fork. That said, when you get it set, don't be like those guys on TV who rest their hand on the shifter as they drive. Unless you want to wear out your transmission syncros.


 nah that is what the console, armrest is for? although it sits 3/4"/1.25" +/- below the level of the door armrest. a forgivable engineering oversight?


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## pontiachristopher (Jun 28, 2020)

pontiachristopher said:


> nah that is what the console, armrest is for? although it sits 3/4"/1.25" +/- below the level of the door armrest. a forgivable engineering oversight?


thank you.


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## PontiacJim (Dec 29, 2012)

pontiachristopher said:


> appreciate your knowledge and willingness to share that in helping others. has guided me numerous times. have a 1971 and corresponding chiltons book. for normal wear adjustment. had a new clutch istalled a few years ago as the crossmember was welded before i got the car. so that was returned to bushing and bolts. anyway clutch has started needed feathering to start off sometimes, only on warm up and usage for the daily commute. says: clutch pedal adjustment 1.disconnect the return spring. 2. with the pedal against the stop, loosen the locknut to allow the adjusting rod to be turned out of the swivel (v8) until the throw uot bearing contacts the release fingers in the pressure plate. 3. turn the adjusting rod into the swivel or pushrod 3 and 1/2 turns, tighten the locknut to 30 lbs. for 69-72. 4. install the return spring and check the pedal lash; it should be approximately 1". so disconnecting the spring leaves the pedal resting on the stop, backoff the locknut, and turn the adjusting rod out of the swivel until the throwout bearing contacts the release fingers on the pressure plate. then, turn the adjusting rod into the swivel 3.5 turns. tighten the locknut. reinstall the return spring. pedal lash is the distance of travel backout from the stop where it starts to catch and engage? this is from underneath, spring on the fork and swivel is the seat indentation on the fork? think i got this from rereading and trying to understand, been awhile. again, thank you for your time and experience. also, happy holidays.


Here is 1968-72 which is different, but similar to the pre-68 which did not have the swivel link.

Pic #1 is the linkage set-up 1968-72

Pic #2 I high lighted in RED the spring used at the adjustment rod down at the clutch fork and where it hooks. This spring simply clamps the fork to the bracket so that the rounded adjustment rod end (non-threaded side) that sits into the clutch for pocket does not drop out. That's all it does, but very important. It does not put any pressure/pull on the clutch fork.

Pic #3 I high lighted in GREEN. This is the return spring that holds your clutch pedal up against the clutch pedal rubber stop under the dash, and where it hooks. However, many/most '68 and up cars do not have the bracket shown in the photo - the spring goes into a hole on the frame instead. This spring pulls the pedal up after you push in the clutch and ALSO pulls on the clutch fork which in turn pulls the throw-out bearing off of the diaphragm/pressure plate fingers. You do not want the throw-out bearing to rest on the diaphragm/pressure plate fingers as this will cause the throw-out bearing to constantly spin and eventually wear it out - it was not designed to spin constantly, only when the clutch is applied.

There can be different versions of the adjusting rod depending if it is factory or aftermarket, but they all work the same. Extending the rod out by unscrewing it lengthens the rod and pushes on the fork which moves the throw-out bearing closer to the diaphragm/pressure plate fingers. As the clutch disc wears, it get thinner, and the diaphragm/pressure plate moves further from the throw-out bearing face and it can get to the point where you push the pedal and the diaphragm/pressure plate fingers are not being pushed in fully and you find the pedal low on the floor when pushing/releasing the clutch and you generally don't get a "clean shift" and scrape or fight with the gears when changing gears.

The cure is to adjust the rod out which lengthens it and pushes on the clutch fork and moves the throw-out bearing closer to the diaphragm/pressure plate fingers and compensates for the clutch disc wear (unless it is slap worn out). To adjust you loosen the lock nut and unscrew the adjusting rod out. Note it will be square near its ball end and this is so you can either use a small open end wrench, or an adjustable wrench as I do. Sometimes if it is not cruddy/rusty, you can adjust by hand - but not my experience unless it was new.

FIRST, move the clutch fork back and forth to get an idea/feel for how much free play you have between the throw-out bearing and diaphragm/pressure plate fingers. That amount of free play is too much, so you know what you don't want. Back the rod out BUT, not so far that it puts the throw-out bearing up against the diaphragm/pressure plate fingers. Simply test this as you adjust the rod by moving the clutch fork back and forth on its pivot ball - you should have a reasonable amount of free play.

Once you think you have it, tighten up the nut to lock the rod into place. Some rods I have used will not have a threaded fitting on the linkage end, but a drilled smooth hole and the rod will slide through and you will have a nut on the back side and nut on the front side and you simply tighten them both up so they clamp the linkage end together like a sandwich.

Once you have it adjusted to where you think it is good, time to test it. Your first test will be free-play travel of the pedal.
You should have about 1 " of travel (Service Manual calls it "lash') where you can easily push the pedal down before the linkage begins to operate the clutch fork and push the throw-out bearing up against the fingers on the diaphragm/pressure plate. If you have this, you are at a good starting point. This can sometimes vary AND, there is a rubber stop that the clutch pedal hits up under the dash. This is more to keep noise down when the pedal is returned fast, but it can be cut down, or even removed, in circumstances where you need a little more pedal travel depending on the type of pressure plate fingers/throw-out bearing being used.

Next, Fire the car up and push the clutch to the floor. Now release the clutch with the trans in gear and see how high the pedal comes up off the floor before the clutch grabs. I like to see it lift up off the floor probably somewhere around 3 inches. I don't like a clutch that grabs near the floor and this is also an indicator that the clutch is worn and is in need of adjustment or flat worn out. Too low and you are not pushing the clutch in completely and it's a matter of time before it is worn out. This height can be somewhat adjusted a little up or down as long as you are pushing the clutch in enough to get a clean release and/or letting the pedal out so the clutch fork is not being pushed against the diaphragm/pressure plate fingers. So this is a "test it" thing to find where you like the clutch pedal height for you.

You will read on many aftermarket clutch suppliers that they recommend and "air gap" setting between the disc face and the flywheel face. It takes 2 people to do this as one person has to push in the clutch while someone under the car uses a feeler gauge to check the air gap. I have never in my life done this and never will. You know when a clutch works and you know when its not. 

If your linkage is old and sloppy, this will not be of help when you go to adjust the adjuster rod. You may still be able to do so, but sometimes you will find you have to extend the rod fully and still may not get enough out of it. They do may longer adjuster rods, but this really is not the way to go unless you can still get enough travel from your clutch pedal to get a clean release. It is also easy to be fooled when you install all new parts and you were given a wrong throw-out bearing length and you figure you can compensate by using a longer/shorted adjuster rod - wrong, not a good band-aid fix. If the factory length adjuster rod does not seem to be a correct length, look for other issues.


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## RMTZ67 (Mar 12, 2011)

I got 1" of play before it starts to engage the clutch.


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## pontiachristopher (Jun 28, 2020)

PontiacJim said:


> Here is 1968-72 which is different, but similar to the pre-68 which did not have the swivel link. Pic #1 is the linkage set-up 1968-72 Pic #2 I high lighted in RED the spring used at the adjustment rod down at the clutch fork and where it hooks. This spring simply clamps the fork to the bracket so that the rounded adjustment rod end (non-threaded side) that sits into the clutch for pocket does not drop out. That's all it does, but very important. It does not put any pressure/pull on the clutch fork. Pic #3 I high lighted in GREEN. This is the return spring that holds your clutch pedal up against the clutch pedal rubber stop under the dash, and where it hooks. However, many/most '68 and up cars do not have the bracket shown in the photo - the spring goes into a hole on the frame instead. This spring pulls the pedal up after you push in the clutch and ALSO pulls on the clutch fork which in turn pulls the throw-out bearing off of the diaphragm/pressure plate fingers. You do not want the throw-out bearing to rest on the diaphragm/pressure plate fingers as this will cause the throw-out bearing to constantly spin and eventually wear it out - it was not designed to spin constantly, only when the clutch is applied. There can be different versions of the adjusting rod depending if it is factory or aftermarket, but they all work the same. Extending the rod out by unscrewing it lengthens the rod and pushes on the fork which moves the throw-out bearing closer to the diaphragm/pressure plate fingers. As the clutch disc wears, it get thinner, and the diaphragm/pressure plate moves further from the throw-out bearing face and it can get to the point where you push the pedal and the diaphragm/pressure plate fingers are not being pushed in fully and you find the pedal low on the floor when pushing/releasing the clutch and you generally don't get a "clean shift" and scrape or fight with the gears when changing gears. The cure is to adjust the rod out which lengthens it and pushes on the clutch fork and moves the throw-out bearing closer to the diaphragm/pressure plate fingers and compensates for the clutch disc wear (unless it is slap worn out). To adjust you loosen the lock nut and unscrew the adjusting rod out. Note it will be square near its ball end and this is so you can either use a small open end wrench, or an adjustable wrench as I do. Sometimes if it is not cruddy/rusty, you can adjust by hand - but not my experience unless it was new. FIRST, move the clutch fork back and forth to get an idea/feel for how much free play you have between the throw-out bearing and diaphragm/pressure plate fingers. That amount of free play is too much, so you know what you don't want. Back the rod out BUT, not so far that it puts the throw-out bearing up against the diaphragm/pressure plate fingers. Simply test this as you adjust the rod by moving the clutch fork back and forth on its pivot ball - you should have a reasonable amount of free play. Once you think you have it, tighten up the nut to lock the rod into place. Some rods I have used will not have a threaded fitting on the linkage end, but a drilled smooth hole and the rod will slide through and you will have a nut on the back side and nut on the front side and you simply tighten them both up so they clamp the linkage end together like a sandwich. Once you have it adjusted to where you think it is good, time to test it. Your first test will be free-play travel of the pedal. You should have about 1 " of travel (Service Manual calls it "lash') where you can easily push the pedal down before the linkage begins to operate the clutch fork and push the throw-out bearing up against the fingers on the diaphragm/pressure plate. If you have this, you are at a good starting point. This can sometimes vary AND, there is a rubber stop that the clutch pedal hits up under the dash. This is more to keep noise down when the pedal is returned fast, but it can be cut down, or even removed, in circumstances where you need a little more pedal travel depending on the type of pressure plate fingers/throw-out bearing being used. Next, Fire the car up and push the clutch to the floor. Now release the clutch with the trans in gear and see how high the pedal comes up off the floor before the clutch grabs. I like to see it lift up off the floor probably somewhere around 3 inches. I don't like a clutch that grabs near the floor and this is also an indicator that the clutch is worn and is in need of adjustment or flat worn out. Too low and you are not pushing the clutch in completely and it's a matter of time before it is worn out. This height can be somewhat adjusted a little up or down as long as you are pushing the clutch in enough to get a clean release and/or letting the pedal out so the clutch fork is not being pushed against the diaphragm/pressure plate fingers. So this is a "test it" thing to find where you like the clutch pedal height for you. You will read on many aftermarket clutch suppliers that they recommend and "air gap" setting between the disc face and the flywheel face. It takes 2 people to do this as one person has to push in the clutch while someone under the car uses a feeler gauge to check the air gap. I have never in my life done this and never will. You know when a clutch works and you know when its not. If your linkage is old and sloppy, this will not be of help when you go to adjust the adjuster rod. You may still be able to do so, but sometimes you will find you have to extend the rod fully and still may not get enough out of it. They do may longer adjuster rods, but this really is not the way to go unless you can still get enough travel from your clutch pedal to get a clean release. It is also easy to be fooled when you install all new parts and you were given a wrong throw-out bearing length and you figure you can compensate by using a longer/shorted adjuster rod - wrong, not a good band-aid fix. If the factory length adjuster rod does not seem to be a correct length, look for other issues.
> View attachment 160049
> View attachment 160050
> View attachment 160051


 thank you sir. this is great, have a bag of parts, been getting to it.... be spendiing christmas under a gto instead of a christmas tree this year.


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