Firewall Adjuster.....Need some Input on a Issue *Please Come In*

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there will be MORE slack in the cable as the clutch wears
 
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there will be MORE slack in the cable as the clutch wears

care to make a bet? If that is the case you should be able to loosen the cable completely and have it slip like mad. It won't.

Why don't you try it rather than posting things that are simply wrong. I just adjusted ours again and had to make the cable longer to compensate for the wear. On a self adjusting cable, you back the two nuts on the end of the cable out, which makes it longer. On the firewall adjuster you screw it in, which makes the cable longer.

BTW if the above were to be true, what would happen as the clutch wears. the pedal would get lower and lower as the cable lengthens. But that isn't what happens, is it? Think about it. The pedal take-up point gets higher and higher and if you don't adjust it, it will start to slip because too much pressure is always on the release fork... If you don't agree with that, then go screw that firewall adjuster _in_ to lengthen the cable, then tell me what happens to the pedal take-up height. And then decide if that is what is happening as the clutch wears (which it isn't).


worse than trying to teach something complex to a group of cub scouts... At least they will try what you tell them to try, first.

You seem to think that the cable engages the clutch. if that were the case, when the cable breaks, you could not move because the clutch would be disengaged. that is not what happens as anybody who has had one knows. The cable _disengages_ the clutch as it is shortened by the pedal.

jeez...

All you have to do is make the measurement I suggested to dispel this nonsense and get back to reality.

Your diagram is wrong. The release fork does not push the pressure plate closer. It presses on the release fingers which are levers pinned in the middle. As they are pressed in in the center, the other end of the lever moves _away_ from the flywheel to disengage the pressure plate. Get a good diagram, not a piece of junk that shows nothing. Or read a good book. Or ask a mechanic. Or ask someone that has actually installed these things. To correct your poor animation, as the release bearing moves toward the flywheel, the pressure plate moves _away_ from the flywheel to disengage. You are showing it backward.
 
View attachment 308843


there will be MORE slack in the cable as the clutch wears


exactly...that's why you need to adjust the collar out...it makes the effective path of the cable longer and has the effect of shortening the cable (since you aren't actually changing the length of the cable, but rather the cable sleeve)

but I'm done with this...to the OP good luck getting it sorted...if your quadrant is good I'd look at a stretched cable :nice:
 
exactly...that's why you need to adjust the collar out...it makes the effective path of the cable longer and has the effect of shortening the cable (since you aren't actually changing the length of the cable, but rather the cable sleeve)

but I'm done with this...to the OP good luck getting it sorted...if your quadrant is good I'd look at a stretched cable :nice:


Sorry, but if you adjust the collar _out_ you are shortening the cable, because you are lengthening the housing which increases the distance from the firewall to the bellhousing termination of the housing.

I know this all sounds backwards, but it works _exactly_ as I (and another) have said. when you screw the firewall adjuster in, the housing becomes shorter, which effectively makes the cable longer. If you screw the adjuster out, it effectively shortens the cable. Try this to convince yourself.

Screw the adjuster all the way in. What happens? The clutch pedal take-up point moves down to the floor and you will feel a lot of pedal play from the top until where the release bearing begins to press on the release fingers. If you remove the fork cover, you will see that the cable is loose and can be pulled out the back of the fork and even removed if you want. Now start to back the firewall adjuster out. And every turn you will notice that the cable end gets closer to the release fork, until when you get it just right, it is just in contact. if you continue to back it out beyond that point, you start to release the clutch engagement and the clutch will begin to slip. If you continue all the way, the clutch won't engage, you can shift while the motor is cranked, but releasing the pedal will not do a thing. Probably the adjuster won't go that far, but it will go far enough for you to look underneath and confirm that if you shorten the adjuster by screwing it _in_ the cable gets longer. If you lengthen the adjuster by backing it out, the cable gets shorter. The cable is not actually changing length, but the path it has to follow thru the housing changes length, which is the same thing...

If he has a newish clutch, his firewall adjuster looks perfect. And as the clutch wears, and the take-up point gets higher and higher on the pedal, he will need to screw it in to lengthen the cable (shorten the path) to provide slack to lower the take-up point back to where it should be.
 
I still think me cable is worn. This is a brand new clutch and i know that the Adjuster moving out shortens the cable. As the clutch wears you need a shorter cable, not a longer cable.

From my understanding, my cable is stretched..... i will prove Bob wrong when i get a new cable and the adjuster is back inside the firewall where it should be.
 
I still think me cable is worn. This is a brand new clutch and i know that the Adjuster moving out shortens the cable. As the clutch wears you need a shorter cable, not a longer cable.

From my understanding, my cable is stretched..... i will prove Bob wrong when i get a new cable and the adjuster is back inside the firewall where it should be.


You still have this backward. As the clutch wears you need a _longer_ cable. Again, look underneath the car at the clutch fork on a new clutch. The fork will be relatively close to the front of its travel. Is the clutch disk wears, the pressure plate has to move closer to the flywheel to take up that slack, and that causes the release fingers (which are levers pinned underneath the pressure plate cover) to move away from the flywheel. This makes the throwout bearing have to move farther back to fully engage the clutch. And to move the throwout bearing back, the clutch fork has to go back farther. Hence the need for a longer cable. So as the clutch wears, the cable has to lengthen, or your take-up point will get higher and higher, to the point where the clutch will not fully engage and start to slip. Lengthen the cable solves this.

trust me, your cable sounds fine. Stop by and ask anyone that actually works on these things how it works before buying something that you don't need. Several in this thread simply don't have a clue. It works _exactly_ as I have explained. Do a google search and you can find some good videos that show how this goes clearly and understandably...

If you really want to buy a new cable, go for it. But don't be surprised when nothing changes except that your wallet is 80-90 bucks lighter. :) And you are not going to prove me wrong, any more than you can prove that the motor will run with the spark plugs installed upside down. There's no doubt on this issue, absolutely none. we just adjusted ours again this afternoon after a trip to the strip last night. I keep about 1" of freeplay at the top of the clutch pedal travel, and when it goes away, which signals some wear has occurred, we _lengthen_ the cable to get it back to the original take-up point about 1/2 way off the floor or so...

Be waiting on your report, so we can close this silly thread...

BTW, if, after the new cable, your adjuster has to be screwed all the way in to get proper clutch function, you are going to be so far beyond screwed, it will take sunlight six months to get from screwed to where you are. Because you have _zero_ adjustment left as the clutch wears... The adjuster has to go _in_ as the clutch wears, not out.
 
Although I agree with Bob on the actual wear issues of the clutch and how the FW adjuster will have to be adjusted in, the cable being old and stretched is what the issue is here. If you have "lengthened" the cable all the way out with the FW adjuster then the new cable being shorter will allow the adjuster to be moved to a more satisfying position instead of all the way out as is his issue now. Granted that as the clutch wears the adjuster will have to be moved to compensate but the issue glaring is the adjuster is way out from the norm.
 
well first of all i do understand how a clutch works and didnt feel like spending hours drawing out a super detailed animation of how a clutch works. i have done numerous clutch and transmission swaps as well as a bunch of motor work so im not just making stuff up


but i will admit when im wrong and further thinging about it you are correct about the cable needing more slack as it wears. the TOB rides on the fingers and as the clutch wears the fingers move back, requiring MORE cable.
 
I have not seen a cable stretch for an inch or more without (a) getting tough to press the clutch pedal as the wires have to break to let it stretch; (b) breaking soon thereafter due to the individual cable wires breaking...

On my fork-end adjuster, the threaded stud is probably 1.5" of threads, maybe 2", and on a new clutch, the nut is all the way on the stud, when it is time to replace, the nut is just barely on the end of the stud. So the firewall adjuster needs at least 1.5" and probably closer to 2" of travel, plus slop on either side to account for varying clutch disk thickness, etc...
 
It ought to be proportional. As you screw the firewall adjuster out by 1/4", you essentially shorten the cable by that same amount. Looked like his adjuster was something like 2.5" extended, which seems reasonable since it will probably be screwed in about 2" or so over the life of the clutch.
 
I have not seen a cable stretch for an inch or more without (a) getting tough to press the clutch pedal as the wires have to break to let it stretch; (b) breaking soon thereafter due to the individual cable wires breaking...

On my fork-end adjuster, the threaded stud is probably 1.5" of threads, maybe 2", and on a new clutch, the nut is all the way on the stud, when it is time to replace, the nut is just barely on the end of the stud. So the firewall adjuster needs at least 1.5" and probably closer to 2" of travel, plus slop on either side to account for varying clutch disk thickness, etc...
also have to take into account that he is using an aftermarket quadrant that probably dosent eat up as much cable as the stock one
 
See sig...and I've also had to replace 2 clutch cables and a clutch.

so as your clutch wears the pedal gets firmer and higher and you have to adjust the firewall adjuster IN and loosen the cable to get the travel correct???

'cause on mine when I adjust it IN the pedal gets sloppier and looser (and if it goes in enough it'll fall off the quadrant)...and as the clutch wears I need to adjust OUT a bit to get the clutch pedal snug again :shrug: it's only worked that way for about 85/90,000 miles so maybe I've been doing it wrong
 
also have to take into account that he is using an aftermarket quadrant that probably dosent eat up as much cable as the stock one

That's a possibility. we bought a complete kit at Advanced a while back, which came with a billet aluminum quadrant, plus the fork-end adjustable cable I mentioned.

But no matter what kind of quadrant, you are going to need around 2" of travel after it is properly adjusted to compensate for future wear...
 
so as your clutch wears the pedal gets firmer and higher and you have to adjust the firewall adjuster IN and loosen the cable to get the travel correct???

'cause on mine when I adjust it IN the pedal gets sloppier and looser (and if it goes in enough it'll fall off the quadrant)...and as the clutch wears I need to adjust OUT a bit to get the clutch pedal snug again :shrug: it's only worked that way for about 85/90,000 miles so maybe I've been doing it wrong


That is correct. But you don't adjust it that far in. I personally like a little slop at the top, so that when that is just about gone, I know to crawl under and lengthen the cable to add the slop back. That little bit of slop also makes the take-up point a bit lower which helps on shifting since there is less pedal travel required when we are at the strip...

It is easier to explain when you are looking at the clutch fork, but the basic idea is that the fork moves toward the rear of the car as the clutch wears, because the disk is thinner and the pressure plate has to move forward toward the flywheel to grab. And as it wears, if you don't loosen the cable, it will not let the fork move far enough back to remove all pressure from the release fingers, which will act sort of like keeping your foot on the clutch to let it slip a little.... when you loosen the cable, it is like pulling your foot the rest of the way off the pedal and you now get full pressure-plate clamping force.
 
I just stumbled across this thread and thought it would be very useful to explain why Bob Hyatt is 100% correct.

I suspect that some people are being fooled by the animation in post #21. That post should be deleted, because it is missing a critical component. The Pressure Plate. The spring in the pressure plate is a conical lever. The inner end of the cone is the pressure plate fingers. The outer end of the cone is the part which presses on the friction ring of the pressure plate, to clamp the friction disc. This means that as the friction disc gets thinner (wears), the fingers on the pressure plate get closer to the rear of the car, because lever. This becomes very obvious if you have ever installed a pressure plate on a flywheel. Before the bolts are tight, the fingers are rearward on the pressure plate, because the friction disc is effective very thin (pressure ring far forward). As the bolts are tightened (friction disc getting thicker = pressure ring rearward), the fingers move forwards in the car.

Because the clutch fork is a class 2 lever (not a class 1), as the pressure plate fingers move rearwards, the end of the clutch fork must also get longer, so the cable must get longer to maintain a constant tension.
 

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