Clutch won't disengage

[kc92awd]

1992 AWD 5-speed. I put an ACT 2100 in and it won't release when I push on the pedal.

I already tried bleeding it.

I put it on the lift and have some more information. It seems that the rod coming out of the slave cylinder does not push the clutch fork far enough. So, I put 3 nickels between the fork and the slave cylinder rod. Even with the added "spacer", I measured and the fork did not move any further. So it is like the slave cylinder just can't push hard enough.

The clutch is adjusted almost all the way under the dash. What do you think is the problem?

 

[turbo90gsx]

Pull the boot back on the master cylinder inside(under the dash). It there is fluid coming out of the seals, replace the master cylinder. If not, screw the adjustment rod 1/4in into the adjustment bracket. Bleed bleed bleed. NOW keep unscrewing the adjustment rod out untill you are satisfied. Never start bleeding the clutch line with the adjustment rod all the way out, it doesn't do anything to change the pressure.

 

[coldshard]

first off inspect the entire clutch assy, all the lines, master cyl, pedal assy, and fork. then go out and get a ss clutch line. i had a similar problem the stock rubber line has a tendency to bulge after a few years and putting an upgraded clutch in without changing it may be causing your problem. you might also want to put a lock washer under the fork ball, it will move the release point up off the floor a bit, if one doesn't work try two. those are the first things i would check.

 

[oldman]

Make sure you don't just crank open the bleeder valve when bleeding.

 

[GTM]

first off inspect the entire clutch assy, all the lines, master cyl, pedal assy, and fork. then go out and get a ss clutch line. i had a similar problem the stock rubber line has a tendency to bulge after a few years and putting an upgraded clutch in without changing it may be causing your problem. you might also want to put a lock washer under the fork ball, it will move the release point up off the floor a bit, if one doesn't work try two. those are the first things i would check.

These are all valid and reasonable. If I may offer that the lock washers should be considered temporary fix if they work.

I thought there was a good article on Vfaq.com which addressed the clutch pedal linkage but couldn't find it. The linkage unfortunately runs behind the heater and I've only tried a little to see where parts get worn and broken. (my son's car and he didn't want to get that involved) Perhaps with proper light and maybe even a mirror you can take a look without removing things. The author offered a couple different ways to fix the problem, one was to replace the damaged plastic worn part or to braze a couple tabs/ears on the linkage lever. I am of the opinion IF memory serves and this is your problem that the job would take 2-3 hours to complete outside of the brazing job which then doesn't require the plastic part and a more positive connection. I suspect that many of the complaints regarding clutch release could be cured by making this fairly simple repair.

Wish I could be more specific other than you loose a lot of pedal travel when it needs it most. Maybe someone else can jump in here who have done the job or know where to find the article online.

Cheers,
GTM

 

[oldman]

http://www.taboospeedshop.com/clutch_pedal_assembly.htm

There are two more tech articles as well on this site. You don't need to look at it, you can just check for freeply by letting the pedal come up and pull it with your hand to see if it comes up more. I only had about 1/2 " freeplay and it caused all kind of problems.

 

[kc92awd]

I see what you're saying guys, but here's the thing: If I'm thinking correctly, fixing these likages and stuff will simply allow the rod of the slave cylinder to extend further, therefore pushing the fork further and allowing the clutch to release.

That would probably fix the problem on many cars.

BUT, as I stated in my first post, I already put 3 nickels between the rod and clutch fork. What this should've done is pushed the fork 3 nickel-widths further, plus the depth of the hole in the clutch fork that the rod goes into. But, I measured and the fork was not pushed any further.

Therefore, in my case, I think even if I did adjust linkages and such, as soon as the slave cylinder gets the fork to point where it is pushing on the pressure plate, it still wouldn't go any further.

It is like my problem isn't the slave cylinder pushing FAR enough, the problem is with the slave cylinder not pushing HARD enough to overcome the force of releasing the pressure plate.

Let me know if I am way off here.

 

[GTM]

http://www.taboospeedshop.com/clutch_pedal_assembly.htm

There are two more tech articles as well on this site. You don't need to look at it, you can just check for freeply by letting the pedal come up and pull it with your hand to see if it comes up more. I only had about 1/2 " freeplay and it caused all kind of problems.

That url does depict some of what I remember though not as extensive, but had seen it before also. I was ASSuming they had at least checked / adjusted free play at the pedal cluster. The site offers "bronze" replacment bushings which they may custom make for the application. You know I love to fix things and have made similar bushings from Oilite bearings which you can buy at any "good" hardware store for less than $2. All you need is a bit of common sense, a hacksaw, a reasonable selection of drill bits with index, and a "mill bastard" (a type of cut designed in the file) file.

Using the clevis pin and the drill index select the best size drill bit and drill the bearing(s) you may have to stack 2 bearings to span the clevis pin length. If you drill just through them and not to ream them out they will be snug on the drill bit. With them stuck on the drill bit you clamp the drill motor down and turn it on, using the file you machine the outside diameter to fit where the plastic bushing were located. Keep the file clean, use candle wax on the file to keep it from loading the file teeth just as you would with aluminum or any soft metal. What you won't have is the flair at the end so you will need to cut the length so you have room for a flat washer at each end of the clevis pin and snug enough so it can't move very much side to side in the clevis fork. Coat the bearings with oil or Vasoline when you make the final install.

Should last forever.

Cheers,
GTM

 

[oldman]

It is like my problem isn't the slave cylinder pushing FAR enough, the problem is with the slave cylinder not pushing HARD enough to overcome the force of releasing the pressure plate.

Let me know if I am way off here.

You're exactly right about the hard/far part. Welding the clutch pedal lever allows you to get the full stroke on the master cylnder to generate higher pressure to make the system push harder. Also make sure you follow the bleeding method prscribed on vfaq so air doesn't get back in.

 

[oldman]

That url does depict some of what I remember though not as extensive, but had seen it before also. I was ASSuming they had at least checked / adjusted free play at the pedal cluster. The site offers "bronze" replacment bushings which they may custom make for the application. You know I love to fix things and have made similar bushings from Oilite bearings which you can buy at any "good" hardware store for less than $2. All you need is a bit of common sense, a hacksaw, a reasonable selection of drill bits with index, and a "mill bastard" (a type of cut designed in the file) file.

Using the clevis pin and the drill index select the best size drill bit and drill the bearing(s) you may have to stack 2 bearings to span the clevis pin length. If you drill just through them and not to ream them out they will be snug on the drill bit. With them stuck on the drill bit you clamp the drill motor down and turn it on, using the file you machine the outside diameter to fit where the plastic bushing were located. Keep the file clean, use candle wax on the file to keep it from loading the file teeth just as you would with aluminum or any soft metal. What you won't have is the flair at the end so you will need to cut the length so you have room for a flat washer at each end of the clevis pin and snug enough so it can't move very much side to side in the clevis fork. Coat the bearings with oil or Vasoline when you make the final install.

Should last forever.

Cheers,
GTM

Yea don't even bother with the taboo bushing kit. I email them about it in July, haven't heard a thing from them. I welded it with the plastic bushings, just got to be careful with it.

 

[GTM]

I see what you're saying guys, but here's the thing: If I'm thinking correctly, fixing these likages and stuff will simply allow the rod of the slave cylinder to extend further, therefore pushing the fork further and allowing the clutch to release.
That would probably fix the problem on many cars.
BUT, as I stated in my first post, I already put 3 nickels between the rod and clutch fork. What this should've done is pushed the fork 3 nickel-widths further, plus the depth of the hole in the clutch fork that the rod goes into. But, I measured and the fork was not pushed any further.

Therefore, in my case, I think even if I did adjust linkages and such, as soon as the slave cylinder gets the fork to point where it is pushing on the pressure plate, it still wouldn't go any further.

It is like my problem isn't the slave cylinder pushing FAR enough, the problem is with the slave cylinder not pushing HARD enough to overcome the force of releasing the pressure plate.
Let me know if I am way off here.

No not off base, been there and done that when sorting out problems.

Do consider the fork could be bent, the ball pivot is not correctly adjusted or the incorrect one.

When you got the disk did you check it's thickness against what you took out and what is specified? When you assembled the disk were the fingers essentially level, concave, or conves?

A proper assemble will be level though I've seen both slightly concave and convex. As a diaphram clutch wears they will protrude outward (convex) and will become harder and harder to push the pedal until it starts to slip when it's worn out. This is because of the overcenter design requires it to travel further before it releases.

The slave cylr should be able to compress till it bottoms out, (fully retracted) if you can't then the master cylr is adjusted too tight and not allowing it to take a full charge of fluid. You can crack a fitting and see if you can retract any further, if you can then the problem more than likely is upstairs.

If the master cylr clevis rod (they call it a "C-bracket" god only knows why) has a threaded end you can adjust for a little freeplay, not a lot, and not snug. Ahha, can't remember when and why I tried this but some slave clyrs use a rubber hose like a brake line... that may have been mentioned here. Put a pair of Vice Grips on the hose and pinch it off. Now carefully try the clutch pedal with your hand, this will either come up rock solid or show you if the linkage is needing attention.

Your description of "not pushing hard enough" is what I think is the classic symptom of worn linkage. Early Datsuns 510, 610, 240 and maybe 260 cars had an adjustable push rod on the slave but you can't use this push rod without there being a hole in the T/O bearing for the rod to extend beyond the ball / socket. Later models were self adjusting and never gave any problems and the thought of drilling a hole in the fork gives me chills for it's been carborized and ground... like trying to drill bearing steel.

If you try the Vice Grips make sure you have all the free play properly adjusted at the pedal cluster and at the clevis on the master cylr for it has to take a charge of fluid and the port is almost at the very end.

Keep us posted on what you find.

Cheers,
GTM

 

[GTM]

Yea don't even bother with the taboo bushing kit. I email them about it in July, haven't heard a thing from them. I welded it with the plastic bushings, just got to be careful with it.

What a bunch of nonsense... good customer relations eh.

I'm no DSM expert, but have seen a few of those plastic bushings cracked and broken on other makers but still using Tokiko or Toyo hardware. I also think the weld/braze job will realize the most gains... a whole lot more than just changing the plastic bushing. They use to make windshield wiper motors and window winder with that same eleptical hole which would wear out just like Murphy's Law when you need it most.

Am I correct in saying that link rod can be removed from either end so if you weld it you can still take apart for service or greasing??
...................

What we are saying is the linkage gets to a certain pressure and then starts to slip in the eleptical hole because it's worn and thus cannot push the slave cylr far enough. There is a pretty beefy spring on the linkage and thus when you release it slips back until the next time you push the pedal.

Cheers,
GTM

 

[oldman]

Am I correct in saying that link rod can be removed from either end so if you weld it you can still take apart for service or greasing??

If I remember correctly, no. The cross rod can only be removed from one side so once you weld it, you are pretty much stuck with it. As for customer sevice on the part of Taboo, read their policy and you'll get a good idea.

 

[GTM]

If I remember correctly, no. The cross rod can only be removed from one side so once you weld it, you are pretty much stuck with it.
...
As for customer sevice on the part of Taboo, read their policy and you'll get a good idea.

Ok, so once welded then it's necessary to remove the heater to get to all the support bracket mounting bolts? I remember thinking about brazing but you can't put a torch under the dash.
Think I got my hand on the lever but couldn's see what I was feeling so wasn't sure if it was slipping. My son sold his car so I don't really have to worry about it but feel it's common enough problem with DSMs that I wish I'd made the repairs just so I could give better advice.
.............

On their home page they indicate they have had email problems along with family illness, still it's a drag when you need some little trinket that makes the difference between having wheels and borrowing a car. That's just one of the reasons I've had to make my own parts. I'm sure Devcon aluminum epoxy could be cast in place of the nylon plastic bushings and it would work. Just put a good Carnuba wax where you don't want things to stick and use masking tape as a dam to keep it from running out.

Cheers,
GTM

 

[kc92awd]

Do consider the fork could be bent, the ball pivot is not correctly adjusted or the incorrect one.

The fork is brand new. On RRE's site they have a way to check. They say to pull the fork toward the passenger side of the car. When it stops, it should be pointing straight forward or still angling toward the driver's side. Mine is still angling toward driver side so I think it's fine.

When you got the disk did you check it's thickness against what you took out and what is specified? When you assembled the disk were the fingers essentially level, concave, or conves?

The clutch disk was brand new so it was thicker than old one b/c that one was worn. I'm not sure that's what you mean though. I don't know what you mean by fingers.

The slave cylr should be able to compress till it bottoms out, (fully retracted) if you can't then the master cylr is adjusted too tight and not allowing it to take a full charge of fluid. You can crack a fitting and see if you can retract any further, if you can then the problem more than likely is upstairs.

I can compress the slave cylinder, but I don't know how to tell if it's bottomed out. What do you mean by "crack a fitting"?

I will check everything you suggested today and report back. Thanks.

 

[kc92awd]

You're exactly right about the hard/far part. Welding the clutch pedal lever allows you to get the full stroke on the master cylnder to generate higher pressure to make the system push harder. Also make sure you follow the bleeding method prscribed on vfaq so air doesn't get back in.

Oh, I see. Thank you for correcting me. I am much more optimistic about this working now. There is a little pin that goes into a hole in the clutch pedal when it come up all the way. My pedal doesn't come up far enough to reach that. Then by hand I can pull it up a little more until that pin goes in and it stops.

 

[oldman]

Oh, I see. Thank you for correcting me. I am much more optimistic about this working now. There is a little pin that goes into a hole in the clutch pedal when it come up all the way. My pedal doesn't come up far enough to reach that. Then by hand I can pull it up a little more until that pin goes in and it stops.

You are wlecome. I've struggle this problem last year, changed mc, sc, clutch line, extended slave push rod and bled it god knows how many times all because I refuse to beleive 1/2" inch of play can make such a difference. Have fun.

 

[GTM]

Oh, I see. Thank you for correcting me. I am much more optimistic about this working now. There is a little pin that goes into a hole in the clutch pedal when it come up all the way. My pedal doesn't come up far enough to reach that. Then by hand I can pull it up a little more until that pin goes in and it stops.

No not quite. The clevis pin is allowed to pivot within the holes in the fork and the lever. They don't drop into anything when the pedal is operated. The clevis pin is attached through the clevis fork and the lever, it is held in place with a cotter pin. Where it goes through the lever that is known to wear there is a plastic bushing that wears. On that same lever there is an eleptical hole where the cross shaft is attached with a nut so you can't see the eleptical hole until you remove the nut. It is there where it slips and enlarges the eleptical hole and wears the cross link shaft as well.

You could try tightening the nut but you run the risk of breaking or stripping the threads. You also can go to dealer for new plastic bushings.

Look at the pictures, they show the important parts and the repairs suggested.
.................................

The "fingers" are part of the pressure plate where the throw-out bearing presses, might be 10-15 of them on a diaphram clutch but usually only 3 on a spring clutch. I asked about the disk thickness and the finger position because people make mistakes and give you the wrong parts. Though they may fit they don't work correctly and the easy way to prevent problems before putting tranny back in is to check. Disks come in different thicknesses, usually in the 8,9,10 mm area, slip an open end wrench on them is the fastest way, takes 10 seconds. Same when checking if it's worn to thin. These were things to have observed when it was apart and if the lever and other repairs don't solve the problem and you have to pull it apart again. Things happen even to professionals.
................

"Cracking a line" hmmm not sure where I learned that one... British cars? It means to loosen a hydraulic or fluid fitting just enough to let a small amount of fluid out, usually not a full rotation. Not all slave cylrs have bleeders so you have to use the line, thus when you need to check if the piston is fully retracted it allows the fluid and bubbles to escape without being forced back up the line and into the circuit. You only need to worry about these things if those other repairs/adjustments mentioned don't solve the problem.

Cheers,
GTM

 

[kc92awd]

http://www.taboospeedshop.com/clutch_pedal_assembly.htm

There are two more tech articles as well on this site. You don't need to look at it, you can just check for freeply by letting the pedal come up and pull it with your hand to see if it comes up more. I only had about 1/2 " freeplay and it caused all kind of problems.

I have more than 1/2". I am about to pull that assembly to have it welded. But before I do, is there anything else that would cause the pedal to not come up all the way on its own? Or can I conclude that this is my problem based on the free play because it doesn't come up even with the brake pedal until I pull it quite a bit?

 

[ss94s10]

try clamping the rubber clutch line open the slave bleeder get some shop air and give a little blow. then gravity bleed.
good luck

dc

 

[GTM]

I have more than 1/2". I am about to pull that assembly to have it welded. But before I do, is there anything else that would cause the pedal to not come up all the way on its own? Or can I conclude that this is my problem based on the free play because it doesn't come up even with the brake pedal until I pull it quite a bit?

I'm not sure anyone can give you absolutes, these are educated guesses that past experience has taught. It's a miserable job for you are standing on your head with your feet up over the backrest or twisted in knots getting burned with drop lights etc. Wear a watch cap, come equipped with some bad words, and a small pillow for your head.

As I suspected the master cylr is not coming all the way back to expose the port that feeds the piston and take a full charge of fluid. This is then just oscillating back and forth and _cannot_ advance the slave piston as it adds fluid to complete the demand. I really don't think repairing the shaft linkage will be a wast of time. No mechanic wants to be wrong and recommend repairs that don't solve problems, you have done and tried everything else.

When bleeding the slave use a small bottle and a hose, keep the end of the hose below the fluid level in the bottle so it can' suck air back into the circuit. Don't pump the pedal rapidly for this causes large bubbles to get broken into tiny one which don't rise as fast. The bleeder doesn't need to be wide open (3 turns?) except the first few pumps, after that maybe 1/2-1 turn. I use a 3 pump sequence once I have fluid coming out the hose. Add fluid as needed, pump 3 times, lock bleeder down just snug, chk pedal, repeat a couple more times.

I expect to see smiles in your next post.

Cheers,
GTM

 

[kc92awd]

I got it to release! The adjustment rod was almost all the way adjusted. But I decided to turn it a few more turns to see what happened. As I turned it, the pedal started coming up more and more. Finally, it got to the point where the clutch released.

But this is VERY temporary. The adjustment rod is literally hanging on by a couple of threads. It doesn't poke through the threaded hole anymore. So the assembly is definitely worn, right? Can an exhaust shop weld it or a machine shop or what?

 

[GTM]

I got it to release! The adjustment rod was almost all the way adjusted. But I decided to turn it a few more turns to see what happened. As I turned it, the pedal started coming up more and more. Finally, it got to the point where the clutch released.

But this is VERY temporary. The adjustment rod is literally hanging on by a couple of threads. It doesn't poke through the threaded hole anymore. So the assembly is definitely worn, right? Can an exhaust shop weld it or a machine shop or what?

I didn't want to even go there for it just gives you a false sense you fixed the problem. You only added to the problem of it NOT being able to take a full charge of fluid.

Yes, a muffler shop is quite capable of welding, I prefer brazing because there is a remote chance you could take things apart and things don't have to get so hot and loose some heat treating. If you have a power wire brush clean any dirt, rust, grease, or paint away, do quench it in water the moment it gets solid.

Hurry up, the shops are going to close.

Cheers,
GTM

 

[kc92awd]

I didn't want to even go there for it just gives you a false sense you fixed the problem. You only added to the problem of it NOT being able to take a full charge of fluid.
GTM

Yeah, but it also helps confirm the real problem.

I've never heard of brazing. Can a muffler shop do that?

 

[oldman]

Yeah, but it also helps confirm the real problem.

Just make sure you don't drive with the rod all the way out for too long or you'll be replacing the slave cylnder as well.


edit: After you weld the assembley, make sure you turn the rod in before you start the bleeding process, readjust it afterwards if needed.