SodiumFlouride

I need gentle advice on ADJUSTING clutch pedal bolt please.

No matter whether I adjust the bolt all the way inside the clutch pedal (turning it CCW facing the pedal like a foot would).
Or if I turn the adjusting bolt all the way out of the clutch pedal (turning it CW).
Or halfway between...

I can't figure out WHAT to measure.

I don't feel any "slop" anywhere (e.g., between the rounded tip and the master cylinder piston cup).

WolfMann

This might help, its from an 83 pickup fsm, I'd recommend picking up a Chilton or factory service manual for your truck.

SodiumFlouride

Thanks for that diagram as it helps a lot to visualize what to measure.
It seems there are three things, which seem to only really be two things.
1. The pedal height from floorboard to the top of the pedal rubber (about 150mm).
2. How far the pedal goes down pushed with one finger until a click is heard as the round end of the bolt hits the master cylinder piston cup

This #2 measurement seemed to be about 10mm but my only confusion left is that these two things seem to be the same thing:
A. Pedal freeplay
B. Pushrod play

The reason they seem to be the same thing is that, with one finger on the pedal, you can push the pedal down about 5mm until you hear and feel the pushrod hit the master cylinder piston cup. I can't distinguish between the two with my finger or measurement at the top of the rubber part of the pedal position.

akwheeler

You really seem to be over-thinking things, could you fill us all in on what you are trying to accomplish? is your clutch not working or are you trying to return your truck to exact factory adjustments?

SodiumFlouride

Not mine. My sisters. I rebuilt her master and slave and replaced the transmission fluid and just wanted to adjust the clutch after all that.
I drive an automatic, so I don't know how this one is supposed to feel.

It engages late in the pedal cycle with the measurements above. It doesn't slip. It has at almost 100K miles on the existing clutch which was replaced about 8 or so years ago from new.

I'm just trying to put it where it's supposed to be.
Any help is appreciated.

akwheeler

This is one of those thing where if it's not broke don't fix it. As long as the clutch works, the clutch switch only allows the truck to start when the clutch pedal is depressed and you get full release from the clutch master cylinder you are golden.

Thommo Thompson

if its dissengaging late, close to the floor, then u need to bleed the system more.
did u bench bleed the master before installing? if not, thats ok its not the end of the world, but u will have ti vacuum suck all the air out as itw near impossible to bleed it using the open n close method. open n close method only really works to flush the system. air bubblea want to rise and they just stay in the pipe unless u suck them out.

SodiumFlouride

It's engaging too late and with little "feel", which just seems wrong.
So I think there is something wrong - but I don't know what because they're self adjusting, so the engagement isn't in my control other than the adjusting bolt.

Maybe. Maybe not.

Years ago, I replaced her torsion clutch pedal return spring with the linear Toyota brake pedal return spring, so that's out of the picture. A while ago, she couldn't get into or out of gear - but there was no grinding sounds whatsoever.

Knowing they're basic maintenance items, I changed her lube to Redline MT90 and replaced the green and white shifter bushings with Marlin Crawler aftermarket bushings, but they didn't solve the problem (but there was no harm done since they're both maintenance items anyway).

When I rebuilt the slave and master - that instantly solved the hard shifting problem.

Now the only problem is that the "feel" of the pedal stinks. It's hard to describe, but it just doesn't grab right. It's not slipping. I can stall the car putting it in third and trying to start.
It's just grabbing all of a sudden and within only an inch or so of travel, and late in the up-pedal cycle.

The only adjustment there is, is this pedal bolt - so I just want to ensure that it's in the perfect spot since there's nothing else that can be done.

SodiumFlouride

Thanks for the help as it's hard to describe.
It's engaging and disengaging far from the floor, near the top of the upswing of the pedal cycle.

I spent a long time on that "bench bleeding" before I realized a bunch of things about bench bleeding this vehicle.
Certainly some clutch master and slave cylinders 'trap air' inside, due to the angle of mounting and the 'loops' of the piping, but these are horizontal and don't trap air in the tubes.

So I've concluded, after much effort and research, that bench bleeding, while important on some vehicles, is not going to help on this vehicle.
[I could be wrong - so I bench bled meticulously anyway - but I don't think it mattered because I bled thoroughly with blue DOT fluid so it's completely bled free of air and old fluid.]

I could be wrong (it wouldn't be the first time) but I'm pretty confident, for two reasons, that the bleeding I did is perfect.
1. It's not hard to bleed these things, and while I did meticulously bench bleed, it didn't matter that I did.
2. It's not a "spongy" pedal feel that I'm trying to describe - it's a "late engagement and quick engagement" feel.

It's really hard for me to describe the "problem" which is that the engagement and disengagement is *late* in the pedal upcycle, near the top of the pedal travel upward.
It could be as simple as a worn clutch, as I don't know what an "almost worn" clutch feels like when it's not slipping - so that's part of my question.

Q: If a clutch isn't slipping - how do you know if it's worn?

(It's sort of like brake pads, I would think, where the only thing you'd feel is "pedal travel" - but aren't these self-adjusting clutches?)

akwheeler

So, with a hydraulic clutch they are self adjusting, the only way to tell if the clutch is worn out is by functionality, if it slips you need a clutch. If you can't shift or disengage the clutch all the way you need to bleed it or troubleshoot the hydraulics. other signs of clutch issues are chatter or noises that come and go when you push the pedal in. Pedal height makes no difference as long as you get complete clutch release when it's depressed and the switch actuates for the starter enable, also when releasing the pedal it returns to a comfortable working height and fully releases pressure from the master cylinder pushrod. If you have a funny feel to the pedal it is most likely not going to be fixed with adjustment to the pedal, check the bracket for cracks, hoses for ballooning, air in the system etc. If you are working with a high mileage clutch or one that has been warped you could have some other issues, but you have given us nothing more to go on. This is why we ask questions, like "what vehicle and how many miles?", or "what are you trying to fix?" Some times it comes across as snotty, but it saves time when you don't know who you are talking to or what they know and they ask something like "how do I set my timing" when they don't realize they have a blown motor.

SodiumFlouride

What happens to the pedal position when the clutch wears normally?
Does the engagement/disengagement point move up in the pedal return cycle?

That's why I'm so confused.
1. As far as I can tell, it's not slipping, but,
2. It sure is engaging "funny" in that it engages and disengages high up in the pedal uplift position (almost at the top of travel)

That's exactly what happened prior, where rebuilding the clutch master and slave cylinders instantly solved the problem of a balky (but noiseless) shift in the morning when doing a K turn out of the garage.
No noises here. The "squeak" was solved long ago with the Toyota brake-pedal return tension spring replacing the original double-coil torsion spring.
This does seem to be happening, as far as I can tell.

That's what it's starting to look like.

Maybe it's normal for the clutch to engage way high up in the pedal return position?

This vehicle isn't high mileage for its age (about 20 years old and 170K miles).
The owner doesn't abuse it.

I agree. I mostly just wanted to know how to adjust the pedal position - which - from the measurements - is adjusted ok.
There's nothing else to adjust and I already replaced the common parts.

What happens to the pedal position when the clutch wears normally?
Does the engagement/disengagement point move up in the pedal return cycle?

akwheeler

If it's still on the original clutch it is likely ready to be changed and that is likely why it engages so far from the floor.

Thommo Thompson

OK I under stand ur symptoms now.
u want it to open the clutch a little cloaer to the floor, and therefor also have the friction point a little closer to the floor.
as has already been said, it Is self adjusting, but I don't like that term because it implies there is some mechanical auto adjustment system, which there is not.
No offense to anyone there, I just know that the term self adjusting bumsteers a lot of ppl.
When the clutch pedal is fully at rest, the one way valve (on reservoir outlet) or the anti reverse flow squish washer, one of those 2, depending on the design of ur master, allows the system to refill with fluid from the reservoir or return back to the reservoir only when the piston is fully retracted. So to start with, make the push rod is as small as possible without it wiggling around. This will ensure that the piston can move all the way back to open the one way valve or squish washer to equalise pressure and reset the systems "at rest" positions.
If this doesnt help, and the pedal still engages too high, then it's possible that the master cylinder is too big or the slave is too small.
A larger master will make the clutch fork travel further with less pedal movement. And it also makes it feel really inaccurate, as there is not enough mexhanical advantage for ur foot, compared to the slave.

Thommo Thompson

Also, don't just flog off the idea that there may still be air trapped.
Air is compressible, so in a clutch aystem, it simply adds a buffer to the tension felt bybthe foot, but as soon as it's compressed as much as it can be, then it's no longer an issue. So u don't necessarily feel sponginess with air in the clutch, but it does make the friction point feel a little bit ˟˟˟˟, just as u describe.
As u let go slowly, the bubble stays compressed until the clutch fork starts to become soft, then the bubble expands and u end up with what I would describe as a very wide and loose friction point.

SodiumFlouride

It's not on the original clutch, by the way - so if I accidentally implied that - I never said that - so it's my mistake for not being clear.
The original clutch was replaced somewhere around 75K miles and now it's 175K miles.

I have no problem with the concept of replacing the clutch myself - but I don't like replacing things without any diagnostics.
And I certainly don't like replacing things if they're not the actual problem.

Hence my questions.

SodiumFlouride

Thank you for offering your advice and help.

Yes. Exactly.
If the clutch is actually "bad", I'll replace it (of course).
But I have no indication that it is bad.
My only indication is that the engagement and disengagement feeling sucks in that it's too high up in the pedal cycle.
I'd prefer a more 'linear' engagement than merely "on/off" within an inch.
I'd prefer that linear engagement to be about halfway in the pedal upswing cycle.

I'm going to have to agree that it's basically a "non adjustable" clutch.
The only adjustment we have is pedal position.
This is good advice because it fives a pedal-adjustment procedure.
a. Start with the bolt screwed all the way into the pedal (hence, away from the clutch master cylinder).
b. Then lengthen the bolt by unscrewing it out of the clutch pedal, until the clutch pedal engagement point is where you want it (about mid-way in the pedal return cycle).


The vehicle has been owned by the same family so the equipment is OE.
The only thing that changed is I put in an OE rebuild of the clutch master cylinder and clutch slave cylinder, which instantly solved the hard-shifting at idle in the morning problem.

akwheeler

It's been a while since I studied up on this, but it seems to me when you get to the end of your clutch discs life it will begin to show just what you are describing, only grabbing at the end of your pedal travel. If they have 100K on it and they only got 75K out of the first one...
"It's not on the original clutch, by the way - so if I accidentally implied that - I never said that - so it's my mistake for not being clear.
The original clutch was replaced somewhere around 75K miles and now it's 175K miles."


Keep working on adjustment if you like, but I'm betting a new clutch is just around the bend and then you will be readjusting pedal travel again. By the way, all of the information we have been pulling out of you one painful piece at a time is something you should have included in your original post. When your question is about your personal rig it helps to have all of the vital statistics in your signature.

Thommo Thompson

See I think op actually only encountered the positional difference problem after the rebuild, which kinda makes it sound like something isn't perfect in the new setup. .Sodium, did the clutch take-up position change between before the rebuild and now?
The most important thing is to make sure u don't try to adjust the friction point in a hydraulic clutch, by lengthening the pushrod. All that does is stop the piston returning to rest and the system never equalizes and therefor never "automatically adjusts".
same with brakes, if u lengthen the brake pushrod, ull have "stuck on" brakes that never get released.
to test this theory, u should notice that the clutch slave cylinder should actually be able to be pressed back further into it's hydraulic bore, when the pedal is at rest. If not, the adjustment rod is too tight (too long) and the one way valve in the master is being held tight closed by hydraulic pressure.

SodiumFlouride

That's what I'm beginning to think, which is that, as the clutch friction disc wears, the pedal-engagement position 'might' move upward (away from the floorboard).

Assuming the clutch disc wears, say, 1/4 inch, that movement is multiplied by the geomentry of the pedal levers such that it might be four inches in engagement travel that results.

If this is, indeed, what happens - does anyone have this disc-to-pedal wear distance characterized?

I followed the advice here, which I consider kind, helpful, and well intentioned advice, such that the pedal engagement position is as "good" as I can make it at this point.

Thanks.

SodiumFlouride

It's not my rig, but I did test it beforehand as I wrote up a report on the rebuilding of the clutch master and slave cylinders, and their bench bleeding, and bleeding of the system, and replacement of the shift lever bushings in the cabin console.
[*] 1997 Toyota 4-runner 3RZFE 2WD 5speed manual W59 transmission shifting issue

I think it remained the same.
The only thing that changed it was my adjustment of the pedal position bolt.

This is good advice, which I very much appreciate.

Thanks for that advice, which I appreciate.

In the end, here's what I did, overall, which is going to have to be all that I can do, at the moment, for my sister.

1. I replaced the shift lever bushings (no change in operation resulted).
2. I replaced the transmission fluid with 2.7 liters of Redline MT90 (no change in operation resulted).
3. I rebuilt the clutch master & slave cylinders & bled the system (this solved the hard shifting at idle problem).
4. I adjusted the clutch pedal bolt (this ameliorated some of the late clutch engagement problem).

At this point, until and unless I replace the clutch itself, I don't think there is any more I can do.

Thank you all for your kind advice as I know nobody has to help anyone here. I hope this thread helps others who are as new to clutch issues as I am.