Technical Input/experience with pull-type slaves please?

Good evening all.
I wondered if anyone has ever had an issue with lack of travel on a pull-type slave cylinder and could recommend a particular brand or style?
I have a 283 mated to a T5 and all is well there, but the Speedway pull slave is not travelling quite far enough to release the clutch.
I'm pretty certain the system is bled and properly adjusted to the best of my knowledge, and the pressure plate will release fine if I manually pull on the clutch arm, I'm just not getting quite enough travel on the Speedway pull slave to release it and I'm curious if anyone else has had this issue and what the solution was, and or any other experiences with this issue as this is my first sbc/T5 conversion.
Thanks and regards, John.

 

I haven't used their cylinder John but wonder what travel was it rated at? This would allow you to at least verify that it is traveling the correct distance per their rating. If it is and that's still not enough, it seems a longer-travel cylinder is needed.

- EM

- EM

 

just some thoughts on basics;
Can you tell how much throw length is available on the slave, if the slave was unhooked from the line and the clutch arm?
Then when it's together and bled, is it still going that far? If not, it could be not enough master volume.

also post a measurement at the fork, as to how far the arm tip moves right now, with it not working right.

 

Move the attachment point where the slave is on the fork closer to the center of the trans. This will change your lever ratio. The clutch force will be a little stiffer but will increase the throw at the clutch throw out bearing.

 

Move the attachment point where the slave is on the fork closer to the center of the trans. This will change your lever ratio. The clutch force will be a little stiffer but will increase the throw at the clutch throw out bearing.

 

Move the attachment point where the slave is on the fork closer to the center of the trans. This will change your lever ratio. The clutch force will be a little stiffer but will increase the throw at the clutch throw out bearing.

 

I used the Speedway one too. Not enough travel. I did some research and found that the "Howe" brand pulls farther. It works. The Willwood has even a longer throw, but if you read the reviews, they seem to get a high percentage of leakers. The Howe one leaked, they replaced it no problem. The replacement has just started leaking. Time to do a rethink and make a bracket for the pusher style.

 

Push. Novak Adapters.

Rock solid.

 

Triple post because told me problem with upload.

 

Ok thanks guys, appreciate the input. The slave has about 7/8'' travel, the travel is the same either whether it is attached to the clutch arm or just loose. The slave is a 7/8'' bore and the master is a 3/4'' bore so I think I have those properly matched for this application.
The clutch arm needs to travel approximately 2.5'' at the very end in order to release the pressure plate, which seems like a lot to me, but I have limited experience with this, which is why I was curious if anyone else has had this issue using the Speedway slave. Or if it's the local auto parts store replacement Chinese clutch. There is some 'play' in the clutch arm on the release bearing, the clutch arm moves about 3/16'' on the bearing before it comes into contact with the bearing flange and pushes it into the pressure plate, which translates into some lost travel there as well but I have nothing to compare that to.
This has been done a million times and seems pretty straightforward which usually means I'm missing something obvious. I thought about re-drilling the clutch arm and moving the pivot point inward but from everything I have read prior to this doing this conversion that wasn't necessary. I did mount a stock GM push type on it originally but still wasn't getting enough travel and it looked pretty incongruous so I wanted to tuck everything back under the floor.
I can post pics or possibly a video of the assembly if someone requests something specific if they would be kind enough to share their experience.
Thanks and regards, John.

 

I do mostly early Olds/Cad engines with push slaves and one Olds with mechanical linkage on a T5.

I believe the push slaves on Olds fork was 1" total on a perfectly working clutch. So that 7/8" sounds short to me.

The 2.5" seems very wrong to me at this point

I am lost on that description. As I said I use push or mechanical only, but in either case, the freeplay needs to be adjusted out by the adjusting rod to the fork. You can't have a slave trying to take up that 3/16" travel "slop". Your slave needs to begin the start of it's movement with the TOB almost touching the pressure plate.

That 3/16" freeplay at bearing/fork that you have, is wasting a good percentage of your total 7/8" pull, if that makes sense

.

.

 

Ok thank you sir, appreciate the input.
The release bearing is properly adjusted to about 1/8'' from the pressure plate with an adjustable pivot ball.
The play I am referring to is the clutch arm IN/ON the release bearing. I will crawl under later & take a picture but if you can visualize this, the clutch arm itself is about 1/2'' thick at the release bearing end. The release bearing surface/distance where the clutch arm snaps on is about 11/16'' long.
So the clutch arm physically travels about 3/16'' within the flanges of the release bearing before it starts to move it against the pressure plate and that travel is ultimately lost. It's a 'short' GM release bearing but it seems to have a lot of travel area available for the clutch arm.
If the clutch arm were off the car, and you slid the release bearing in it, you could slide it back & forth about 3/16'' on the arm on an imaginary input shaft? Not sure if this is normal or not, guessing it is not, hence all my questions.
The 2.5 inches travel at the end of the clutch arm translates into about 1/2'' at the bearing end, which just isn't quite enough to release the pressure plate, so I think the problem is either the slave doesn't have enough travel, or the clutch is a poorly manufactured unit that doesn't release properly, or the release bearing is too long.
I've never done this conversion before so I figured I'd ask prior to tearing it all apart and replacing parts.
Thanks and regards, John.

 

My replies are based on post 1 when you said you know the clutch DOES release by manually moving the arm. We need to know that this is definite, not a guess, because sometimes a T5 TOB guide tube can be too long and is pressing the disc into the flywheel. If we are positive you can release the disc by hand, we can assume the pressure plate is OK, and disc is not jambed or wrong.


But I'm still lost on this statement:

I've never used a pull type, but the TOB "must" be almost touching the pressure plate,( as in thousandths of an inch, certainly not 3/16"), before the clutch linkage/fork/whatever, starts to move.

Example: a late model car/truck with an internal hyd TOB,.. those have zero play between bearing face and pressure plate.

3/16" freeplay measured at the TOB end of any given fork, translates to massive excessive movement at the outside end of the fork, due to the ratio of where the fulcrum ball is, to the bearing, and to the slave end.

 

Also, trying to fix things over the net with words...lol

Basics on external hyd operated clutches:

-master cyl adjustment; you need just thousandths of an inch freeplay between the push rod tip and the internal piston in the master. Excessive freeplay there reduces the "total displaced volume" of fluid.

-when setting the freeplay for the TOB fork; pull backwards on the fork till you feel contact between the TOB and the pressure plate. Now adjust the rod from slave to fork almost to that same pulled back position, leaving a very minimal amount of slack so that the slave almost instantly starts to move the bearing. All you need for freeplay at the bearing-to-plate is thousandths of an inch. Only enough to not touch the bearing when clutch is hot or cold.

.

 

I appreciate the comments sir. The clutch does release by moving it by hand, I have confirmed this a few times and confirmed all is well. Input shaft has been shortened, splines extended, throwout bearing tube cut down etc. Everything works internally as it should. The pressure plate just seems to need an abnormal amount of travel before it releases, but my manual transmission experience is negligible which is why it may be ok and I thought the slave just wasn't travelling far enough.
The throwout bearing is adjusted to within about 1/16'' of the pressure plate, just enough to keep the bearing from resting on it.
The 3/16'' of freeplay is the clutch fork travelling IN the throwout bearing. Almost like it needs a shim to take up the slack but I've never heard of shimming a release bearing.
The clutch arm is about 1/2'' thick. The 2 flanges on the release bearing where the fork snaps in are about 11/16'' apart, so the arm can slop back and forth in the bearing before it hits either flange.
When the clutch arm is fully retracted, no pressure in the system, foot of the clutch etc, the clutch arm travels back 3/16'' IN the throwout bearing. Bearing is not moving it is still resting about a sixteenth from the pressure plate.
Pressurize the system and the clutch arm travels along inside the bearing again about 3/16, hits the inner flange of the bearing then starts to press it against the pressure plate but by then a lot of travel is lost.
I know pictures would help. If I wasn't wearing a shirt & tie & giving the appearance of productivity at work I'd crawl under there right now and take some.
Just thought this may be a common problem and someone has had a similar experience. I'm missing something obvious but damned if I can see what it is.

 

This sounds odd to me. If the bearing "snaps into" the fork with spring clip, the TOB should not have front to back slop in the fork. The spring clip is supposed to hold it in position.

I'll look at some forks and bearings I have today.

Back to what you said about a TOB being too short: We can determine if it is by looking at the angle of the fork when you pull the outer tip backwards and the TOB touches the pressure plate. If that arm is oddly angled way too far back, then the bearing can be too short, or the arm pivot fulcrum ball stud can also be too short. I did run into this on a T5 to early Olds; The arm was angled way too far back on test mock up. Going by what space I had in the rectangular "window" hole in the bell, I determined that a longer pivot ball stud was the correct fix. That longer stud ball brought the arm out more or less straight, and there was plenty of room in the bell window hole to allow the fork to move forward and backwards enough.

But if your fork angle is pretty decent now, I still say you need to deal with the 3/16 slop at the bearing...at this point.

.

 

Good enough sir, thank you. The fork is adjusted so it is angled approx. 5 degrees towards the engine & the bearing not quite resting on the pressure plate. But I wonder if that is a based on a push slave, and it should be 5 degrees the other way for a pull slave?
I will take some pictures later and if you could offer your input I would appreciate it. No doubt that 3/16'' slop in the bearing is also an issue but not sure how to correct that, as far as I know there are only short and long release bearings and I'm quite sure this is a short bearing.
Thanks and regards, John.

 

that is Ok, not a problem

I looked for Chevy forks and I don't have one to look at.

From your description, your spring clip is holding the fork to the back of the groove in the TOB. It should be opposite, with the clip holding the face/front of fork, to the front of the groove on the TOB.

This is your problem in my opinion.

I doubt you can get a pic of how the bearing fits the clip and fork, through the bell window hole

 

If you want to know for sure if that 3/16" is the real issue..

And if you have enough adjustment left on your slave rod;

-adjust the slave rod until most of that 3/16" is gone. Yes the bearing will be hitting the plate, but this is just a test. Now start the car and try it. If it will go into 4th or 5th without grinding at all, but still grinds in 1st or reverse, you'd need to gain a bit more throw at the bearing, even if you fix the clip issue.

If you fix the clip, and still need a tiny bit more, you either need a slave with a longer pull, or if possible, you could shorten the outer part of the fork a bit. I would not shorten the fork if the clutch is somewhat stiff already. If it is very soft pedal right now, yes, a shorter fork would be a fix.

.

 

Sounds good sir thank you. What is throwing me off is the bearing only fits into the fork 1 way, I think it's one of the newer style bearings designed so it fits in properly and you don't accidently fit the bearing in the wrong groove.

It WILL work with the slop adjusted out of the fork on the bearing, but in doing so it preloads the bearing against the pressure plate. The clutch is pretty stiff already so I'm leery of shortening the arm as well.

I will get under the car and get pictures. Failing that, I will pull the engine & trans and get pictures that way as this is driving me nuts, it is the last major part of this build. Thank you again for all your advice sir.

Regards, John.

 

here is a great video. The first 1-1/2 minutes should solve your problem.

 

Thank you for taking the time to post that video sir, I actually watched that as well to ensure I had the bearing in properly.
I will get under the car asap this evening and try and take some pictures to better illustrate the problem. The bearing only fits in the fork one way because of the way the flanges are designed, but it still allows it to slop back & forth on the input shaft.
Thanks, John.

 

I have a push type in my Ford, Wilwood 3/4" master, Speedway 7/8" slave. I originally had the clutch rod at the pedal fairly low, it was a convenient spot on the pedal arm. With everything bled and adjusted, I needed 2 feet to push the clutch pedal in and with only a partial release, definitely a mechanical advantage/ travel issue.

I tried a bell crank thing with limited success, spent a lot of time machining up parts with limited success. In the end I moved the pivot point up the arm and this worked. I made up a bracket to hold the brake and clutch masters out of aluminum, but it was weak and had flex in it. 1/4" steel to the rescue. I moved the clutch master up and over from where I had it initially. Mechanical advantage is vastly improved, the pedal works easily and the clutch fully releases. I still have adjustment up top and at the rod to the fork.

 

Thanks to all for the advice & help, was able to identify part of the problem. For whatever reason, the pivot ball pocket on the clutch fork is spaced too far in, thus pulling the release bearing partly OUT of the clutch fork when installed on the input shaft. Should have caught this sooner but I didn't, never occurred to me the pivots would be in different spots.
Snap the bearing into the fork & install the trans, by the time I got it all lined up & mounted the bearing was pulled halfway out of the clutch fork- thus allowing the fork to slop back & forth in the bearing. Tossed that clutch fork & found another one with the divot spaced a bit further out & all is centered now. Still don't have enough pull on the Speedway pull slave to release the pressure plate though but at least a lot of future problems have been prevented. Thanks to all for the assistance.

 

Is this picture from before you switched forks, or after?

If that is how it is now, it is still wrong. The pads on the fork tip are angled, and it seems to me that there would be a "wasting of available throw" as the fork finally moves enough to get a straight push. At least I think there is wasted movement like that...and with a paltry 7/8" slave stroke, every tiny bit helps.

.

 

This is before sir.
The release bearing wasn't fully seated in the fork, it was pulled partly out once the input shaft went in, as the pivot point on the clutch fork is wrong, the pivot point was too far inward on the fork so the fork ends were not centered around the input shaft if that makes sense, thus allowing the fork to slop back & forth and wasting a lot of throw.

I stuck in what I'm guessing is about a '65 GM truck fork which had a different pivot point and centered the forks on the release bearing when the transmission was installed, the angle is correct now and there is no wasted throw on the bearing, but the Speedway slave still will not pull it far enough to release.

 

That surprises me about the speedway slave not working enough. Chevy is by far, the biggest buyers group for aftermarket drivetrain parts, so you'd think their slaves would have been designed to have more than enough travel for the various Chevy forks and pressure plates.

what a bummer that is.

I don't have a chevy standard shift car here to measure how far the stroke would be at the outer end of the fork. All I have here are early Olds V8 with 3 finger pressure plates, Olds forks.
.

 

Regardless sir I thank you for your help thus far. Without you posting that video earlier the light bulb would not have come on and I likely would not have caught that bearing/fork issue until it was too late. It's also entirely possible I have something assembled wrong as well which is why I was curious about others experiences with the Speedway pull slave.
If it was a unanimous opinion it had enough travel to release any GM clutch then I would have looked elsewhere but a couple other guys mentioned it was possible it doesn't have enough travel so that may be the culprit. I'm pretty confident in the assembly otherwise, other than the clutch being stiff as hell to release, but I think because it was expertly forged in Korea under the strictest tolerances on a Friday afternoon it's fine too.

With the old GM fork back in now, the clutch will release, just not quite far enough, I can still hear the pressure plate riding on the clutch disk just a bit. Another 1/8th or 3/16'' travel on the clutch arm and it would work perfectly.

 

When I set stuff up from scratch, I lay the pressure plate on the floor, and use my heel to see how stiff a plate is.

It is very likely that too small of a slave bore, versus too big of the master bore can cause your very stiff clutch.

I have always used OEM pieces as far as master/slave combos just for that reason. I figure that the OEM had better engineers for getting pieces to work together properly. I normally build mechanical linkage if the pedals are below the floor, and normally use hyd push slaves with hanging pedals. Whatever seems best for a given build, is figured in as well.

I've never used a hyd bearing as I see no need, and would not be thrilled to have one leak and need to pull the trans or engine just for a leak.
.

 

What bell housing do you have? I'm running a '55 Chevy unit with a Chevy truck forged steel fork. No missing how the TO bearing goes onto that. I still think you have a pedal geometry issue going on.