I was thinking about using allthread to make my own extended pushrod for my slave. Now my thinking is that it will allow me to have more fluid flowing per stroke of the pedal, but I was also thinking that this will allow my clutch to engage/disengage sooner? Could it damage my slave cylinder? What is the general consensus for length.

it wont change when the clutch disengages.
and, I think it will make it take longer for it to engage, being its now pushed further out.
only damage I cant think of is with an older worn slave, it probably has a "worn" path, and with a longer rod, it will nowbe pushed into a new, unused area of the slave.
I dont think this will help any, or even change anything, being the master get thrown thru it full range of motion, so the slave movement will remain the same, you will just have the slave using a different area of the cyl.
if you want more throw on the slave, you need either a smaller salve cyl, or a larger master cyl. and, still I dont see why any of this would help. the clutch disengages plenty, unless theres air in the clutch line.

A longer pushrod will not help in getting a clutch to disengage properly. You are not affecting the amount of fluid moved by the clutch master cylinder. There is only a couple of things that you can do to get it right. Bleed the clutch and we all hate that operation.

Get Rodneys adjustable banjo for the clutch. It can be adjusted to take up slack in the clutch pedal/master cylinder assembly.

And I have a third option. I am a hydraulic specialist by trade so bear with me.
I wrapped teflon back rings around the small part of the slave cylinder where the spring attaches. They are about 1/32" in thickness but have the diamater slightly smaller than the slave cylinder bore. A few quick measurements and minor math skills and I needed 4 rings to take up some area.

This has the affect of decreasing the amount of available fluid area inside the slave cylinder. It requires taking the slave cylinder apart and making the minor change but the result for my car was a that little bit of extra displacment made a world of difference in shifting. This after a new slave, new master and new FS clutch pedal I still could never get the car to shift to smoothly. I had a rock hard pedal with the push rod out and the slave piston extended all the way in its bore.
I used teflon high pressure back up rings as they are unaffected by brake fluid, tolerant of extreme heat/cold and easy to install. They are cheap and can be bought at any decent hydraulic shop. They just hang there and have no purpose other than taking up space.

Just my .02 cents.
88Ironduke

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Pilots with out maintainers are just pedestrians with a cool jacket and sunglasses.
I.Y.A.M.Y.A.S.

having a longer pushrod will make the pedal enguage sooner, and if you do want ot FINE tune your pedal a good way to do this is to cut the PR in half, then thread both ends, and have a long nut screwed onto both ends of the PR... then just unscrew either end until you get the right pedal feel. just remember that you should have at least 1-2" of pedal play before it begins to enguage.

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1986 Silver 5 speed Fiero 3.4 DOHC
Bored .30,Fully balanced and blueprinted
13.93@101mph as it is on the street

355/380hp sbc, 4 bolt main
spec stage 3, and many other extras.
87 GT 5-speed Getrag, power everything.

quote Originally posted by flames4me: having a longer pushrod will make the pedal enguage sooner, and if you do want ot FINE tune your pedal a good way to do this is to cut the PR in half, then thread both ends, and have a long nut screwed onto both ends of the PR... then just unscrew either end until you get the right pedal feel. just remember that you should have at least 1-2" of pedal play before it begins to enguage.

This doesn't make sense to me. If it was a mechanical clutch and not a hydraulic it might make sense. He was asking about lengthening the slave rod not the rod between the pedal and MC. The free play applys to mechanical not hydraulics. Technically having no free play at the pedal is best for hydraulic systems. Yes there would be a small amount of "free play" at the clutch arm, but it is not used.

The answer to the original question: As stated above the longer slave push rod does nothing more than pushes the piston further up the cylinder and makes it use a slightly different part of the cylinder. If you have pits at the outer end of the cylinder this can help you temporarily, but if the pits are at the normal rest postion of the piston it won't help
.

Dave

Archie-ism 7 describes it clearlyly to me. v8archie.com. the hydraulic displaces 1.2" he says and the clutch needs 1.15". My thought after thinking about it...if the master cylinder starts all the way back in mormal operation, the result is shifting the range the clutch moves through. It cannot change the size of the range. If it is not dis-engaging now, it might not fully engage with the longer rod. I suspect that a clutch would be toasted in short order when not fully engaging.

My $0.00001 opinion

Brian

i did it once on my 87 coupe (isuzu 5sp). i was having problems with my clutch so i drilled a hole through the actuator so the all thread could go through, and used two nuts to lock together in the spot i wanted on the actuator.

it didn't work, and eventually i took it in to be repaired. it turned out that i needed a clutch and no amount of fiddling with it was gonna halp me. they also had me find the stock rod and they put a new actuator on. they said there is no adjustment to the system.

Go to the Fiero Factory website and read what Ed Parks has to say about clutch problems.
He has some excellent advice there.
http://www.thefierofactory.com/qahydraulicclutch.htm
http://www.thefierofactory.com/qamain.htm
Jeff

[This message has been edited by jeffndebrus (edited 05-04-2006).]

I am not having any clutch problems yet...I also thought that the longer pushrod would allow me to have smoother shifts because my 4 speed 3.65 shifts good when I pussy foot but seems to gring if I shift too fast when racing, but if I "granny shift" when I race it is fine. Just thought that a longer pushrod would help.

sounds like your clutch is not fully disengaging, or your cables need slight adjustment.
or, maybe your timing is alittle off on your shift/clutch dump on fast shifting

From Mr. Ed Park's

Having clutch problems ?

There are basically two potential problems with any clutch system. 1st is "no pull" and 2nd is no disengagement.

"No pull" is always mechanical, and is usually the disc worn down or the friction material missing. Requires replacement. Smart thing is to also replace the plate and the release bearing, since it is so much work to remove the transaxle.

Worn disc is caused by long term use (slippage), abusive use(slippage), or a mechanical malfunction (slippage), which would be: release bearing shaft binding in its bushings, or release bearing binding on its slide collar. Both conditions result in a partially applied plate that allows slippage (wear). All clutch replacements should include inspection/correction of these conditions, or premature wear will happen.

No disengagement is trickier, since this can be caused by hydraulic or mechanical malfunction.

Start at the begining, the pedal. It should be an inch higher then the brake. If not, then look for the standoff bracket (the squared U riveted to the pedal) to be bent. Use will bend it toward the center and toward the rear of the car (away from the clutch master cylinder). You need this inch for a full hydraulic push of fluid. This bracket can very often be bent back into shape with a large set of channel lock pliers. Much maligned pedal is seldom bent.

If there is slack at the top of the pedal, until resistance is felt, then there is also not enough push. This is usually caused by the master cylinder groument missing, or the pushrod being bent. Make sure
pushrods offset hole is in the "up" position.

While in this area (upside down on the drivers floor), pull the master cyl boot loose and check for any moisture. If any is found, then master cylinder rear seal is leaking. Replace it, unless you want a 50/50 chance on rebuilding it. Bench bleed before installing. If all is OK, then slowly have the clutch pedal
depressed, while watching the resevoir fluid (cap off). If fluid level rises any at all, then check valve in master cylinder is allowing some pressure to bypass, and you will not have a full disengagement.

This completes the mechanical and hydraulic inspection at the front.


In the rear, clear area above the slave cylinder of air intake tubes. Have the clutch slowly depressed again. Some movement of the slave cylinder is normal, but you are looking for two things. Broken mounting bracket, and length of pushrod stroke. (At this point we have removed oil pump drive shafts, drum brake adjusters, valve pushrods, various modified bolts, and a piece of broomstick, all in an attempt to get the last 1/16 of stroke.) Stroke should be at least 15/16". 7/8 will not allow full release. We measure this with the pedal depressed, tape measure against clutch lever, then read tape measure "backwards" as pedal is released. Do this several times, as it is easy for tape to slip.

If measurement is good, then so are hydraulics. If not, then pull slave cylinder boot loose to check for moisture. If found, replace slave cylinder, or the 50/50 rebuild rule applies here also. If no moisture
is found at the front or rear, you can reasonably expect that someone has replaced a unit, and not done a "proper" bleeding.


But, wait a minute! 84-86 4 spd and 5 spd Fiero's (except 86 getrag) were delivered with a stamped steel clutch lever that has a plastic block that the slave cylinder pushrod pushes against to rotate the release bearing shaft. This lever can crack where it is clamped to the shaft, and the plastic block can "push through". Many expensive clutch jobs have been done, when only this lever was the cause of" no disengagement". Replacements, 87-88, and all getrags are cast.

Further disengagement problems will be inside the bellhousing, and require removing the transaxle. On 4 spd cars, a broken/bent release bearing fork will usually make much noise and make the clutch pedal
feel as though it has a brick under it. It could be on 4 spds and will be on both 5 spds, a broken disc dampner spring, that has a piece lodged in the plate release springs, that make it feel that you are pushing against a brick.

This completes mechanical and hydraulic inspection in the back.
Our bleeding procedure is not found in Clymer, Chilton, Haynes, or Helms (Pontiac) service manuals. Therefore, must not be authorized, but has worked without fail for over 10 years.

Jack car from front about 1 foot (until master cyl is above height of slave). Remove resevoir cap. Open (not remove) bleeder on slave cyl. Gravity feed 1/2 pint of hydraulic (brake) fluid. If gravity doesn't
start fluid movement, SLOWLY depress clutch pedal until fluid starts to move. After 1/2 pint has gone through system, close bleeder.


Needle nosed vise grips work best (especially 6 cyl, which may require removal of slave cyl from bracket). Clamp vise grip pliers to slave cyl pushrod. Pull pushrod into the barrel of the slave cyl, while at the same time "cracking" the bleeder. The bleeder is at the wrong end of all three different slave cylinders. Air can be trapped at the end where the pushrod is, and must be pulled to the bleed valve.

Check resevoir after first "pull" (can be nearly empty). We repeat this 5 times, or until no more bubbles appear. After 6 times, if there is still a bubble, Start over at the clutch pedal. Step 1, along time ago.

Caution: do not shave (cut, machine) the flywheel. Hydraulic clutch systems typically have 0 to .003 clearence between the face of the release bearing and the fingers on the clutch plate. Removing material
from the flywheel will move the plate that much further away from the release bearing, perhaps causing a non-release condition. Remanufactured clutches will usually have as much as 1/16" variation in the height of the plate fingers. Also resulting in a non-release condition. If the release bearing fork is too worn, then the same applies.

Hydraulic clutch systems are called self adjusting, because they can only move a predetermined amount of fluid. The spring pressure of the plate will override the hydraulic pressure, so, extending the slave cyl pushrod length will not "adjust" the system.