Real, PROPER clutch adjustment? (Page 1/1)
CSM842M4 NOV 27, 12:15 PM
Every time I have to do anything to any of our Fiero's for the first time and have to refer to my Chilton's manual, I am reminded of just how inadequate it really is. This time, it's the clutch on my wife's '86 4-cylinder 5-speed. Master and slave cylinders are new, bled to within an inch of their lives, and I have twisted all the slack out of both pushrods. However, it still seems as though there should be a more complete disengagement of the clutch when the pedal is down, especially when shifting into 5th or Reverse. And that cursed book says, more or less, that since the clutch is hydraulically actuated, there is no adjustment necessary or possible. To which I say "Balderdash!", whatever that means. So, what is the actual correct adjustment procedure to ensure a complete disengagement? Any and all input... Thanks in advance - Chris
fierosound NOV 27, 04:49 PM
Change to an adjustable master cylinder banjo (pushrod).
http://rodneydickman.com/pr...o.php?products_id=56

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[This message has been edited by fierosound (edited 11-27-2021).]

Skybax NOV 27, 06:28 PM
If anything is wrong with the external system (master, slave, air, bent pedal, banjo, etc) it will bring the engagement/disengagement points lower to the floor. A healthy system will have no disengagement problems and you shouldn't have to jam your foot into the floor to get it.

I would also like to add that the Getrags are the only ones with a larger slave bore (15/16") so they have a shorter slave throw. You often hear the Fiero needs roughly 1" slave throw for full disengagement, but that only applies to Muncie 4-sp and Isuzu 5-sp with 13/16" slave bore.

All Fiero clutch master cylinder bore = 11/16" (roughly 1.5" throw)
Muncie 4sp & Isuzu 5sp slave bore = 13/16" (roughly 1" throw)
Getrag 5sp slave bore = 15/16" (roughly 0.75" throw)
[NOTE: These are GM Parts and throws are approximate]

So 3 things...

1. Make sure you have the correct replacement parts (bores) for your transmission to have the proper throws (sometimes parts stores give you wrong slave).

2. Make sure your 86 aluminum slave bracket is not cracked because it could be flexing (have somebody operate pedal while you watch) and could break off in future.

3. Make sure your pedal isn’t bent, remove it and look at it closely, the first 2 photos below show a good pedal, the second 2 photos show a bent pedal...







[This message has been edited by Skybax (edited 11-28-2021).]

Dennis LaGrua NOV 28, 05:01 PM
If your Fiero has the aluminum clutch pedal assembly chances are that it has bent. Also the bleeding process on the manual cars is very critical. I've had good luck using the Performance Tool brake bleeder. There is no adjustment on the factory setup.

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theogre NOV 28, 10:48 PM
Unless have system defects like bent pedal problem above...

Hydraulic Clutches for 90+% cars and most trunks are Not adjustable. System will self adjust sim to Brake systems.

Another common defect is bent arm between slave and pivot rod.
Some were weak from GM but others can bend if pivot rod, throw-out bearing and/or other parts are binding.

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[This message has been edited by theogre (edited 11-28-2021).]

Blacktree NOV 29, 10:48 AM
In this regard, the Chilton's manual is actually correct. The clutch hydraulic system is not adjustable. It should be able to self-adjust, to an extent. But it's a very small extent. Worn or damaged parts can easily take it beyond its ability to self-adjust. That includes the clutch pedal arm, and the slave cylinder actuator arm, as mentioned above. Those are both common failure points.

For many of us, those parts started failing back in the 1990s. So if your car hung in there until 2021, you're pretty lucky.

Some Fieros came with a clutch pedal arm made of aluminum. Those are notorious for bending, and causing clutch issues. Later models had steel pedal arms. IIRC there are also aftermarket parts available. Also, some Fieros came with a slave cylinder actuator arm made from stamped sheet metal. Those are notorious for cracking or bending. The stamped part was replaced with a solid cast metal part. Those are also available OEM or aftermarket.
ZaraSpOOk NOV 29, 05:50 PM

quote
Originally posted by Dennis LaGrua:

If your Fiero has the aluminum clutch pedal assembly chances are that it has bent.




if the system is properly bled and you aren't getting enough movement, I'd put my effort (and money) on the peddle before the adjustable banjo
I've now owned my 88 highly desirable (sic) Getrag 33 years, bled it countless times, the only new part has been a new clutch peddle (why do you suppose the Fiero Store sells those things and not a brake peddle?)
there is a reason
Will NOV 29, 08:17 PM

quote
Originally posted by CSM842M4:
And that cursed book says, more or less, that since the clutch is hydraulically actuated, there is no adjustment necessary or possible. To which I say "Balderdash!", whatever that means.



As noted above, if the hydraulics are in good order and all the metal is straight, the book is exactly right about that.

Are your master cylinder & slave/follower cylinder anything other than Rodney Dickman's cast aluminum units or GM NOS fabbed steel units? A few years back, anything other than these two is hot garbage and will fail and cause problems within tens of miles... not joking. Looking at RockAuto... *maybe* that's gotten better, but I'm not holding my breath.
skywurz NOV 29, 08:37 PM
Did you by chance do a v6 clutch? I ask because i started having this similar issue after swapping my l4 to a v6 clutch.