I am making this post due to some clutch issues for an '84 fiero 2M4 i have been having clutch issues with since buying it. There is a lot of unknowns for this car and I do not have the owners manual or any form of documentation from GM for this car so I am left in the dark for a lot of issues. One main issue I am currently battling is an issue of knowing which type of clutch master cylinder is stock in an 84 fiero such as mine. Pictured above is the type of master cylinder that is currently in my car and is offered by many sites as replacement '84-'86 clutch master cylinder Next image will be of a master cylinder that is offered by many sites and also listed as a replacement '84-'86 master cylinder, but is not the type installed in my fiero So my confusion lies in the fact that I want to know if the clutch master cylinder I have installed in my car is an OEM one since I have no way of being able to tell unless I get an 84 fiero owners manual or you lovely people can help me out.
There are two styles of clutch master cylinders in Fieros. The components are ordered like this:
Early style master cylinder firewall - hydraulic fitting - reservoir
Later style master cylinder firewall - reservoir - hydraulic fitting
From the factory, the hydraulic line was bent differently (depending on early/later master cylinder), to mate with the master cylinder's fitting.
Since you apparently have a hydraulic line that's currently hooked up, buy the same style master cylinder as what's in the car right now so that the replacement drops into place.
There are 2 style Fiero Clutch master cylinders, the early style and the late style. Either will work with what ever slave you have. The First and fore most thing with Fiero hydraulic clutch issue that is well known, well documented and often not passed on is a bent clutch pedal.
Before you do any hydraulic clutch diagnoses, open the driver door and hook your peepers on ( look at) the clutch pedal height in relation to the brake pedal. If is not a1/2 inch or more sitting higher than the brake pedal, it will never work no matter what you replace.
Visually check the clutch pedal height compared to the brake pedal and get back to us before you go any farther.
[This message has been edited by jelly2m8 (edited 11-13-2022).]
There are 2 style Fiero Clutch master cylinders, the early style and the late style. Either will work with what ever slave you have. The First and fore most thing with Fiero hydraulic clutch issue that is well known, well documented and often not passed on is a bent clutch pedal.
Before you do any hydraulic clutch diagnoses, open the driver door and hook your peepers on ( look at) the clutch pedal height in relation to the brake pedal. If is not a1/2 inch or more sitting higher than the brake pedal, it will never work no matter what you replace.
Visually check the clutch pedal height compared to the brake pedal and get back to us before you go any farther.
Hey jelly, I have been down this road a couple times when troubleshooting, my pedal was substantially lower than my brake, yesterday i used some rope to pull the pedal more into place but I am interested in seeing if there's a more permanent solution. The pedal itself does not seem to be bent, but rather the U-Bracket is bent. (which i assume is the normal cause) Currently the clutch pedal is about a half inch above the brake but i have a feeling my solution is quite temporary. Even with the pedal in the correct position the slave only actuates about a half inch (ik it needs to go to 1.15")
Out of curiosity do you know how early the "early" version was used? Just curious because I have no history on the car whatsoever, so getting an idea of when it was manufactured would be pretty cool.
Out of curiosity do you know how early the "early" version was used? Just curious because I have no history on the car whatsoever, so getting an idea of when it was manufactured would be pretty cool.
If I recall, it's 84 and 85 that had the pressure port in the rear of the reservoir, 86 and up it's in the front. having said that, the early clutch slave with work with the late slave and vice versa. You shouldn't manipulate the clutch pedal to sit higher than the brake pedal, it needs to be neutral in that position. Yes, it's the U bracket that tends to bend, being it's riveted to the clutch pedal proper; we call it a bent clutch pedal. it needs to sit noticeably higher than the brake pedal. if it's not in its natural state you got to look under there, the clutch slave rod needs to be straight, the connection Hole pointing up, not down. if the rod is straight, and the U bracket is perpendicular with the vertical of the pedal assembly and you have limited slave travel you have air in the system. At this point is where one needs to determine if it's not bled properly, or if there is a slave or master issue.
Bleeding a Fiero Clutch is not complicated, open the bleed screw and wait. when the fluid starts to run steadily it's bled. people that say jack up the front are idiots, the car / system is designed that on level ground, the Clutch master cylinder is higher than the slave cylinder, the bleed screw is at the high point of the slave., they are just trying to compensate for an under lying issue.
Also, the 84 has a steel Slave cylinder bracket, although its design is not as prone to bending as the 85 and up Izuzu trans, that is a far off possibility making the bleed screw of the slave bracket on the low side. Being it's an 84, I doubt that if both bolts are in place for the slave bracket.
One other thing, the 84 originally came with a clutch release arm (on the transmission) that was made from a stamped and folded metal plate. It is prone to cracking and becoming flexible. The fix is to install the improved arm, which is a much more robust cast metal piece.
------------------ Rod Schneider, Ball Ground, Ga. "You can't have too many toys!" 1988 Fiero GT 1988 Porsche 928S4 1987 Corvette 2016 Mustang EcoBoost Van's RV-6 airplane
Not sure why the first design with the outlet fitting behind the reservoir was changed, but I found it to be the most reliable of all after a good number of remanufactured later design units, some that were bad out of the box because they contained one cup seal and an o-ring, where the original contained two cup seals. I bent the line as necessary on an 86 and 87 in order to adapt the 84 first design master cylinder and never had a problem with them. I'd consider it in the case of repeat problems with the later design.
Not sure why the first design with the outlet fitting behind the reservoir was changed, but I found it to be the most reliable of all after a good number of remanufactured later design units, some that were bad out of the box because they contained one cup seal and an o-ring, where the original contained two cup seals. I bent the line as necessary on an 86 and 87 in order to adapt the 84 first design master cylinder and never had a problem with them. I'd consider it in the case of repeat problems with the later design.
Years ago someone posted a cross-section of the two master cylinder designs. As I recall, it was changed to improve the valving and fluid return. I, too in my early Fiero years, before knowing about Pennock's, bent the fluid line on my 85GT because the replacement master cylinder had the port at the front end.
It seems my pedal is the issue right now, I believe I have bled the system properly, Is there any way to bypass the master cylinder to test the slave? not sure how to troubleshoot further other than try to fix the bend pedal
[This message has been edited by glwalker04 (edited 11-18-2022).]
You shouldn't manipulate the clutch pedal to sit higher than the brake pedal, it needs to be neutral in that position. Yes, it's the U bracket that tends to bend, being it's riveted to the clutch pedal proper; we call it a bent clutch pedal. it needs to sit noticeably higher than the brake pedal. if it's not in its natural state you got to look under there
I have only pulled at the pedal to try to bend it back into place, still seems to not want to rest naturally above the brake pedal after i press it down, it will simply return to almost level with the brake. Is there an effective way to bend the u-bracket back into being flush/perpindicular with the pedal without having to take out the whole pedal assembly?
Is there an effective way to bend the u-bracket back into being flush/perpindicular with the pedal without having to take out the whole pedal assembly?
Bending it back will only further fatigue the metal. Short of installing a new pedal, your best bet is to install an adjustable banjo. They're easy enough to make, but Rodney also sells them.
In case you have disconnected the master cylinder pushrod at any time, Patrick's image is the incorrect way to install it. Many of us have made that mistake. I know it looks like that would be the right way, but the curl actually goes upward. If it's down, the piston stroke will be too short to fully disengage the clutch.
