Intermittent clutch issue (Page 1/2)
1985 Fiero GT APR 18, 12:23 PM
I have driven my Fiero for 3 days with no issues at all, yesterday the clutch engaged a little low once or twice, today about 1/5 of the time I press my clutch it acts like air in the line, goes down (a few inches, half way, or fully, at random) with no effort and doesn't disengage the clutch, I've had this happen about 15 times today, clutch fluid is full, with no leaks at all. Rodney master, slave, and clutch release arm (on transmission), and the clutch pedal return spring removed (when changing bushings). Fiero ran fine all last year without issue, and the first 3 days out of hibernation, but now seems like it has air in the system, can air be intermittent like this, one press full pedal, next to the floor? When it goes to the floor, it will "pump up" in that if I press it again one or twice it will firm up. I will bleed the system in 5 hours when I get home, but I want to know if that is the issue before embarking on that.
1985 Fiero GT APR 18, 08:52 PM
Ok, I discovered the issue, it was in fact my Rodney Dickman early master cylinder. The valve between the reservoir and the cylinder failed, allowing fluid pumped by the piston to flow back to the reservoir instead of to the slave cylinder.

My thought is that it might have something to do with the non OEM travel of the master cylinder, with the piston bottoming out every shift, instead of the pedal stopping on the floor, might have damaged the valve in some way. My thread addressing this problem when I first got the master cylinder: https://www.fiero.nl/forum/Forum2/HTML/147068.html

For every other product, quality and support has been exceptional, but with this one, the best Rodney did was offer to have it shipped back to see what was different with it (while confirming that his stock measured the same as my example, which measured short of my OEM cylinder, and other replacements)

I will likely end up with another Rodney master, whether a "warranty" replacement, or if I must buy another, I love the feel, but am now very concerned about the longevity of future replacements if my problem is connected to the short travel.

Nothing against Rodney, but I feel something in this product was either designed wrong or messed up in production, which wasn't noticed until it was "too late"
Patrick APR 18, 11:01 PM

quote
Originally posted by 1985 Fiero GT:

Ok, I discovered the issue, it was in fact my Rodney Dickman early master cylinder. The valve between the reservoir and the cylinder failed, allowing fluid pumped by the piston to flow back to the reservoir instead of to the slave cylinder.

Nothing against Rodney, but I feel something in this product was either designed wrong or messed up in production, which wasn't noticed until it was "too late"



I don't know when you bought that Dickman clutch master, but he did have a problem a few years ago with them. It might've been limited to a bad batch, I don't recall the finer details.

Dickman clutch slaves with their dual-seal pistons are fantastic, and I wouldn't wish to own a manual transmission Fiero that doesn't have one of these installed. Having said that, the clutch master is far less critical. I replaced the clutch master cylinder in my Formula a couple of years ago with the cheapest one I could find at RockAuto. It's been absolutely fine ever since.

[This message has been edited by Patrick (edited 04-18-2024).]

1985 Fiero GT APR 19, 05:53 AM

quote
Originally posted by Patrick:

I don't know when you bought that Dickman clutch master, but he did have a problem a few years ago with them. It might've been limited to a bad batch, I don't recall the finer details.

Dickman clutch slaves with their dual-seal pistons are fantastic, and I wouldn't wish to own a manual transmission Fiero that doesn't have one of these installed. Having said that, the clutch master is far less critical. I replaced the clutch master cylinder in my Formula a couple of years ago with the cheapest one I could find at RockAuto. It's been absolutely fine ever since.




I got mine last July, he was running on overstock then and still is, it seems, as the manufacturer quit or something. Yeah I just put the rock auto one back in, but I love the feel of the Rodney one much more, oh well, I'll see what Rodney says about it.
Patrick APR 19, 05:38 PM

quote
Originally posted by 1985 Fiero GT:

Yeah I just put the rock auto one back in, but I love the feel of the Rodney one much more...



I don't really understand what you're saying here. A clutch master cylinder either works properly or it doesn't. Where does "the feel" come in?
1985 Fiero GT APR 19, 05:56 PM

quote
Originally posted by Patrick:

I don't really understand what you're saying here. A clutch master cylinder either works properly or it doesn't. Where does "the feel" come in?



My old Rodney one failed, it feels horrible now because it's broken, but when it worked it "felt"much better then the rock auto one, smoother, more precise, etc. so I will likely end up getting another one, whether a "warranty"replacement due to the early failure, or I might have to buy another one, as I much prefer the feel of the working Rodney one then the working rock auto one
Patrick APR 19, 06:08 PM

I still don't understand how a properly functioning clutch master cylinder could feel much different than any other properly functioning one. The length of the banjo could effect how the overall operation of the clutch "feels", but IMO that's much more dependent on the banjo itself rather than of the master cylinder.
1985 Fiero GT APR 19, 06:12 PM

quote
Originally posted by Patrick:


I still don't understand how a properly functioning clutch master cylinder could feel much different than any other properly functioning one. The length of the banjo could effect how the overall operation of the clutch "feels", but IMO that's much more dependent on the banjo itself rather than of the master cylinder.



Even off the car, empty of fluid, the rock auto one is stiffer, more jerky, Rodney one is smoother, either the bore is more polished or the piston is a better fit, also I do think the rock auto one is a slightly smaller bore then the Rodney and OEM (speculation), only slightly, as pedal pressure is slightly less (which I personally don't like).
Patrick APR 19, 06:52 PM

This LuK unit is what I bought three years ago. It was about $22(US) at the time. Operation is smooth as glass. "Feels" good to me.

1985 Fiero GT APR 19, 07:00 PM

quote
Originally posted by Patrick:


This LuK unit is what I bought three years ago. It was about $22(US) at the time. Operation is smooth as glass. "Feels" good to me.




Interesting, is that cast iron? Usually the aluminum ones aren't black. If so that might have an impact on it, I got the perfection clutch one, externally looks very very close to Rodney's, but lower quality, more burrs, different reservoir, etc.