I searched here, and there was this other thread, but this is different.

I only hear the noise when the clutch is disengaged. When I am idling in neutral at a stop light, there is no noise unless I rest my foot on the clutch pedal. Even the slightest pressure on the clutch pedal brings on the noise. The noise is the same, from just resting my foot on the clutch pedal, to pushing the clutch pedal all the way down for complete disengagement, and anything in between.

The first word that comes to mind is "chattering". It has a regular rhythm or cadence. Until I showed it to my mechanic (don't do much for it myself, beyond installing makeup oil) I thought it might have been coming directly from the engine. When I was a mere tadpole and had a bicycle, I saw where someone could wedge a playing card in a way that would make a "click" from every wheel spoke, as the wheel rotated. It has that regular rhythm to it. Or a clock ticking off the seconds.

I want to see if anyone already knows what I am talking about, before I go back to my mechanic. His specialty is Corvettes, but he has worked on Fiero before, and he has already done major mechanical on this one to restore it to running condition. He says that this could be related to GM having changed the supplier from Borg-Warner to Getrag. That it may have something to do with a manufacturing dimension or tolerance that got changed slightly (not by intent) when that change was made. I know that he has been looking at a tech writeup that he found online, but I am not sure whether it is something from Rodney Dickman, or The Fiero Factory.( I just Googled for that myself, but I did not find it.)

I don't have any other symptoms or problems. It is just a noise. Tolerable, but not something I particularly want. My mechanic thinks that if he starts going into this and it turns out to be this problem that he has in mind (as I just described), it will cost me an arm and a leg to repair it. He says that he would have to remove the transmission and also the engine (I think), and that he would have to use a mechanical grinder to reduce the dimension of a part by some very small fraction. I think he means part of the transmission or clutch assembly.

It's the 88 GT, 5-speed stick, dead stock, including the stock 2.8 V6 engine. It has just over 47,000 miles. I acquired it used umpteen years ago. It broke down right away (drive train problems). It sat in my garage for umpteen years until 2010, when I had it towed to this mechanic (same guy I have been talking about) and he did a thorough overhaul to get it running again. Most of the mileage was from the previous owners. He put in a re-manufactured Getrag 5-speed transmission and a standard or street duty Centerforce clutch. It's not a heavy duty or racetrack level clutch. It's got factory AC, which he overhauled and converted to R134, but I don't think it matters whether the AC compressor is running or off. I have been running with this setup since 2010, only about 3000 miles "on my watch", but I did not really become aware of this noise until just recently.

What do you think of what this mechanic is telling me? Could this be something different than what he is describing? Something that would not involve such a large mechanical work order to eliminate? Is there an easier way to diagnose it, without removing the transmission?

[This message has been edited by rinselberg (edited 08-04-2014).]

If I had to bet money on it, I'd wager that the sleeve on your input shaft bearing has broken free and the release bearing is now moving improperly against the clutch release fingers.

https://www.fiero.nl/forum/Forum2/HTML/128457.html

If this is the case, it's not impossible, but it's not fun to fix at all.

This could be helpful as well...

https://www.fiero.nl/forum/Forum9/HTML/000008.html

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Patrick W. Heinske -- LZeitgeist@aol.com

1988 Fiero Formula - Automoda convertible
repainted PPG Ferrari 'Giallo Modena' yellow
1988 Fiero 4-cyl Coupe - Dad's car, the Indy 'clone'
(soon to be back on the road after a 6 year rest)

I was going to say the infamous "getrag rattle" but that only happens when there is no foot pressure on the pedal.
https://www.fiero.nl/forum/A...130314-2-115782.html

This noise (rattle, or "chattering") that I was having whenever I disengaged the clutch--full "clutch pedal all the way down to the floor" disengagement or just partway, or just resting my left foot lightly on the clutch pedal as if ready to disengage it--has gone away. I have driven almost 350 miles, and if it is still present, it is no longer intrusive enough to catch my attention, even when I have primed myself to listen for it. It seems to have abated all at once. An instantaneous vanishing act.

The only work that I have had on it during this period was at the Corvette specialty shop which I always rely on. This was to diagnose engine symptoms (uneven power delivery, surging and stalling). They put in a new ignition coil, and that eliminated the engine symptoms. Just a few weeks ago, and almost 350 miles (backwards from today) on the odometer. Which now reads just over 48,000 miles.

The shop owner also picked up that this clutch noise had largely (if not entirely) abated. He offered me an explanation. He said that he thinks there was some bolt or fastener with a head that was contacting a moving (rotating) part. That was the source of the noise. And that over the last 300+ miles, the friction at this point of contact had (in effect) "machined" this bolt or fastener head and reduced it dimensionally so that it no longer is having this unintended contact.

I'm not enough of a clutch and transaxle boffin to be able to name the parts. I even browsed through some diagrams in this full length Fiero repairs and service manual that I have, but it's all "Greek" to me.

I had a new clutch installed (as part of a gi-normous mechanical overhaul to get it running again). That was in 2010, with just over 43,000 miles on it.

I did not notice this clutch-related noise as intrusive enough to draw my attention until more recently, at about 47,000 miles. As far as my memory and notes go for me, it had been OK after the big overhaul, until it got to about 47,000 miles. So what brought on this noise in the first place? I guess if it could go away by itself, it could have started in the same way. Expected wear from normal driving patterns causing the dimensional changes that brought the two parts into unintended mechanical contact..?

[This message has been edited by rinselberg (edited 04-27-2015).]

The only "bolt head" scenario that I can picture, would have manifested itself as soon as the car was started on day one, after the overhaul. (Usually the result of the wrong pressure plate being installed, and whacking a protrusion on the inside of the tranny case, when it turns. NOT likely, with a stock tranny.)
That is, unless one of the pressure plate bolts had backed out, and is now ground down or fallen off. If that's the case, I would expect some vibration - pretty much all the time. A missing bolt will cause an out-of-balance condition. Hard to tell how noticeable.
I would be inclined to keep driving it, while paying attention to what's going on.
Other than slipping, or not releasing, the most common malady that I'm familiar with, concerning a stock Fiero clutch, is a spring escaping from the clutch disk hub. When that happens, it also tends to cause "non-release" issues, as well as making popping or ticking noises when you step on the clutch.
If that's what happened, it'll likely be back.
The good news is that, if that's what happened, a clutch replacement will fix it, unless it damaged something else (not terribly likely.)
The trans and maybe the engine will still have to come out in order to do it, depending upon how your mechanic does things.

Good luck.


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Raydar
88 Formula IMSA Fastback. 4.9, NVG T550

Praise the Lowered!

[This message has been edited by Raydar (edited 04-28-2015).]

If all operates as normal, I too go with GRS. Getrag Rattle Syndrome. You are not alone. There are support groups for this affliction. We can hug. No, I do not have man tits.

quote Originally posted by Tony Kania: ... We can hug. No, I do not have man tits.

Damn. Another fantasy, shot to hell.

It's not the "Getrag rattle". That's an input shaft and gear noise which happens when the clutch is engaged. When disengaged, nothing is moving in the transmission, so it's not the "Getrag rattle".

The problem is most likely something with:

- the throwout bearing guide sleeve, which can break off from the rest of the input shaft bearing assembly
- the throwout bearing itself (damaged bearing)
- the pressure plate (broken fingers).

None of these can be addressed without separating the engine and transmision.

[This message has been edited by Steven Snyder (edited 04-28-2015).]

sounds like throw out bearing failure. mine did that sound when i installed it backwards.... dont ask and after i installed it correctly i made that sound every time i drove it. I replaced it and it went away.

My first choice is also throw out bearing.