Pennock's Fiero Forum
  Technical Discussion & Questions
  Failing Clutch - Hydraulics?

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
Failing Clutch - Hydraulics? by thesameguy
Started on: 07-13-2014 02:19 AM
Replies: 6 (104 views)
Last post by: TopNotch on 07-13-2014 09:50 PM
thesameguy
Member
Posts: 1414
From: California
Registered: Dec 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post07-13-2014 02:19 AM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi guys -

Since the big suspension upgrade last year my Fiero has been kicking ass and taking names... until super early Thursday morning. I'd hustled the car up to Lake Tahoe Wednesday evening and stayed overnight. In the morning I went to back the car out of the garage and could not get into any gear. I turned the car off, put it in reverse, started it, and backed out. 1st was unpleasant, but each gear was gradually easier. No further issues on the drive home through 3rd, 4th, and 5th. I figured it was a fluke.

Didn't drive it for a couple days, today the same thing - except worse. I drove it around the block and shifting was an impossibility. Pumping the pedal didn't help. I took it home and parked it. The clutch master cylinder reservoir was low - at the "add" line. I looked around and saw no leaks. I hooked up the Motive pressure bleeder and put 8psi in the system. Still no leaks. I cracked the slave cylinder bleeder screw and got a small burst of air, followed by a steady stream of fluid. I took out 12 full ounces, no bubbles or anything. The weird thing, however, was that my year old (almost exactly), 2,000 mile ATE Super Blue was GREY.

Regardless, I sealed it back up and it worked great. I ran my errands without incident. Five hours later, clutch is hosed again in exactly the same way. I was only able to move it by starting in gear. Poop.

I'm pretty sure I am dealing with a hydraulics failure - the pedal feels VERY spongy at the top (like nothing is happening), the air blowing out when I bled it, the grey fluid (from deteriorating seals?), and the spontaneous failure/repair/failure. When I bought the car at 98,000 miles I was told the clutch was new at 75,000 miles (when the 3.4pr was installed) so I'm inclined to believe it's not that.

Couple questions:

1. Is there any way to inspect the clutch without taking things apart?
2. Any opinions on whether the issue is more likely the slave or the master? From reading here, sounds like the slaves on these cars are crap so that's where I am leaning. (I know the advice is to buy Rodney's, however I need to keep this cheap right now *and* this car will be getting a powertrain swap this winter, so it doesn't need to last very long)
3. Anything else?

Thanks guys!
IP: Logged
PFF
System Bot
phonedawgz
Member
Posts: 17009
From: Green Bay, WI USA
Registered: Dec 2009


Feedback score:    (23)
Leave feedback





Total ratings: 290
Rate this member

Report this Post07-13-2014 02:55 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
If you want to look at the clutch take off the inspection plate at the bottom 'front' of the bellhousing and look at it. A mirror will let you see the thickness of the clutch disk lining.

Since your trouble is that the clutch won't fully disengage it's not like you are going to find a worn out clutch (that doesn't fully engage).

The typical problem of repeatedly finding air in the slave cylinder can usually be solved with Rodney's slave cylinder, or perhaps you can get away with just the piston upgrade.

http://rodneydickman.com/ca...g/index.php?cPath=61

Bad master cylinders usually leak fluid into the carpet underlayment and thus manifest themselves as running out of brake fluid regularly but the owner can't figure out where it is going.

When you can't get the car in gear - before you fix this problem - pump the clutch pedal three times quickly and then hold it on the last pump. See if that isn't a temp fix until you replace the slave piston

The clutch piston seals are umbrella type seals. Thus when they are under pressure (from you having your foot on the clutch pedal) the hydraulic fluid presses the seal against the cylinder walls. When there is no pressure (the system at idle) only the flex of the rubber is holding the seal against the wall. So they tend to leak at rest, and when the slave leaks it tends to leak by letting air in, not fluid out.

[This message has been edited by phonedawgz (edited 07-13-2014).]

IP: Logged
thesameguy
Member
Posts: 1414
From: California
Registered: Dec 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post07-13-2014 06:14 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
That's great info - thanks!

I'm wondering if maybe the cold+altitude (Tahoe is 5,000' above Sacramento) "encouraged" air to get sucked into the slave. Last night when I checked the reservoir the fluid was just slightly lower than when I left it - a hair's width below the "full" line versus at the line. I suppose I should go check it again now. I did check the MC both inside the cabin and under the hood and it's bone dry - but then so is the slave. However if the slave's common failure mode is sucking air, maybe that's all there is to it. My pretty blue fluid certainly didn't turn grey by itself - it's gotta be deteriorating seals. The actual brake fluid still looks brand new (as it should!)

It's definitely not the clutch disc, but I was wondering if perhaps it was the pressure plate - I've had springs break and fingers crack on other cars leading to similar symptoms, although typically those type of mechanical failures are permanent, and tend to make noise. Not always though - my Honda limped along with failed springs for months.

Rodney's slave is a lot less than I recalled it being, so I may just go ahead and order it. Napa has their own brand for $27 that I can pick up today, so that's on the table as well. $30 is the difference between overkill and instant gratification.
IP: Logged
Patrick
Member
Posts: 30117
From: Vancouver, British Columbia, Canada
Registered: Apr 99


Feedback score: (1)
Leave feedback





Total ratings: 442
Rate this member

Report this Post07-13-2014 07:12 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post

This sounds like a classic example of a worn slave sucking in air.

Don't do a half-assed job. Buy Rodney's dual-seal slave. It's worth the money and/or the wait.
IP: Logged
Arns85GT
Member
Posts: 11147
From: London, Ontario, Canada
Registered: Jul 2003


Feedback score: (1)
Leave feedback





Total ratings: 200
Rate this member

Report this Post07-13-2014 07:36 PM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
The slave will fail long before the MC. If you are ordering a slave from Rodney you might as well order his adjustable banjo as well. It is well worth the small investment. You might also consider the all steel pedal from the Fierostore too.

Arn
IP: Logged
thesameguy
Member
Posts: 1414
From: California
Registered: Dec 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post07-13-2014 09:41 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Upon reflection there is no way I can wait to get Rodney's - it's gonna have to be Napa's - I can pick it up tomorrow and have the car on the road by noon. It only needs to last about six months, and based on my driving habits (~2,000 miles annually) only a few tanks of gas. I appreciate the advice all!
IP: Logged
TopNotch
Member
Posts: 3537
From: Lawrenceville, GA USA
Registered: Feb 2009


Feedback score:    (7)
Leave feedback





Total ratings: 59
Rate this member

Report this Post07-13-2014 09:50 PM Click Here to See the Profile for TopNotchClick Here to visit TopNotch's HomePageSend a Private Message to TopNotchEdit/Delete MessageReply w/QuoteDirect Link to This Post
A leaking master can also cause clutch problems. Check the carpet liner just under where the banjo goes into the master. I had to replace both my slave and master with Rodney's to fix my clutch problems.
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock