Pennock's Fiero Forum
  Technical Discussion & Questions
  3800SC w/5 Speed Slipping Clutch Root Cause Analysis and solution

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


next newest topic | next oldest topic
3800SC w/5 Speed Slipping Clutch Root Cause Analysis and solution by wpg_87gt
Started on: 11-13-2023 10:17 AM
Replies: 3 (346 views)
Last post by: Frenchrafe on 11-15-2023 05:01 AM
wpg_87gt
Junior Member
Posts: 1
From: Winnipeg, Manitoba, Canada
Registered: Aug 2023


Feedback score: N/A
Leave feedback

Rate this member

Report this Post11-13-2023 10:17 AM Click Here to See the Profile for wpg_87gtSend a Private Message to wpg_87gtEdit/Delete MessageReply w/QuoteDirect Link to This Post
I purchased a 1987 Fiero GT with a 3800SC and 5 Speed manual and have had some clutch slipping issues, on a fairly new Centerforce Dual Friction clutch installed by the previous owner.

Currently I've removed the clutch to determine what is causing these issues and I was hoping to get some input from others to determine if I am on the right track to a solution.

So far I've found the following:
1. Clutch will slip in 4th and 5th gear when accelerating aggressively.
2. Clutch disengagement point is closer to the top of the pedal travel.
3 Clutch Cover Rivets were contacting the transmission bellhousing and have worn a groove into it.
4. The clutch release fingers also were contacting the clutch pressure pressure plate.
5. There are some metal shavings on the transmission input shaft, which I suspect came from interference 3 and 4.
6. When measuring the fly wheel thickness, I end up with 0.885", which based on my reading is about 0.065" thicker than it should be.

My current theory and plan are as follows:

The excess fly wheel thickness was causing the clutch to contact the transmission housing, potentially also not completely engaging the clutch, creating the slipping issue.

To address this, I plan to have flywheel machined down to 0.820" or order the Spec SC62A Aluminum flywheel designed for this application, then install a new clutch.

Thoughts?

[This message has been edited by wpg_87gt (edited 11-13-2023).]

IP: Logged
PFF
System Bot
Larryinkc
Member
Posts: 688
From: Kansas City, MO USA
Registered: Nov 2012


Feedback score: (3)
Leave feedback

Rate this member

Report this Post11-13-2023 03:18 PM Click Here to See the Profile for LarryinkcSend a Private Message to LarryinkcEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have a Series III SC 3800 with a Spec aluminum flywheel and Stage 3+ clutch. I drive it enthusiastically and have about 12,000 miles on it and no problems.

Aluminum flywheel bolt to crank info.

https://www.fiero.nl/forum/Forum2/HTML/131343.html

https://www.fiero.nl/forum/Forum2/HTML/139634.html

https://www.fiero.nl/forum/Forum2/HTML/146745.html
IP: Logged
olejoedad
Member
Posts: 19681
From: Clarendon Twp., MI
Registered: May 2004


Feedback score: (5)
Leave feedback





Total ratings: 206
Rate this member

Report this Post11-14-2023 06:29 PM Click Here to See the Profile for olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
I think you are spot on with your analysis and solution.
IP: Logged
Frenchrafe
Member
Posts: 476
From: Locmiquelic France
Registered: Feb 2017


Feedback score: N/A
Leave feedback

Rate this member

Report this Post11-15-2023 05:01 AM Click Here to See the Profile for FrenchrafeSend a Private Message to FrenchrafeEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yep! Flywheel too thick.
I use a SPEC aluminium flywheel and my clutch never slips.
Though the steel insert (contact/pressure plate that the clutch disc runs on) of the flywheel will wear out quicker than the rest. I've replaced one already and I don't do more than a few track days each year ans no more than 2000km/year.
I'm hard on clutches!😅

------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

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
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock