Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > Porsche 911 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Still here
 
pmax's Avatar
 
Join Date: May 2014
Location: SF Bay Area
Posts: 18,079
Garage
915 Clutch Helper "Omega" Spring Function

Why did Porsche add the helper "omega" spring to the 915 clutch mechanism ?

If it is to reduce clutch effort, as far as I can tell, that remains the same sprung or unsprung though the pickup point is much lower, arguably better in fact, in the latter case.


Last edited by pmax; 03-09-2025 at 04:30 PM..
Old 03-09-2025, 04:27 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered
 
Join Date: Jun 2011
Location: Kalifornia
Posts: 1,461
Garage
Quote:
Originally Posted by pmax View Post
Why did Porsche add the helper "omega" spring to the 915 clutch mechanism ?

If it is to reduce clutch effort, as far as I can tell, that remains the same sprung or unsprung though the pickup point is much lower, arguably better in fact, in the latter case.
I think the spring helps lessen the peddle effort when first pushing the peddle in.
Old 03-09-2025, 05:34 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered
 
Join Date: Apr 2022
Location: Orange County, CA
Posts: 160
Garage
I don't know what it is officially designed to do. However, that spring was broken when I bought my '84 Carrera. After I had it replaced, the clutch did seem to work a bit more smoothly, especially when first pushing it in - as porschedude said, above.
__________________
Roger

1984 911 Carrera coupe
1972 911T coupe (owned 1978-1995, sold after divorce. . . . bummer)
Old 03-09-2025, 09:01 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered
 
walt's Avatar
 
Join Date: Apr 2002
Location: Raleigh, NC
Posts: 1,351
Garage
It does give the pedal a snap action feel to it when first depressed.
__________________
Walt
82SC 3.0
81SC 3.6
Old 03-10-2025, 03:21 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Still here
 
pmax's Avatar
 
Join Date: May 2014
Location: SF Bay Area
Posts: 18,079
Garage
So, a power mechanism which adds more force to the arms during the initial travel from sprung to unsprung.

Quote:
Originally Posted by Fab64 View Post
I don't know what it is officially designed to do. However, that spring was broken when I bought my '84 Carrera. After I had it replaced, the clutch did seem to work a bit more smoothly, especially when first pushing it in - as porschedude said, above.
Curious, by smoother, do you mean easier ?

The reason I ask is that snap action leads to a non-linear feel in the sense that the foot feels the spring action first then the resistance of the short arm as it moves the TOB is the way I understand it.
Old 03-10-2025, 12:54 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered
 
Join Date: Jan 2011
Location: Gulf Coast FL
Posts: 1,482
Drive a 75 or older car and you will understand. I've considered converting my old 74.
Old 03-11-2025, 05:50 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Still here
 
pmax's Avatar
 
Join Date: May 2014
Location: SF Bay Area
Posts: 18,079
Garage
Quote:
Originally Posted by eastbay View Post
Drive a 75 or older car and you will understand. I've considered converting my old 74.
The earlier simpler mechanisms.




The later 915 standard clutch lever install with the dead space introduced by the two arm omega spring setup

Sorry about the "dirty" pic, not mine, a good example being harder to find that I expected.

In the later 915s there's a spring on the short arm in tension which preloads the TOB fork whereas the earlier variant's all in the clutch cable. Is the cable tension much higher in the latter ? The omega spring assists in the initiation of the clutch pedal movement but how much does it help if at all beyond that phase ? I believe by the time the omega reaches the "red" position, it is largely unsprung. And arguably the leverage of the later version has been lengthened somewhat so that helps.

So I suppose the combination of all these factors contribute to easier clutching. In my SC, the omega spring doesn't seem to do much for this purpose.

Threads of interest.
Examples of the clutch lever backdate, the advantages being elimination of the dead space caused by the 1/1.2mm gap contributing to a more direct linear feel in addition to simplifying the mechanism.
930 Clutch Throw Out Lever / Helper Spring Issue
Clutch Adjustment Help
https://forums.pelicanparts.com/porsche-911-technical-forum/1163942-what-can-you-tell-me-about-my-engine.html#post12278738
https://forums.pelicanparts.com/porsche-911-technical-forum/1178995-clutch-positioning-lever-broken-spring-attachment-2.html
https://forums.pelicanparts.com/porsche-911-technical-forum/417364-convert-early-915-clutch-arm.html#post4033069

Omega snap facilitates cable tensioning which allows long arm to "float".


Last edited by pmax; 08-03-2025 at 09:47 AM..
Old 03-11-2025, 08:31 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Reply


 


All times are GMT -8. The time now is 05:02 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2025 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.