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Author
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Topic: Clutch return spring Elimination?
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Crystalnet
Gearhead Posts: 129
From: Hoschton, GA USA
Registered: Dec 2003
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posted 02-09-2006 06:24 PM
 
It's been suggested to me by a reply on this forum to permanently remove my clutch return spring (under dash)since I wanted to install a King Cobra clutch setup for a T-5 in my 289. It sounds logical but I've never heard that before. Has anyone else done this. My setup is a 67 w/289, a '93 T-5 with late model bellhousing. I plan on getting a RAM 28oz 157 flywheel for a 5.0 and a hydraulic kit for the linkage. The clutch and flywheel and hydraulic kit have not been bought yet so any suggestions would be helpful. Just looking for a nice stock ride.------------------
Randy F.
67 Convertible 289
http://mustang.crystal-ga.com
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68mustang351w
Gearhead Posts: 558
From: San Jose, Ca
Registered: Sep 2004
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posted 02-09-2006 06:48 PM
Im not familiar with the King Cobra clutch but i know that with Centerforce (and possible ALL diaphragm style clutches) you are suppose to remove the spring because there is the possibility of the clutch pedal stick at higher rpm. Hopefully that helps a bit... David F.
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Crystalnet
Gearhead Posts: 129
From: Hoschton, GA USA
Registered: Dec 2003
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posted 02-09-2006 08:18 PM
Thanks David, that is just what I needed to hear.------------------
Randy F.
67 Convertible 289
http://mustang.crystal-ga.com
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exlocal
Gearhead Posts: 1552
From: hacienda hts., CA, USA
Registered: Dec 2004
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posted 02-09-2006 10:31 PM
quote:
Originally posted by 68mustang351w:
.....with Centerforce (and possible ALL diaphragm style clutches) you are suppose to remove the spring because there is the possibility of the clutch pedal stick at higher rpm. Hopefully that helps a bit... David F.
I just had a Centerforce II clutch installed on my 67 coupe, and you're right, the return spring under the dash is gone. I guess the shop forgot to tell me they removed it. ------------------
reliving youth
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68 S-code GT
Gearhead Posts: 3835
From: Sayreville, NJ, US
Registered: Mar 2000
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posted 02-10-2006 09:37 AM
quote:
Originally posted by 68mustang351w:
i know that with Centerforce (and possible ALL diaphragm style clutches) you are suppose to remove the spring because there is the possibility of the clutch pedal stick at higher rpm. Hopefully that helps a bit... David F.
Is this only with a hydraulic or cable setup? I would like to here more about this and if it affects the mechanical original setup also. ------------------
Ed S. 68 S-code FB GT 4spd(now C6)/3.25 PS PDB
68 J-code(now 289) Cp Sprint"B" C4/3L00-9" PDB PS AC Bla-Bla-Bla
99 F150 XLT Ext/cab, 4X4, 5.4L, 3L55
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exlocal
Gearhead Posts: 1552
From: hacienda hts., CA, USA
Registered: Dec 2004
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posted 02-10-2006 11:43 AM
quote:
Originally posted by 68 S-code GT:
Is this only with a hydraulic or cable setup? I would like to here more about this and if it affects the mechanical original setup also.
I still have the original Z-bar setup.
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reliving youth
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68mustang351w
Gearhead Posts: 558
From: San Jose, Ca
Registered: Sep 2004
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posted 02-10-2006 12:53 PM
quote:
Originally posted by 68 S-code GT:
Is this only with a hydraulic or cable setup? I would like to here more about this and if it affects the mechanical original setup also.
I cannot remember the reason why it sticks but it was because the type of clutch and not how its released, but I could be wrong... David F.
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68mustang351w
Gearhead Posts: 558
From: San Jose, Ca
Registered: Sep 2004
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posted 02-10-2006 12:56 PM
Here you go, did some searching on another forum for you. Click here ... David F.
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bifs66
Gearhead Posts: 313
From: Maryland
Registered: Apr 2000
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posted 02-10-2006 03:10 PM
I have the original 1966 Z-bar setup and bellhousing in the Fastback; however, the engine, flywheel, and Centerforce Dual Friction clutch are 5.0 based components. When I first put the car on the road, the clutch worked perfectly for daily driving/cruising. Unfortunately, the first time I ran it at the track and shifted up around 5+K rpms, the clutch pedal stuck to the floor and didn't return until the rpms dropped down. The MSD 6AL rev limiter prevented engine damage (solid roller cam). Apparently, Centerforce diaphram clutches "add" plate pressure with rpms, and old "long" three finger style clutches don't. The large underdash spring had two purposes: In the upper half of pedal travel, the spring acts as a "return" spring to bring the pedal all the way off of the throughout bearing (providing the 1" freeplay). In the lower half of pedal travel, the big spring acts as an "assist" to help push the pedal down (taking some effort off of your left leg). With the Centerforce clutch, this "assist" business is enough to hold the pedal to the floor at high rpms. Removing the spring stops the problem. However, in the case of the 66 linkage, I had to add a pure "return" spring because with the big spring gone, there was nothing to pull the pedal off of the troughout bearing. Other year Mustang clutch linkages can be slightly different than mine in that they may have additional springs attached to various parts of the stock linkage. In those cases, they may not need the big underdash spring removed, or if it's removed, may not need an additional "return" spring added. I have no experience with cable or hydraulic setups. If you are using the stock linkage, it may be a good idea to try it out first, and then see if you need to remove or modify anything.------------------
66 Fastback restomod (12.8 @ 112mph)
85 GT (preserved)
2000 SVT CONTOUR
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Hemikiller
Gearhead Posts: 726
From: Killingworth, CT
Registered: Feb 2002
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posted 02-10-2006 05:58 PM
bif66, I agree with everything you say, except about the Long style clutch not adding pressure with RPM's. They most certainly do. The design is such that the the driving lugs (the three "T" shaped parts protruding from the pressure plates) act as a lever on the plate a higher RPM's.  The higher the RPM, the more force is exerted on the pressure plate. If you've ever free revved a Ford holding the clutch on the floor, you'd feel it kick in about 2500 rpm or so, depending onthe clutch. This helps prevent it from having the same problem at hi-rpms that is inherent to the diaphragm clutch; the release fingers sticking "in", causing the clutch pedal to stick to the floor. Centerforce uses the diaphragm clutch design, but gets around that problem with their unique daisychain of centrifugal weights on the release fingers. You get the best of both worlds, the low pedal effort of a diaphragm clutch, with the hi-rpm holding capabilities of a Long clutch. FWIW, the assist spring that you're talking about is the "overcenter" spring. As you push and release the clutch pedal, the axis of the spring crosses the axis of the pedal shaft, providing assist in both directions.
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68 S-code GT
Gearhead Posts: 3835
From: Sayreville, NJ, US
Registered: Mar 2000
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posted 02-14-2006 08:51 AM
So if I have the overcenter spring installed along with the other two smaller springs do you think I?ll be ok? I have a Ram clutch but haven?t installed it yet.
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FSTBK65
Gearhead Posts: 483
From: Salem, Virginia 24153
Registered: May 2004
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posted 02-14-2006 10:13 PM
I have a Zoom kevlar clutch and it is a diaphragm style. I still have the spring under the dash. Should I get rid of it?------------------
65 fastback. 302, Paxton Supercharger 7PSI, Edelbrock heads and intake, comp cam, Motorsport rockers,flowtechs with cutouts, x pipe and 2.5in flowmasters. Subframe connectors and shelby traction bars. 4 speed, hurst shifter,Zoom clutch. 368hp and 378ft lbs at the wheels on pump gas. 8.01 @ 87.72 mph 1/8 mi with a 1.78 60ft.
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 02-14-2006 11:49 PM
I've never been a fan of diaphragm style clutches,or hydraulic clutch linkages.I don't see any reason to add pressure to the clutch in a daily driver.In a high horsepower application it makes perfect sense and there are long style pressure plates that have adjustable counter weights and provisions for adjusting overall pressure that would be a much better choice than a centerforce unit. The thing to keep in mind is that the amount of static pressure is largely dependent on the coefficiant of friction of the clutch facing material.The higher the c/f the lower the static pressure can be.In my bracket race 302 4spd. I use a Ram six finger metallic disc and an old sheifer pressure plate with three of the nine springs removed. It's rated at about 1900lbs.The car 60ft's in the 1.59-1.60 range.In my opinion ,if you can, use a long style clutch and mechanical linkage.Call the manufacturer and ask their recommendations.They should be able to point you in the right direction as far as facing material and spring weight. 
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BryanM
Journeyman Posts: 78
From: Friendswood, TX
Registered: Dec 2005
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posted 02-15-2006 08:15 AM
quote:
Originally posted by Mark Ugrich:
I've never been a fan of diaphragm style clutches,or hydraulic clutch linkages.I don't see any reason to add pressure to the clutch in a daily driver.
I don't think hydraulic clutch linkages add constant pressure to the clutch do they? The one I had on a jap road race car had a little adjustment rod that gave it a little free play while not depressed.
------------------
Bryan - 1965 coupe / front bench seat / 289 / T5.
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 02-15-2006 10:14 AM
A hydraulic clutch shouldn't effect the pressure on the pedal at all. What I meant was there is no reason to add centrifugal assist, like the weights on the centerforce pressure plate.
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mikulh
Journeyman Posts: 15
From:
Registered: Aug 2005
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posted 02-15-2006 03:36 PM
Here's the deal...
That spring under the dash is not a clutch pedal return spring. It is a clutch pedal assist spring. (The return spring is in the engine compartment attached to a bracket on the firewall.) Since the newer diaphragm style clutches take less pressure the fingers sometimes don't put enough pressure back on the throwout bearing to push the pedal back enough to overcome the spring and return... thus sticking the pedal to the floor.
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68mustang351w
Gearhead Posts: 558
From: San Jose, Ca
Registered: Sep 2004
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posted 02-15-2006 07:34 PM
quote:
Originally posted by mikulh:
Here's the deal...
That spring under the dash is not a clutch pedal return spring. It is a clutch pedal assist spring. (The return spring is in the engine compartment attached to a bracket on the firewall.)
Actually its an over-center spring, it helps in both direction and typically not needed with a diaphragm style clutch... David F.on edit: just re-read my post (a couple hours later) and i thought i came off as an @$$#o!& so i just wanted to clear that up... [This message has been edited by 68mustang351w (edited 02-16-2006).]
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68 S-code GT
Gearhead Posts: 3835
From: Sayreville, NJ, US
Registered: Mar 2000
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posted 02-16-2006 09:29 AM
quote:
Originally posted by mikulh:
Here's the deal...
That spring under the dash is not a clutch pedal return spring. It is a clutch pedal assist spring.
Thats what I thought. I guess it?s just a matter of trying your setup out and removing the spring if it needs to be. There are just too many variables to just say yes or no. You have the car year (spring rates vary), pressure plate type, size of clutch (relates to the size of pressure plate), whether on not you installed roller bearings in the support and if you have the mechanical linkages, cable or hydraulic setup.
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