Rookie Question
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Rookie Question
Hello Olds Fans! Wondering if I can pick your brains for some clutch info. I'm looking to set up a 4-speed behind a 500 cu in Caddy motor, I have a bell housing, #1249599, that fits the block fine, and has a release arm that pulls the throw-out bearing away from the pressure plate. I've heard this called a "pull-type" clutch. In trying to buy a clutch kit I have so far stumped my local Napa store, Summit Racing's Tech support line, McLeod's tech line, ClutchMaster's tech line, and others. Anybody have any ideas?
Phil Rennegarbe, Inyokern, Ca.
'56 Nash Rambler, '64 International Scout, '57 GMC (that's getting the Caddy motor), '68 Spitfire, '61 Traveleze trailer. (Lots of projects!)
Phil Rennegarbe, Inyokern, Ca.
'56 Nash Rambler, '64 International Scout, '57 GMC (that's getting the Caddy motor), '68 Spitfire, '61 Traveleze trailer. (Lots of projects!)
Old(s) Fart
Joined: Mar 2007
Posts: 50,791
From: Northern VA
Hello Olds Fans! Wondering if I can pick your brains for some clutch info. I'm looking to set up a 4-speed behind a 500 cu in Caddy motor, I have a bell housing, #1249599, that fits the block fine, and has a release arm that pulls the throw-out bearing away from the pressure plate. I've heard this called a "pull-type" clutch. In trying to buy a clutch kit I have so far stumped my local Napa store, Summit Racing's Tech support line, McLeod's tech line, ClutchMaster's tech line, and others. Anybody have any ideas?
Phil Rennegarbe, Inyokern, Ca.
'56 Nash Rambler, '64 International Scout, '57 GMC (that's getting the Caddy motor), '68 Spitfire, '61 Traveleze trailer. (Lots of projects!)
Phil Rennegarbe, Inyokern, Ca.
'56 Nash Rambler, '64 International Scout, '57 GMC (that's getting the Caddy motor), '68 Spitfire, '61 Traveleze trailer. (Lots of projects!)
Your understanding of a "pull type" clutch is in error. The throwout bearing ALWAYS has to push in on the clutch fingers to release the clutch. The "pull" part of the description comes from the fact that your bellhousing is designed for a cable style clutch linkage. The cable PULLS on the fork, which is why the fork pivot is on the opposite side of the bellhousing from a normal "pushrod" style clutch linkage.
If you had typed your bellhousing casting number into Google, you would have found that it was originally used on the 1975-1980 H-body cars with the Buick V6 (Olds Starfire, Buick Skyhawk, Pontiac Sunbird, and Chevy Monza). Get a throwout bearing for one of these cars.
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Joined: Oct 2017
Posts: 2
I had found this bell housing listed as fitting '76-'79 Pontiacs and Buicks, and '75 Oldsmobiles with Muncie transmissions. My thinking was that since those cars were available with big block V-8's, you folks might have some info that the others don't. To put a stick behind a Caddy motor either requires an adapter to the Chevy pattern, or using a BOP bell housing, Not sure a clutch from a v-6 would last in my application. Thanks though.
Modern passenger cars are fitted with several different types of clutches, depending on the design and specification of the drive train. The two principal designs are, push type clutches and pull type clutches. This bulletin has been produced to explain the operation of these designs.
www.valeoservice.co.uk Valeo Service (UK) Ltd, Heming Road, Washford, Redditch, Worcestershire, B98 0DZ Tel: 01527 838300 Fax: 01527 523732
Push Type Clutches Conventional push type - On a push type clutch when you depress the clutch pedal, the release bearing pushes the diaphragm fingers to disengage the clutch.
The push type clutch is the most common type of clutch used due to its ease of assembly and is suitable for a wide number of vehicles applications.
Conventional push type - On a push type clutch when you depress the clutch pedal, the release bearing pushes the diaphragm fingers to disengage the clutch.
Pressure Plate
Friction Plate
Flywheel
Example of a push type clutch cover
There is more information about pull type clutch and a fitting procedure in TSB CL016-09
Push type clutch - Self adjusting mechanism SAT A development of the push type clutch is the self adjusting system, which ensures the same diaphragm finger height throughout the life of the clutch, maintaining consistent pedal feel. The other advantages of a self adjusting system are: ● Allows 20 to 30% more torque to be transmitted (direct injection engines). ● Size and weight is reduced. ● Increase in product life (to match longer manufacturer warranty’s) Valeo have designed a new type of clutch that is designed to have the same advantages of the SAT clutch and has the same appearance as a conventional push type clutch. This design of clutch is a high efficiency clutch (HEC). More information about these clutches can be found in TSB CL010-08. SAT is a revolutionary technology that uses a self adjusting friction wear compensator on the pressure plate. This increases its effective thickness as the drive plate facings wear. Upon detecting a reduction in friction plate thickness, the compensation device adjusts the position of the pressure plate (within the cover assembly) in order to maintain a constant pedal load.
Pull type clutch As shown in the diagram, a pull type clutch pull the diaphragm fingers away from the flywheel. The design of the pivot in the cover allows the pressure ring to come away from the friction plate, disconnecting the engine drive from the gearbox. The advantages of a pull type system are: a. grater clamp loading b. lighter in weight c. smaller diameter d. improved cooling
Modern passenger cars are fitted with several different types of clutches, depending on the design and specification of the drive train. The two principal designs are, push type clutches and pull type clutches. This bulletin has been produced to explain the operation of these designs.
www.valeoservice.co.uk Valeo Service (UK) Ltd, Heming Road, Washford, Redditch, Worcestershire, B98 0DZ Tel: 01527 838300 Fax: 01527 523732
Push Type Clutches Conventional push type - On a push type clutch when you depress the clutch pedal, the release bearing pushes the diaphragm fingers to disengage the clutch.
The push type clutch is the most common type of clutch used due to its ease of assembly and is suitable for a wide number of vehicles applications.
Conventional push type - On a push type clutch when you depress the clutch pedal, the release bearing pushes the diaphragm fingers to disengage the clutch.
Pressure Plate
Friction Plate
Flywheel
Example of a push type clutch cover
There is more information about pull type clutch and a fitting procedure in TSB CL016-09
Push type clutch - Self adjusting mechanism SAT A development of the push type clutch is the self adjusting system, which ensures the same diaphragm finger height throughout the life of the clutch, maintaining consistent pedal feel. The other advantages of a self adjusting system are: ● Allows 20 to 30% more torque to be transmitted (direct injection engines). ● Size and weight is reduced. ● Increase in product life (to match longer manufacturer warranty’s) Valeo have designed a new type of clutch that is designed to have the same advantages of the SAT clutch and has the same appearance as a conventional push type clutch. This design of clutch is a high efficiency clutch (HEC). More information about these clutches can be found in TSB CL010-08. SAT is a revolutionary technology that uses a self adjusting friction wear compensator on the pressure plate. This increases its effective thickness as the drive plate facings wear. Upon detecting a reduction in friction plate thickness, the compensation device adjusts the position of the pressure plate (within the cover assembly) in order to maintain a constant pedal load.
Pull type clutch As shown in the diagram, a pull type clutch pull the diaphragm fingers away from the flywheel. The design of the pivot in the cover allows the pressure ring to come away from the friction plate, disconnecting the engine drive from the gearbox. The advantages of a pull type system are: a. grater clamp loading b. lighter in weight c. smaller diameter d. improved cooling
Old(s) Fart
Joined: Mar 2007
Posts: 50,791
From: Northern VA
Oh, well, it's in the Interwebs, so it must be true...
Let's try this again. NO GM car built in the US during at least the 1960s-1980s ever used a clutch that pulled on the fingers of the clutch spring, period. You got a puzzled look from the guy at the auto parts store because the thing you were asking for does not exist.
Communication requires the use of common terms to refer to ideas and concepts. In the US, the push vs pull designation is used to refer to the method of actuating the clutch fork, NOT how the throwout bearing works. The bellhousing you picked uses a cable operated by the clutch pedal to PULL the clutch fork (and throwout bearing) towards the clutch fingers, where it PUSHES on them. Conventional rod-style clutch linkages use a rod to PUSH the fork, which pivots in the middle and thus also PUSHES the throwout bearing towards the clutch fingers. The throwout bearing is the same in either case. FYI, there are also hydraulic clutch slave cylinders. These may either push or pull, depending on which side of the fork they are mounted on and where the fork pivots, but in all cases, the throwout bearing PUSHES on the clutch fingers.
You did not specify what vehicle you plan to install this drivetrain in. Does the Caddy block even have a provision for a pivot ball for a conventional clutch linkage Z-bar? I suspect not, so the cable style clutch may be a better choice for you. You may also want to consider a hydraulic throwout bearing and eliminate all this linkage entirely. There are many BOP compatible bellhousings. The two most common are 5778881 and 9785581. These can be found for $50-$75 used. Both are designed for a conventional rod-style clutch linkage and fork and were used in nearly all BOP cars from 1965-1977.
Let's try this again. NO GM car built in the US during at least the 1960s-1980s ever used a clutch that pulled on the fingers of the clutch spring, period. You got a puzzled look from the guy at the auto parts store because the thing you were asking for does not exist.
Communication requires the use of common terms to refer to ideas and concepts. In the US, the push vs pull designation is used to refer to the method of actuating the clutch fork, NOT how the throwout bearing works. The bellhousing you picked uses a cable operated by the clutch pedal to PULL the clutch fork (and throwout bearing) towards the clutch fingers, where it PUSHES on them. Conventional rod-style clutch linkages use a rod to PUSH the fork, which pivots in the middle and thus also PUSHES the throwout bearing towards the clutch fingers. The throwout bearing is the same in either case. FYI, there are also hydraulic clutch slave cylinders. These may either push or pull, depending on which side of the fork they are mounted on and where the fork pivots, but in all cases, the throwout bearing PUSHES on the clutch fingers.
You did not specify what vehicle you plan to install this drivetrain in. Does the Caddy block even have a provision for a pivot ball for a conventional clutch linkage Z-bar? I suspect not, so the cable style clutch may be a better choice for you. You may also want to consider a hydraulic throwout bearing and eliminate all this linkage entirely. There are many BOP compatible bellhousings. The two most common are 5778881 and 9785581. These can be found for $50-$75 used. Both are designed for a conventional rod-style clutch linkage and fork and were used in nearly all BOP cars from 1965-1977.
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