5. Bellhousing/Clutch Fork/Inspection Cover

5.1. Mechanical Clutch Linkage

Due to the geometry of the 1978-1981 A body mechanical clutch linkage, it is not possible to use a commonly available Chevrolet mechanical bellhousing (such as casting 3840383, 3858403, or 3899621) in conjunction with the factory A body clutch linkage. The clutch fork used in the 1978-1981 A body applications has a downward drop (Figure 5-1) at the push point and the ballstud in the bellhousing has been lowered to retain a straight imaginary line between the center of the release bearing, the ballstud, and the push point of the clutch fork.

Figure 5-1: 1978-1981 GM A Body Clutch Fork (Chevrolet and Buick-Oldsmobile-Pontiac {BOP}) - GM 14007356

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To the best of my knowledge, the following are the only bellhousings that will work with the factory 1978-1981 A body mechanical clutch linkage:

  • 1978 A body (casting 464697; Figure 5-2) for 168-tooth flywheel; Chevrolet; use with clutch fork: GM 14007356

Positive identifiers: casting 464697, lowered clutch fork ballstud, and 697 cast onto inside clutch fork ballstud boss (Figure 5-3).

  • 1978 A body (casting 469697; Figure 5-2) for 168-tooth flywheel; Chevrolet; use with clutch fork: GM 14007356

Positive identifiers: casting 469697, lowered clutch fork ballstud, and 697 cast onto inside clutch fork ballstud boss (Figure 5-3).

  • 1978-1981 A body (casting 462606; Figure 5-4) for 153-tooth flywheel; Chevrolet; use with clutch fork: GM 14007356

Positive identifiers: casting 462606, lowered clutch fork ballstud, and 606 cast onto inside clutch fork ballstud boss (Figure 5-5).

  • 1978-1981 A body (casting 10008979, 10000808, 563441, 547975; Figure 5-6) for 153-tooth flywheel; Buick-Oldsmobile-Pontiac [BOP]; use with clutch fork: GM 14007356

  • 1982 V8 F body (casting 14037657; Figure 5-7) for 153-tooth flywheel; Chevrolet/BOP; use with clutch fork: GM 14037647

  • 1983 V8 F body (casting 14060627; Figure 5-8) for 153-tooth flywheel; Chevrolet; use with clutch fork: GM 14037647

  • 1984-1988 Corvette (casting 14048867; Figure 5-9) for 153-tooth flywheel; Chevrolet; use with clutch fork: GM 14066235

  • Lakewood Industries 15015 for 1982-1983 V8 F body (Figure 5-10); use with clutch fork: Lakewood Industries 15500, GM 340278, or GM 14066235

Figure 5-2: 1978 GM A Body Bellhousing (casting 464697/469697; Chevrolet)

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Photograph courtesy of Bill Fair

Figure 5-3: 1978 GM A Body Bellhousing Clutch Fork ballstud Location - 697

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Photograph courtesy of Bill Fair

Figure 5-4: 1978-1981 GM A Body Bellhousing (casting 462606; Chevrolet)

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Figure 5-5: 1978-1981 GM A Body Bellhousing Clutch Fork ballstud Location - 606

Figure 5-6: 1978-1981 GM A Body Bellhousing (casting 10008979, 10000808, 563441, or 547975; BOP)

 

Figure 5-7: 1982 GM V8 F Body Bellhousing (casting 14037657; Chevrolet/BOP)

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Photographs courtesy of J. Matthew Daugherty

Figure 5-8: 1983 GM V8 F Body Bellhousing (casting 14060627; Chevrolet; Hollander 784)

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Photographs courtesy of J. Matthew Daugherty

Figure 5-9: 1984-1988 Corvette Bellhousing (casting 14048867; Chevrolet)

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Photograph courtesy of Darryl Gilbert

Figure 5-10: Lakewood Industries 15015 for 1982-1983 V8 F Body; Chevrolet

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Photograph courtesy of Chris DiChiara

Beware: There are two versions each of casting 462606, 464697, and 469697. The casting number alone is not enough to positively identify a suitable bellhousing. When investigating bellhousings bearing these casting numbers, the location of the ballstud and the number cast onto the inside of the clutch fork ballstud boss is critical to locating the appropriate bellhousing. When the ballstud on casting 462606 is in the upper position, it is equivalent to older casting 3840383 and will have 383 cast onto the inside clutch fork ballstud boss. When the clutch fork ballstud on casting 464697 or 469697 is in the upper position, they are equivalent to older casting 3899621 and will have 621 cast onto the inside clutch fork ballstud boss.

As an alternative, the incorrect 462606, 464697, or 469697 bellhousing can be made to work if the existing clutch fork ballstud hole is filled and a hole drilled and tapped in the correct lowered location. Pete Birrell and Lee Josephs have both successfully performed this modification to casting 464697 (Figure 5-11).

Figure 5-11: 11-inch Bellhousing (464697 Casting; 621 cast onto ballstud boss) Modified to Accept 1978-1981 GM A Body Clutch Fork

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Photograph courtesy of Lee Josephs

The push point on the end of the clutch fork for the two F body bellhousings and for the 1984-1988 Corvette bellhousing measure to be in the same relative location as that of the 1978-1981 A body clutch fork and, therefore, they are suitable bellhousings. The Corvette bellhousing was originally used with hydraulic linkage, however the location of the ballstud accommodates the use of a conventional fork and mechanical linkage. J. Matthew Daugherty successfully installed a 1983 V8 F body mechanical bellhousing in his 1986 Monte Carlo SS. He says the geometry of the lower pushrod is correct. Figure 5-12 demonstrates that the 1984-1988 Corvette bellhousing is suitable.

Figure 5-12: 1984-1988 Corvette Bellhousing (casting 14048867; Chevrolet) Installed With Linkage

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Photograph courtesy of Darryl Gilbert

When using the 1978-1981 A body bellhousing on a 1985 and earlier engine, the 1978-1981 A body dust shield may be used with no modification. When using the 1978-1981 A body bellhousing on a 1986 and later engine, a dust shield from either a 1978-1981 A body or a 1986-1992 F body may be used. Either dust shield will need to be modified. The F body dust shield has two bolt holes that align with the bolt holes in the 1978-1981 A body bellhousing and two that do not. Two additional holes must be drilled in the dust shield to align with the remaining two holes in the bellhousing. The A body dust shield must be modified to fit the shape of the oil pan on 1986 and later engine (Figure 5-13). If an inspection cover is available that does not require modification when used on 1986 and later engines with the 1978-1981 A body bellhousing, please drop me a note.

Figure 5-13: 1978-1981 GM A Body Dust Shield (lower) Modified for Use With 1986 and Later Chevrolet Engine; 1986-1992 V8 F Body Dust Shield (upper) Used as Template

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Photograph courtesy of Bob Morris

5.2. Hydraulic Clutch Linkage

If any of the previously mentioned bellhousings cannot be located, or if you prefer hydraulic clutch linkage, you may want to try installing the hydraulic components and bellhousing from a third-generation F body. The following two bellhousings can be used:

  • 1984-1992 V8 F body (casting 14075723; Figure 5-14) for 153-tooth flywheel; Chevrolet; use with clutch fork: GM 14075725

  • Lakewood Industries 15020 for 1984-1992 F body (Figure 5-15); use with clutch fork: GM 14075725

Figure 5-14: 1984-1992 GM V8 F Body Bellhousing (casting 14075723; Chevrolet)

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Photograph courtesy of J. Matthew Daugherty

Figure 5-15: Lakewood Industries 15020 for 1984--1992 V8 F Body; Chevrolet

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Photograph courtesy of Jay Orbison

Because the 1984-1988 Corvette bellhousing (casting 14048867; Figure 5-9) was originally used with hydraulic linkage, it may be possible to adapt the Corvette master cylinder/slave cylinder assembly. If this has already been done, please drop me a note.

Another hydraulic alternative is to use a commonly available Chevrolet mechanical bellhousing (such as casting 3840383, 3858403, or 3899621) in conjunction with a hydraulic release bearing. My research has revealed that Howe Racing Enterprises (PN 82870), McLeod, Quarter Master, Tilton, and Ram sell hydraulic release bearings. Some of the designs slip over the existing transmission front bearing retainer and others replace the bearing retainer.

 


Originally Released 11 February 2002

updated 19 May 2014