Refurbishing the Clutch Pivot

Details
Category: ah_garage
Published: Thursday, 04 February 2021 02:23
Written by Super User
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Part of the slop or free play in the clutch can be due to clutch fork shaft and bushing wear. This note describes how I replaced the shaft (Item #8 - see exploded assembly drawing) and bushings (Items #2).

Parts required:

The following parts are the same for the side-shift and center shift transmissions (At least for the BT-7 and BN-7 series). Most of the supplies for this project were purchased from McMaster-Carr.

  1. Oilite Bushings (Item #2)
    • PN AEC3102
    • 5/8" OD, 1/2" ID and 3/4" long
    • 2 required
    • McMaster-Carr PN 6391K214
  2. Taper Pin (Item #10)
    • PN TPS0010
    • #2 taper pin (1/4" taper/foot)
    • 1 1/4" long
    • 1 required
    • McMaster-Carr PN 98390A222(Qty 100)
  3. Clutch Fork Shaft (Item #8)
    • PN AEC3104
    • 1 required
    • described below

Special Tools required

  1. #2 Taper Pin Reamer(McMaster-Carr PN 2990A19)
  2. bushing removal/installation drift
  3. slide hammer with a 1/4"-28tpi (external threads) attachment

Disassembly

The clutch fork (Item #7, PN AEC3324) is held on the pivot shaft with a taper pin. The taper pin is installed from the engine side of the bellhousing. So if one is going to push the taper pin back out, one needs to work through a small hole on the transmission side of the bellhousing. And as the hole is partially covered by the transmission case, the bellhousing needs to be removed from the transmission.

Taper pin and plastic washers can be seen in bellhousing photo showing the access hole used to punch tapered pin out

I haven't got a lot of ideas for removing stuck taper pins. One pin came out when I used a sturdy punch and a lead hammer. Another pin hasn't budged. Heat is probably not the best idea as there are two plastic washers (Item # 11, PN AEC3105) on either side of the clutch fork.

When the taper pin is removed, the shaft (Item #8) may just pop out of the lever. If not, remove the brass screw (Item #9, PN AEC3221) from the end of the shaft and use a slide hammer attached to the 1/4"-28 threaded hole.

The bushings can be removed from the bellhousing with a 5/8" diameter drift with a 1/2" diameter pilot. The same drift can be used for the installation, install the inner bushing first.

Making a New Shaft

I made a new fork shaft out of 1/2" steel rod. The overall length is 3.1" and the hole for the taper pin is at the center, 1.55". For the taper pin hole, I started with a 11/64" drill, drilled through. The shaft was then inserted into the fork lever which I then used for a reamer guide. Use a taper pin to test the fit and keep in mind that it doesn't take much of a increase of the hole diameter to move the taper pin deeper into the hole. The 1/4"-28 threaded hole on one end is about 1 and 1/16 inches deep.

Assembly

Can I get away with saying that assembly is the reverse of the disassembly procedure?

A couple of thoughts - When installing the new bushings, it's probably easier to do if the bell housing has been heated to 350 degrees F. Second, taper pin shouldn't require any loctite or other locking method. The taper angle is shallow enough for the pin to be self-locking.