ERRATIC/NO UPSHIFTS/THM 700 R4 DIAG. WORN GOV. GEAR

Model and Year THM 700-R4

In diagnosing any THM 700-R4 transmissions for erratic or no upshifts, the cause may be from a worn governor gear. The cause of the worn governor gear may be from one or more of the following conditions:

1. The output shaft to input carrier assembly snap ring came off.

2. Metal scale on the output shaft gear.

3. The governor dowel pin dimension may be incorrect.

4. An incorrect governor gear may have been installed.

When servicing any THM 700-R4 transmission for an erratic or no upshift condition, refer to the following diagnosis chart. Follow guidelines given in your service manual for servicing the transmission governor gear.

CONDITION CAUSE CORRECTION --------- ----- ---------- 1. Governor gear 1. Flash, scale or 1. Replace governor is worn in an nicks on the gear (P/N "Apple Core" output shaft 8642928) wire shape (refer gear. brush output to Figure 1). shaft gear to

2. Incorrect gover- remove scale of nor gear (THM flash. Replace 350C type). output shaft if nicked.

2. Replace governor gear (P/N 8642928) Do not use THM 350C type as re- placement.

2. Governor gear is 1. The governor dowel 1. Replace the trans- worn in the middle pin is located too mission case. but on one side far into its case Check replacement only (refer to bore. (Refer to case for correct Figure 2). Figure 3 for cor- dimension. rect dimension.)

2. Governor sleeve 2. Replace governor stuck in case bore. assembly and trans- mission case. 3. The output shaft to input carrier snap 3. Disassemble the ring is loose or transmission, re- has come off. The place the output output shaft has shaft to input moved rearward. carrier snap ring. (P/N 8642230).

3. Governor gear is The governor dowel Arbor press the worn at the edge pin is located too dowel pin into the of the gear on one far out of its case case to the correct side only (refer bore. (See Figure 3 dimension. (Refer to Figure 4). for correct dimen- to Figure 3). sion.)

4. Governor gear is 1. The incorrect gover- 1. Replace the gover- worn slightly, nor gear was in- nor gear (P/N the entire length stalled. 8642928). Do not of the gear. (Re- use a THM 350C gear fer to Figure 5). as a replacement gear.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.