A/T - Revised Drive Link Wear Specifications
90cadillac08Bulletin No. T-90-75
File in Group 7
Number 220
Corp. Ref. No. 977158R
Date May, 1990
SUBJECT: CHECKING DRIVE LINE FOR POSSIBLE WEAR - 3T40 (THM 125-C) AND 4T60 (440-T4)
MODELS AFFECTED: 1982-1988 CIMRRONS 1985-1990 DE VILLES AND FLEETWOODS 1986-1990 ELDORADOS AND SEVILLES
This bulletin supersedes Service Bulletin T-90-35 which should be discarded. This bulletin is being revised to change the drive link wear specifications.
The Hydra-Matic 3T40 (THM 125-C) drive link wear specification has been changed from a maximum of 1-1/16" (27 mm) to 7/8" (22.2 mm) to minimize noise. The THM 440-T4 (4T60) specification remains 1-1/16" (27 mm). It is important to inspect the drive link assembly (chain) for possible wear whenever service repair requires disassembly of the transaxle. This is especially important if drive link wear is the suspected cause (i.e., chain whine noise and/or slip due to looseness). The service procedure is listed below:
Figure 1 - Checking Drive Link Wear:
1. Midway between the sprockets and at right angles to drive link push the slack strand (bottom strand) of the drive link unit down until all slack is removed, and mark with pencil on the bottom side of the drive link. Refer to Figure 1.
2. Push up on the drive link in the same manner and put a second mark on the case making sure that both marks are made from the same point on the drive link.
IMPORTANT: If the distance between the two marks exceeds the specification, replace the drive link. Make sure the three machined surfaces indicated in Figure 1 are flush with the machined surface of the case. If not, drive link measurement will be inaccurate.