Section 4  - Rear Axle, Universal Joints & Springs

Slide the ball and collar forward and install the four cap screws to the transmission. Fill the joint housing with transmission lubricant through the speedometer gear opening.
Trucks use all needle bearing type universal joints, with 27 rollers in each bearing, with excep­tion of the bushing type front joint on 3/4 and 3/4-ton special trucks.
When removing the trunnion and bearings from the rear yokes of the front or intermediate and the front yoke of the rear universal, remove the snap rings and lubrication fittings. Support the yoke in a bench vise, then using a soft drift and hammer, drive on the end of one trunnion bearing. The blows are transmitted through the trunnion to the other bearing, driving it out of the yoke, Fig. 63.
Care should be exercised when driving through the trunnion not to drive it into the side of the yoke. When one bearing is removed, support the other side of the yoke in the vise and drive the other bearing out by using a brass drift on the end of the trunnion pin.
When reassembling the bearings they should be pressed into the yokes just far enough to install the snap rings. Then, while holding the trunnion in one hand, strike the yoke a few light blows with a hammer to firmly seat the bearings against the lockrings.
In some special types of operation, purchasers of Chevrolet cars and trucks may desire to use tires of a different size or rear axles of different ratios than those furnished as standard equipment for the various units. Either one, or both, of these things will, of course, change tire revolutions per mile and result in speedometer inaccuracies.
When such change or changes are made, it is necessary to change the speedometer gears or to use a speedometer adapter with the present gears. In certain combination changes of both rear axle and tires it may be necessary to change the gears and use the adapter also to bring about proper speedometer readings.
Speedometer gears are serviced in sets to avoid inaccuracies that would naturally be caused by using just one new gear with a worn gear. The dif-
ferent service gear sets may be identified by the part number which is stamped on the face of the drive (worm) gear. The gears used in production as original equipment are not so marked, however, they are easily identified by counting the number of teeth on each gear and referring to the chart shown below.
Gear Set Part No.
No. of Drive Gear Teeth
No. of Driven Gear Teeth
Gear Ratio
3-Spccd 3-Spced 3-Speed
4-Speed 4-Speed 4-Speed
605061 605062 605063
602798 603074 603075
4 5 6
4 4
14 19
12 15 13
3.000 2.800 3.166
3.75 3.25
When changes are made in the field to tire equipment or sizes, and rear axle ratios, the cor­rect speedometer gear set and/or adapter should be installed. Complete information concerning gears and adapters to use will be found in the Master Parts Price List.
The following speedometer adapters are avail­able in service:
Part Number               Gear Ratio
No. 1565812                      17-16
No. 1565814                      16-17
The adapter is installed by removing the speed­ometer cable fitting from the transmission case and screwing the adapter into the case. The speed­ometer cable is then connected to the adapter.
When replacing speedometer gears, it is very im­portant that the drive (worm) gear be pressed onto the spacer or front yoke of the universal joint with the shoulder (chamfer on 1-1/2-ton trucks) on the gear away from the universal joint.
The following chart covers the various speed­ometer gear sets used as original production equip­ment according to rear axle ratio, transmission and regular production tires on the different models.
When tire equipment and sizes other than the regular production is specified as original equip­ment, the car or truck is equipped in production with the proper speedometer gear set and/or adapter as may be necessary to bring about proper speedometer readings.





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