1. JITTER, a shake similar to tire unbalance. It can be felt but not heard and occurs at speeds above 50 mph. It is NOT throttle conscious and can be felt coasting with engine turned off.
2. BOOM (body-drumming), a low pitch noise that can be HEARD but not FELT and often causes a drumming effect on the ears that changes in intensity when moving head toward side, front or rear. Can be heard as low as 30 mph up to 80 mph.
3. MOAN, sometimes referred to as exhaust system moan. It IS throttle conscious and can be FELT and HEARD at 25 to 35 mph and/or 55 to 65 mph.
4. ROUGHNESS, similar to noise heard or felt while driv-ing on gravel
topped asphalt roads. It can be felt or heard at speeds above 35 mph.
| DESCRIPTION (From Above) | CONDITION | CORRECTION |
| 1. JITTER | 50-70 mph, smooth roads not throttle conscious | 1. Check static and dynamic balance of tires. |
| 2. Replace if runout exceeds specifications. | ||
| 3. Install a known good set of tires. Reinstall original tires one at a time and evaluate after each change. | ||
| 2. BOOM | 30-80 mph, not throttle conscious | Install a known good set of tires. Reinstall original tires one at time and evaluate after each change. If boom phases in and out (beats), two tires are at fault. |
| 25-40 mph, throttle conscious | Check U joint bearings, torque U joint nuts to 14 ft. lbs. | |
| 50-80 mph, throttle conscious | Check propeller shaft runout at front and rear. Should be less than .015". If above, rotate shaft 180 degress and recheck. If still above .015", replace shaft. | |
| Noticeable in neutral at same engine rpm as when driving. (50-70 mph) | Rotate converter mounting position on flywheel 120 degrees and evaluate. If boom is still objectionable, rotate convertor position another 120 degrees. | |
| 3. MOAN | 25-35 mph, throttle conscious | Carefully torque mounting bolts and bracket bolts on A/C compressor, power steering pump and Delcotron. Remove any non Oldsmobile "hang on" equipment such as an air conditioning compressor. |
| 55-65 mph, throttle | 1. Check U joint bearings, torque U joint nuts to 14 ft. lbs. | |
| 2. Check propeller shaft angles and set to specifications. | ||
| 4. ROUGHNESS | Felt and/or heard above 35 mph | Install known good set of tires. Reinstall original tires one at a time. If not production tires, all tires on car could be at faul |
Universal joints - testing for wear
1 Wear in the needle roller bearings is characterized by vibration in the transmission, 'clonks' on taking up the drive, and in extreme cases of lack of lubrication, metallic squeaking and ultimately grating and shrieking sounds as the bearings break up.
2 It is easy to check if the needle roller bearings are worn with the shaft in position, by trying to turn it with one hand, the other hand holding the rear axle flange when the rear universal joint is being checked, and the front half coupling when the front universal joint is being checked. Any movement between the shaft and the couplings is indicative of considerable wear.
3 A further test for wear is to attempt to lift the shaft and note any movement between the yokes of the joints.
4 If wear is evident, either fit a new propeller shaft assembly complete or replace the universal joints, as described later in this Chapter.
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