A rhythmic knocking when slowing down is caused by UJ problem either due to
1. worn UJs
2.Worn yoke or flange (bit of this evident with people lately(
2. End float in UJ
Wear in UJ is cured by replacement but read on…………..
Wear in the yoke or flange is evident in the circlip rubbing against the UJ and causing a shinny ring and the only permanent cure is replacing the flange or half shaft and yoke assemble.
If all the above has been done and still there is this tapping noise……… end float in the UJs is the answer and this is cured by fitting oversize circlips to give preload (tightness) in both planes.
When the needle roller starts to wear it eats its way into the shaft causing a graunching grinding noise of munched metal from one side of the rear of the car. Often the noise is worse with light cornering. This is an expensive noise as it invariably means the half shaft is scrap and must be replaced. Putting the job off until the noise is excruciatingly loud can result in damage to the bearing housing. To do any work in the shaft required the removal of the hub – a job which must be done with the proper equipment to avoid scrapping the hub. (Churchill puller)
The differential gets blamed on too many occasions when experience has shown that in general differentials do not cause knocking vibration or rattling. Whining s usually the sign that the hardening in the crown wheel has worn through and the noise will be loudest on acceleration either disappearing entirely or becoming very low on overrun/deceleration. The pinion bearings can be a problem but the noise is from the center of the car(not one side) and is very short term – ie. The bearing collapses, the oil leaks out and the diff seizes.
Propshaft vibration which comes in at about 55 miles per hour…. that is UJs
Evan the smallest wear, stiffness or misalignment can cause am incredible amount of vibration through the car. Just changing the UJs can put a shaft out of balance – please note that unlike the halfshaft UJs the ones in a propshaft should not be tight.
The type of driveshaft you have fitted determines the cure.
Solid Propshaft – Change UJs, rebalance and re fit
Strapdrive – Check for broken straps and that there is no wear in the pin which fits into the propend – a worn pin means the prop is scrp as it will not balance on the car even though it may balance on a machine. If it is all OKL, change UJs and rebalance.
Sliding Joint – Check for wear/play in the joint and that the UJs are in line with each other. (When you look down the length of the prop, the UJs should be sitting exactly above each other) If OK change UJs sand rebalance.
CV Joint – Check for wear in joint. If any wear shows have sliding joint from Marina/Dolomite welded on. Fit new UJs and rebalance.