I found these interesting Youtube videos outlining the correct procedure for fitting polyurethane bushings as opposed to the traditional bonded rubber to metal better known as Metalastic bushings.
Correctly fitted poly bushes have many advantages including: improved ride quality, less/no stiction in operation and no degradation when in contact with oil.
The primary difference IMHO is that when fitted correctly Poly Bushes function as a 'bearing' and do not resist rotation so problems associated with shear are discounted.
NB. There's no need to prescriptively watch each video but if you scan through each as I did there's quite a few interesting tech points to be picked up with regard to fitting and removal.
The first video is probably technically the best (sounds like a professional mechanic) and the last illustrates a range of suspension arms with similar functions to the Rover...and yes the presenter is very young and keen...showing my age...skip his intro.
Post by johnwp5bcoupe on Feb 10, 2020 10:20:54 GMT
Interesting Vince in the fact the Poly Bushes are dead length to the Ferrule where the standard Rove OEM or Pattern ones the rubber is longer than the Ferrule? So is the Top Hat type correct for the P5 or has it to be a Bonded type?
AFAIK John...all poly bushes meant for rotating movement through an arc (eg. P5 top suspension wishbones) are designed to act like bearings. They need to rotate on the inner sleeve, hence the requirement for grease between the sleeve and the bush. The first video ilustrates this very well.
The sleeve should be only fractionally less in length than the combined length of each paired set of bushes. The top poly bushes of a P5 need to be a firm interference fit on their outer surface within the locating hole of the wishbone. When the spindle nut is tightened (large washer positioned at each bush face) the inner sleeve is locked immobile. The bush should then only rotate on its sleeve. The large bush faces (add a smear of appropriate grease) rotates against the faces of the large side washers.
Given the correct sized poly bushes, the spindle nuts can be locked up firmly on initial assembly as there is no shearing forces acting on the poly bushes as there are on the OEM metalastic bushes.