The following is intended as an aid for the diagnosis and solution of vibration problems on 1986 model year Range Rovers. When investigating complaints of vibration in the vehicle, it is important that the vehicle is assessed in a logical manner, so that, by a process of elimination, it is possible to determine the exact source of the problem. Therefore the first part of this bulletin gives a step by step sequence for the diagnosis of vibration sources and their elimination. Before initiating any investigation, however, check the vehicle to ensure that the cause is not due to an obviously simple fault. For example: check that all engine and gearbox mountings are of the correct specification and are correctly fitted; check that all exhaust mountings are correctly fitted, in particular check that there is no metal to metal contact between the mountings and the body; check the torque of the propshaft drive flange bolts, the universal joints for excessive play and transfer box and differential bearings for excessive wear.

If your initial investigations do not identify a problem it will be necessary to carry out the following procedure, which will involve some testing of the vehicle.

NOTE: Should it be found at the outset that several vibrations are evident at different road or engine speeds, each must be treated individually. It is highly unlikely that the vibrations will be due to the same problem and therefore each will require a separate cure.

Similarly, if a vehicle is found to be suffering from a particularly harsh vibration, it may not be possible to detect other, less noticeable vibrations which may exist. However, once the primary vibration has been eliminated, the secondary vibration, which again will only be evident at different road or engine speeds, will then become prominent. Again each vibration must be treated separately, allowing the causes to be isolated and the necessary remedial action taken.