Home
Главная
BMW
Мотоцикл
K75
Руководство по эксплуатации Страница: 23

BMW K75 [23/236] Abnormal frame and suspension noise

Содержание

Похожие устройства

Fault diagnosis 23 42 Handlebar vibrates or oscillates 45 Poor rear suspension performance Tyres worn or out of balance Either condition particularly in the front tyre will promote shaking of the fork assembly and thus the handlebars A sudden onset of shaking can result if a balance weight is displaced during use Tyres badly positioned on the wheel rims A moulded line on each wall of a tyre is provided to allow visual verification that the tyre is correctly positioned on the rim A check can be made by rotating the tyre any misalignment will be immediately obvious Wheel rims warped or damaged Inspect the wheels for runout as described in Routine Maintenance Swinging arm bearings worn Renew the bearings Wheel bearings worn Renew the bearings Steering head bearings incorrectly adjusted Vibration is more likely to result from bearings which are too loose rather than too tight Re adjust the bearings Loose fork component fasteners Loose nuts and bolts holding the fork legs wheel spindle mudguards or steering stem can promote shaking at the handlebars Fasteners on running gear such as the forks and suspension should be check tightened occasionally to prevent dangerous looseness of components occurring Engine mounting bolts loose Tighten all fasteners Rear suspension unit damper worn out or leaking The damping performance of most rear suspension units falls off with age This is a gradual process and thus may not be immediately obvious Indications of poor damping include hopping of the rear end when cornering or braking and a general loss of positive stability See Chapter 8 Weak rear spring If the suspension unit spring fatigues it will promote excessive pitching of the machine and reduce the ground clearance when cornering Swinging arm flexing or bearings worn See Sections 40 and 41 Bent suspension unit damper rod This is likely to occur only if the machine is dropped or if seizure of the piston occurs 43 Poor front fork performance Damping fluid level incorrect If the fluid level is too low poor suspension control will occur resulting in a general impairment of roadholding and early loss of tyre adhesion when cornering and braking Too much oil is unlikely to change the fork characteristics unless severe overfilling occurs when the fork action will become stiffer and oil seal failure may occur Damping oil viscosity incorrect The damping action of the fork is directly related to the viscosity of the damping oil The lighter the oil used the less will be the damping action imparted For general use use the recommended type of oil changing to a slightly higher or heavier oil only when a change in damping characteristic is required Overworked oil or oil contaminated with water which has found its way past the seals should be renewed to restore the correct damping performance and to prevent bottoming of the forks Damping components worn or corroded Advanced normal wear of the fork internals is unlikely to ocur until a very high mileage has been covered Continual use of the machine with damaged oil seals which allows the ingress of water or neglect will lead to rapid corrosion and wear Dismantle the forks for inspection and overhaul See Chapter 7 Weak fork springs Progressive fatigue of the fork springs resulting in a reduced spring free length will occur after extensive use This condition will promote excessive fork dive under braking and in its advanced form will reduce the at rest extended length of the forks and thus the fork geometry Renewal of the springs as a pair is the only satisfactory course of action Bent stanchions or corroded stanchions Both conditions will prevent correct telescoping of the fork legs and in an advanced state can cause sticking of the fork in one position In a mild form corrosion will cause stiction of the fork thereby increasing the time the suspension takes to react to an uneven road surface Bent fork stanchions should be attended to immediately because they indicate that impact damage has occurred and there is a danger that the forks will fail with disastrous consequences 44 Front fork judder when braking see also Section 56 Wear between the fork stanchions and the fork legs Renewal of the affected components is required Slack steering head bearings Re adjust the bearings Warped brake disc If irregular braking action occurs fork judder can be induced in what are normally serviceable forks Renew the damaged brake components Abnormal frame and suspension noise 46 Front end noise Oil level low or too thin This can cause a spurting sound and is usually accompanied by irregular fork action Spring weak or broken Makes a clicking or scraping sound Fork oil will have a lot of metal particles in it Steering head bearings loose or damaged Clicks when braking Check adjust or replace Fork yokes loose Make sure all fork yoke pinch bolts are tight Fork stanchion bent Good possibility if machine has been dropped Repair or replace tube 47 Rear suspension noise Fluid level too low Leakage of a suspension unit usually evident by oil on the outer surface can cause a spurting noise The suspension unit should be renewed Defective rear suspension unit with internal damage Renew the suspension unit Brake problems 48 Brakes are spongy or ineffective disc brakes Air in brake circuit This is only likely to happen in service due to neglect in checking the fluid level or because a leak has developed The problem should be identified and the brake system bled of air Pad worn Check the pad wear and renew the pads if necessary Contaminated pads Cleaning pads which have been contami nated with oil grease or brake fluid is unlikely to prove successful the pads should be renewed Pads glazed This is usually caused by overheating The surface of the pads may be roughened using glass paper or a fine file Brake fluid deterioration A brake which on initial operation is firm but rapidly becomes spongy in use may be failing due to water contamination of the fluid The fluid should be drained and then the system refilled and bled Master cylinder seal failure Wear or damage of master cylinder internal parts will prevent pressurisation of the brake fluid Overhaul the master cylinder unit Caliper seal failure This will almost certainly be obvious by loss of fluid a lowering of fluid in the master cylinder reservoir and contamination of the brake pads and caliper Overhaul the caliper assembly Brake pedal improperly adjusted Adjust the clearance between the pedal and master cylinder to take up lost motion as recommended in Chapter 9

Скачать