Diagnosing Transmission Problems.

Sometimes it can be difficult to gauge where in the driveline a transmission fault lies. You can come to Central Axle Services for a free, no obligation, vehicle inspection and road test report by contacting us on 0121 772 0121 and the following few paragraphs will help you work out what part of your transmission needs repairing before you are left stranded.

Grumbling Noises

If the grumbling/ rumbling noise is more pronounced when the vehicle is cornering, it is most likely to be the wheel bearings on the opposite side of the vehicle to the direction of the bend. It should be easy to gauge whether the noise is from the front or rear wheel.

Recommendation – go to your nearest competent mechanic for wheel bearing replacement.

On rear wheel drive vehicles, if the grumbling gets louder and more pronounced with higher speeds the cause is likely to be the axle or differential bearings.

Recommendation – Contact Central Axle Services on 0121 772 0121 to arrange an inspection and road test report.

If the noise is worse when the clutch pedal is depressed, the clutch release bearing is worn out and needs replacing.

Recommendation – Contact Central Axle Services on 0121 772 0121 to arrange an inspection and road test report.

Other Noises

On rear wheel drive vehicles, if the noises changes significantly between accelerating and decelerating the cause is worn or damaged crown wheel and pinion

Recommendation – Contact Central Axle Services on 0121 772 0121 to arrange an inspection and road test report.

Jumping out of gear

In most cases, jumping out of gear is caused by wear in the gear selector linkage bushes and joints. There are other causes like weak detent springs or wear in the selector forks.

Don’t be tempted to live with poor gear selection, the picture below is of a selector fork from an Iveco LGV, the owner persisted, with a sloppy gearchange for several weeks, eventually the selector fork ends broke causing even more damage to the gearbox and leaving the driver stranded. If they had contacted us sooner, the gearbox will have been relatively cheap to repair, instead the broken bits of selector jammed between the gear teeth meaning the mainshaft had to be replaced as well as all the bearings.

Crunching into Gear

There are two main causes for gearboxes crunching into gear.

  1. The clutch isn’t fully activating.
  2. Worn synchro rings

Recommendation – If the clutch is hydraulic, check the fluid level is correct and that there are no leaks in the clutch hydraulic circuit. If that checks out OK contact Central Axles on 0121 772 0121 for a free inspection and road test