Gearbox repairs are another fairly simple type of repair in Car Mechanic Simulator 2015. There are only a few places that these problems can hide and they are usually fairly easy to access.
Many of the vehicles in Car Mechanic Simulator 2015 have rear wheel drive. This implies a transmission, or Gearbox, and a Drive Shaft. You won't be able to get that gearbox off until you have removed the drive shaft.
However, once you have removed the driveshaft it's simple work to pull the gearbox and get to the last few parts of the 'Gearbox' part of the repairs. This includes the clutch plate, clutch pressure plate, clutch release bearing and flywheel. Only a few vehicles are equipped with a transfer case, which is mostly used on 4x4 vehicles.
Of these parts the only ones I have really had any luck repairing include the clutch plate, gearbox, drive shaft, and transfer case. Keep in mind you won't be able to remove the gearbox until you have removed the starter. Front wheel drive vehicles usually have it under the hood. Rear wheel drive is usually accessed under the car, along with the gearbox.
Front wheel drive vehicles are a little more involved but are not that different once you get to the Gearbox. You'll have to pull both front wheels, both drive shafts, and the drive axle before you can get to the Gearbox (transaxle). Once you are at the Gearbox, underneath it is the same story. A clutch release bearing, clutch pressure plate, clutch plate, and flywheel. On all vehicles, you'll need to pull the starter before you can remove the gearbox.
It is almost pointless to run any tests when the car only has gearbox problems. By looking under the car you'll know right away if any of the visible parts are damaged. If they are not, then the only other place they can be is behind the gearbox. By pulling the gearbox you have an instant visual of these parts. So to save yourself time, head under the car and take a look.
To help you learn the diagnostics side of Car Mechanic Simulator 2015 as quickly and easily as possible, I have created a few short but comprehensive guides covering each problem category. For a complete listing of these guides, check here:
Diagnostics & Repairs - Car Mechanic Simulator 2015
If you are looking to learn about the early and mid-stages of the game, you may find these pages of interest:
Your Garage, Tools, Tests, & Upgrades, Jobs & Job Management
And if you are wonding what awaits beyond and where the real cash is hiding, check out this link:
Rebuilding Guide - Car Mechanic Simulator 2015