We are experts in gearbox rebuilding and repairs

If you are having problems with your vehicles gearbox then we are the garage to come to for help and advice. We are experts in rebuilding and repairing gearboxes from manual gearboxes and automatic gearboxes and have serviced hundreds upon hundreds.


Here are two recent gearbox rebuilds and repairs we have carried out for a vehicle owner. First we look at a manual gearbox where you will be able to see from the photos below our experienced mechanics stripping the gearbox, diagnosing the problem and then rebuilding it.



The problem with this vehicle owners gearbox is the bearings had collapsed as shown in the photos below. When the bearings collapse the vehicle will find it hard to select gears leading to noises coming from inside the vehicle.



Secondly we look at an automatic gearbox. We not only repair and build manual gearboxes but vehicles that select gears automatically, so if you have an automatic vehicle and are getting problems then don’t worry automatics are no problem for us. Here are photos of our mechanics stripping an automatic gearbox that could not select reverse gear and then putting the gearbox back together with all repair work carried out.





Here are a few symptoms for you to look out for when your having gearbox problems and why you should come into our Cardiff based garage to have things checked over.

Rough and tough shifting between gears

When you are trying to negotiate gears and select gears are you finding this difficult? Often when a vehicle is experiencing gearbox problems the teeth on the cogs of the gear maybe warn away making it hard for the other gears to select properly.

Can’t get past certain gears

When your trying to get into fourth gear from third or fourth to fifth and the vehicle wont let you then this is a clear sign you have an issue with the gearbox and you should get it checked out before any more damage is done.

Loud noises coming from the engine

When a vehicle is getting gearbox problems it can be due to the bearing’s collapsing in the gearbox. When the bearings collapse then it makes it very hard for the vehicle to select the gears and you will often here loud noises coming from the engine.

Slipping Gears

When you are in gear is the vehicle slipping into other gears? This is a sign there is a problem with the vehicles gearbox and a reason for you to get this checked out.

Leaking oil

A sign that the gearbox is having problems is the vehicle is leaking oil. If you are seeing large amounts of oil or patches coming from underneath the vehicle after parking then this is another sign there could be a gearbox problem.

The engine management light will light up on the dashboard

Often when there is a gearbox problem the engine management light will light up on the dashboard. With a gearbox problem you will likely know about it from all of the other signs we have previously mentioned as they will be apparent but if you don’t here loud noises or slipping gears the engine management light will come on.

If you are experiencing these symptoms then come to us and get the vehicle checked out. If you leave it and do not come for a check up the problems could lead to even more serious gearbox damage leading to costly repairs. Not only will the gearbox be further damaged you can also cause other problems within the engine leading to costly engine repairs.

Contact A1 Diagnostics

Our contact details are below, give us a call to arrange an appointment or if you need any gearbox advice we are happy to help.


A1-Diagnostics and ECU Repairs
64 Sloper Road
CF11 8AB

Tel: (029 20) 220380
Fax: (029 20) 223172

Opening Times

Mon – Fri: 8:00am – 6:00pm

Email: info@a1-diagnostics.com

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