The Zf6 & ZF8 Automatic Gearboxes are controlled by the transmission control unit (TCU) which work the Torque Converter, clutch and solenoid valves to change gear. The ZF Gearbox internals are made of lightweight components meaning it is designed to be flexible, efficient, and economical.

If the gearbox is not serviced, the oil can become dirty, lose viscosity, and overheat causing the clutch packs to burn out. This will affect the smoothness of the gear changes or possibly cause the failure of the full transmission system.

ZF 6HP Servicing Options and Costs

We offer a few different options when servicing these ZF 6HP gearbox:

We offer servicing for ZF 6HP gearbox codes 6HP19, 6HP19 X, 6HP21, 6HP21 X, 6HP26, 6HP26 X, 6HP28, 6HP28 X, 6HP32

We can service both Rear Wheel Drive & Xdrive variants.

1. OEM Parts Only Service inc. Sump Strainer & ZF Lifeguard fluid £600Inc of VAT
2. OEM Parts Only Service Inc. Sump Strainer, Gearbox Mechatronic Sleeve, Valve body tubes & ZF Lifeguard fluid £680Inc of VAT
3. Millers ATF Oil Sump Strainer & ZF Lifeguard fluid £480Inc of VAT
4. Millers ATF Oil Sump Strainer, Gearbox Mechatronic Sleeve & Valve body tubes £580Inc of VAT

We offer a few different options when servicing these ZF 8HP gearboxes:

We offer servicing for ZF 8HP gearbox codes 8HP45, 8HP45 HIS, 8HP45X, 8HP50, 8HP50X, 8HP70, 8HP70H, 8HP75, 8HP75 HIS, 8HP75X and 8HP75X HIS

We can service both Rear Wheel Drive & Xdrive variants.

1. OEM Parts Only Service inc. Sump Strainer & ZF Lifeguard fluid £600 Inc of VAT

2. OEM Parts Only Service Inc. Sump Strainer, Gearbox Mechatronic Sleeve, ZF Lifeguard fluid £640 Inc of VAT

3. Millers ATF Oil & Sump Strainer £480 Inc of VAT
4. Millers ATF Oil Sump Strainer, Gearbox Mechatronic Sleeve £520Inc of VAT

Our processes when servicing the ZF 6HP & ZF 8HP Transmission

During the service of your ZF6 HP & ZF 8HP we will undertake the following health checks and implement safety procedures to make sure your vehicle is returned in the best possible condition:

• Check for any leaks around the seals and gaskets on the mechatronics and output shafts
• Drain all fluid from the transmission – we do not flush and replace oil as our preference to service these gearboxes by removing the sump dropping all gearbox fluid
• Clean all mating surfaces to make sure the gearbox sump/filter seals with no leaks
• Use OEM or equivalent high-quality fluids to maintain vehicle warranty, if in place with the manufacturer.

Using non-approved/recommended products can damage the mechatronics and will also void the manufacturer warranty. As we use only OEM parts and oil when servicing these vehicles, so you can maintain your warranty with the manufacturer*.

* The EU Block Exemption Regulations allow independent garages to service and carry out small repairs to vehicles to allow fair competition. If specified genuine parts are used during the warranty period, the manufacturer must maintain their agreement in terms of warranty on the vehicle.

For any more information feel free to give us a call and we will be happy to assist with any enquiries you may have. For those interested in the process of servicing these gearboxes please see our step-by-step guide below.

How to Change the Transmission fluid on a ZF 6HP / ZF 8HPA Step-by-Step Guide

1. Preparation before changing the transmission fluid

Make sure that the vehicle has not been run with low transmission fluid and undertake a diagnostic scan to make sure there are no codes relating to the automatic transmission stored. If the vehicle has any transmission faults, then a service will not fix a damaged gearbox.

• Check the automatic transmission fluid temperature, it is easier to drain the fluid when the vehicle has been driven and the fluid is hotter.
• Get vehicle onto ramp and make sure it is level. Once the vehicle is safely secure and level you will now be ready to start the service.

Tools required for servicing procedure:

• 3/8 Ratchet
• Torque wrench
• 8mm & 10mm Hex/Allen
• Torx socket T40
• Upfill Fluid filling tool
• Fluid/Oil catch pan
• OBD diagnostic tool

2. Draining the ZF fluid

• Remove all undertrays, trims and covers necessary to gain access to the transmission sump.
• Unscrew the fill plug using 8mm Hex/Allen (doing this allows vacuum to empty the fluid faster)
• Remove the drain plug using a 10mm Hex/Allen (around 4-5 litres will now drain)
• Place oil drain under the drain plug before removing and dispose of fluid environmentally friendly
• Drain fluid and inspect to make sure there is no evidence of metal fragments (this indicates the transmission may be damaged)
• Smell the fluid to make sure it does not smell burnt (this indicates the transmission may be damaged)

• Using a T40 Torx bit, remove all 21 bolts holding the sump on
• Remove sump
• If you are replacing the mechatronics sleeve you may need to lower the gearbox mount to gain access easier to remove
• ZF 6HP Only – if you are replacing the valve body tubes, this is the time to remove these

• Clean all mating surfaces for the new sump so you get a good seal when replacing

4. Installing the Sump / Mechatronics Sleeve

• Fit mechatronics sleeve before fitting the sump pan
• Using only OEM parts fit the new sump using the fresh screws provided
• Sump Screws – 10Nm for steel screws, 4Nm + 45 degrees for aluminium screws
• Tighten the screws in the specific sequence to seal the sump correctly
• The drain plug should be preinstalled on an OEM sump pan but check the torque is 12nm using a 10mm Hex/Allen on a torque wrench

Once you have checked that all the bolts and drain are torqued down to spec, it is time to perform the initial fill of the transmission. As the ZF transmissions do not have a dipstick or level indicator, the fill hole acts as your level indicator. You will need to fill the fluid in through an upfilling fluid tool until a steady stream pours back out of the fill hole.

• Pour around 5 litres of fluid into your upfill tool
• Pump fluid into the fill hole until a steady stream comes back out (around 4 – 4.5 litres)
• Once it comes to a small trickle of fluid coming from the fill hole replace the fill plug loosely
• Make sure no more fluid is coming from the fill plug area

Once you have completed the initial fill, it is now time to bring the transmission fluid up to temperature and prepare to complete the second fill of the fluid. To do this correctly you will need to cycle through each of the gears to cycle the new fluid through the whole transmission mechanism. The fluid changes consistency depending on the heat it is at and expands when hotter than room temperature, in order to get the exact fill level, correct you will need the fluid to reach 30-35°C (ZF 6HP) & 35°C -40°C (ZF 8HP)

• Plug in your diagnostic tool and find the ATF temperature
• Start the engine
• Keeping your foot on the brake
• Shift transmission into “Reverse” and “Drive” 4/5 times
• Shift transmission in manual and move from 1st to 3rd and hold gear for at least 3 seconds
• Shift transmission in manual and move from 1st to 4th and hold gear for at least 10 seconds
• Select each gear in manual mode from 1st to 6^th(ZF 6HP) and 1st to 8^th (ZF 8HP) and hold gear for 10 seconds
• Keep engine speed at 2000 RPM to ensure torque converter fills with fluid
• Check temperature and verify that fluid temp is between 30°C – 35°C (ZF6 HP) and 35°C – 40°C (ZF 8HP)

Now that the fluid has reached the specified temperature, you can resume filling the transmission to the required level.

• Pour the remaining 2 litres of fluid into your upfill tool
• Remove fill plug and check for fluid coming out (there shouldn’t be after cycling gears but if there is no need to fill anymore)
• Pump fluid into the fill hole until a steady stream comes back out
• Once it comes to a small trickle of fluid coming from the fill hole replace the fill plug
• Fill plug – 35Nm for M18x1.5 plugs, 80Nm for M30x1.5 plugs
• Make sure no more fluid is coming from the fill plug area
• Replace all undertrays, trims and covers
• Service completed

You can switch off the engine now. The ZF Transmission service is complete.

• Sump Pan Screws – 10Nm for steel screws, 4Nm + 45 degrees for aluminium screws
• Fill plug – 35Nm for M18x1.5 plugs, 80Nm for M30x1.5 plugs
• Drain Plug – Comes preinstalled on new plastic pans, 12Nm