Other Articles - January/February - 2020

The ZF 8-Speed Transmission Fluid and Filter Change

Changing transmission fluid after the vehicle is out of warranty is important for the life of the transmission. The issue of helping the customer understand that their vehicle’s transmission needs servicing is something different. Especially when we’re talking about the ZF 8-Speed.

  1. The dealer says that the transmission fluid and filter last the life of the vehicle.
  2. You must tell the customer that the Fluid and Filter Change on their vehicle will cost them 3 to 5 times what it did on their last vehicle.

How do you overcome these obstacles?

The first problem is relatively easy to fix. If the customer is coming to you, the vehicle is probably over its 100,000-mile warrantee. In most, if not all other vehicles that have the 8 speed ZF transmission, the manufacturer recommends a transmission fluid and filter change at 70,000 to 80,000 miles. This is also the interval that ZF themselves recommend.

The second problem is more difficult. The customer must be reassured that you are not pocketing three times the money. To this end you can show them the dealer cost on the pan/filter and oil, a cost of over $350 dollars. Now they know you’re not taking advantage of them.

What can we do to reassure the customer that they are not wasting their money? The traditional way of dropping the pan to evaluate the fluid is very expensive. You can pull the plug and look at the fluid, but the fluid is $25 dollars a quart to replace. So, what do we do? Use your scanner.

That’s right, your scanner. Your scanner can check the health of the five clutch packs in the transmission. Each clutch has four numbers associated with it. The four in order on the scanner are:

  1. Fast Filling Counter in counts
  2. Filling Counter in counts
  3. Filling Pressure in mBar (millibar)
  4. Filling Time in ms (milliseconds).

What the scanner is telling us is as follows:

  1. The Fast Filling counter records the number of filling-time events that have taken place.
  2. The Filling counter is indicating the number of filling pressure events that have taken place.
  3. The Filling Pressure calculates the filling pressure. It’s measured in millibars so you’ll have to do a little math. One millibar is equivalent to 0.014psi.
  4. The Filling Time is measured in milliseconds (0.001 second).

Using these figures you can examine the deviation from the standard value (what it should be) and get an idea of the condition of the transmissions. With good standard deviation numbers, we can reassure the customer of the transmission’s health. So, for the cost to scan of the transmission we can give the customer the numbers in all the clutch packs. It takes about 15 minutes. An example of the readout from a 2014 Dodge 1500 Truck with 160,000 miles is shown in figure 1.

These figures are If you were at the ATRA seminar in 2017 you learned that the fill counter needed to be above 14 to give you a good indicator of the clutch pack health. If not, then the history has been cleared too recently and you do not have enough data since then to get a reliable counter value. The Fast fill values are not as sensitive if the fill counter number is met.

If you were at the ATRA EXPO in 2018. You learned from the ZF presenter that the fill pressure needed to be between -350 and 350 mBar to be fully functional. In 2019 he updated that to -300 to 300 mBar as a healthier number.

If you were at the ATRA EXPO in 2019. You learned from the ZF presenter that the fill time needed to be between -120 and 120 milliseconds to be healthy. While he stated that the pressure was more important than time.

You could take this information, and either reassure the customer that they had a healthy transmission and then recommend a fluid and filter change. You could also let them know if their transmission was on the brink and then work on the next steps that would be best for them. Either way the transmission shop wins. If the numbers are good, then the customer will feel more comfortable spending the money to get the fluid and filter done to maintain the transmissions health.

There is one caveat, the scan alone can’t indicate the health of the planets and bearings. You will find that answer by driving the vehicle and listening for gear whine. The final confirmation of the unit’s health will be to check the pan when you drop it.

On the other hand, if the numbers are bad. You can tell them, “I don’t suggest a fluid and filter as the unit is too far gone”. Which gives you the options to either sell a transmission job or at least have the good will of not wasting the customer’s money, which could lead to a transmission job later. The scan in figure 2 is the same vehicle 5,000 miles later.

We hope this can help you meet one of the opportunities that Chrysler has passed on to you to satisfy their customer’s needs.

By the way, you can use the same procedure on the ZF 9-Speed.