Looking at a cutaway of the new 2020 Chevrolet Corvette shows us a lot about how engineers packaged many of the components, and one item that stands out is an aluminum block in the middle of the front crossmember. At first glance, it appears to be an ABS module, but all is not as it seems.
Upon further examination, we find that the ABS block is much higher up in the car closer to the cabin, and our module below is actually there to control the front axle lift system.
This is a pretty interesting piece of technology that raises the front axle so it can cross speed bumps, curbs, steep grades and more. It’s a first for the Corvette. And what’s really neat is that it’s linked to GPS so in many cases the lift happens automatically. Read more about it here.
Although the module is not used for the brakes in this application, it does have some roots in braking systems. Chevrolet engineers explored multiple options for implementing front axle lift and decided that hydraulic was the way to go. Instead of sourcing new pumps or replicating what their competitors use they decided to use a block similar to what is used on ABS systems for some cars and just re-purpose it.
The motor inside the block is supplied by BWI and is a very common unit that is found in a variety of ABS modules around the world. A quick search shows that the motor is very popular for vehicles in Asia where BWI appears to have a large market. The body and connector for the electronics also appear to be common as shown in the BWI ABS unit illustration above.
This type of parts sharing likely further reduced costs and gives us an idea of just one of the areas that GM was able to find clever solutions to keep overall costs down.
While Chevrolet would not confirm which exact vehicles share that motor, we were able to find used parts that appeared to match from a wide variety of vehicles that ranged from stuff like the VPG MV-1 to the Lifan X60 crossover.
While some may balk at the idea of re-purposing such a part for a sports car, the idea here is actually pretty revolutionary as it reduces costs and provides for a mass-market compment to be used in a new way. This reduces the costs of manufacturing and should reduce replacement costs down the road.
The idea to use a BWI part in this location was pretty straightforward, according to a GM engineer I spoke to last month at Petit Le Mans. BWI also builds the dampers for the new Corvette which allowed them to design the whole system to work together. The dampers that are equipped for front axle lift have a chamber at the bottom that is connected to the hydraulic line that originates at the lift pump. Once the lift system is commanded hydraulic pressure is built into this chamber to raise the car. Once the front axle lift is activated, those chambers fill with fluid in around 2.8 seconds and raise the front of the car 40 millimeters—around 1.6 inches.
According to the engineer, no special fluids are required as the system is filled from the factory with standard DOT4 fluid that is available at any parts store. Since the system does not have to be opened up for any type of scheduled maintenance, there are no refills or bleeding required.
Brake fluid usually degrades due to heat so I asked if they had a chance to record any temperatures and if there was any potential for boiling. The engineer said they equipped their track tester with the axle lift type dampers and only saw the temperatures of the dampers rise to around 100 degrees Celsius, which is less than half of the boiling point of DOT4 fluid. So getting anywhere close to boiling the fluid is very unlikely.
They also took advantage of the data available on the CAN-BUS and interfaced the control module for the front axle lift with the GPS location data that the vehicle collects for the navigation system. Using that data they are able to add a unique element to the front axle lift by saving locations where the car needs to go up which should make it more convenient for owners that consistently visit locations that require it.
Right now, the car has to be moving at 24 mph or less to engage the lift, which is plenty for traversing speed bumps in an office parking lot. But the technology is there to use it at higher speeds, so maybe we’ll even see used it in some performance aspect in the future.