The motive for developing the GTX was to provide an automatic transmission in a dune buggy. While the Subaru and VW engines are great engines, when put in a buggy they were still connected to a stick shift transmission, and we saw no way to economically change that. After a great deal of research we came to the conclusion that the drive train in many of the GM offerings would work in a buggy. They were plentiful as they were offered in a variety of models, they were reasonably priced, especially in a salvage condition, and technical assistance was readily available. Lastly, it fit within the bodies we were already producing.
If your body was designed to mount on a VW pan that was shortened 14 ½”, and matches the basic physical dimensions of our Nostalgia or Lancer then with some internal fiberglass removal, your body should be able to be mounted on the GTX frame. The critical dimension is the height of the body at the rear of the passenger compartment. This is the area where the struts are mounted, and cannot be changed. Your body needs to be tall enough to clear the rails in that area. To confirm that dimension, sit your bare body on a level floor. Lay a long strait piece across the top of your body at the rear of the rear jump seat. Measure vertically, from the floor to the BOTTOM of the straight piece. The minimum height can be no less that 23 ¼”.
Berrien Buggy has formed a technical alliance with our newest GTX dealer, S&S Automotive, who will be doing the reconfiguring on the engine harness, as well as the computers (ECU & TCU).
After you have purchased your donor car and disassembled it, you should ship your engine harness and computers to S&S, including the year and serial number of your donor car. S&S will work their magic then ship your harness back to you. We are doing this so that the harness will plug into your engine sensors without any problems. GM changed plug configurations throughout the production years, and this method we believe will avoid a mix & match confusion.
The GTX frame is designed to use General Motors, O.E.M. motor mounts designed for 2006 thru 2010 Chevrolet Cobalt and HHR cars. With the exception of a spacer needed for the anti vibration mount at the transmission, all mounts are available from GM dealers, after market suppliers, or on line. The spacer is produced by Berrien Buggy and is included with the frame. Please note that as we produced the production version of the frame, we sourced all necessary parts from our local Advanced Auto Parts or GM dealer. Engine
The original Cobalt radiator and electric fan is used. The GTX frame has mounting tabs welded to the frame to make the radiator installation fairly simple. 4, O.E.M. mounting grommets are used to secure the radiator to the frame mounts. The original surge tank is used. Currently the builder will have to fabricate their own water lines from the engine to the radiator. We are developing a cooling system kit which will be available shortly.
The GTX uses a VW type ball joint front suspension. We recommend that an aftermarket disc brake conversion be installed or that a beam from a Karman Ghia be used as it is equipped with disc brakes. Front brake rotors drilled and tapped for either of the Cobalt/HHR wheel patterns are available from Berrien Buggy. A disc brake conversion kit in either wheel pattern is available for the VW ball joint front end.
At the rear the entire Cobalt/HHR brake system is used. Tabs are welded onto the frame in order to use the original rubber brake lines from the wheel to the frame. The builder will have to fabricate steel brake lines from the VW dual circuit, big bore master cylinder to the wheel lines.
The brake pedal is original VW. A VW brake, clutch cluster is used, but the clutch pedal and shaft are removed, and only the brake pedal is used, including a VW master cylinder push rod. A pedal stop is included with the GTX frame.
An emergency brake system is under development, and should be available by late fall.
As manufactured the Cobalt & HHR’s had 2 wheel patterns. They were 4 lug X 100mm and 5 lug X 110mm. Either pattern is usable on the GTX. Both patterns are popular on many non GM cars, making it possible to select a very wide variety of wheel styles, and sizes. As stated earlier, Berrien Buggy can provide front brake rotors drilled and tapped for either wheel pattern.
There are basically 2 separate wiring systems in this car. The engine wiring system is a separate fused system, which controls all the engine functions, including the electric fuel pump. It is powered thru a wire connection to the ignition switch. All the other functions, lights, wipers, stop lights, radio, etc. are powered through a second fuse block in exactly the same fashion as a standard buggy.
The GTX uses a modified VW type-1 gas tank that is modified for buggy use. On the top of the tank, the original fuel fill is blocked off and an external fill bung is welded to the tank, it then uses a marine-grade stainless steel fuel fill assembly. On the bottom, the original fuel connection is removed and 2 steel bungs (1/4” NPT ) are welded into the tank, along with a 1 quart baffled sump. A -6 fitting is inserted into the lower bung, which is then plumbed to a high-pressure electric fuel pump. This pump must be capable of producing constant pressure of 40 lbs.. A -6 line is routed through the tunnel to the engine where a pressure regulator is mounted, along with a pressure gauge, then plumbed into the fuel rail. In order for the fuel regulator to work properly, a -6 line is run through the tunnel back to the tank, into a -6 SAN fitting in the second bung in the tank. A vent is needed to vent the fuel tank.
The engine for the GTX is known as the EcoTec, and has been in the GM family for quite some time. The engines we are recommending were produced as 2.2 and 2.4 liter engines. Many have variable valve timing. All are electronic fuel injection, with coil packs on the spark plugs. Three induction systems were used in the 2006 thru 2010 period. They were normal aspirated, turbo charged and a limited number with belt driven superchargers. Flywheel horsepower ranges between 165 and over 300.
We do not recommend the supercharged version. It was only produced with a standard transmission. We did not intend for the GTX to have a manual transmission so it is uncertain if that combination would fit. We also would not be able to provide a correct wire harness. For those who may want to try such an installation we suggest you call and talk to Jason at our technical partner S&S Automotive.
Because we have moved the entire power train and suspension from a front-wheel-drive car and installed it into a rear-wheel-drive car, the rear wheels are actually able to turn. By removing the steering assembly from the Cobalt/HHR, and fastening the tie rods to mounts which are part of the GTX chassis, we have stabilized the rear wheels. The GTX now also has the ability to adjust rear wheel toe in or out easily. The actual steering is accomplished by using the front components from a VW Beetle years 1969 through 1976. The entire front suspension assembly ( the beam ), steering box, tie rods, & steering arm are all used. A VW or aftermarket steering column is also used.
The GTX frame is supplied with an MCO, and that along with the title of a donor car should be sufficient in most states. When purchased together, the body and frame will have matching serial number plates. In all paperwork from Berrien Buggy by Acme, the GTX will be referred to as a Roadster, to avoid issues that have arisen in several states concerning the vehicle type.
Each state Department of Transportation has their own rules and regulations regarding titling. We suggest you check your State’s web site or talk to an experienced builder regarding your particular States requirements