Now that the right engine and transaxle has been chosen for my V8 MR2 engine swap, I needed to mount them in the car, and try to make it work with the stock MR2 cross member. The rear cross member of the MR2 does several things:
- provides structural support at the back of the car
- mounts the rear of the transaxle and engine
- mounts the MR2 exhaust system
- mounts the rear suspension main swing arms (call the Lower Control Arms) of the MR2
- mounts the sway bar for the MR2. Note that the MR2 Turbo has a larger diameter sway bar than the MR2 base model (normally aspirated).
When I first located the engine and transaxle in the engine bay of the MR2, I found that the case of the transaxle interfered with the cross member. The portion of the transaxle case that interfered was the area that enclosed the differential and final drive gears. The axle CV joints and their boots also interfered with the cross member.
At first the only solution I could see was to build a cross member from scratch. I was disappointed with this solution because my hope was to make this swap accessible to the average DIY gear head. Also, I wasn’t sure that this solution was feasible for me, because it involved bending high strength tubing, and welding it together. I did some research on custom tubular cross members that were available aftermarket for some cars like the Camaro or Mustang. These were front members, but they did mount the engine and the front suspension, which is similar in duties as my application. Note that NO one makes an aftermarket cross member for the MR2. junkyards near me
I knuckled down and bought a tubing bender, and some DOM (Drawn Over Mandrel) seamless steel tubing. I built one cross member out of this tubing by welding and bending it. It didn’t go too well, as this is a very complicated piece, and I ended up making a second one. This came out only a little bit better. By this time I was frustrated, and decided to take another look at the location of the engine.
As an experiment, I removed all of the stuff attached to the front firewall of the MR2. This is a bulkhead that forms the rear wall of the passenger cabin area. Attached to this bulkhead are many things like the rear brake tubes, fuel filler pipes, engine coolant pipes, insulation, and a lot of miscellaneous things. I then put the engine and trans back into the bay. They were floating on a transmission jack. I then found that I could move the engine and trans further forward in the car. Now my drive train would be further forward than a stock MR2 engine and transaxle, but this is OK for weight distribution. Moving the engine/trans furthur forward had two huge advantages:
- The pseudo frame rails of the unibody of the MR2 now interfered a LOT less
- The trans and the axles now cleared the rear cross member except in some areas that were minor problems
Problem solved! I love it when a plan comes together! Now that I could re-use the stock cross member, I went ahead and put it back on, and with the engine still floating there, I proceeded to build the four required motor mounts. This went fairly quickly. Progress at last!