Thread: engine swap

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Matt, I encountered this trans crossmember problem so many times in my own experience of engine swaps that I developed the following procedure:

You have the crossmember from the recipient car. Get the crossmember from the donor car, along with the driveshaft. Before you pull the motor/trans out of the recipient and with the recipient crossmember still bolted into the car, place a jack and piece of 2x4 under the trans pan to keep the tailshaft from falling on you. (If memory serves, you've had a little experience with this). Use STURDY jackstands at each corner of the car, two on the lower control arms and two on the differential axle tubes close to the rear wheels. Crawl under with a Sawzall and cut the recipient crossmember on each side of the transmission, somewhere in the middle between the trans and the frame rail/crossmember mounting point. Leave the middle piece to come out with the trans and the two side pieces still bolted to the recipient.

When you drop the donor trans in and have it positioned properly, measure from the transmission mount bolt holes in the tailshaft to the edges of the recipient crossmember stubs. Now, transfer these measurments from each side to the donor crossmember and cut the middle section out so that you have a donor middle piece that will somewhat line up with the recipient side pieces. Tack weld. Remove the crossmember as one piece and finish welding, using whatever filler material you need to make a stout member. Run short stitches of weld and alternate positions to prevent excessive heat in any one place that will warp the crossmember and make it difficult to bolt back in.

You want to wait until you get the donor transmission in place before you cut the donor crossmember to allow for any lateral change in engine/trans placement from what was used originally with the recipient engine/trans.

This is a cheap, effective way of making a proper crossmember and it works every time. Been there, done that.

As far as the driveshaft, wait until you can get the car on all four wheels with the weight on the suspension, again, with the four jackstands under the lower control arms and diff tubes. Disassemble the cross and bearings at the front of the donor shaft. Push the yoke onto the trans tailshaft until it bottoms out. Pull it back out 3/4". Now, measure from the centerline of the cross and bearings on the front yoke to the centerline of the cross and bearings on the pinion yoke. That will be the measurement to give the driveline shop to make your new driveshaft to the proper length. Provide him with the front donor yoke and the rear recipient yoke from the recipient driveshaft.