One of the many things I learned from Gary (the machinist who rebuilt our motor) is that with original vintage Datsun Z motors and transmissions, the original parts are much higher quality than most new parts you’d buy to replace them. For example, the original Z motors came with forged pistons, which means in almost all cases you’re going to end up with a stronger motor by using the old pistons with new rings than buying the cheaper, cast pistons available in the aftermarket. The same general rule applies to the crank and many other engine parts. In the end we’ll pay about the same amount we would have paid for an off-the-shelf motor but we’re going to know that everything has been fixed first-rate.
With our engine and transmission, “in the oven” so to speak, it was time to dig into the rest of our 280Z. Not surprisingly, after stripping out the interior and starting to remove body pieces, it became clear our rust problems were worse than originally thought. The driver’s side floorboard was rusted through and the driver’s side fender is like swiss cheese. Both will have to be replaced. However, compared to other Z rust horror stories, I’m still feeling lucky.
Our next research item was frame rails. Ours were no longer sound, to put it mildly. Our first thought was that we were going to have to drill out the spot welds on the old ones and buy replacements. This was the job that had us quaking in our boots (a little). Once again turning to the trusty ZCar forum and doing a few searches, a name came up with an ingenious solution: Bad Dog Parts . The proprietor, John, an obvious Datsun Z-car nutcase, fabricates brand-new frame rails that fit neatly over your old ones and are then welded in place. Genious! They’re twice the thickness of the original frame rails, providing a solid, good-looking fix that appeared to be an easier solution than taking the old rails completely off.
In our case, getting these rails on was a little more tricky than originally planned. Both our frame rails were not only rusted out but dented in, with the tops of the old rails mushroomed out, making it so the new ones wouldn’t fit over. Overcoming this required cutting away the bottom half of the old rails with a saws-all. It wasn’t all that hard but it caused us to wonder if it would have been just as easy to replace the complete rails rather than use the slip-over solution. It seem like if your rails are just rusted, the Bad Dog rails are a great solution. However, if your rails are damaged and rusted, you might consider replacing them entirely. The other problem we faced was that the rusted-out floor panels were right above the frame rails. To do it right, we had to first repair the metal on the floor so we’d have a solid surface to weld the new frame rails to.