cracked trans crossmember and broken mount, '67 Coronet

I noticed a small vertical crack on my trans crossmember so I pulled it off to weld it up only to discover that my brand new poly trans mount was also broken... then discovered that my small crack was nothing compared to my huge crack hidden behind my trans mount. The rear end, trans, and engine, all seem where they should be, no obvious misalignments... My only theory is that awhile back I had both engine mounts go, and in the week or so that it took me to replace them I may have stressed out the trans crossmember so much it started to crack, though when I replaced the engine mounts and then the trans mount as well, I somehow didn't notice the cracking occurring... they may have been pretty small at the time and I just didn't notice (?), and only started to separate badly since then (not a great theory but it's all I got). What are your thoughts on this? My '67 Coronet 4-dr 440 has a 318 LA and a Torqueflite, I've been driving it every day for the past several years unrestored as my daily driver (my main vehicle's engine seized, this was originally my wife's project car but became our daily driver), and I've been replacing and upgrading parts while driving it. We got it with supposedly 39,000 original miles (could've been 139,000 as well of course), and it's now at 112,000 (or 212,000). Car is doing well, the engine is hurting (#8 cylinder is dead, valves are probably sunk, and the crank thrust bearing ended up in the pan recently), but other than that it still pulls strong. I upgraded it so far with an Eddy RPM Air-Gap dual-plane and QF carb, headers, dual exhaust to Flowmasters, TrickFlow balancer, Powermaster high amp alternator, Deraile elec fan and Champion alum rad, Moroso water pump, MSD dizzy, a few other things, and 15" wheels, but for the most part it's still stock, though runs strong nonetheless. I race on the side (on another car of course), though I'm very careful not to foot-brake the Coronet at traffic lights as I know it ain't in any shape to handle it, so I don't think I've abused it too much, though I do drive it hard every day. Any thoughts on my cracked crossmember and broken trans mount? I welded up the cross member (I'm a welder by profession, though TIG welding that cheesy crossmember was more of a patch than a fix, I'm going to fab a better quality one as soon as I figure out why this one cracked so badly)... But would like to see what you guys think... Also, my bellhousing is not cracked either, and no other signs of stress anywhere.

A318 for you tear up the car parts in the oil pan but you still run strong

I'd take another look at your new motor mounts....whether now, or when they went out, that engine is moving around which is causing your other problems. Maybe chain down the driver's side if your new motor mounts look in perfect shape? If the motor mounts are bad, maybe consider a solid mount at least on the driver's side?

PurpleBeeper said:

I'd take another look at your new motor mounts....whether now, or when they went out, that engine is moving around which is causing your other problems. Maybe chain down the driver's side if your new motor mounts look in perfect shape? If the motor mounts are bad, maybe consider a solid mount at least on the driver's side?

Click to expand...

Yeah I checked them out, they look good. They're your basic Anchor Industries stock-style rubber mounts, I have almost no engine movement at all footbraking it a little to see how much movement there is.