Cracked subframe!

[SubGothius]

I've just discovered that the front crossmember of my subframe has become cracked, right in the middle near the lower front tranny mount. :o

Mind, this is not as nasty nor surprising a development as you may think, as that region came pre-mangled and rewelded-up when I got it, a decent-enough looking job that it wasn't a deal-breaker for my (perhaps naive in hindsight) purchase of the car. The PO wasn't sure if that was evidence of a poorly-placed floorjack once, or part of the driver's front-quarter damage it apparently had once sustained, all of which had long since been passably repaired by the time he found and rescued the car from a junkyard.

At any rate, naturally, those subframe-repair welds apparently have now started breaking, badly enough I can hear it creaking every time I get underway in reverse (as that activity causes the powertrain to torque forwards and bear down against that crossmember). Could I get this rewelded in situ affordably and reliably (at least, no worse than before), or is that a fool's errand? At present, the cracks are just forming and not (yet) spread apart, so might I have a chance? :'(

[Jim Fierst]

I would think that a muffler shop should be able to weld those cracks assuming of course they can get to them. I always like to choose little independent guys who have been in business forever for this kind of work.

[Geoff T]

Hi Jim,
My Montecarlo has suffered a similar problem, and apparently it is not unusual!! The subframe itself is relatively thin wall material, and mine cracked across the top of the box section right next to the forward engine mount. It had also cracked down both sides so actually only the double skinned lower piece was carrying any load.
The best way to fix it is to remove the subframe from the car (4 bolts plus the engine mount, forward A arm pivot bolts, and the lower gear selector bush). Not a big job really.
Once removed, I took it to my local muffler shop who fabricated three plates to suit, about 1/8 thick and welded them over the broken sections. He also fusion welded the remaining visible crack areas. This was done about 4 years ago and I have had no trouble since. Might pay to check your engine mounts too as a tired shock mount will allow the engine to move more than it should. As Monte's don't have torque rod steady bars, all the engine twist is taken through the mounts only.
Weld job is much easier and neater if you drop the cross member!

Geoff T,
1982 S2 Montecarlo.

[Will]

Hi Tye;
Like Geoff, I can only give you advice relative to the Scorpicarlo since I don't remember exactly how the Beta sets up. I think you have a similar problem in that one edge of the front motor mount creates a stress raiser of the crossmember. The best way to fix this IMO is to weld a scarf plate across the front of the box section and a second, longer scarf plate across the rear of the crossmember so that you are redistributing rather than moving this stress raiser. The problem is, (at least on the scorpicarlo) the metal is damn thin and you can easily blow right through it unless you have a TIG welder or turn your voltage way down. It's hard to weld the thicker scarf plate to the thin metal, it may be easier to remove than to do in situ. You can try, but if you are just burning holes in it, it may have to come out. I don't consider myself a world-class welder, so took it out.

[the_superhero]

Will, I love how you carry on with "Scorpicarlo!" My legacy lives on in at least one way. Thanks. I didn't have the heart to stay here myself after losing one gorgeous car after another.

As for that crack. Its typical to the design of all those Beta Subframes. And Lancia wasn't the best bunch of welders either. Never mind doing it yourself if you can't just look at it and think, "Sure. I can do that." The chance you get my just be taking chances. Either cut the whole thing in two and put a box in it and weld it back. Or drill a hole and insert a backing, weld it and plug the hole. Cutting it in two is the better way but I know that sounds crazy. A professional welder may be in order though. Exhaust shop welding is very different from what you want done.

Good luck! _Trevor

[Jim Fierst]

Beg to differ on who to choose as a welder.. Good exhaust shops ( not talking about national chains)are specialists in welding thin gauge materials.The modern ones are all equiped with the various wire machines. Many race car chassis have come from these shops. If you need something completely redesigned and fabricated from scratch thats a different story.

[SubGothius]

Well, the deed is now already done, and I'm fairly pleased with the job done for the price (having zero experience nor familiarity with welding, personally). The first venerable indie muffler shop (literally named "Indy Muffler Pit" ;D ) that I went to had a sound grasp of the situation, thought repair was futile anyway, refused to touch it and expressed further distaste for any future exhaust-work business on my car, as well! Must be generally averse to "dem weird furrin jobbers", but brownie points for honesty, at least...

My next stop was an indie shop called Precision Engineering, which I'd noticed on my commutes as offering a rather eclectic range of automotive services, including "welding" featured on the marquee, and which also recently added a Major Muffler franchise sign as well. Some consultation with their welder, who talked the right talk evaluating the problem and solution with an affordable estimate, sealed the deal:

$60 to have the old weld debris ground smooth, the cracks fused shut, and two differing lengths of L-section angle irons fully edge-stitched under the compromised region of subframe, respectively reinforcing the leading and trailing edge corners of that U-section channel. Not bad, eh? I did mention Will's idea of using two different lengths to distribute the stress, to which he apparently concurred, but I found his decision to use L-section pieces particularly inspired. 8)