Crossmember

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A crossmember is a section of steel, usually boxed, that is bolted across the frame of a vehicle, to support the engine and/or transmission.

A K member is a crossmember in a vehicle with a longitudinally mounted engine, contains the engine mounts.


An "X" crossmember is an X-shaped section of steel, usually boxed, that is bolted or welded to the frame of a vehicle to support the engine and/or transmission. The X crossmember gives torsional strength and rigidity to the frame of vintage Fords, particularly those made between 1928-31 (Model A) as these cars had limber stock chassis, and is quite popular with street rod and hot rod enthusiasts.

Although it used more substantial rails than a Model T, the Model A frame was still just a simple "ladder" design. Unlike the '32 frame, which had a K-member, and '33 to '48 frames, which were equipped with a substantial X-member, the A-frame was only fitted with front, center, and rear crossmembers.

For the suspension of any car to operate as it should, for proper handling, and even to keep the body panels in alignment, the frame has to be strong enough to cope with the loads applied to it. It must not deflect, and it has to have enough torsional strength to resist twisting. Model A frames didn't have a particular problem with deflection, but they certainly lacked torsional rigidity, as street rodders quickly discovered when they replaced the Model A's 40hp four-bangers with Flathead V8s or OHV engines.

See pp. 63-69 Street Rodder Magazine, May 2002 issue for details on how to install an "X" crossmember to a 1928-1931 Ford (Model A).