TR2/3/3A TR3 and TR4 Frame Width?

[karls59tr]

How much wider is a TR4 frame than a TR3 frame or was it the TR4A frame that was wider?

 

[TR3driver]

Through most of the length of the TR4 frame, the frame itself was the same width. I'm not certain if the body mounting points were exactly the same, but the frame rails and so on were. The big difference was at the front suspension, where there were extra pieces welded to the outside of the frame rails, to increase the track by about 4" or so. The spring towers moved outward (onto the extensions) as did the motor mounts.

At the rear, the axle was wider, but the springs were exactly the same distance apart. I know because I once installed a TR4 axle in a 3A and didn't realize my mistake until I tried to insert the halfshafts from the 3A. The suspension bolted right up, and in fact I drove that way for several years (using the halfshafts from the TR4).

The 4A frame is completely different, not even a "ladder" design. They reworked the frame to accept the IRS; then modified that again to accept a solid rear axle (for solid axle 4As).