I have a 1958 C1 with a Borg Warner T-10 4 speed transmission. I have sealed the transmission 2 times now & this time noticed a hair line crack vertically through the side shift cover. It appears to be cast aluminum. The only replacements I can find are cast steel & are slightly larger & the bolt holes don’t align very well.
Has anyone tried to weld the cast aluminum with any success or is there anywhere that reproduces these aluminum covers?
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Found this . Might be something helpful here hopefully.
For a replacement cast aluminum side shift cover on an early T-10, Corvette Central appears to sell a correct 1957–1958 side cover, and it’s described as a new A-356 alloy, heat-treated part . That is the closest direct replacement I found for the cracked cast aluminum cover issue you described.
What matches your transmission
The 1957–1958 T-10 side cover is the version without the later 1959–1960 ribs, and forum discussion notes that the 1958 cover is a distinct piece from the ribbed later covers . Corvette Central’s listing specifically says “57-58 Transmission Side Cover - T-10 4 Speed - Correct,” which lines up with a 1958 C1 application .
Availability and fit
A common problem is that some replacement covers are cast steel or later-design parts, and those may be slightly larger with bolt-hole alignment issues . The Corvette Central part is advertised as the correct 57–58 style, so it is the best lead if you need a direct-fit replacement rather than a workaround .
Practical next step
Before ordering, compare your old cover’s ribbing, fork-shaft hole layout, and casting shape to confirm it is the 57–58 style, since 1958, 1959, and 1960 covers are not the same .
