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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Oct 2009 Posts: 8 New Guy | | New Guy Joined: Oct 2009 Posts: 8 | I'm rebuilding my MC and find out mine is 1 1/4" whereas the rebuild kits for 54 are for a 1 1/8". I had to get a kit that was listed for a '47 to get one that was big enough. The MC had obviously been on there for a long time by the looks of it so I think this is the original MC but... anyone hear of a different stock MC on a different year truck? My dad says sometimes they use leftover parts for the next year's models but this is several years off.
Jen
Take the time to do it right.... | | | | | Joined: Jul 2001 Posts: 3,887 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Jul 2001 Posts: 3,887 | I've seen both 1.125" and 1.25" in the TF years [55-59, but same brakes as 54], 1.125 is factory standard, but maybe there was a 1.25 "heavy duty" option, or some aftermarket had that bore, but the 1.125 is all I've found at any vendor, either repro or local
Bill | | | | | Joined: Sep 2009 Posts: 433 'Bolter | | 'Bolter Joined: Sep 2009 Posts: 433 | Chevy Jen Check the cast no. on your master cylinder ? You may find it listed here ...
1954 Chevy 3104 3 Window Hydra-Matic in my family for over 60 Years
Once in a while you get shown the light in the strangest of places if you look at it right... "Scarlet Begonias" Grateful Dead 1974
| | | | | Joined: Sep 2001 Posts: 29,270 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,270 | Over the past 57 years, the master cylinder might have been replaced more than once. It was common for people to simply put in whatever available part fit (usually a used part, if one was available - and, cheap used parts were readily available). In the late 60s, I worked on these trucks for a dealer. At that time, these trucks were considered to be junkers and it was common to do the cheapest repairs to keep these trucks running at the lowest cost. There were two 1/2 ton master cylinders in 1954: the one used on manual-transmission trucks and the one used on Hydra-Matic equipped trucks. I think they both had the same bore but I am not certain of that. If you checked the 1954 Shop Manual, you saw that the bore was 1 1/8" on 1/2 ton through 1 ton trucks. 1947 MC specs 1948-52 MC specs | | | | | Joined: Oct 2009 Posts: 8 New Guy | | New Guy Joined: Oct 2009 Posts: 8 | Great info, thanks! The 1.25 kit works fine of course. I'll check those casting numbers just for interest's sake.
Jen
Take the time to do it right.... | | |
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