My 1951 GMC 281-22 Series is a strange bird. Since this is the "General Forum," I figured this was the best place to post this question. Where does she fit in? I mean, specifically, when searching for parts via the internet and/ or catalogs, I find this rare bird is lacking in representation. It was via the Stovebolt Forums that I discovered my truck is not a 1 ton and not a 1 1/2 ton, but she was this rare bird GMC made for a while: she is a 1 1/4 ton. You just don't find that when looking for parts. Should I gamble and follow a 1 ton or 1 1/2 ton? There are many things I need, but recently, for example, I believe one of the wheel cylinders on the back is leaking. As many of you know, there are 2 of them on each side, and they are different within one wheel. So, do I follow a 1 ton or 1 1/2?
Appreciate the input.
Last edited by Peggy M; 01/30/20244:19 PM. Reason: added more info to the title
Can you tell from the photos on Rock Auto what the difference is between the two trucks? Which one looks like the ones on your truck? It looks like you have a choice of 1" , 1.125", 1.375", or 1.5" bore for the cylinders.
Once you figure them out, you can rebuild them yourself or send them to this company for rebuilding:
Specializing in antique, vintage, classic, obsolete, unique and hard-to-find brake parts, bonding, riveting, rebuilding, drum and rotor machining, custom made brake hoses
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
Some time ago, I salvaged a set of extremely expensive GMC wheel cylinders by honing the bores about .020" oversize to eliminate pits, and machining new pistons to fit the bigger bore. A standard wheel cylinder rubber cup was able to expand to fit the bigger bore without leaking. Another method is to install a stainless steel sleeve to eliminate the pitted surface. Either way is better than hoping you can order the correct replacement parts. The master cylinder can also be salvaged by installing a sleeve in the bore. It's not a terribly difficult project for any machinist worthy of the name. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Mike, there is some parts commonality between your 280 series and other GMC same year, different model trucks. I'd suggest contacting 'Bolter SlimSix and purchasing his 1939-1953 GMC Master Parts Book .pdf scan which covers 100 thru 350 models.
Below is the page from that manual that deals with rear brakes on 280 models. Not only are there two wheel cylinders for each rear wheel on your 280, there are different parts used on 280s with serial number 2863 and lower vs. 2864 and higher. The good news is that the same wheel cylinders were used with 280, 300 and 350 model trucks. The better news is that the first two are available on ePay, the third from either Dorman or Chevs of the 40s and the last through all those places.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
