Automatic

C

chicknlittle

Member
Hi All
I have a 1951 mercury it came with a merc o matic should I stick with it or would the aod be a better choice I have both transmissions both need rebuilds the mercury is going to be mostly stock Thanks
 
those trans are power hungry, especialy the torque converters, they have about 20% slippage, and they dont lock up like the newer torque converters, the question is do you have enough horse power to drive the aod in high gear, a rule of thumb is, change one thing from stock and you will change 2 more some where down the line
 
If it were mine I would keep it stock with the Mercomatic, The other alternative would be 3 speed manual with overdrive which I personally like. Just my 2 cents.
Gary.
 
If you keep the stock 3:31 Merc rear and install a merc transmission with OD you would have a real highway cruiser, i think.
 
A viable alternative is a change over to the C-4 with a Flat-O adapter. The Ford-O-Matic and the Merc-O-Matic are getting harder to source parts for all the time.
 
Thanks for all the advice I think I will go with the mercomatic they want 600 to rebuild it and 800 for my aod I have a over drive stick in my parts car but I want my dad to enjoy driving the car as well thanks again
 
fair decision. I have a fordomatic in front of a warmed up 276. In town I sure don't notice the 20% power loss. I have 3.92 gears in this old truck. So far she'll run 65 all day on the freeway. I think I'll run the fom till it quits. I may put on some better road gears, just to get the rpm's down. At this point I think I have more motor than suspension. I'm still running a single 94. I have 2 97's ready to go when i have the time.
 
Back in the early 50's hot rod mag. Did a story on barny navarro's 51 ford car tow vehicle with a 284 cid and a fordomatic trans it goes into good details about the trans modifications.
 
i didnt mean 20% power loss, i meant the torque conveter has a 20% slipage so the gas milage is not the best on the old trans because of the slippage in the torque converter, they dont have the stall capabilites of the newer converters, many lock up or stop slipping at 2200 rpm, with the older converters the engine never goes 1 to 1 with the trans in final drive, thats the 20% in talking about
 
Anybody,
By some dumb luck I have that issue of HOT ROD with the Navarro
Fordomatic story. As everything Navarro it goes into minute detail including some
seemingly simple 'beef up' tips.
As an early Christmas present I'll send copies to any & all interested for
$2 postage included....it's about 10 pages.
Use my personal e mail if you please. cas5845@yahoo.com
Charlie ny
 
I have a friend with an AOD behind a 276 and 4.11in the rear. This is a real runner and gets 19mpg on a trip with an L-100 cam
 
When we first found our '51 Merc. I was disappointed that it had a Merc-a-.matic. Really wanted a 3 speed w/ overdrive, but it was such a clean car that we bought it. Now 5 years later both of us love the automatic. Moves down the road easily at high way speeds, handles Oregon hills just fine and we are almost always the only Merc-a-matic at the cruise ins. Every day I drive the car someone asks "3 on the Tree?" I can can point out Mercurys first Automatic shifter. Easy on the arthritis too.

Les
 
Both are a great choice. Advantage AOD; less engine wear from highway use and better fuel economy. Disadvantage is that you need a $500.00 (+/-) adapter kit which comes with a late model starter that is more durable. You will want to use a 3.55:1 rear gear(I don't know what comes in the Merc with the automatic, that may be what you have. Makes that old flathead plenty responsive and yet keeps the RPM to about 1700 at 70 mph highway speed. You'll never wear it out like that!

I was warned that the automatic would consume too much HP; that is not the case. I can tell you from years of experience that the old rule of thumb that an A/T takes away 40 HP is just a myth.
 
Again thanks for all of your advice and help if I rebuild the aod myself I could fit the aod swap into a price I can afford Thanks Jimmy
 
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