Johnnydidd
Well-known member
in 57 mercury made a turnpike cruiser, was the automatic transmission the same as the 56 or did they upgrade the transmission so the engine runs at a slower speed, my 56 312 turns 3000 at 70 mph
1956 Mercury
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streetdreams
Well-known member
All final gears in older transmissions, auto or manual are 1:1 ratio. Transmissions with overdrive will usually have an O.D ratio of around .67. With a final ratio of 1:1 which your Merc auto has, engine rpm in high gear is determined by the rear differential gear ratio.
Johnnydidd
Well-known member
so 57 turnpike cruiser had to a higher ratio rear end
miker98038
Well-known member
Here’s a gear calculator link. Guessing at your tire size and converter slippage, I came up with 3.40. Based on K’s chart, I’d say you’ve got the 3.54. I used the default value of 5% slippage, which is probably too little for an older transmission.
http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php
General question, was Merc using the Dana 44 in those days?
http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php
General question, was Merc using the Dana 44 in those days?
KULTULZ
Well-known member
Yes, SEDAN DANA 44 and WAGON DANA 45.
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rotorwrench
Well-known member
The 56 & 57 Mercury both used the 10 7/32" length Medium Case transmission that was also used in Lincoln cars at the time. Rear axle ratios were usually tall due to the efficiency loss of the transmission at normal road speed. Different ratios were available for mountain country and overdrive but the automatics were mostly always a taller ratio. 1957 was the intro year for the 9-inch but FoMoCo likely kept using Dana rear axles for Lincoln & some Mercury cars at least till after the Cruise-O-Matics came out in 1958. Lincoln used them for a lot longer. Dana 45 rear axles are rare and hard to find parts for if it has one of those. Dana 44 axles were around for several decades with FoMoCo car and pickup applications. Jeep and a few others kept using them even longer.
Johnnydidd
Well-known member
What ratio gear for the rear end would make engine run at around 2000+ rpm or is this not advisable
miker98038
Well-known member
Optimum gear ratio is a matter of driving style, geography, traffic etc. If you go to the gear ratio calculator and enter your correct tire size, 2500rpm, 70 mph, use 5% default on converter slippage, it says you’re looking for a 2.83:1 rear gear. That’s pretty tall, and taller than any of the options.
If your merco starts in second like a fordo, it’s really going to be slow leaving stop. In Seattle with the hills, it would be a disaster, you’d be manually selecting low all the time. Same problem on the freeways, we’ve got lots of long grades and that ratio would put you downshifting to 2nd. And worse in our usual bumper to bumper traffic.
Kansas, I don’t know. If you leave the driveway on the levels and go 50 miles before you slow down, might work.
The other concern is the availability of parts for a 45. My bird had a 44 out of a truck, but even so, it’s not cheap to work on, and since the “pumpkin” doesn’t come out, it’s all under the car.
Assuming the engine is in good condition, your not going to hurt it driving at 3000rpm. Truck y blocks did a lot of that. Bit noisy, but it mostly disconcerting because we’re no longer used to it.
If your merco starts in second like a fordo, it’s really going to be slow leaving stop. In Seattle with the hills, it would be a disaster, you’d be manually selecting low all the time. Same problem on the freeways, we’ve got lots of long grades and that ratio would put you downshifting to 2nd. And worse in our usual bumper to bumper traffic.
Kansas, I don’t know. If you leave the driveway on the levels and go 50 miles before you slow down, might work.
The other concern is the availability of parts for a 45. My bird had a 44 out of a truck, but even so, it’s not cheap to work on, and since the “pumpkin” doesn’t come out, it’s all under the car.
Assuming the engine is in good condition, your not going to hurt it driving at 3000rpm. Truck y blocks did a lot of that. Bit noisy, but it mostly disconcerting because we’re no longer used to it.
streetdreams
Well-known member
3.10 to 3.25:1 should be fine.
KULTULZ
Well-known member
You also have to take into account that when these cars were new there was very little interstate highway and lesser highway speed. These cars had a lesser amount of HP and torque than today's engines and they had to be buzzed.
To raise/lower rear gears, you have to know at what RPM HP and torque is produced and at what speed you want to have those values fall in. The first thing you need to know is the diameter of your drive tires and go from there with the calculators provided.
Those ratios I showed are what MERC installed. There are several different ratios for the D44, or you might start considering an AOD retro-fit.
The 57 TPC was named for cruising the new Interstates especially with the LYB 386 (1957) and the 430 MEL (1958).
To raise/lower rear gears, you have to know at what RPM HP and torque is produced and at what speed you want to have those values fall in. The first thing you need to know is the diameter of your drive tires and go from there with the calculators provided.
Those ratios I showed are what MERC installed. There are several different ratios for the D44, or you might start considering an AOD retro-fit.
The 57 TPC was named for cruising the new Interstates especially with the LYB 386 (1957) and the 430 MEL (1958).
Daves55Sedan
Well-known member
The Lincoln and Mercury cars around that time used the Medium-case Ford-O-Matic transmission and Dana integral housing rear end.
Basically all your transmissions have a nominal 1:1 ratio at the tail shaft. What you are looking for is a different rear end gear ratio. Not sure what is available for the Dana 8.8".
But if you can find somewhere around 3.0:1 or 3.5:1 ring and pinion set for the Dana, you should be all right.
My '55 Sedan has the stock 3.10:1 with small-case Ford-O-Matic and it is just fine. I also have a '55 Courier with a 223 I-block 6-cyl with small-case Ford-O-Matic with 3.25:1 ratio and it is just fine also.
I had a '57, 9" banjo housing rearend with the 4.67:1 ratio behind a 292 V8. You had to red-line the engine to get it going 65 MPH. Rediculous.
I found a '57 in a junkyard that had a rearend with stock 2.91:1 ratio. I grabbed that rearend faster than a New York second.
Basically all your transmissions have a nominal 1:1 ratio at the tail shaft. What you are looking for is a different rear end gear ratio. Not sure what is available for the Dana 8.8".
But if you can find somewhere around 3.0:1 or 3.5:1 ring and pinion set for the Dana, you should be all right.
My '55 Sedan has the stock 3.10:1 with small-case Ford-O-Matic and it is just fine. I also have a '55 Courier with a 223 I-block 6-cyl with small-case Ford-O-Matic with 3.25:1 ratio and it is just fine also.
I had a '57, 9" banjo housing rearend with the 4.67:1 ratio behind a 292 V8. You had to red-line the engine to get it going 65 MPH. Rediculous.
I found a '57 in a junkyard that had a rearend with stock 2.91:1 ratio. I grabbed that rearend faster than a New York second.
Johnnydidd
Well-known member
thanks guys, I just had my 312 and automatic all rebuilt