56 with Dana 44 diffy

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P

Philt

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Oct 18, 2017
Thunderbird Year
1956
Enjoying my recently acquired 56 bird. Thunderbird green, full power and modern a/c. But on the highway it runs about 2500 rpm for 60 and 3k for 70.
I have been told there are replacement ring and pinion sets available. A 2.73 would be a nice improvement over the 3.7 I suspect we have now.
Anyone offer source for Dana 44 ring/pinion sets and recent experience with the swap out?
Phil in Nashville
 
I don't have experience with it in the Thundrbird but…. I did with a Jeep Grand Cherokee. Those also have Dana differentials in them. There are quite a few Jeep Parts suppliers (not dealers) that have parts, kits and even some instructions on-line. I used o get a lot of my parts from Morris 4 by 4.
Another option could be to get a different complete rear end from another Ford. If I remember correctly an eight inch rear out of a Maverick is an easy swap out.
 
If you choose to go with te Morris 4 by 4 website I would think the 56 Jeep CJ5 would be the correct rear. They also have a tab at the top of the page that says "more". Under that tab you can find instructions on repairs and on how to identify the rear differentials.
 
The numerically lowest ratio for standard-rotation, 26-spline pinion found on Summit is 3.07. Like you, I did not care for my 55's 3.31 ratio/w Fordomatic on the highway. I guess I'm used to new cars/w overdrive. After doing considerable research, I discovered that early 80s Corvettes had Dana 44 differentials/w 2.72 ratio standard. I could find just one new set, offered by a Corvette parts house, but way too expensive. After searching from coast to coast, I found a matching used set at a differential shop in my home town. At the time, I could have purchased a new set of 3.00 gears, but the shop's owner said that if I didn't like 3.31 gears for the highway, I wouldn't like 3.00. I bought the 2.72 gears, had the axle housing powder-coated, and an Auburn limited-slip differential was installed. Normally I would not us used gears, but these were a matched set, in good condition, and I trusted the owner.
 
I just recently completed a conversion from the 3.31 ratio to the 3.07. Because of winter weather here in Utah it maybe a couple more months before I can comment on how the new rearend ratio works on the freeway here where the speed limit is 70 with some places up to 80. If anyone is interested the following are the part numbers I used for the change over.
Ring and pinion Yukon YG D44-308 also available from US gear brand about $100 cheaper. Couldn't find out what the difference was because they are the same company. I bought my gear set from a off road company for $258. which was the Yukon brand.
New spider & axle gears Not needed for the conversion but I changed mine out anyway. Bought from Nitro Gear P/N IPKD44-S-19 for $170 with shipping.
U-joint flange Needed because the change to a 26 spline pinion with the 3.07's Again Yukon P/N YYD44-1310-26S. I found one on eBay for $50.
U-joint straps YYSTR004 Needed because the the 55/56 used U-bolts with nuts and the new flange uses straps and bolts.
I also changed the speedometer gear to a 20 tooth to correct for the gear change.
The end result should be a drop of 300 rpm at 70 mph. I don't know how much good that will be but it is at least in the right direction.
 
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