pflaming Posted January 13, 2014 Report Posted January 13, 2014 (edited) This chart is in the Service Manual. Since my interest now includes 1954 and 1956 mechanics I closely reread this chart. The conventional ratio for a 3 speed tyranny in a 1954 auto was 3.73. So then if a three speed over drive tyranny replaces a standard three then it powers a 3.73 axle. To my limited knowledge, that would be a sweet setup, then put a 230 in front. I like that a lot. edit: I've added two more charts. I have begun to look at all three of these whenever I look at one, so decided to copy, print them out and pin them on my shop bulletin board. Edited January 13, 2014 by pflaming 1 Quote
DCurrent Posted January 13, 2014 Report Posted January 13, 2014 I wonder if my rear end has been replaced at some point. I think someone deciphered it and told me it has 3.73, and it looks like they weren't offered until 49. Quote
Don Coatney Posted January 13, 2014 Report Posted January 13, 2014 This chart is in the Service Manual. Since my interest now includes 1954 and 1956 mechanics I closely reread this chart. The conventional ratio for a 3 speed tyranny in a 1954 auto was 3.73. So then if a three speed over drive tyranny replaces a standard three then it powers a 3.73 axle. To my limited knowledge, that would be a sweet setup, then put a 230 in front. I like that a lot. I don't understand your question/statement? Your posted chart clearly states that in 49-54 cars with overdrive the differential ratio is 4.11/1. I think you are still missing the most important issue and that is ideal engine RPM at any given speed. Did you plug these numbers into the speed indicator link I sent you a while back. Do you know what tire size you will be using? 1 Quote
pflaming Posted January 13, 2014 Author Report Posted January 13, 2014 Don asks a very important question and makes an equally important point. All the specifications do NOT determine the speed on the road, tire size applied to these makes that determination. My point was implied that if the tire size did NOT change and an overdrive tyranny replaced a standard three speed tyranny, which is what I will do, then the top speed would increase because then the OD would be servicing a 3.73 as opposed to a 3.93. Lots of details in total results, and I enjoy the research, even though at times I don't get it all correct the initial times. 1 Quote
james curl Posted January 13, 2014 Report Posted January 13, 2014 Most MoPar overdrives have a .70 overdrive which is multiplied times the rear end ratio for the finial drive ratio in OD. You have to be careful about the starting rear end ratio to avoid having a final drive that is too high for the engine to pull without high loads. Quote
Plymouthy Adams Posted January 13, 2014 Report Posted January 13, 2014 Paul..I do not understand this also as we have talked on the phone to great lengths on the very axles available, possible upgrade ratios if you decide to go modern and the very fact that you may or may be running a OD in the future...and why is this not on your build thread you have open....? Quote
pflaming Posted January 13, 2014 Author Report Posted January 13, 2014 (edited) My response: (1) this post was only to post the three charts that might be helpful to someone who has not as yet purchased a manual and who may not be following my thread; (2) I know what engine, tyranny, differential ratio, and tire size I need for the result I want. And I know what will happen if I change the standard tyranny to an OD and I like that result. Edited January 14, 2014 by pflaming Quote
plyroadking Posted January 14, 2014 Report Posted January 14, 2014 I've been running a 3.73 diff with an od trans behind a stock 230 for at least 5 years, with 225/75/15s it was great in the northern California foothills and pretty good out in the flat Midwest, she runs very happily at 70mph, if i had one id probably try a 3.54 rear ratio. Quote
Dodgeb4ya Posted January 14, 2014 Report Posted January 14, 2014 I ran my 1953 savoy with a replacement 3.73 and it couldn't handle the NW freeway steeper grades. The engine was fairly new so I went back to a 4.11 as I always was hauling a heavy load in that old wagon. My 52 belvedere came with a 4.3 and OD factory. I like it-hauls ass! 1 Quote
austinsailor Posted January 14, 2014 Report Posted January 14, 2014 Slight change on the basic subject - I do have a set of NOS 3:54 gears and I've been trying to figure out what I need to do to put them into my 40 Dodge sedan, or possibly my 48 B1B. As I understand it, going to the taller gears, some were there is a cross over point of the carrier for lower and higher gears. We talked about it a year or two ago and I don't think I got it down. I think, but am not sure, that 4:11 and up take a different carrier than say 3:54 gears. I think the thickness or offset was different. What would be good to know is where the two choices are, if I am even at all understanding it. For example, will all 3:73 and taller gears interchange, then all 4:11 and lower gears, pickup or car? (or some other division point) If I find a carrier out of any Chrysler with a certain gear set, or after a certain year, can I put in my 3:54 gears? Sort of frustrating. I've got the gears, but don't know what I need to watch out for, and certainly don't want to start disassembling all sorts of axles to sort it out. I think when I get that 251 CI motor I bought recently, I'd be better off to stick in that set of gears in the 40 Dodge sedan. Or, when I get this motor picked up that I bought the other day, maybe I should put it and them in the B1B. Quote
plyroadking Posted January 15, 2014 Report Posted January 15, 2014 You bought that 251 on the des moines craigslist? I dont know about changing the gears around, i just bolted the 3.73 third member into my 40's stock housing, and used the 40 axles as the 3.73 rear end was shorter than mine. Only difference is that now i have two fill plugs for lube Quote
austinsailor Posted January 15, 2014 Report Posted January 15, 2014 I only have a new gear set. I know they won't work on my 40 Dodge carrier, I'd like to get a better idea what they will fit. I got it off the Milwakee list, but probably the same ad. Quote
DJ194950 Posted January 15, 2014 Report Posted January 15, 2014 (edited) Slight change on the basic subject - I do have a set of NOS 3:54 gears and I've been trying to figure out what I need to do to put them into my 40 Dodge sedan, or possibly my 48 B1B. As I understand it, going to the taller gears, some were there is a cross over point of the carrier for lower and higher gears. We talked about it a year or two ago and I don't think I got it down. I think, but am not sure, that 4:11 and up take a different carrier than say 3:54 gears. I think the thickness or offset was different. What would be good to know is where the two choices are, if I am even at all understanding it. For example, will all 3:73 and taller gears interchange, then all 4:11 and lower gears, pickup or car? (or some other division point) If I find a carrier out of any Chrysler with a certain gear set, or after a certain year, can I put in my 3:54 gears? Sort of frustrating. I've got the gears, but don't know what I need to watch out for, and certainly don't want to start disassembling all sorts of axles to sort it out. I think when I get that 251 CI motor I bought recently, I'd be better off to stick in that set of gears in the 40 Dodge sedan. Or, when I get this motor picked up that I bought the other day, maybe I should put it and them in the B1B. 40_motor.jpg Suggest you buy a hollander interchange book as you have many projects that I believe will answer many of you questions. The rear gear info is on there but is too much and somewhat spread between pages to try to put on the forum. The hollander interchange classic edition #2 covers 1946-1956 but when parts fit from earlier models that is also there. For an example many mopar rearend parts are listed back to 1937 model. Check out: hollanderinterchange.net Look for classic edition #2 $45 plus ship. New May find it somewhere cheaper, but I could not. Best, Doug Edited January 15, 2014 by DJ194950 1 Quote
austinsailor Posted January 15, 2014 Report Posted January 15, 2014 I had no idea those existed. I thought the only option was the massive expensive books at the junk yard. I didn't know there were versions that were practical for us. I just ordered #1 and #2. I can tell a great tool when I see it! This might even be better than the visor I bought for my '53 Plymouth today! Thanks a lot. Gene Quote
DCurrent Posted January 15, 2014 Report Posted January 15, 2014 Suggest you buy a hollander interchange book as you have many projects that I believe will answer many of you questions. The rear gear info is on there but is too much and somewhat spread between pages to try to put on the forum. The hollander interchange classic edition #2 covers 1946-1956 but when parts fit from earlier models that is also there. For an example many mopar rearend parts are listed back to 1937 model. Check out: hollanderinterchange.net Look for classic edition #2 $45 plus ship. New May find it somewhere cheaper, but I could not. Best, Doug I didn't know about this either. I knew they existed, but didn't really know how to acquire one or what to buy. Now I do! Thanks! Quote
DJ194950 Posted January 15, 2014 Report Posted January 15, 2014 Lots of interresting reading especially the retail suggested price list at the end of most parts sections. example 42-48 cpe. & sdn. frame only $127.75.! This copy has an original copywrite date of 1957. Hope you'll like them. Doug Quote
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