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How To Change Rearend Gears


morson82

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Hello all, it's been quite awhile since I have been to the forum but its great to be back. I am restoring my 42 dodge sedan and am about to have the frame and suspension parts blasted and primered. I just finished taking the rear end apart and was wondering if there was a way to change the gears so that I would have a better cruising speed. I did have the car on the highway and she whined quite a bit. If there is a way to change out the gears what would be a good set and where could I get them. I know installing an OD tranny would be the easiest but I do want to keep her original as possible and want to keep the fluid drive as well.

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I don't know all the ins and outs of the differences with the rear ends, but from what I have gathered, you want to find a center pumpkin with the same axle spline count and one with the same number of housing bolts in it. I just swapped in a 3.54 from a 55 Plymouth into my 52 Dodge trucks 4.11 housing and it worked perfectly. Some are 11 or 16 count axle splines and some are 10 or 11 bolt rear ends I believe. I'm sure someone knows more than me and will correct me if I'm wrong. 

 

Your original rear end pumpkin will be have the ratio stamped in it somewhere. A good ratio for cruising would be a 3.73 or a 3.54. I think I'd prefer the 3.73 over a 3.54 for a little better acceleration and a little more power. The 3.54 in my truck is a little more sluggish than the 3.73 in our 41 Desoto it seems and the Desoto can cruise all day at 60-65 mph still and get up to 70-75 for a few miles if needed. 

 

Answers when I first asked: http://mopar.pairserver.com/p15d24ph_forum/index.php?/topic/28233-rear-end-ratios/?hl=%2Brear+%2Bend+%2Bratios

 

My swap: http://mopar.pairserver.com/p15d24ph_forum/index.php?/topic/23400-some-progress/page-10?hl=%2Brear+%2Bend+%2Bratios#entry325765

Edited by 52b3b Joe
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pulled apart...as in you disassembled a timed gear unit for wear pattern matched device just to say it was apart...

most will just swap out the pumpkin...watch for the right years...and as for change ratios..you cannot restore and do this to your ride...pick restored or customize you cannot have both

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Thanks for the replies.

Yes, the rear end is disassembled. The pumpkin is still together but out of the unit.

Has anyone done this and if so, where did u get the materials to complete the task. What are the pitfalls I need to look out for/ things to not over look.

And as for whether or not I'm "restoring" or "customizing" my car, that is all in the eyes of the beholder. She will be stock when I'm done, less the rear end gears. To me, she will be restored and that's all that matters.

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  • And as for whether or not I'm "restoring" or "customizing" my car, that is all in the eyes of the beholder. She will be stock when I'm done, less the rear end gears. To me, she will be restored and that's all that matters.

Improper use of the word but if you happy that is all that counts today..follks have butchered the language so bad what is one more word thrown under the bus......as for the pumpkin..they will swap but you cannot go to some lower gears due to carrier size..you can go taller and with that you will only have to watch the donor years for proper axle spline count.  It is best to do a pumpkin swap overall for ease and long life of the product...the preload/backlash heel/toe engagement all plays an important part in quiet long life operation..

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