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New User
Posts: 3
| I'm new to the forum and need some help from the mopar gurus!
I'm looking for a higher ratio differential for my dad's 53 Plymouth belvedere. He currently has 3.73 gears and would like to be able to cruise at 60 to 65 with lower rpms. He doesn't drive any hills and isn't worried about he power loss. Since I went through the work of putting disk brakes on the rear axle I am hoping to keep the axle housing and just swap in a higher differential.
Here is my question, what years of differentials will swap into the stock 1953 Belvedere axle housing? It is the drop out type differential and I'm assuming being that old it is a 8.25 differential and not a 8.75. Will a 8.75 work anyway? I believe 1953 is the year they went to 16 splined axles. I am hoping to go with a 3.23 or 3.18 ratio if I can find it, and am curious what Mopars came with 3.23 or 3.18 differential that will interchange with the 53 axle. I've done some searches, but haven't come up with much. Any help is appreciated.
Thanks
Chuck
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Expert 5K+
Posts: 5139
  
Location: cornpatch county, Southwest IOA | Bout the omly help i can offer is--there is a Plymouth club that serves all years--maybe someone here can direct you to it.........................MO |
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Expert 5K+
Posts: 6203
Location: Big pimpin' | The 8 3/4 rear "Hogshead" Won't fit the 8 1/4 rear...Would have to swap the entire rear...
The 8 3/4 rear should work in the car, just depends on the width, whether or not a stock 8 3/4 rear is gonna work without having to be narrowed...You would need to get a measurement of how WIDE the rear is in your car now....
Edited by dukeboy 2009-01-14 12:49 PM
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Expert
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Location: NorCal |
The tallest ratio ever offered in the early 8 1/4" was 3.54, not much of an improvement on the 3.73. |
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New User
Posts: 3
| Thanks for the input. The car isn't near me, but my dad crawled under and verified that it does have 11 bolts so it must be the 8.25. I'm dissapointed to hear I can't go higher than 3.54. Could I go higher than 3.54 with an aftermarket ring and pinion on my differential or is it physically not possible to go higher? Randy's ring and pinion does make high gears for newer 8.25 Chryslers, but I didn't know if they would work.
Also my dad found some other numbers on the differential, here they are: C-23, 1141544-3, 3.0 (there is a box around the 0,) and the 3.73 ratio stamp. Didn't know if this helps in idenitifying what I can and can't do to this differential.
Thanks for all the great help!
Chuck |
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Expert 5K+
Posts: 9654
Location: So. Cal | You have to swap out the ring and pinion as a set. The pinion on a newer 8.25" is certainly not going to work in the old 8.25" rear, and the ring isn't likely either. The choices are pretty clear. Find and live with a 3.54:1, put in an overdrive, or swap in a different axle.
The 3.54 is only 5% faster than the one you have, which would be 63mph at the old 60mph. That is probably not worth the trouble. An A518 overdrive is a very nice solution if it will fit and if you need to change the trans anyway. 3.73:1 is about perfect for the .69:1 overdrive ratio. |
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New User
Posts: 3
| I agree it's not looking good for an easy differential swap.
Is the A518 a typical 3 speed overdrive tranny? I hear you can put them in and even keep the hydrive (fluid coupling) if you swap the input shaft from the hydrive 3 speed tranny. Your right my gear ratio is pretty good if I put in an overdrive.
Thanks,
Chuck |
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8.25 differential interchange and ratios help needed!!
